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S R Vincent

Publications and source records attributed to S R Vincent.

At least 127 records · Page 7Linked to original sources
PubMed1982

A histochemical study of GABA-transaminase in the efferents of the pallidum.

Kainic acid lesions of the globus pallidus reduce the histochemically detectable GABA-transaminase activity in the ipsilateral subthalamic nucleus. A similar decrease in enzyme activity occurs in the lateral habenula following lesions of the entopeduncular nucleus. Previous results on the localization of GABA-transaminase in efferents of the striatum indicated that such histochemistry may be a useful adjunct for the demonstration of GABA pathways. The present data are consistent with some previous literature indicating that these two pallidal efferents may contain GABA.

4-Aminobutyrate Transaminase↗
PubMed1982

Immunohistochemical demonstration of plasticity in GABA neurons of the adult rat dentate gyrus.

The distribution of GABA fibers within the dentate gyrus was immunohistochemically examined following lesions of the entorhinal cortex in the adult rat. A major change in the pattern of the GAD immunoreactive fibers within the molecular layer, characterized by a marked increase in the density of fibers in the outer molecular layer, was observed. This change in the lamination of the dentate GABA fibers following entorhinal lesions appeared very similar to the changes which occur in acetylcholinesterase staining following entorhinal denervation of the dentate. These results provide morphological support for the sprouting of GABA fibers in the dentate gyrus in response to perforant path destruction.

Acetylcholinesterase↗
PubMed1982

Coexistence of somatostatin- and avian pancreatic polypeptide (APP)-like immunoreactivity in some forebrain neurons.

The indirect immunofluorescence technique was used to demonstrate the coexistence of somatostatin together with avian pancreatic polypeptide-like immunoreactivity within certain neurons of the rat forebrain. Numerous neurons containing these peptides were observed in the neocortex, hippocampus, olfactory tubercle, striatum, nucleus accumbens and lateral septum. In studies of serial sections stained alternately for these two peptides, and in restaining experiments, It could be determined that in many neurons in these areas these two peptides coexisted. In other brain areas such as the anterior periventricular hypothalamus, somatostatin cells were never found to contain avian pancreatic polypeptide-like immunoreactivity. Also, within the pancreas these two peptides were never found to coexist in the same cells. The findings represent a further example of the coexistence of more than one neuropeptide within a single neuron.

Animals↗
PubMed1982

GABA neuron systems in hypothalamus and the pituitary gland. Immunohistochemical demonstration using antibodies against glutamate decarboxylase.

The distribution of gamma-aminobutyric acid (GABA) nerve fibers and cell bodies in the rat hypothalamus and pituitary gland was immunohistochemically examined using antibodies against the GABA-synthesizing enzyme glutamate decarboxylase (GAD). The dense network of GAD-positive nerve fibers was observed to be essentially evenly distributed throughout the hypothalamus. A plexus of GABA terminals was also demonstrated both in the median eminence and with in the posterior and intermediate lobes of the pituitary. Three distinct clusters of magnocellular GABA neurons were discovered in the posterior hypothalamus. In the addition, GAD immunoreactive cell bodies were observed in many other hypothalamic nuclei, such as the arcuate nucleus and in the perifornical region. The results provide a morphological basis by which GABA of hypothalamic origin may regulate the neuroendocrine system.

Animals↗
PubMed1981

The histochemical localization of GABA-transaminase in the efferents of the striatum.

The striatum is known to contain GABA neurons projecting to the globus pallidus, entopeduncular nucleus and substantia nigra. Following lesions of striatal neurons with kainic acid, we have observed a decrease in the histochemically detectable activity of GABA-transaminase, the enzyme responsible for GABA catabolism, in both the striatum and in those areas to which it is known to send GABA projections. These results suggest that GABA-transaminase may be contained in striatal GABA neurons and thus that GABA-transaminase histochemistry may be a useful adjunct to the biochemical demonstration of GABA pathways in the brain.

4-Aminobutyrate Transaminase↗
PubMed1981

A substance P projection to the hippocampus.

Electrolytic lesions of the septal area in the rat resulted in a major decrease in the activity of choline acetyltransferase in the hippocampus, consistent with the interruption of the septo-hippocampal cholinergic pathway. These lesions also significantly decreased the levels of substance P in the hippocampus. It is suggested that a substance P projection to the hippocampus arises in or passes through the septal area.

Animals↗
PubMed1981

Organization of substance P fibers within the hippocampal formation demonstrated with a biotin-avidin immunoperoxidase technique.

