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Papers by Judy Morris

Research paper thumbnail of Pertussis toxin attenuates postsynaptic actions of neuropeptide Y or the guinea-pig uterine artery

European Journal of Pharmacology, 1991

The mechanisms by which neuropeptide Y (NPY) mediates its postsynaptic actions on the guinea-pig ... more The mechanisms by which neuropeptide Y (NPY) mediates its postsynaptic actions on the guinea-pig uterine artery, were investigated by incubating arterial segments in culture medium containing pertussis toxin (PTX). Arteries were incubated with 0, 0.25 or 1 pg. ml-' PTX for 24 or 48 h. Arterial segments incubated in culture medium without PTX showed the three postsynaptic responses to NPY which were reported previously in uncukored arteries: NPY further contracted segments which were precontracted with prostagl~ndin F,,; NPY reduced the maximom relaxations produced by vasoactive intestinal peptide (VIP); and NPY produced I rightward shift in the VIP concentration-response curves. PTX attenuated the three actions of NPY on the uterine artery to different degrees. PTX also reduced the magnitude of contractions produced by prostaglandin F,,, but did not affect contractions produced by 0.126 M KCI, or ;&xations produced by VIP in the absence of NPY. These data indicate that all postsynaptic actions of NPY on the uterine artery, and contractions produced by prostaglandin Fr,, are at lea?! partly mediated by pertussis toxin-sensitive GTP-binding proteins. It is not clear whether these multiple actions of NPY are mediated by one, or more than one, GTP-binding protein.

Research paper thumbnail of Non-noradrenergic sympathetic neurons project to extramuscular feed arteries and proximal intramuscular arteries of skeletal muscles in guinea-pig hindlimbs

Journal of the autonomic nervous system, Jan 7, 1996

This study set out to examine the non-noradrenergic sympathetic innervation of extramuscular and ... more This study set out to examine the non-noradrenergic sympathetic innervation of extramuscular and intramuscular arterial vessels supplying hindlimb muscles of guinea-pigs, using multiple-labelling fluorescence immunohistochemistry. Non-noradrenergic axons, identified by their immunoreactivity (IR) to vasoactive intestinal peptide (VIP) and neuropeptide Y (NPY), innervated nearly all (> or = 88%) extramuscular feed arteries supplying muscles of the medial thigh. The distribution of non-noradrenergic axons along extramuscular feed arteries was often patchy, with increased density near some branch points. The density of axons with VIP-IR and NPY-IR at the adventitia-medial junction of the largest extramuscular arteries was similar to the density of noradrenergic axons identified by IR to tyrosine hydroxylase (TH) and NPY. The proportion of arterial vessels innervated by VIP-IR axons decreased in more distal, intramuscular arterial segments, and when present, the VIP-IR axons were few...

Research paper thumbnail of Botulinum neurotoxin A attenuates release of norepinephrine but not NPY from vasoconstrictor neurons

American journal of physiology. Heart and circulatory physiology, 2002

We examined effects of botulinum neurotoxin A (BoNTA) on sympathetic constrictions of the vena ca... more We examined effects of botulinum neurotoxin A (BoNTA) on sympathetic constrictions of the vena cava and uterine artery from guinea pigs to test the role of soluble NSF attachment protein receptor (SNARE) proteins in release of the cotransmitters norepinephrine (NE) and neuropeptide Y (NPY). Protein extracts of venae cavae and uterine arteries showed partial cleavage of synaptosomal associated protein of 25 kDa (SNAP-25) after treatment in vitro with BoNTA (50-100 nM). The rising phase of isometric contractions of isolated venae cavae to field stimulation at 20 Hz, mediated by NE acting on alpha-adrenoceptors, was reduced significantly by 100 nM BoNTA. However, sustained sympathetic contractions mediated by NPY were not affected by BoNTA. In uterine arteries, noradrenergic contractions to 1-Hz stimulation were almost abolished by BoNTA, and contractions at 10 Hz were reduced by 50-60%. We conclude that SNARE proteins are involved in exocytosis of NE from synaptic vesicles at low freq...

Research paper thumbnail of Projections of intrinsic cardiac neurons to different targets in the guinea-pig heart

Journal of the Autonomic Nervous System, 1996

We set out to determine the projections of the major immunohistochemically-defined populations of... more We set out to determine the projections of the major immunohistochemically-defined populations of intrinsic cardiac neurons to different target tissues within the guinea-pig heart. Ultrastructural studies, and immunoreactivity to the neuronal marker, neuron-specific enolase, suggested that the number of axons of intrinsic neurons in most regions of the heart was low when compared with the populations of axons projecting from extrinsic sensory and sympathetic ganglia. Multiple-labelling immunofluorescence was used to demonstrate the terminals of the major populations of peptide-containing intrinsic neurons. The intrinsic nature of peptide-containing axons was confirmed by long-term organotypic culture of cardiac tissue, which resulted in degeneration of axons of extrinsic neurons. The relative density and peptide content of intrinsic axons throughout the heart was not consistent with the relative proportions of peptide-containing intracardiac nerve cell bodies observed previously. The most commonly-encountered axons contained immunoreactivity (IR) to vasoactive intestinal peptide (VIP) alone, although nerve cell bodies with VIP constituted less than 5% of the total population of intrinsic neurons. Populations of axons containing IR to somatostatin alone, somatostatin and substance P, neuropeptide Y (NPY) alone, somatostatin and NPY, or VIP and NPY, also were observed. Intrinsic axons containing substance P-IR were very rare, much more so than would be predicted from the peptide content of intrinsic nerve cell bodies. The regions of the heart with the most dense innervation by axons of intrinsic neurons were the cardiac valves, the atrio-ventricular node and the sino-atrial node. Each of these targets was innervated by several populations of peptide-containing axons. Thus, each population of peptide-containing intrinsic neurons projected to a variety of target tissues within the heart. One possible interpretation of these results is that immunohistochemically-distinct populations of intrinsic neurons belong to different functional classes of neurons (sensory neurons, interneurons, final motor neurons), each of which innervates many regions of the heart.

Research paper thumbnail of Pathway specific expression of neuropeptides and autonomic control of the vasculature

Regulatory Peptides, 2000

In this article, we review the immunohistochemical evidence for the pathway-specific expression o... more In this article, we review the immunohistochemical evidence for the pathway-specific expression of co-existing neuropeptides in autonomic vasomotor neurons, and examine the functional significance of these expression patterns for the autonomic regulation of the vasculature. Most final motor neurons in autonomic vasomotor pathways contain neuropeptides in addition to non-peptide co-transmitters such as catecholamines, acetylcholine and nitric oxide. Neuropeptides also occur in preganglionic vasomotor neurons. The precise combinations of neuropeptides expressed by neurons in vasomotor pathways vary with species, vascular bed, and the level within the vascular bed. This applies to both vasoconstrictor and vasodilator pathways. There is a similar degree of variation in the expression of neuropeptide receptors in the vasculature. Consequently, the contributions of different peptides to autonomic vasomotor control are closely matched to the functional requirements of specific vascular beds. This arrangement allows for a high degree of precision in vascular control in normal conditions and has the potential for considerable plasticity under pathophysiological conditions.

