GABA in the Nervous System of the Cestodes Diphyllobothrium dendriticum (Diphyllobothriidea) and Caryophyllaeus laticeps (Caryophyllidea), with Comparative Analysis of Muscle Innervation (original) (raw)
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Immunocytochemistry of GABA in the brain and suboesophageal ganglion ofManduca sexta
Cell and Tissue Research, 1987
We have used specific antisera against proteinconjugated 7-aminobutyric acid (GABA) in immunocytochemical preparations to investigate the distribution of putatively GABAergic neurons in the brain and suboesophageal ganglion of the sphinx moth Manduca sexta. About 20000 neurons per brain hemisphere exhibit GABA-immunoreactivity. Most of these are optic-lobe interneurons, especially morphologically centrifugal neurons of the lamina and tangential neurons that innervate the medulla or the lobula complex. Many GABA-immunoreactive neurons, among them giant fibers of the lobula plate, project into the median protocerebrum. Among prominent GABAimmunoreactive neurons of the median protocerebrum are about 150 putatively negative-feedback fibers of the mushroom body, innervating both the calyces and lobes, and a group of large, fan-shaped neurons of the lower division of the central body. Several commissures in the supra-and suboesophageal ganglion exhibit GABA-immunoreactivity. In the suboesophageal ganglion, a group of contralaterally descending neurons shows GABA-Iike immunoreactivity. The frontal ganglion is innervated by immunoreactive processes from the tritocerebrum but does not contain GABAimmunoreactive somata. With few exceptions the brain nerves do not contain GABA-immunoreactive fibers.
The subcommissural organ of the frog Rana perezi is innervated by nerve fibres containing GABA
Cell and Tissue Research, 2000
The innervation of the frog subcommissural organ was studied by light-microscopic and ultrastructural immunocytochemistry using antisera against serotonin, noradrenaline, dopamine, γ-aminobutyric acid (GABA), glutamic acid decarboxylase, different GABA receptor subunits and bovine Reissner's fibre material (AFRU). In the proximity of the organ, serotonin-and noradrenalinecontaining fibres were rare whereas dopamine-immunoreactive fibres were more numerous. Many GABA-and glutamic acid decarboxylase-containing nerve fibres were found at the basal portion of the ependymal cells of the subcommissural organ. Under the electron microscope, these GABA-immunolabelled nerve endings appeared to establish axoglandular synapses with secretory ependymal cells of the subcommissural organ. In addition, the secretory ependymal cells expressed high amounts of the β 2 -subunit of the GABA A receptor. Since GABA-immunoreactive neurons were present in the frog pineal organ proper and apparently contributed axons to the pineal tract, we suggest that at least part of the GABAergic fibres innervating the frog subcommissural organ could originate from the pineal organ.
The Journal of Comparative Neurology, 1991
In the present study several techniques were employed to test the hypothesis that gamma-aminobutyric acid (GABA) is a neurotransmitter in the central nervous system (CNS) of the pond snail Helisoma trivolvis (Mollusca, Pulmonata). First, by using chromatographic techniques, the presence of GABA and its differential distribution among the ganglia constituting the CNS was demonstrated. Second, de novo synthesis of 3H-GABA from 3H-glutamate was shown by the CNS. Levels of both endogenous and newly synthesized GABA were greatest in the buccal, cerebral, and pedal ganglia. Third, indirect immunohistochemistry of wholemounts revealed a central network of GABA-like immunoreactive neurons. With the possible exceptions of two pairs of fibers in nerve trunks, all projections from GABAimmunoreactive neurons were confined to the CNS, suggesting a predominantly central role for GABA. Stained neurons were found on the dorsal surface of the buccal ganglia and throughout the cerebral and pedal ganglia. No GABA-immunoreactive cell bodies were observed in the parietal, pleural, or visceral ganglia. Finally, uptake of 3H-GABA was examined autoradiographically in sectioned ganglia. A pattern of radiolabelled cells was observed that closely resembled the distribution of GABA-immunoreactive neurons. The data described above fulfill several criteria necessary to establish GABA as a transmitter in the nervous system of Helisoma. Taken together with previously obtained pharmacological evidence demonstrating that GABA acts on Helisoma central neurons, GABA is considered to be a strong candidate for a neurotransmitter in Helisoma.
Neuroscience, 1987
A~~act-~-Aminobutyric acid (GABA)-confining elements have been studied by light and electron microscopy in the rat spinal cord, using immunocytochemistry with anti-GABA antibodies. Light microscopy showed immunoreactive somata localized principally in laminae I-III, and occasionally in the deeper laminae of the dorsal horn and in the ventral horn. Small somata were also observed around the central canal. Punctate GABA-immunoreactive profiles were particularly concentrated in laminae I-III, and moderately abundant in the deeper laminae and in the ventral horn where they were observed surrounding the unlabelled motoneurons.