The distribution of substance P-containing fibers within the hippocampal formation of the cat was examined using an immunohistochemical approach. A new, indirect immunoperoxidase method based on the high affinity binding of vitamin H (biotin) by avidin was developed to demonstrate substance P-like immunoreactive fibers. The neocortex contained only occasional single substance P fibers. In contrast, the archicortical structures contained a well organized substance P innervation. The entorhinal area of the parahippocampal gyrus contained a delicate network of varicose axons which appeared to ascend from the subcortical white matter to terminate predominantly in layer II. The subiculum contained a network of positive varicosities throughout the neuropil of both the pyramidal and the molecular layers. These substance P terminals appeared to arise, at least in part, from fibers entering laterally across the angular bundle. Within the ventral hippocampus the substance P innervation was predominantly in the pyramidal cell layer, and was heaviest in field CA3 and weakest in CA1. Some fibers were also observed in strata oriens, lucidum, and radiatum. Occasional varicose fibers could be seen entering the hippocampus from the fimbria. Within the dentate gyrus the substance P fibers were most concentrated in the supragranular layer and among the more superficial of the granule cells. A moderately dense plexus of fibers also occurred in the neuropil of the hilus among the polymorphic cells. In addition, a distinct, narrow band of varicosities was found at the outer edge of the inner molecular layer, while the outer molecular layer did not contain any positive elements. It is concluded that the hippocampal formation receives a distinct, well organized substance P innervation. Substance P fibers appear to enter the hippocampus both laterally across the angular bundle and ventrally through the fimbria. From this detailed examination of the distribution of the substance P fibers within the hippocampus in relation to the other known inputs to this area it is suggested that many of the substance P fibers arise in or, more probably, pass through the septal area to innervate the hippocampus.

Animals↗
PubMed1980

Neurotransmitters contained in the efferents of the striatum.

The transmitters contained in the efferent projections of the striatum were studied by producing two types of lesions: coronal hemitransections just anterior to the globus pallidus, and semi-circular knife cuts that isolated a considerable portion of the globus pallidus from the striatum to produce 'GP islands'. The levels of substance P and Met-enkephalin in the globus pallidus, entopeduncular nucleus and substantia nigra were measured after these lesions. For comparison, the effect of these lesions on glutamic acid decarboxylase (GAD) and choline acetyltransferase (CAT) in some of these projection areas of the striatum was assessed. Both lesions caused similar reductions in substance P levels in each of the three striatal projection areas. In contrast, hemitransections reduced Met-enkephalin levels only in the globus pallidus. Both lesions reduced pallidal and entopeduncular GAD activity while nigral GAD activity was reduced only by the hemitransections. CAT activity was reduced in the globus pallidus by both lesions but was unaltered in the entopeduncular nucleus. However, additional experiments ruled out the existence of a striato-pallidal cholinergic projection. GAD activity and Met-enkephalin levels were significantly increased in the striatum anterior to the lesions. In contrast, CAT activity and substance P levels did not change in this region. The results support and broaden emerging view of the organization of the neurons containing the various transmitter candidates of the efferent projections of the striatum.

Animals↗
PubMed1980

Neurotoxic action of capsaicin on spinal substance P neurons.

The effects of capsaicin injections into neonatal rats on the ultrastructure of the neonatal dorsal horn and on some biochemical and behavioral parameters in the adult were examined. Electron microscopic observations revealed degeneration and glial engulfment of boutons and umyelinated axons in the dorsal horn 2 and 6 h after neonatal subcutaneous capsaicin injections. Capsaicin treatment had no effect on the activities of glutamic acid decarboxylase and choline acetyltransferase in the dorsal horn. Results of substance P measurements in the CNS showed no effect of capsaicin administration on striatal, hypothalamic or nigral substance P content, whereas substance P levels in the dorsal horn of the spinal cord were reduced by half. The density of [3H]naloxone binding sites in the dorsal horn was significantly reduced, while the affinity was not affected. Capsaicin-treated animals showed significantly increased latencies to respond to a noxious thermal stimulus in both tail-flick and hot-plate tests. The results are discussed in relation to the current concepts of the involvement of substance P and opiate systems in nociception and the potential use of neonatal capsaicin as a selective neurotoxin for the elucidation of the spinal mechanisms of pain.

Animals↗
PubMed1980

A comparison of sodium-dependent glutamate binding with high-affinity glutamate uptake in rat striatum.

The specific sodium-dependent binding of [3H]glutamate to membranes of the rat striatum was examined and a comparison made with high affinity glutamate uptake. In the presence of sodium, [3H]glutamate binding was saturable and of high affinity. No binding could be detected in the absence of sodium. Removal of the cortical afferents to the striatum resulted in a parallel decrease in Na+-dependent glutamate binding and in high-affinity glutamate uptake. After the injection of the neurotoxin kainic acid into the striatum, the density of Na+-dependent glutamate binding sites was reduced by 40%, while high-affinity uptake showed no significant decrease. Drugs which inhibit high-affinity uptake were also effective at inhibiting Na+-dependent binding. The results suggest that about half the Na+-dependent glutamate binding sites in the striatum represent high-affinity uptake sites on the corticostriatal terminals. The remainder of the binding sites are located on striatal neurons and may also be uptake sites.

Animals↗
PubMed1980

The pharmacohistochemical demonstration of GABA-transaminase.

A method for the histochemical demonstration of cells with the capacity to synthesize the enzyme GABA-transaminase is described. Intraventricular injection of ethanolamine-O-sulfate irreversibly inhibits brain GABA-transaminase activity. Within 17 h after the injection sufficient new enzyme is synthesized to allow histochemical visualization of positive soma against unstained neuropil. The implications of this technique for the anatomy of GABA systems is discussed.

4-Aminobutyrate Transaminase↗
PubMed1979

Morphine, naloxone and kainic acid neurotoxicity.

Local neuronal damage, as indicated by choline acetyltransferase and glutamate decarboxylase activities, elicited by intrastriatal injections of kainic acid was increased by local injection of morphine and decreased by prior injection of naloxone. Peripheral injections of morphine or naloxone had little significant effect although the same trends appeared.

Animals↗