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V Chan-Palay

Publications and source records attributed to V Chan-Palay.

At least 55 records · Page 3Linked to original sources

Somatostatin-like immunoreactive neurons in the hippocampus: an immunocytochemical study in the rat.

Using antibodies to somatostatin in combination with the avidin-biotin immunohistochemical method, the laminar distribution and morphology of somatostatin-like (SOM-L) immunoreactive cells have been studied in the hippocampal formation of the rat. SOM-L positive cells are present throughout the longitudinal axis of the hippocampus. Most of these neurons are of medium (15-20 micrometers) to large (25-30 micrometers) size with soma of multipolar or fusiform shape. No pyramidal or granule cells contained SOM-L immunoreactivity. SOM-L-positive cells show a preferential distribution in the stratum oriens and stratum pyramidalae of Ammon's horn, and match the description of the polymorphic cells of the hilus area dentata. This geographic segregation may imply a chemical compartmentation of function in the hippocampus.

Animals↗

The distribution of cholecystokinin-like immunoreactive neurons and nerve terminals in the retrohippocampal region in the rat and guinea pig.

The distribution of cholecystokinin (CCK)-like (CCK-L) immunoreactive cells and nerve terminals was studied in the brains from rats and guinea pigs by using antibodies to the octapeptide cholecystokinin (CCK-8). Analysis of serial horizontal and sagittal sections through the retrohippocampal region in colcicine-pretreated rats revealed a relatively large number of CCK-L immunoreactive cells in the pre- and parasubiculum, subiculum, and the medial and lateral entorhinal area (EA) at all dorsal to ventral levels of the region. In the EA, the CCK-positive cells were scattered in all layers without any clear pattern. Analysis of CCK-positive cells in the retrohippocampal region showed that these cells form a morphologically heterogeneous group. The types of CCK-L immunoreactive cells ranged from small (approximately 10 micrometers) round, ovoid, or fusiform to large (approximately 30 micrometers) multipolar and pyramidal. CCK-L immunoreactive nerve fibers and preterminal processes were unevenly distributed in the retrohippocampal region. The densest innervation was found in the parasubiculum, subiculum, and the ventrolateral entorhinal area. Only a few scattered fibers were detected in the molecular layers of these structures and the outer layers of the presubiculum. Within the EA and CCK innervation indicated a heterogeneous laminar distribution that was densest in layers II and IV of the medial and lateral EA and diffuse in layers I and II. In layer II the immunoreactive nerve terminals encircled the pyramidal cell bodies, while in layers IV to VI and the most ventral part of lateral entorhinal area (LEA) and the transitional area between LEA and piriform cortex the CCK processes were distributed in a netlike fashion without clear relation to the cytoarchitectural characteristics of the area.

Animals↗

The distribution and origin of serotonin-containing fibers in the septal area: a combined immunohistochemical and fluorescent retrograde tracing study in the rat.

The distribution of 5-hydroxytryptamine (serotonin, 5-HT)-containing nerve fibers and terminals in the septal area of the rat was studied by using immunohistochemistry with specific antibodies to 5-HT in combination with fluorescent retrograde tracing methods. The 5-HT innervation of the septum is heterogeneous with regard to both the morphology of individual processes and the density of distribution in different parts of the septum. Three major classes of 5-HT like immunoreactive processes can be distinguished: 1) thin, convoluted fibers with small, round or elongated varicosities; 2) thick and relatively straight fibers with few varicosities; and 3) pericellular plexuses with large varicosities in close association with perikarya in the lateral septum. Three areas of the septum receive a prominent innervation by 5-HT processes: the diagonal band of Broca, the ventral part of the lateral septum, and an area bordering the medial edge of the islands of Calleja (insula magna). Whereas the two latter areas contain dense terminal networks, the diagonal band of Broca is occupied primarily by 5-HT fibers en route to other parts of the septum. Intraseptal injections of HRP or fluorescent dyes (granular blue, propidium iodide) resulted in retrograde labeling of neuronal cell bodies in several nuclei of the brainstem which are known to contain 5-HT neurons: the dorsal raphe, the median raphe, the nucleus reticularis tegmenti pontis, the raphe pontis, and the raphe magnus. Where fluorescent retrograde tracing was performed with 5-HT immunohistochemistry on the same tissue section, a prominent 5-HT containing pathway and a non-5-HT-containing pathway from the raphe nuclei to the septum were revealed. Finally, double retrograde fluorescent labeling after injections of granular blue or propidium iodide into the septum and entorhinal area respectively of the same rat revealed extensive branching of the raphe efferents. Thus, individual raphe neurons may simultaneously connect with septum and the entorhinal area, two structures essential for normal hippocampal function.