Research paper thumbnail of Postganglionic Neurotransmitter

Encyclopedia of Neuroscience, 2009

Research paper thumbnail of Interleukin-1 receptor immunoreactivity in sympathetic vascular and non-vascular neurons in guinea-pig coeliac ganglion

Neuroscience Letters, 2002

Immunoreactivity (IR) for the interleukin-1 receptor type I (IL1RI) was examined in sympathetic n... more Immunoreactivity (IR) for the interleukin-1 receptor type I (IL1RI) was examined in sympathetic neurons in guinea-pig coeliac ganglion using multiple-labelling immunofluorescence. IL1RI-IR was present in 8% of sympathetic neurons in untreated preparations. The proportion of neurons with IL1RI-IR increased significantly after incubation in interleukin-6 (200 ng/ml) for 2-4 h (16-26% neurons), or after incubation for 4 h without cytokine (16%), with interleukin-1beta (IL1beta, 200 ng/ml; 18%) or tumour necrosis factor-alpha (200 ng/ml; 16%). This increase occurred predominantly in neuropeptide Y-IR, vasoconstrictor neurons. IL1RI-IR also was present in varicose axons, some of which projected from the gut, and in vascular smooth muscle cells and endothelium. These potential binding sites for the proinflammatory cytokine, IL1beta, on vasoconstrictor neurons and blood vessels may modulate sympathetic regulation of intestinal blood flow in inflammatory conditions.

Research paper thumbnail of Peripheral fields of sympathetic vasoconstrictor neurons in guinea pigs

Neuroscience Letters, 1998

We have combined retrograde axonal tracing using Fast Blue and DiI, with immunohistochemistry, to... more We have combined retrograde axonal tracing using Fast Blue and DiI, with immunohistochemistry, to estimate the maximum size of peripheral fields of identified sympathetic vasoconstrictor neurons projecting to guinea-pig ear tips. Many neurons in the superior cervical ganglia were labelled with both Fast Blue and DiI after dye injections up to 7 mm apart. Few neurons were labelled when dye injections were 8-10 mm apart. Neurons labelled with both DiI and Fast Blue after dye injections 5-7 mm apart had, on average, larger somata (436 ± 84 mm 2 , mean ± SEM, n = 47) than neurons labelled with DiI only (388 ± 11 mm 2 , n = 147). Typically, 50-100 neurons innervated a region of vasculature 1 mm in diameter. We conclude that sympathetic vasoconstrictor neurons branch widely before converging on to their target blood vessels. Progressive recruitment of vasoconstrictor neurons with increasing field size would provide an efficient mechanism for graded neural control of the circulation.

Research paper thumbnail of Five inhibitory transmitters coexist in pelvic autonomic vasodilator neurons

NeuroReport, 1997

Here we describe the localization of a potent vasodilator, calcitonin gene-related peptide (CGRP)... more Here we describe the localization of a potent vasodilator, calcitonin gene-related peptide (CGRP), in pelvic autonomic neurons containing four other inhibitory transmitters: vasoactive intestinal peptide (VIP), neuropeptide Y, nitric oxide and acetylcholine. These neurons mediate endothelium-independent vasodilation by releasing nitric oxide and one or more neuropeptides. Sixty percent of nerve cell bodies in guinea-pig paracervical ganglia with immunoreactivity (IR) for VIP, choline acetyltransferase (ChAT) and nitric oxide synthase (NOS), also contained IR for CGRP. Furthermore, many VIP-IR varicose nerve terminals at the adventitia-medial junction of the guinea-pig uterine artery contained IR for CGRP, ChAT and NOS. Both alpha-hCGRP and beta-hCGRP were potent dilators of the uterine artery (pD2 values 8.1, 8.3, respectively), but 1 microM hCGRP(8-37) did not antagonize dilations produced by either agonist. Dilations produced by alpha-hCGRP were unaffected by removal of the endothelium. Taken together with results of our previous studies, we propose that CGRP can contribute directly to autonomic vasodilation, possibly via CGRP2 receptors on smooth muscle cells, and that CGRP is the fifth inhibitory transmitter co-existing in pelvic vasodilator neurons.

Research paper thumbnail of Projections of Sympathetic Non-Noradrenergic Neurons to Skeletal Muscle Arteries in Guinea-Pig Limbs Vary with the Metabolic Character of Muscles

Journal of Vascular Research, 1997

This study set out to examine in detail the distribution of axons of sympathetic non-noradrenergi... more This study set out to examine in detail the distribution of axons of sympathetic non-noradrenergic neurons innervating the arterial bed in skeletal muscles of the forelimb and hindlimb of guinea-pigs. The distribution of non-noradrenergic axons with immunoreactivity to vasoactive intestinal peptide (VIP) was examined in limb muscles of different histochemical character. The immunohistochemical demonstration of myosin heavy chain from fast-twitch muscle, and the histochemical demonstration of adenosine triphosphatase and succinic dehydrogenase, were used to determine the muscle fibre profile of 6 different limb muscles. Muscles included the oxidative type I muscle fibre-rich accessory semimembranosus muscle, the predominantly glycolytic type II muscle fibre-rich cranial gracilis and biceps brachii muscles and the plantaris, gastrocnemius medial head and triceps brachii long head of mixed muscle fibre composition. The frequency with which the VIP-immunoreactive (VIP-IR) axons innervated intramuscular arterial vessels was compared between categories of muscles defined by their muscle fibre profile. This study demonstrated that the projection of non-noradrenergic sympathetic neurons to skeletal muscle vasculature was widespread in guinea-pig limb muscles, but that it was not uniform. VIP-IR axons were more likely to innervate the arterial vasculature of muscles with a high proportion of type I and/or oxidative muscle fibres than of muscles with a large proportion of type IIb muscle fibres. This relationship between the distribution of sympathetic non-noradrenergic axons and the metabolic characteristics of muscle suggests that these presumed vasodilator neurons have an important role in matching blood flow to the particular metabolic demands of different limb muscles.

