Ultrastructural evidence for direct excitatory retroambiguus projections to cutaneous trunci and abdominal external oblique muscle motoneurons in the cat (original) (raw)

Differential pontomedullary catecholaminergic projections to hypoglossal motor nucleus and viscerosensory nucleus of the solitary tract

Journal of Chemical Neuroanatomy, 2007

In individuals with a narrow or collapsible upper airway, sleep-related hypotonia of upper airway muscles leads to recurrent airway obstructions. Brainstem noradrenergic neurons reduce their activity during slow-wave sleep and become silent during rapid eye movement sleep; this may cause state-dependent changes in the motor output and reflexes. The loss of noradrenergic excitation is a major cause of sleep-related depression of activity in upper airway muscles innervated by the hypoglossal nerve. Our goal was to identify and compare the pontomedullary sources of catecholaminergic (CA) projections to the hypoglossal motor nucleus (Mo12) and the adjacent viscerosensory nucleus of the solitary tract (NTS). In 10 Sprague-Dawley rats, retrograde tracers, Fluoro-Gold or B sub-unit of cholera toxin, were microinjected (5-20 nl) into the Mo12, NTS, or both nuclei. Tyrosine hydroxylase (TH) was used as a marker for CA neurons. Following tracer injections into the Mo12, retrogradely labeled and TH-positive neurons were found in the A1/C1 (18.5%), A5 (43.5%), A7 (15.0%), and sub-coeruleus (21.0%) regions, and locus coeruleus (1.7%). In contrast, following injections into the NTS, these proportions were: 48.0, 46.5, 0.2, 0.9, and 4.3%, respectively. The projections to both nuclei were bilateral, with a 3:2 ipsilateral predominance. In four animals with one tracer injected into the Mo12 and the other in NTS, TH-positive cells containing both tracers were found only in the A5 region. Thus, the pontomedullary sources of CA projections to the Mo12 and NTS differ, with only A1/C1 and A5 groups having significant projections to these two functionally distinct targets. #

Nuclei of origin of monoaminergic, peptidergic, and cholinergic afferents to the cat trigeminal motor nucleus: A double-labeling study with cholera-toxin as a retrograde tracer

Journal of Comparative Neurology, 1990

The aim of the present study was to determine the brainstem afferents and the location of neurons giving rise to monoaminergic, cholinergic, and peptidergic inputs to the cat trigeminal motor nucleus (TMN). This was done in colchicine treated animals by using a very sensitive double immunostaining technique with unconjugated cholera-toxin B subunit (CT) as a retrograde tracer.After CT injections in the TMN, retrogradely labeled neurons were most frequently seen bilaterally in the nuclei reticularis parvicellularis and dorsalis of the medulla oblongata, the alaminar spinal trigeminal nucleus (magnocellular division), and the adjacent pontine juxta-trigeminal region and in the ipsilateral mesencephalic trigeminal nucleus. We further observed that inputs to the TMN arise from the medial medullary reticular formation (the nuclei reticularis magnocellularis and gigantocellularis), the principal bilateral sensory trigeminal nucleus, and the dorsolateral pontine tegmentum.In addition, the present study demonstrated that the TMN received (1) serotonergic afferents, mainly from the nuclei raphe obscurus, pallidus, and dorsalis; (2) catecholaminergic afferent projections originating exclusively in the dorsolateral pontine tegmentum, including the Kölliker-Fuse, parabrachialis lateralis, and locus subcoeruleus nuclei; further, that (3) methionin-enkephalin-like inputs were located principally in the medial medullary reticular formation (nuclei reticularis magnocellularis and gigantocellularis and nucleus paragigantocellularis lateralis), in the caudal raphe nuclei (Rpa and Rob) and the dorsolateral pontine tegmentum; (4) substance P-like immunoreactive neurons projecting to the TMN were present in the caudal raphe and Edinger-Westphal nuclei; and 5) cholinergic afferents originated in the whole extent of the nuclei reticularis parvicellularis and dorsalis including an area located ventral to the nucleus of the solitary tract at the level of the obex.In the light of these anatomical data, the present report discusses the possible physiological involvement of TMN inputs in the generation of the trigeminal jaw-closer muscular atonia occurring during the periods of paradoxical sleep in the cat.