Animals↗

Inhibitory effects of motilin, somatostatin, [Leu]enkephalin, [Met]enkephalin, and taurine on neurons of the lateral vestibular nucleus: interactions with gamma-aminobutyric acid.

Motilin, [Met]enkephalin, [Leu]enkephalin, somatostatin, taurine, gamma-aminobutyric acid (GABA), and glycine were tested for their effects on Deiters neurons of the lateral vestibular nucleus in rabbits. Iontophoresis was carried out with multibarrelled micropipettes. All four peptides and three amino acids produced depression of neuron firing. No facilitatory responses were observed. The depressant action of each peptide when iontophoresed alone was dose-dependent and was rapid in onset and recovery. Their characteristic actions suggest the possibility of their independent roles as strong inhibitors, although the experimental paradigm does not allow conclusions about the individual potency of each peptide. When GABA was administered together with motilin, [Met]enkephalin, or somatostatin, the effects of the peptide and GABA were additive, producing depression greater than that with application of either substance alone. When GABA was applied in conjunction with [Leu]enkephalin, more complex interactions were observed. At low iontophoretic currents, [Leu]enkephalin antagonized the action of GABA, producing a depression less than that of GABA alone and of considerably slower onset, suggesting an additional modulatory effect. These observations support the conclusion that all substances tested are chemical mediators in the lateral vestibular nucleus and [Leu]enkephalin may be a neuromodulator as well. Because recent immunocytochemical studies indicate that Purkinje cells in the cerebellar cortex are chemically heterogeneous and exhibit immunoreactivity for motilin, taurine, the enkephalins, and somatostatin, as well as for the GABA-synthesizing enzyme glutamic acid decarboxylase, it is suggested that the Purkinje cell projections to vestibular and cerebellar nuclei are multimodal in their chemical coding. The uniformly depressant action of the peptides and amino acids reported here is consistent with earlier observations that Purkinje cells exert an inhibitory influence on the vestibular and central cerebellar nuclei.

Action Potentials↗

Sagittal cerebellar microbands of taurine neurons: immunocytochemical demonstration by using antibodies against the taurine-synthesizing enzyme cysteine sulfinic acid decarboxylase.

Taurine neurons in the cerebellum of rabbit, rat, and mouse were localized at the light microscope level by using polyclonal antibodies against cysteine sulfinic acid decarboxylase (CSADCase; EC 4.1.1.29), the enzyme responsible for the conversion of cysteine sulfinic acid to hypotaurine and of cysteic acid to taurine. The indirect peroxidase-antiperoxidase method was used on Vibratome sections and on serial sections of paraffin-embedded tissue. Intensification of CSADCase immunoreactivity was achieved by pretreatment of the animal with L-cysteine or L-cysteic acid intravenously 1-2 hr prior to perfusion. A combination of L-cysteic acid and demecolcine, which retards axoplasmic flow, was most effective in maximizing CSADCase immunoreactivity. Although these treatments intensified immunoreactivity in neurons, no more cells were reactive than in untreated controls. L-Glutamic acid did not increase CSADCase immunoreactivity but did increase immunoreactivity with antibodies against L-glutamic acid decarboxylase (GAD; EC 4.1.1.15), the synthetic enzyme for gamma-aminobutyric acid. Specificity was established by negative results obtained with various control incubations including the use of CSADCase antiserum preabsorbed with the antigen. Taurine neurons of the cerebellar cortex are arranged in sagittal microbands, defined by intensely CSADCase-reactive Purkinje neurons and their axons and dendrites, together with stellate, basket, and Golgi cells and their processes. In the vermis there is a narrow midline band, flanked laterally by three wider bands on either side, each separated from the next by an unreactive zone. Although the zonal borders are sharp, the interzonal areas contain some CSADCase-immunoreactive axons but no cell bodies. The seven vermal bands are best observed in the anterior lobe. Others exist in the lateral hemispheres. The paraflocculus and flocculus contain numerous intensely immunoreactive neurons, and banding is difficult to discern. Lobule X of the vermis is also heavily endowed with taurine neurons. Numerous large and medium-sized deep cerebellar and vestibular nuclei are also immunoreactive. These observations indicate that cerebellar neurons are chemically heterogeneous but that neurons of similar chemical signature in the cerebellar cortex are organized into sagittal microbands. This corroborates our earlier evidence that Purkinje cells containing motilin and those containing both motilin and gamma-aminobutyric acid are also arranged in vermal sagittal microbands. The midline vermal band contains Purkinje neurons with multiple neuroactive substances-taurine, gamma-aminobutyric acid, and motilin. It remains to be determined how this chemical zonation in the cerebellar cortex relates to the banded afferent innervation from spinal, vestibular, reticular, and olivary sources.