Research paper thumbnail of Heterogeneous expression of SNAP-25 and synaptic vesicle proteins by central and peripheral inputs to sympathetic neurons

The Journal of Comparative Neurology, 2003

Neurons in prevertebral sympathetic ganglia receive convergent synaptic inputs from peripheral en... more Neurons in prevertebral sympathetic ganglia receive convergent synaptic inputs from peripheral enteric neurons in addition to inputs from spinal preganglionic neurons. Although all inputs are functionally cholinergic, inputs from these two sources have distinctive neurochemical and functional profiles. We used multiple-labeling immunofluorescence, quantitative confocal microscopy, ultrastructural immunocytochemistry, and intracellular electrophysiologic recordings to examine whether populations of inputs to the guinea pig coeliac ganglion express different levels of synaptic proteins that could influence synaptic strength. Boutons of enteric intestinofugal inputs, identified by immunoreactivity to vasoactive intestinal peptide, showed considerable heterogeneity in their immunoreactivity to synaptosome-associated protein of 25 kDa (SNAP-25), synapsin, synaptophysin, choline acetyltransferase, and vesicular acetylcholine transporter. Mean levels of immunoreactivity to these proteins were significantly lower in terminals of intestinofugal inputs compared with terminals of spinal preganglionic inputs. Nevertheless, many boutons with undetectable levels of SNAP-25 immunoreactivity formed morphologically normal synapses with target neurons. Treatment with botulinum neurotoxin type A (20-50 nM for 2 hours in vitro) generated significant cleavage of SNAP-25 and produced similar dose- and time-dependent inhibitions of synaptic transmission from all classes of inputs, regardless of their mean level of SNAP-25 expression. The simplest interpretation of these results is that only synaptic boutons with detectable levels of SNAP-25 immunoreactivity contribute significantly to fast cholinergic transmission. Consequently, the low synaptic strength of intestinofugal inputs to final motor neurons in sympathetic pathways may be due in part to the low proportion of their boutons that express SNAP-25 and other synaptic proteins.

Research paper thumbnail of Most peptide-containing sensory neurons lack proteins for exocytotic release and vesicular transport of glutamate

The Journal of Comparative Neurology, 2005

We used multiple-labeling immunohistochemistry and confocal microscopy to examine coexpression of... more We used multiple-labeling immunohistochemistry and confocal microscopy to examine coexpression of immunoreactivity for vesicular glutamate transporters (VGluTs), synaptic vesicle proteins, and soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins in peptide-containing sensory neurons of guinea pigs, mice, and toads. Axon terminals in the superficial layers of the dorsal horn of the spinal cord with immunoreactivity (IR) for both substance P (SP) and calcitonin gene-related peptide (CGRP) lacked IR for synaptosomeassociated protein of 25 kDa (SNAP-25), syntaxin, synaptotagmin, synaptophysin, and synapsin, although adjacent varicosities without neuropeptides had IR for these synaptic proteins. Similarly, peptide-containing axon terminals in the superficial dorsal horn lacked IR for VGluT1 and VGluT2, despite the presence of VGluT2-IR in nearby nonpeptide varicosities. VGluT3-IR was sparse in the dorsal horn of the mouse spinal cord and was not present in peptide-containing axons. Most peripheral terminals of sensory neurons with both SP-IR and CGRP-IR in the skin, viscera, and autonomic ganglia of guinea pigs and mice also lacked IR for synaptic vesicle proteins, SNARE proteins, VGluT1, and VGluT2. In dorsal root ganglia from guinea pigs and mice, most small neurons with IR for both SP and CGRP lacked IR for SNAP-25, VGluT1, and VGluT2. Thus, proteins considered essential for vesicular uptake and exocytotic release of glutamate are not expressed at detectable levels by most sensory neurons containing SP and CGRP in rodents and toads. These data raise the possibility that most peptide-containing sensory neurons may not normally release glutamate as a transmitter.

Research paper thumbnail of Functional organization of vasodilator neurons in pelvic ganglia of female guinea pigs: Comparison with uterine motor neurons

The Journal of Comparative Neurology, 2003

Neurons producing vasodilation during reproductive activity constitute a large population of neur... more Neurons producing vasodilation during reproductive activity constitute a large population of neurons in pelvic autonomic ganglia. We used intracellular recording, dye-filling and multiple-labeling immunohistochemistry to determine the morphology and electrophysiological properties of, and number of synaptic inputs to, vasodilator pelvic neurons in female guinea pigs. Vasodilator neurons, identified by their immunoreactivity for vasoactive intestinal peptide (VIP) and their location in paracervical ganglia, had simple dendritic arbors (1 primary dendrite) compared with nonvasodilator neurons (3 dendrites). Vasodilator neurons had more depolarized resting membrane potentials (-47 mV) than other paracervical neurons (-55 mV) and had smaller apparent cell capacitances (65 pF vs. 110 pF). Vasodilator and nonvasodilator neurons could not be distinguished on the basis of their action potential discharge characteristics or current voltage relationships. Most pelvic neurons ( approximately 70%) had tonic (slowly adapting) discharges. Fifty-five percent of vasodilator and 60% of nonvasodilator neurons showed inward rectification when hyperpolarized below -90 mV. Around 65% of neurons showed evidence of M-current. Both vasodilator and nonvasodilator neurons ( approximately 80%) expressed an A-like current. Vasodilator neurons and nonvasodilator neurons received 1-2 fast synaptic inputs following stimulation of pelvic or hypogastric nerve trunks. Most neurons received a least one strong synaptic input. These results indicate that vasodilator neurons and neighboring neurons projecting to other pelvic targets, primarily in the myometrium, express a similar range of ionic conductances and integrate few synaptic inputs. The similarities between these two populations of neurons may be related to their coactivation as part of spinal somato-pelvic reflexes. Vasodilation and uterine contraction during reproductive behavior in female guinea pigs are likely to involve input from preganglionic neurons at both lumbar and sacral spinal levels.

Research paper thumbnail of Subpopulations of sympathetic neurons project to specific vascular targets in the pinna of the rabbit ear

The Journal of Comparative Neurology, 1999

We have characterised sympathetic neurons projecting to a range of cutaneous and striated muscle ... more We have characterised sympathetic neurons projecting to a range of cutaneous and striated muscle vascular targets in the pinna of the rabbit ear by examining neurotransmitter-related enzymes and peptides in perivascular axons and in somata identified by retrograde axonal tracing. Fast Blue was injected into one of seven sites in each pinna (n = 21 pinnae). The soma cross-sectional area and immunoreactivity (IR) for tyrosine hydroxylase (TH) and neuropeptide Y (NPY) were determined for each of 2,041 retrogradely labelled neurons in the ipsilateral superior cervical ganglion (SCG) or stellate ganglion (StG). Larger neurons in the SCG with TH-IR but not NPY-IR projected predominantly to veins along the medial edge of the pinna. Larger neurons in the StG with TH-IR but not NPY-IR projected predominantly to arteries and veins in the tip and lateral edge of the pinna. Smaller neurons in the SCG with IR to both TH and NPY projected predominantly to arteries in the striated muscles at the base of the ear. The smallest retrogradely labelled neurons in the SCG or StG lacked TH-IR but contained NPY-IR and projected almost exclusively to arterial vessels in the lateral muscle at the base of the ear. Thus, somata of sympathetic neurons projecting to cutaneous versus striated muscle vessels or to different regions of the cutaneous bed could be distinguished by a combination of location, size, and immunohistochemical profile. Consequently, regulation of blood flow within the rabbit ear is likely to involve coordination between neuronal pathways containing neurochemically and morphologically distinct populations of sympathetic neurons.