Gating of transmission to motoneurones by stimuli applied in the locus coeruleus and raphe nuclei of the cat

The Journal of physiology, 1993

1. Neuronal systems activated by stimulation in the region of the locus coeruleus/subcoeruleus (LC/SC) and raphe nuclei have previously been shown to depress transmission from group II muscle afferents in regions of the midlumbar spinal segments in which premotor interneurones are located. The aim of the present investigation was to determine the extent to which such depression is paralleled by depression of the reflex actions of group II afferents on motoneurones. 2. The effects of short trains of conditioning electrical stimuli applied within the LC/SC and raphe nuclei were examined on postsynaptic potentials (PSPs) evoked by group I and group II muscle afferents in hindlimb motoneurones. The effects were examined over a wide range of conditioning-test intervals but particular emphasis was placed on the effects produced at long intervals (> 100 ms) since such effects are more likely to be mediated by the descending noradrenergic and serotonergic neurones of the LC/SC and raphe ...

Transmission from group II muscle afferents is depressed by stimulation of locus coeruleus/subcoeruleus, K�lliker-Fuse and raphe nuclei in the cat

Experimental Brain Research, 1992

The effects of brief trains of electrical stimuli applied within the locus coeruleus and subcoeruleus, the K611iker-Fuse nucleus and the raphe magnus, obscurus and pallidus nuclei were tested on transmission from group I and group II muscle afferent fibres in mid-lumbar spinal segments of chloralose anaesthetized cats. Changes in the effectiveness of transmission from these afferents were assessed from changes in the size of monosynapt'c extracellular field potentials evoked by them. The depression of group II field potentials occurred at conditioningtesting intervals of 20-400 ms, and was maximal at intervals of 40-100 ms and 30-60 ms for potentials recorded in the intermediate zone and dorsal horn, respectively. At intervals up to about 30 ms it was combined with the depression of group I components of the intermediate zone field potentials. However, at longer intervals the conditioning stimuli depressed group II components of these potentials as selectively as monoamines applied ionophoretically at the recording site (Bras et al., 1989a, 1990). Thus, only the late depressive actions are considered as being possibly mediated by impulses in descending noradrenergic and/or serotonergic fibres. No major differences were found in the relative degree of depression of transmission from group II afferents by stimulation of the locus coeruleus/subcoeruleus, K611iker-Fuse or raphe nuclei, either in the dorsal horn or in the intermediate zone. Since field potentials at these locations are preferentially depressed by ionophoretic application of serotonin and noradrenaline (Bras et al., 1990), and since the locus coeruleus/subcoeruleus, K611iker-Fuse and raphe nuclei are interconnected, the study leads to the conclusion that both noradrenergic and serotonergic descending pathways can be activated by stimuli applied within either of them. Selective depression of field potentials of group II origin was also evoked by stimulation at other sites, e.g. the periaqueductal grey and medullary

Pattern of monosynaptic Ia connections in the cat forelimb

The Journal of physiology, 1989

1. In anaesthetized cats intracellular records were obtained from antidromically identified motoneurones. The motor nuclei to the elbow extensor and flexor muscles and to the muscles innervated by the deep radial, ulnar and median nerves were investigated. The maximum Ia EPSPs from electrical stimulation of various peripheral nerves were measured. The characteristic convergence and projection patterns to each motor nucleus were established from pooled data. 2. The total aggregates of the Ia EPSPs between the different motor nuclei ranged from 3.5 to 11.7 mV. The smallest aggregates were found in the nuclei to the digit muscles. The ratio of the heteronymous versus homonymous EPSP amplitudes varied between 3.9 and 0.5. A general rule which would govern the distribution of the EPSP aggregates, such as a proximo-distal gradient, was not observed. 3. The Ia connections followed a complex but highly organized pattern. Bidirectional and unidirectional pathways were present. In many cases ...

Immunohistochemical properties of motoneurons supplying the trapezius muscle in the rat

Polish Journal of Veterinary Sciences, 2011

Combined retrograde tracing (using fluorescent tracer Fast blue) and double-labelling immunofluorescence were used to study the distribution and immunohistochemical characteristics of neurons projecting to the trapezius muscle in mature male rats (n=9). As revealed by retrograde tracing, Fast blue-positive (FB + ) neurons were located within the ambiguous nucleus and accessory nucleus of the grey matter of the spinal cord. Immunohistochemistry revealed that nearly all the neurons were cholinergic in nature [choline acetyltransferase (ChAT)-positive]. Retrogradely labelled neurons displayed also immunoreactivities to calcitonin gene-related peptide (CGRP; approximately 60% of FB + neurons), nitric oxide synthase (NOS; 50%), substance P (SP; 35%), Leu 5 -Enkephalin (LEnk; 10%) and vasoactive intestinal polypeptide (VIP; 5%). The analysis of double-stained tissue sections revealed that all CGRP-, VIP-and LEnk-immunoreactive FB + perikarya were simultaneously ChAT-positive. The vast majority of the neurons expressing SP-or NOS-immunoreactivity were also cholinergic in nature; however, solitary somata were ChAT-negative. FB + perikarya were surrounded by numerous varicose nerve fibres (often forming basket-like structures) immunoreactive to LEnk or SP. They were also associated with some CGRP-, NOS-and neuropeptide Y-positive nerve terminals.