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Synthesizing enzymes for four neuroactive substances in motor neurons and neuromuscular junctions: light and electron microscopic immunocytochemistry.

Immunocytochemical evidence is presented for the existence of choline acetyltransferase (ChoAcTase), cysteine sulfinic acid decarboxylase (CSADCase), tyrosine hydroxylase (TyrOHase), and glutamic acid decarboxylase (GluDCase) in large motor neurons of the hypoglossal nucleus and the spinal cord and in nerve terminals of motor end plates in tongue and skeletal muscle of five mammalian species, including man. These enzymes, which are responsible for the synthesis of acetylcholine (AcCho), taurine, dopamine, and gamma-aminobutyrate (GABA), respectively, were detected by immunocytochemical studies with monoclonal or polyclonal antibodies raised against the enzymes. Electron microscopy of the neuromuscular junctions showed that the immunoreactivity in each case was confined to the cytoplasmic matrix of presynaptic nerve terminals. Immunoreactivity obtained for each enzyme antibody varied with the species. It was highest in fresh, unfixed muscle and lowest in aldehyde-fixed specimens. Negative controls were obtained with preimmune sera and antisera preabsorbed with pure ChoAcTase, CSADCase, or GluDCase antigen. Double-labeling studies with ChoAcTase antibodies and acetylcholinesterase (AcChoEase) antibodies, AcChoEase enzyme activity, or alpha-bungarotoxin binding indicated that ChoAcTase, AcChoEase, and AcCho receptors were colocalized at the same end plates.

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Coexistence in human and primate neuromuscular junctions of enzymes synthesizing acetylcholine, catecholamine, taurine, and gamma-aminobutyric acid.

Coexistence of neurotransmitter-synthesizing enzymes choline acetyltransferase, cysteine sulfinic acid decarboxylase, tyrosine hydroxylase, and L-glutamic acid decarboxylase was demonstrated at human and primate neuromuscular junctions with specific antibodies directed against these enzymes. Motor end plates were identified in unfixed cryostat sections by standard cholinergic markers for acetylcholinesterase and the acetylcholine receptor. Each of the four transmitter-synthesizing enzymes was localized at end plates displaying these markers. The presence of any two of the four enzymes at a given end plate was established by (i) showing immunoreaction for one enzyme followed by elution and demonstration of immunoreaction for a second enzyme, and (ii) paired immunofluorescence with simultaneous demonstration of one enzyme with a rhodamine-labeled second antibody and of the other enzyme with a fluorescein-labeled second antibody. These findings imply that motor nerve terminals have the capacity for synthesizing not only acetylcholine but also taurine, catecholamines, and gamma-aminobutyric acid. These substances, in turn, may participate in the normal regulation of nerve-muscle interaction or be significant in specific disorders involving the motor unit.

Acetylcholine↗

Taurine in the mammalian cerebellum: demonstration by autoradiography with [3H]taurine and immunocytochemistry with antibodies against the taurine-synthesizing enzyme, cysteine-sulfinic acid decarboxylase.