Research paper thumbnail of Structure of peripheral synapses: autonomic ganglia

Cell and Tissue Research, 2006

Final motor neurons in sympathetic and parasympathetic ganglia receive synaptic inputs from prega... more Final motor neurons in sympathetic and parasympathetic ganglia receive synaptic inputs from preganglionic neurons. Quantitative ultrastructural analyses have shown that the spatial distribution of these synapses is mostly sparse and random. Typically, only about 1%-2% of the neuronal surface is covered with synapses, with the rest of the neuronal surface being closely enclosed by Schwann cell processes. The number of synaptic inputs is correlated with the dendritic complexity of the target neuron, and the total number of synaptic contacts is related to the surface area of the post-synaptic neuron. Overall, most neurons receive fewer than 150 synaptic contacts, with individual preganglionic inputs providing between 10 and 50 synaptic contacts. This variation is probably one determinant of synaptic strength in autonomic ganglia. Many neurons in prevertebral sympathetic ganglia receive additional convergent synaptic inputs from intestinofugal neurons located in the enteric plexuses. The neurons support these additional inputs via larger dendritic arborisations together with a higher overall synaptic density. There is considerable neurochemical heterogeneity in presynaptic boutons. Some synapses apparently lack most of the proteins normally required for fast transmitter release and probably do not take part in conventional ganglionic transmission. Furthermore, most preganglionic boutons in the ganglionic neuropil do not form direct synaptic contacts with any neurons.

Research paper thumbnail of Differential involvement of N-type calcium channels in transmitter release from vasoconstrictor and vasodilator neurons

British Journal of Pharmacology, 2004

1 The effects of calcium channel blockers on co-transmission from different populations of autono... more 1 The effects of calcium channel blockers on co-transmission from different populations of autonomic vasomotor neurons were studied on isolated segments of uterine artery and vena cava from guinea-pigs. 2 Sympathetic, noradrenergic contractions of the uterine artery (produced by 200 pulses at 1 or 10 Hz; 600 pulses at 20 Hz) were abolished by the N-type calcium channel blocker o-conotoxin (CTX) GVIA at 1-10 nM.

Research paper thumbnail of Cloning of a C-terminally truncated NK-1 receptor from guinea-pig nervous system

Molecular Brain Research, 2003

In order to examine the possibility that some actions of substance P may be mediated by a variant... more In order to examine the possibility that some actions of substance P may be mediated by a variant of the neurokinin-1 (NK-1) receptor, we isolated and sequenced the cDNA encoding a truncated NK-1 receptor from guinea-pig celiac ganglion and brain mRNA by two-step RT-PCR based on the 39RACE method. The truncated NK-1 receptor sequence corresponded to a splice variant missing the final exon 5, and encoded a 311-amino acid protein that was truncated just after transmembrane domain 7, in an identical position to a truncated variant of the human NK-1 receptor. Thus, the truncated NK-1 receptor lacked the intracellular C-terminus sequence required for the phosphorylation and internalisation of the full-length NK-1 receptor. Using a sensitive one-step semi-quantitative RT-PCR assay, we detected mRNA for both the full length and truncated NK-1 receptors throughout the brain, spinal cord, sensory and autonomic ganglia, and viscera. Truncated NK-1 receptor mRNA was present in lower quantities than mRNA for the full-length NK-1R in all tissues. Highest levels of mRNA for the truncated NK-1 receptor were detected in coeliac ganglion, spinal cord, basal ganglia and hypothalamus. An antiserum to the N-terminus of the NK-1 receptor labelled dendrites of coeliac ganglion neurons that were not labelled with antisera to the C-terminus of the full length NK-1 receptor. These results show that a C-terminally truncated variant of the NK-1 receptor is likely to be widespread in central and peripheral nervous tissue. We predict that this receptor will mediate actions of substance P on neurons where immunohistochemical evidence for a full-length NK-1 receptor is lacking. 

Research paper thumbnail of Chemical Coding of Neurons and Plurichemical Transmission

Annual Review of Pharmacology and Toxicology, 1989

Research paper thumbnail of Colocalization of VIP with Other Neuropeptides and Neurotransmitters in the Autonomic Nervous System

Annals of the New York Academy of Sciences, 1988

Since the first histochemical demonstration of VIP immunoreactivity in autonomic numerous reports... more Since the first histochemical demonstration of VIP immunoreactivity in autonomic numerous reports have appeared showing VIP-immunoreactive fibers in almost every organ of those species studied.' The widespread distribution of nerve fibers containing VIP immunoreactivity together with its potent biological actions on autonomic effectors had led to the proposal that VIP acts as a neurotransmitter in some autonomic nerves?' The use of immunoneutralization of endogenously released VIP in pharmacological studies has lent support to the role of VIP and related peptides as neurotransmitter.610 The idea that VIP acts as a neurotransmitter fell on fertile ground because at the time of its discovery by Said and Mutt" it was known that substances other than acetylcholine and norepinephrine mediate autonomic neurotransmission in a variety of tissues."

Research paper thumbnail of Neurochemical Distinction Between Skeletal Muscle Vasodilator Neurons and Pelvic Vasodilator Neurons In Guinea-Pigs

Journal of the autonomic …, 1998

This study sets out to compare the combinations of potential vasodilator transmitters expressed b... more This study sets out to compare the combinations of potential vasodilator transmitters expressed by sympathetic and pelvic vasodilator neurons of guinea-pigs. Triple-labelling fluorescence immunohistochemistry was used to examine immunoreactivity (IR) to vasoactive intestinal peptide (VIP), nitric oxide synthase (NOS) and calcitonin gene-related peptide (CGRP) in lumbar sympathetic ganglia, and in perivascular axons supplying hindlimb skeletal muscles or pelvic viscera. Only 0.2% of VIP-IR nerve cell bodies in lumbar sympathetic ganglia (n = 4632 VIP-IR nerve cell profiles) contained NOS-IR, and one VIP-IR neuron contained CGRP-IR. The VIP-IR perivascular axons along the common and external iliac arteries, femoral artery and arteries to hindlimb muscles lacked NOS-IR and CGRP-IR. In contrast, all VIP-IR perivascular axons projecting from pelvic ganglia to the main uterine artery, and half of the VIP-IR axons along the internal iliac artery, contained NOS-IR and CGRP-IR. Thus, the neurochemical content of sympathetic vasodilator neurons to skeletal muscle arteries was clearly distinguishable from that of pelvic vasodilator neurons to the uterine vasculature. Furthermore, the autonomic dilation in each vascular bed is likely to be qualitatively different, and matched to the functional requirements of each target organ.