The vertebrate neuromuscular junction. Edited by M. M. Salpeter from the seriesNeurology and Neurobiology 23. Alan R. Liss, Inc., New York, 1987, 439 pp

Synapse, 1988

Book Reviews GABAERGIC MECHANISMS IN THE MAMMALIAN PERIPH-Also, the sequence of chapters does not appear to fol-ERY. Edited by Sandor L. Erdo and Norman G. Bow-low any order in that two chapters on the ovary are ery. Raven Press, New York, 1986. separated by one on the pancreas. This problem could have been rectified by using subsections that would As a neuroscientist with many years of study devoted contain articles related to one specific organ. However, to GABA neuronal function in the mammalian central the lack of such organization is partially compensated nervous system, I have overlooked in my readings many by the excellent subject index that is located at the end of the studies that have reported on GABA function in of the volume. This index facilitates finding the pertithe peripheral nervous system and in other organs of nent citations on a particular subject. the body. This volume is a welcome addition to my The overall quality of the chapters in this volume is library because it successfully provides the reader with high. They are well written and most of them are illusa comprehensive review of GABAergic mechanisms in trated with line drawings, graphs or photomicrographs. such diverse non-brain structures as the autonomic gan-The list of references found at the back of each chapter glia, gut, urinary bladder, female genital tract, pitu-provides a n excellent source for additional readings. itary, pineal gland, liver, adrenal medulla and the Many of the chapters have a summary at the conclusion vascular system. The editors are to be commended for of the text. Although it is somewhat disappointing that compiling into this volume a number of review articles not all of the chapters have these helpful summary from experts on these subjects. To their credit, they have sections, it certainly does not detract from the usefulincluded 23 chapters as well as a lengthy Foreword that ness of this book. together form a n impressive and useful volume. In conclusion, "GABAergic Mechanisms in the Mam-The book is organized into two sections, Elements of malian Periphery" demonstrates that GABA is found in GABAergic Systems in Peripheral Tissues of Mammals many organs of the body and its presence in the periphand Role of Local GABAergic Mechanisms in Peripheral ery is linked to some important functions. A usual ben-Organs. The first section covers the biochemical and efit of such books is to stimulate more research in a anatomical distribution of GABA, its associated en-field. I predict that this volume will foster further rezymes (glutamate decarboxylase and GABA-transami-search interest in the mysteries of GABA in the nase) and receptors. The chapters in the second section periphery. explore GABAergic mechanisms in a number of organs and provide some functional significance. Unfortunately, the organization of the book has some flaws. For example, the illuminating Foreword by Eugene Roberts, a pioneer in GABA research in the brain and spinal cord, is not listed in the table of contents.

Ultrastructural evidence for selective GABAergic innervation of CNS vagal projections to the antrum of the rat

Autonomic Neuroscience, 2011

We reported pharmacological data suggesting that stimulation of a vago-vagal reflex activates GABAergic neurons in the hindbrain that inhibit dorsal motor nucleus of the vagus (DMV) neurons projecting to the antrum, but not to the fundus (Ferreira et al., 2002). The purpose of this study was to use an ultrastructural approach to test the hypothesis that GABAergic terminals form synapses with DMV antrum-projecting neurons, but not with DMV fundus-projecting neurons. A retrograde tracer, CTB-HRP, was injected into the gastric smooth muscle of either the fundus or the antrum of anesthetized rats. Animals were re-anethetized 48 hours later and perfusion-fixed with acrolein and paraformaldehyde. Brainstems were processed histochemically for CTB-HRP, and immunocytochemically for glutamic acid decarboxylase isoenzyme 67 immunoreactivity (GAD67-IR) by dual-labeling electron microscopic methods. Most cell bodies and dendrites of neurons that were retrogradely labeled from the stomach occurred at the level of the area postrema. Examination of 214 synapses on 195 neurons that projected to the antrum revealed that 23.0 +/− 3.6% (n=4) of synaptic contacts were with GAD67-IR terminals. The examination of 220 synapses on 203 fundus-projecting neurons revealed that only 7.9 +/− 3.1% (n=4) of synaptic contacts were with GAD67-IR terminals. The difference between GAD67-IR synaptic contacts with antrum-and fundus-projecting neurons was statistically significant (p < 0.05). These data suggest that brainstem circuitry controlling the antrum involves GABAergic transmission.