Crayfish sensory terminals and motor neurones exhibit two distinct types of GABA receptors
Journal of Comparative Physiology A: Sensory, Neural, and Behavioral Physiology, 1996
Motor neurones of the crayfish walking system display inhibitory responses evoked either byamino butyric acid (GABA) or glutamate, possibly involving the same receptor (Pearlstein et al. 1994). In order to test if this sensibility to both GABA and glutamate was a specific property of crayfish GABA receptors, pharmacological characteristics of GABAevoked responses in both sensory terminals from CB chordotonal organ and motor neurones of the walking system have been compared. Both receptors are GABAgated Cl) channels activated by specific GABA A (muscimol, isoguvacine), GABA B (3-aminopropyl phosphinic acid), and GABA C (cis-4-amino crotonic acid) agonists, and blocked by competitive (-guanidino propionic acid) and non-competitive (picrotoxin) antagonists. They were insensitive to specific GABA A (bicuculline, SR-95531) and GABA B (phaclofen) antagonists. Furthermore, in both cases, nipecotic acid and the modulatory drug diazepam had no effect. However, our results demonstrate that GABA receptors of sensory terminals are different from those of motor neurones. GABA-induced desensitisation only occurred in sensory terminals. Moreover, glutamate was shown to activate GABA-gated Cl) channels in motor neurones, but not in sensory terminals. Therefore, GABA is likely to be the endogenous neurotransmitter of presynaptic inhibition in sensory terminals, whereas inhibition between antagonistic motor neurones would be achieved by glutamate. Key words GABA receptors • Glutamate • Sensory terminals • Motor neurones • Invertebrate Abbreviations 3-APPA 3-aminopropyl phosphinic acid • 3-APA 3-aminopropyl phosphonous acid • CACA cis-4-amino crotonic acid • CBCO coxo-basipodite chordotonal organ • GABA-amino butyric acid •-GP-guanidinopropionic acid • PTX picrotoxin • R i input resistance • T e ejection time • V m membrane potential • V r resting potential
Neuroscience, 1988
AbatraeG-The distribution of axons and axon varicosities containing GABA was studied in the superior cervical ganglion of rat by light and electron microscopic immunohistochemistry. Two different polyclonal antibodies were used, which had been made against GABA conjugated by glutardialdehyde to bovine serum albumin. GABA-like immunoreactivity occurred in many axons within the cervical sympathetic trunk and in axons and axon varicosities around the principal nerve cells in the superior cervical ganglion. GABA-positive axons were intermingled with non-stained axons, except for a small group of fibers in the trunk where the staining was absent. The rostrai part of the ganglion and some scattered patches were more denseiy inne~ated by GABA-~sitive axons than the middle and caudal parts. Within dense areas, some of the large ganglion cells were abundantly surrounded by GABA-positive nerve fibers, while the vicinity of others was devoid of any immunoreactive axon terminals. None of the principal ganglion cells contained GABA-like immunoreactivity, although a class of small cells scattered within the ganglion was stained.
Modulation by GABA of neuroplasticity in the central and peripheral nervous system
Neurochemical Research, 1993
Apart from being a prominent (inhibitory) neurotransmitter that is widely distributed in the central and peripheral nervous system, 7-aminobutyric acid (GABA) has turned out to exert trophic actions. In this manner GABA may modulate the neuroplastic capacity of neurons and neuron-like cells under various conditions in situ and in vitro. In the superior cervical ganglion (SCG) of adult rat, GABA induces the formation of free postsynaptic-like densities on the dendrites of principal neurons and enables implanted foreign (cholinergic) nerves to establish functional synaptie contacts, even while preexisting connections of the preganglionic axons persist. Apart from postsynaptic effects, GABA inhibits acetylcholine release from preganglionic nerve terminals and changes, at least transiently, the neurochemical markers of cholinergic innervation (acetylcholinesterase and nicotinic receptors). In murine neuroblastoma cells in vitro, GABA induces electron microscopic changes, which are similar in principle to those seen in the SCG. Both neuroplastic effects of GABA, in situ and in vitro, could be mimicked by sodium bromide, a hyperpolarizing agent. In addition, evidence is available that GABA via A-and/or B-receptors may exert direct trophic actions. The regulation of both types of trophic actions (direct, receptor-mediated vs. indirect, bioelectric activity dependent) is discussed.
Brain Research, 1991
The distributions of y-aminobutyric acid (GABA)-and serotonin (5-HT)-containing terminals impinging on the surface of the Mauthner (M-) cell were studied at the light microscopic level using double immunofluorescent labefing and were compared with that of the glycine receptor. The latter was visualized indirectly, using a monoelonai mouse antibody which recognizes its 93-kDa associated protein. This neuron has two large principal dendrites: one extending ventrorostrally (ventral dendrite) and the other dorsolaterally (lateral dendrite). There are also two other classes of smaller processes: one that projects ventrally (small ventral dendrites) and one penetrating in the axon cap (cap dendrites), a peeuiiar neuropfl surrounding the initial segment of the M-cell axon. A cellular regionalization of these afferent systems was found: GABA boutons, labeled for glutamic acid decarboxylase (GAD), were localized preferentially on the lateral dendrite while 5-HTfilled endings predominated on the ventral one. The density of these two classes of inputs was comparable in the other areas of the M-cell: less of their terminals were in contact with the soma outside the axon cap, and more numerous boutons, which presented either GABA or 5-HT immunoreactivities, were apposed to the small ventral dendrites. This preferential pattern of innervation differed with the ubiquitous presence of glycine receptor clusters on the M-cell membrane. Finally no evidence of a colocalization of GABA and 5-HT in afferent endings was detected at any portion of the M-cell. Since the studied networks are involved in the inhibitory control of this neuron, and in its modulation, our results are discussed in relation with possible heterosynaptie interactions between them, and between other similarly segregated excitatory inputs.