Research paper thumbnail of Pertussis toxin attenuates postsynaptic actions of neuropeptide Y or the guinea-pig uterine artery

European Journal of Pharmacology, 1991

The mechanisms by which neuropeptide Y (NPY) mediates its postsynaptic actions on the guinea-pig ... more The mechanisms by which neuropeptide Y (NPY) mediates its postsynaptic actions on the guinea-pig uterine artery, were investigated by incubating arterial segments in culture medium containing pertussis toxin (PTX). Arteries were incubated with 0, 0.25 or 1 pg. ml-' PTX for 24 or 48 h. Arterial segments incubated in culture medium without PTX showed the three postsynaptic responses to NPY which were reported previously in uncukored arteries: NPY further contracted segments which were precontracted with prostagl~ndin F,,; NPY reduced the maximom relaxations produced by vasoactive intestinal peptide (VIP); and NPY produced I rightward shift in the VIP concentration-response curves. PTX attenuated the three actions of NPY on the uterine artery to different degrees. PTX also reduced the magnitude of contractions produced by prostaglandin F,,, but did not affect contractions produced by 0.126 M KCI, or ;&xations produced by VIP in the absence of NPY. These data indicate that all postsynaptic actions of NPY on the uterine artery, and contractions produced by prostaglandin Fr,, are at lea?! partly mediated by pertussis toxin-sensitive GTP-binding proteins. It is not clear whether these multiple actions of NPY are mediated by one, or more than one, GTP-binding protein.

Research paper thumbnail of Non-noradrenergic sympathetic neurons project to extramuscular feed arteries and proximal intramuscular arteries of skeletal muscles in guinea-pig hindlimbs

Journal of the autonomic nervous system, Jan 7, 1996

This study set out to examine the non-noradrenergic sympathetic innervation of extramuscular and ... more This study set out to examine the non-noradrenergic sympathetic innervation of extramuscular and intramuscular arterial vessels supplying hindlimb muscles of guinea-pigs, using multiple-labelling fluorescence immunohistochemistry. Non-noradrenergic axons, identified by their immunoreactivity (IR) to vasoactive intestinal peptide (VIP) and neuropeptide Y (NPY), innervated nearly all (> or = 88%) extramuscular feed arteries supplying muscles of the medial thigh. The distribution of non-noradrenergic axons along extramuscular feed arteries was often patchy, with increased density near some branch points. The density of axons with VIP-IR and NPY-IR at the adventitia-medial junction of the largest extramuscular arteries was similar to the density of noradrenergic axons identified by IR to tyrosine hydroxylase (TH) and NPY. The proportion of arterial vessels innervated by VIP-IR axons decreased in more distal, intramuscular arterial segments, and when present, the VIP-IR axons were few...

Research paper thumbnail of Botulinum neurotoxin A attenuates release of norepinephrine but not NPY from vasoconstrictor neurons

American journal of physiology. Heart and circulatory physiology, 2002

We examined effects of botulinum neurotoxin A (BoNTA) on sympathetic constrictions of the vena ca... more We examined effects of botulinum neurotoxin A (BoNTA) on sympathetic constrictions of the vena cava and uterine artery from guinea pigs to test the role of soluble NSF attachment protein receptor (SNARE) proteins in release of the cotransmitters norepinephrine (NE) and neuropeptide Y (NPY). Protein extracts of venae cavae and uterine arteries showed partial cleavage of synaptosomal associated protein of 25 kDa (SNAP-25) after treatment in vitro with BoNTA (50-100 nM). The rising phase of isometric contractions of isolated venae cavae to field stimulation at 20 Hz, mediated by NE acting on alpha-adrenoceptors, was reduced significantly by 100 nM BoNTA. However, sustained sympathetic contractions mediated by NPY were not affected by BoNTA. In uterine arteries, noradrenergic contractions to 1-Hz stimulation were almost abolished by BoNTA, and contractions at 10 Hz were reduced by 50-60%. We conclude that SNARE proteins are involved in exocytosis of NE from synaptic vesicles at low freq...

Research paper thumbnail of Projections of intrinsic cardiac neurons to different targets in the guinea-pig heart

Journal of the Autonomic Nervous System, 1996

We set out to determine the projections of the major immunohistochemically-defined populations of... more We set out to determine the projections of the major immunohistochemically-defined populations of intrinsic cardiac neurons to different target tissues within the guinea-pig heart. Ultrastructural studies, and immunoreactivity to the neuronal marker, neuron-specific enolase, suggested that the number of axons of intrinsic neurons in most regions of the heart was low when compared with the populations of axons projecting from extrinsic sensory and sympathetic ganglia. Multiple-labelling immunofluorescence was used to demonstrate the terminals of the major populations of peptide-containing intrinsic neurons. The intrinsic nature of peptide-containing axons was confirmed by long-term organotypic culture of cardiac tissue, which resulted in degeneration of axons of extrinsic neurons. The relative density and peptide content of intrinsic axons throughout the heart was not consistent with the relative proportions of peptide-containing intracardiac nerve cell bodies observed previously. The most commonly-encountered axons contained immunoreactivity (IR) to vasoactive intestinal peptide (VIP) alone, although nerve cell bodies with VIP constituted less than 5% of the total population of intrinsic neurons. Populations of axons containing IR to somatostatin alone, somatostatin and substance P, neuropeptide Y (NPY) alone, somatostatin and NPY, or VIP and NPY, also were observed. Intrinsic axons containing substance P-IR were very rare, much more so than would be predicted from the peptide content of intrinsic nerve cell bodies. The regions of the heart with the most dense innervation by axons of intrinsic neurons were the cardiac valves, the atrio-ventricular node and the sino-atrial node. Each of these targets was innervated by several populations of peptide-containing axons. Thus, each population of peptide-containing intrinsic neurons projected to a variety of target tissues within the heart. One possible interpretation of these results is that immunohistochemically-distinct populations of intrinsic neurons belong to different functional classes of neurons (sensory neurons, interneurons, final motor neurons), each of which innervates many regions of the heart.

Research paper thumbnail of Pathway specific expression of neuropeptides and autonomic control of the vasculature

Regulatory Peptides, 2000

In this article, we review the immunohistochemical evidence for the pathway-specific expression o... more In this article, we review the immunohistochemical evidence for the pathway-specific expression of co-existing neuropeptides in autonomic vasomotor neurons, and examine the functional significance of these expression patterns for the autonomic regulation of the vasculature. Most final motor neurons in autonomic vasomotor pathways contain neuropeptides in addition to non-peptide co-transmitters such as catecholamines, acetylcholine and nitric oxide. Neuropeptides also occur in preganglionic vasomotor neurons. The precise combinations of neuropeptides expressed by neurons in vasomotor pathways vary with species, vascular bed, and the level within the vascular bed. This applies to both vasoconstrictor and vasodilator pathways. There is a similar degree of variation in the expression of neuropeptide receptors in the vasculature. Consequently, the contributions of different peptides to autonomic vasomotor control are closely matched to the functional requirements of specific vascular beds. This arrangement allows for a high degree of precision in vascular control in normal conditions and has the potential for considerable plasticity under pathophysiological conditions.

Research paper thumbnail of Postganglionic Neurotransmitter

Encyclopedia of Neuroscience, 2009

Research paper thumbnail of Interleukin-1 receptor immunoreactivity in sympathetic vascular and non-vascular neurons in guinea-pig coeliac ganglion

Neuroscience Letters, 2002

Immunoreactivity (IR) for the interleukin-1 receptor type I (IL1RI) was examined in sympathetic n... more Immunoreactivity (IR) for the interleukin-1 receptor type I (IL1RI) was examined in sympathetic neurons in guinea-pig coeliac ganglion using multiple-labelling immunofluorescence. IL1RI-IR was present in 8% of sympathetic neurons in untreated preparations. The proportion of neurons with IL1RI-IR increased significantly after incubation in interleukin-6 (200 ng/ml) for 2-4 h (16-26% neurons), or after incubation for 4 h without cytokine (16%), with interleukin-1beta (IL1beta, 200 ng/ml; 18%) or tumour necrosis factor-alpha (200 ng/ml; 16%). This increase occurred predominantly in neuropeptide Y-IR, vasoconstrictor neurons. IL1RI-IR also was present in varicose axons, some of which projected from the gut, and in vascular smooth muscle cells and endothelium. These potential binding sites for the proinflammatory cytokine, IL1beta, on vasoconstrictor neurons and blood vessels may modulate sympathetic regulation of intestinal blood flow in inflammatory conditions.

Research paper thumbnail of Peripheral fields of sympathetic vasoconstrictor neurons in guinea pigs

Neuroscience Letters, 1998

We have combined retrograde axonal tracing using Fast Blue and DiI, with immunohistochemistry, to... more We have combined retrograde axonal tracing using Fast Blue and DiI, with immunohistochemistry, to estimate the maximum size of peripheral fields of identified sympathetic vasoconstrictor neurons projecting to guinea-pig ear tips. Many neurons in the superior cervical ganglia were labelled with both Fast Blue and DiI after dye injections up to 7 mm apart. Few neurons were labelled when dye injections were 8-10 mm apart. Neurons labelled with both DiI and Fast Blue after dye injections 5-7 mm apart had, on average, larger somata (436 ± 84 mm 2 , mean ± SEM, n = 47) than neurons labelled with DiI only (388 ± 11 mm 2 , n = 147). Typically, 50-100 neurons innervated a region of vasculature 1 mm in diameter. We conclude that sympathetic vasoconstrictor neurons branch widely before converging on to their target blood vessels. Progressive recruitment of vasoconstrictor neurons with increasing field size would provide an efficient mechanism for graded neural control of the circulation.

Research paper thumbnail of Five inhibitory transmitters coexist in pelvic autonomic vasodilator neurons

NeuroReport, 1997

Here we describe the localization of a potent vasodilator, calcitonin gene-related peptide (CGRP)... more Here we describe the localization of a potent vasodilator, calcitonin gene-related peptide (CGRP), in pelvic autonomic neurons containing four other inhibitory transmitters: vasoactive intestinal peptide (VIP), neuropeptide Y, nitric oxide and acetylcholine. These neurons mediate endothelium-independent vasodilation by releasing nitric oxide and one or more neuropeptides. Sixty percent of nerve cell bodies in guinea-pig paracervical ganglia with immunoreactivity (IR) for VIP, choline acetyltransferase (ChAT) and nitric oxide synthase (NOS), also contained IR for CGRP. Furthermore, many VIP-IR varicose nerve terminals at the adventitia-medial junction of the guinea-pig uterine artery contained IR for CGRP, ChAT and NOS. Both alpha-hCGRP and beta-hCGRP were potent dilators of the uterine artery (pD2 values 8.1, 8.3, respectively), but 1 microM hCGRP(8-37) did not antagonize dilations produced by either agonist. Dilations produced by alpha-hCGRP were unaffected by removal of the endothelium. Taken together with results of our previous studies, we propose that CGRP can contribute directly to autonomic vasodilation, possibly via CGRP2 receptors on smooth muscle cells, and that CGRP is the fifth inhibitory transmitter co-existing in pelvic vasodilator neurons.

Research paper thumbnail of Projections of Sympathetic Non-Noradrenergic Neurons to Skeletal Muscle Arteries in Guinea-Pig Limbs Vary with the Metabolic Character of Muscles

Journal of Vascular Research, 1997

This study set out to examine in detail the distribution of axons of sympathetic non-noradrenergi... more This study set out to examine in detail the distribution of axons of sympathetic non-noradrenergic neurons innervating the arterial bed in skeletal muscles of the forelimb and hindlimb of guinea-pigs. The distribution of non-noradrenergic axons with immunoreactivity to vasoactive intestinal peptide (VIP) was examined in limb muscles of different histochemical character. The immunohistochemical demonstration of myosin heavy chain from fast-twitch muscle, and the histochemical demonstration of adenosine triphosphatase and succinic dehydrogenase, were used to determine the muscle fibre profile of 6 different limb muscles. Muscles included the oxidative type I muscle fibre-rich accessory semimembranosus muscle, the predominantly glycolytic type II muscle fibre-rich cranial gracilis and biceps brachii muscles and the plantaris, gastrocnemius medial head and triceps brachii long head of mixed muscle fibre composition. The frequency with which the VIP-immunoreactive (VIP-IR) axons innervated intramuscular arterial vessels was compared between categories of muscles defined by their muscle fibre profile. This study demonstrated that the projection of non-noradrenergic sympathetic neurons to skeletal muscle vasculature was widespread in guinea-pig limb muscles, but that it was not uniform. VIP-IR axons were more likely to innervate the arterial vasculature of muscles with a high proportion of type I and/or oxidative muscle fibres than of muscles with a large proportion of type IIb muscle fibres. This relationship between the distribution of sympathetic non-noradrenergic axons and the metabolic characteristics of muscle suggests that these presumed vasodilator neurons have an important role in matching blood flow to the particular metabolic demands of different limb muscles.

Research paper thumbnail of Heterogeneous expression of SNAP-25 and synaptic vesicle proteins by central and peripheral inputs to sympathetic neurons

The Journal of Comparative Neurology, 2003

Neurons in prevertebral sympathetic ganglia receive convergent synaptic inputs from peripheral en... more Neurons in prevertebral sympathetic ganglia receive convergent synaptic inputs from peripheral enteric neurons in addition to inputs from spinal preganglionic neurons. Although all inputs are functionally cholinergic, inputs from these two sources have distinctive neurochemical and functional profiles. We used multiple-labeling immunofluorescence, quantitative confocal microscopy, ultrastructural immunocytochemistry, and intracellular electrophysiologic recordings to examine whether populations of inputs to the guinea pig coeliac ganglion express different levels of synaptic proteins that could influence synaptic strength. Boutons of enteric intestinofugal inputs, identified by immunoreactivity to vasoactive intestinal peptide, showed considerable heterogeneity in their immunoreactivity to synaptosome-associated protein of 25 kDa (SNAP-25), synapsin, synaptophysin, choline acetyltransferase, and vesicular acetylcholine transporter. Mean levels of immunoreactivity to these proteins were significantly lower in terminals of intestinofugal inputs compared with terminals of spinal preganglionic inputs. Nevertheless, many boutons with undetectable levels of SNAP-25 immunoreactivity formed morphologically normal synapses with target neurons. Treatment with botulinum neurotoxin type A (20-50 nM for 2 hours in vitro) generated significant cleavage of SNAP-25 and produced similar dose- and time-dependent inhibitions of synaptic transmission from all classes of inputs, regardless of their mean level of SNAP-25 expression. The simplest interpretation of these results is that only synaptic boutons with detectable levels of SNAP-25 immunoreactivity contribute significantly to fast cholinergic transmission. Consequently, the low synaptic strength of intestinofugal inputs to final motor neurons in sympathetic pathways may be due in part to the low proportion of their boutons that express SNAP-25 and other synaptic proteins.

Research paper thumbnail of Most peptide-containing sensory neurons lack proteins for exocytotic release and vesicular transport of glutamate

The Journal of Comparative Neurology, 2005

We used multiple-labeling immunohistochemistry and confocal microscopy to examine coexpression of... more We used multiple-labeling immunohistochemistry and confocal microscopy to examine coexpression of immunoreactivity for vesicular glutamate transporters (VGluTs), synaptic vesicle proteins, and soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins in peptide-containing sensory neurons of guinea pigs, mice, and toads. Axon terminals in the superficial layers of the dorsal horn of the spinal cord with immunoreactivity (IR) for both substance P (SP) and calcitonin gene-related peptide (CGRP) lacked IR for synaptosomeassociated protein of 25 kDa (SNAP-25), syntaxin, synaptotagmin, synaptophysin, and synapsin, although adjacent varicosities without neuropeptides had IR for these synaptic proteins. Similarly, peptide-containing axon terminals in the superficial dorsal horn lacked IR for VGluT1 and VGluT2, despite the presence of VGluT2-IR in nearby nonpeptide varicosities. VGluT3-IR was sparse in the dorsal horn of the mouse spinal cord and was not present in peptide-containing axons. Most peripheral terminals of sensory neurons with both SP-IR and CGRP-IR in the skin, viscera, and autonomic ganglia of guinea pigs and mice also lacked IR for synaptic vesicle proteins, SNARE proteins, VGluT1, and VGluT2. In dorsal root ganglia from guinea pigs and mice, most small neurons with IR for both SP and CGRP lacked IR for SNAP-25, VGluT1, and VGluT2. Thus, proteins considered essential for vesicular uptake and exocytotic release of glutamate are not expressed at detectable levels by most sensory neurons containing SP and CGRP in rodents and toads. These data raise the possibility that most peptide-containing sensory neurons may not normally release glutamate as a transmitter.

Research paper thumbnail of Functional organization of vasodilator neurons in pelvic ganglia of female guinea pigs: Comparison with uterine motor neurons

The Journal of Comparative Neurology, 2003

Neurons producing vasodilation during reproductive activity constitute a large population of neur... more Neurons producing vasodilation during reproductive activity constitute a large population of neurons in pelvic autonomic ganglia. We used intracellular recording, dye-filling and multiple-labeling immunohistochemistry to determine the morphology and electrophysiological properties of, and number of synaptic inputs to, vasodilator pelvic neurons in female guinea pigs. Vasodilator neurons, identified by their immunoreactivity for vasoactive intestinal peptide (VIP) and their location in paracervical ganglia, had simple dendritic arbors (1 primary dendrite) compared with nonvasodilator neurons (3 dendrites). Vasodilator neurons had more depolarized resting membrane potentials (-47 mV) than other paracervical neurons (-55 mV) and had smaller apparent cell capacitances (65 pF vs. 110 pF). Vasodilator and nonvasodilator neurons could not be distinguished on the basis of their action potential discharge characteristics or current voltage relationships. Most pelvic neurons ( approximately 70%) had tonic (slowly adapting) discharges. Fifty-five percent of vasodilator and 60% of nonvasodilator neurons showed inward rectification when hyperpolarized below -90 mV. Around 65% of neurons showed evidence of M-current. Both vasodilator and nonvasodilator neurons ( approximately 80%) expressed an A-like current. Vasodilator neurons and nonvasodilator neurons received 1-2 fast synaptic inputs following stimulation of pelvic or hypogastric nerve trunks. Most neurons received a least one strong synaptic input. These results indicate that vasodilator neurons and neighboring neurons projecting to other pelvic targets, primarily in the myometrium, express a similar range of ionic conductances and integrate few synaptic inputs. The similarities between these two populations of neurons may be related to their coactivation as part of spinal somato-pelvic reflexes. Vasodilation and uterine contraction during reproductive behavior in female guinea pigs are likely to involve input from preganglionic neurons at both lumbar and sacral spinal levels.

Research paper thumbnail of Subpopulations of sympathetic neurons project to specific vascular targets in the pinna of the rabbit ear

The Journal of Comparative Neurology, 1999

We have characterised sympathetic neurons projecting to a range of cutaneous and striated muscle ... more We have characterised sympathetic neurons projecting to a range of cutaneous and striated muscle vascular targets in the pinna of the rabbit ear by examining neurotransmitter-related enzymes and peptides in perivascular axons and in somata identified by retrograde axonal tracing. Fast Blue was injected into one of seven sites in each pinna (n = 21 pinnae). The soma cross-sectional area and immunoreactivity (IR) for tyrosine hydroxylase (TH) and neuropeptide Y (NPY) were determined for each of 2,041 retrogradely labelled neurons in the ipsilateral superior cervical ganglion (SCG) or stellate ganglion (StG). Larger neurons in the SCG with TH-IR but not NPY-IR projected predominantly to veins along the medial edge of the pinna. Larger neurons in the StG with TH-IR but not NPY-IR projected predominantly to arteries and veins in the tip and lateral edge of the pinna. Smaller neurons in the SCG with IR to both TH and NPY projected predominantly to arteries in the striated muscles at the base of the ear. The smallest retrogradely labelled neurons in the SCG or StG lacked TH-IR but contained NPY-IR and projected almost exclusively to arterial vessels in the lateral muscle at the base of the ear. Thus, somata of sympathetic neurons projecting to cutaneous versus striated muscle vessels or to different regions of the cutaneous bed could be distinguished by a combination of location, size, and immunohistochemical profile. Consequently, regulation of blood flow within the rabbit ear is likely to involve coordination between neuronal pathways containing neurochemically and morphologically distinct populations of sympathetic neurons.

Research paper thumbnail of Structure of peripheral synapses: autonomic ganglia

Cell and Tissue Research, 2006

Final motor neurons in sympathetic and parasympathetic ganglia receive synaptic inputs from prega... more Final motor neurons in sympathetic and parasympathetic ganglia receive synaptic inputs from preganglionic neurons. Quantitative ultrastructural analyses have shown that the spatial distribution of these synapses is mostly sparse and random. Typically, only about 1%-2% of the neuronal surface is covered with synapses, with the rest of the neuronal surface being closely enclosed by Schwann cell processes. The number of synaptic inputs is correlated with the dendritic complexity of the target neuron, and the total number of synaptic contacts is related to the surface area of the post-synaptic neuron. Overall, most neurons receive fewer than 150 synaptic contacts, with individual preganglionic inputs providing between 10 and 50 synaptic contacts. This variation is probably one determinant of synaptic strength in autonomic ganglia. Many neurons in prevertebral sympathetic ganglia receive additional convergent synaptic inputs from intestinofugal neurons located in the enteric plexuses. The neurons support these additional inputs via larger dendritic arborisations together with a higher overall synaptic density. There is considerable neurochemical heterogeneity in presynaptic boutons. Some synapses apparently lack most of the proteins normally required for fast transmitter release and probably do not take part in conventional ganglionic transmission. Furthermore, most preganglionic boutons in the ganglionic neuropil do not form direct synaptic contacts with any neurons.

Research paper thumbnail of Differential involvement of N-type calcium channels in transmitter release from vasoconstrictor and vasodilator neurons

British Journal of Pharmacology, 2004

1 The effects of calcium channel blockers on co-transmission from different populations of autono... more 1 The effects of calcium channel blockers on co-transmission from different populations of autonomic vasomotor neurons were studied on isolated segments of uterine artery and vena cava from guinea-pigs. 2 Sympathetic, noradrenergic contractions of the uterine artery (produced by 200 pulses at 1 or 10 Hz; 600 pulses at 20 Hz) were abolished by the N-type calcium channel blocker o-conotoxin (CTX) GVIA at 1-10 nM.

Research paper thumbnail of Cloning of a C-terminally truncated NK-1 receptor from guinea-pig nervous system

Molecular Brain Research, 2003

In order to examine the possibility that some actions of substance P may be mediated by a variant... more In order to examine the possibility that some actions of substance P may be mediated by a variant of the neurokinin-1 (NK-1) receptor, we isolated and sequenced the cDNA encoding a truncated NK-1 receptor from guinea-pig celiac ganglion and brain mRNA by two-step RT-PCR based on the 39RACE method. The truncated NK-1 receptor sequence corresponded to a splice variant missing the final exon 5, and encoded a 311-amino acid protein that was truncated just after transmembrane domain 7, in an identical position to a truncated variant of the human NK-1 receptor. Thus, the truncated NK-1 receptor lacked the intracellular C-terminus sequence required for the phosphorylation and internalisation of the full-length NK-1 receptor. Using a sensitive one-step semi-quantitative RT-PCR assay, we detected mRNA for both the full length and truncated NK-1 receptors throughout the brain, spinal cord, sensory and autonomic ganglia, and viscera. Truncated NK-1 receptor mRNA was present in lower quantities than mRNA for the full-length NK-1R in all tissues. Highest levels of mRNA for the truncated NK-1 receptor were detected in coeliac ganglion, spinal cord, basal ganglia and hypothalamus. An antiserum to the N-terminus of the NK-1 receptor labelled dendrites of coeliac ganglion neurons that were not labelled with antisera to the C-terminus of the full length NK-1 receptor. These results show that a C-terminally truncated variant of the NK-1 receptor is likely to be widespread in central and peripheral nervous tissue. We predict that this receptor will mediate actions of substance P on neurons where immunohistochemical evidence for a full-length NK-1 receptor is lacking. 

Research paper thumbnail of Chemical Coding of Neurons and Plurichemical Transmission

Annual Review of Pharmacology and Toxicology, 1989

Research paper thumbnail of Colocalization of VIP with Other Neuropeptides and Neurotransmitters in the Autonomic Nervous System

Annals of the New York Academy of Sciences, 1988

Since the first histochemical demonstration of VIP immunoreactivity in autonomic numerous reports... more Since the first histochemical demonstration of VIP immunoreactivity in autonomic numerous reports have appeared showing VIP-immunoreactive fibers in almost every organ of those species studied.' The widespread distribution of nerve fibers containing VIP immunoreactivity together with its potent biological actions on autonomic effectors had led to the proposal that VIP acts as a neurotransmitter in some autonomic nerves?' The use of immunoneutralization of endogenously released VIP in pharmacological studies has lent support to the role of VIP and related peptides as neurotransmitter.610 The idea that VIP acts as a neurotransmitter fell on fertile ground because at the time of its discovery by Said and Mutt" it was known that substances other than acetylcholine and norepinephrine mediate autonomic neurotransmission in a variety of tissues."

Research paper thumbnail of Neurochemical Distinction Between Skeletal Muscle Vasodilator Neurons and Pelvic Vasodilator Neurons In Guinea-Pigs

Journal of the autonomic …, 1998

This study sets out to compare the combinations of potential vasodilator transmitters expressed b... more This study sets out to compare the combinations of potential vasodilator transmitters expressed by sympathetic and pelvic vasodilator neurons of guinea-pigs. Triple-labelling fluorescence immunohistochemistry was used to examine immunoreactivity (IR) to vasoactive intestinal peptide (VIP), nitric oxide synthase (NOS) and calcitonin gene-related peptide (CGRP) in lumbar sympathetic ganglia, and in perivascular axons supplying hindlimb skeletal muscles or pelvic viscera. Only 0.2% of VIP-IR nerve cell bodies in lumbar sympathetic ganglia (n = 4632 VIP-IR nerve cell profiles) contained NOS-IR, and one VIP-IR neuron contained CGRP-IR. The VIP-IR perivascular axons along the common and external iliac arteries, femoral artery and arteries to hindlimb muscles lacked NOS-IR and CGRP-IR. In contrast, all VIP-IR perivascular axons projecting from pelvic ganglia to the main uterine artery, and half of the VIP-IR axons along the internal iliac artery, contained NOS-IR and CGRP-IR. Thus, the neurochemical content of sympathetic vasodilator neurons to skeletal muscle arteries was clearly distinguishable from that of pelvic vasodilator neurons to the uterine vasculature. Furthermore, the autonomic dilation in each vascular bed is likely to be qualitatively different, and matched to the functional requirements of each target organ.