Taurine neurons and their dendrites and axons were visualized in the mammalian cerebellum by autoradiography, after in vivo injections of [(3)H]taurine directly into the cerebellar cortex or deep cerebellar nuclei, and by immunocytochemistry at the light- and electron-microscope levels with antibodies against cysteine-sulfinic acid decarboxylase (CSADCase; L-cysteine-sulfinate carboxylyase, EC 4.1.1.29). Uptake and sequestration of [(3)H]taurine labeled numerous Purkinje cell somata, primary dendrites, and axons; many granule cell somata, dendrites, and parallel fibers; stellate, basket, and Golgi cells; the larger neurons in all deep cerebellar nuclei; the largest neurons in the lateral vestibular nucleus; and, more rarely, Purkinje cell axonal terminals in the neuropil. The label at all sites was diminished by preinjection into the cerebellum of hypotaurine, p-chloromercuriphenylsulfonic acid, or beta-alanine, and was virtually eliminated by strychnine. Immunocytochemical labeling with polyclonal antibodies directed against CSADCase, the enzyme responsible for the synthesis of hypotaurine from cysteine sulfinic acid and taurine from cysteic acid, had a similar distribution. In electron micrographs, immunoreactivity within Purkinje cell somata and dendrites was localized to the Golgi apparatus, the inner plasma membrane, and condensed nonmembranous foci (120 nm in diameter) marked by clumps of peroxidase reaction product. Large Nissl bodies were usually not CSADCase immunoreactive. Numerous immunoreactive granule cells, dendrites, and parallel fibers were recognized. Pretreatment of the animals with colchicine increased the intensity of CSADCase immunoreactivity but did not change the number or distribution of labeled cells. These experiments indicate that taurine is synthesized and involved in a specific uptake process by cerebellar neurons. Neuroglial cells do not synthesize taurine but some neuroglia take up [(3)H]taurine. These findings call for a reexamination of the physiological function of taurine in the cerebellum. A hypothesis is proposed that taurine may be involved in the regulation of calcium, in dendritic spike generation, and in the inhibition of impulse propagation in major Purkinje cell dendrites.

Animals↗

Evidence for the coexistence of serotonin and substance P in single raphe cells and fiber plexuses: combined immunocytochemistry and autoradiography.

Combined immunocytochemistry and autoradiography after in vivo injections of monoclonal antibody to Substance P and 3H-serotonin provide convincing evidence that the soma and processes of a single neuron can contain serotonin and immunoreactivity with another putative peptide transmitter Substance P in a single permanent preparation suitable for study with light and electron microscopy. The serotonin-Substance P cells have uptake systems for low molarity 3H-serotonin that are not affected by reserpine treatment. They are sensitive to serotonin uptake inhibitors and monoamine oxidase inhibitors and the cells are destroyed by 5,6-dihydroxytryptamine. They contain endogenous stores of serotonin detectable by the Falck-Hillarp technique and microspectrofluorimetry and immunofluorescence by antibody to serotonin. Their Substance P content is identified by specific binding with monoclonal antibody, and by animal antisera against Substance P. The raphe pallidus neurons are a mixed population -- some cells have a majority of Substance P immunoreactivity with little detectable serotonin, others have considerable quantities of both Substance P immunoreactivity and serotonin, and still others have only serotonin but are innervated by Substance P immunoreactive processes. These subtle differences in neuronal content of the two compounds are made more obvious by avoiding the use of colchicine, a drug known to inhibit fast axoplasmic transport. Such differences may be an expression of the dynamic or cyclic functions of neurons with multiple putative transmitter substances. Fluctuating levels of one or both substances may depend upon parameters of rhythm, demands for one or the other mediator during specific types or phases of activity. The fundamental scheme of simultaneous injection of multiple labels, one radioactive, another a specific characterized monoclonal antibody for the detection of multiple, separate transmitter systems opens vast avenues for future investigation.

Animals↗

The distribution and orientation of serotonin fibers in the entorhinal and other retrohippocampal areas. An immunohistochemical study with anti-serotonin antibodies in the rats brain.

The serotonin (5-hydroxytryptamine; 5-HT) innervation of the retrohippocampal region (subiculum, pre- and parasubiculum, area 29e, medial and lateral entorhinal area) in the rat brain has been examined with antibodies against 5-HT used in combination with fluorescence histochemistry. Analysis of consecutive sections cut in the coronal, sagittal, and horizontal planes revealed a widespread distribution of 5-HT immunoreactive fibers throughout the retrohippocampal region. This innervation was with regard to the morphological characteristics of the 5-HT fibers, their density and their spatial orientation. On the basis of morphological criteria, four different types of 5-HT positive processes were distinguished: (a) fine, convoluted fibers with small (approximately 0.5-0.8 micron), round and evenly spaced varicosities: (b) fine fibers with small elongated, irregularly distributed varicosities; (c) thick, possibly myelinated fibers, and (d) a terminal plexus with large (5-10 micron), irregularly spaced varicosities. Analysis of the laminar distribution of the 5-HT fibers showed that whereas all layers contain 5-HT positive fibers, the molecular layer was the most densely innervated. The 5-HT fibers were found to be oriented both parallel and transverse to the longitudinal axis of medial and lateral entorhinal area. This grid-like arrangement was less pronounced in the presubiculum. Although the 5-HT innervation of the retrohippocampal region was found to be dominated by a widespread and apparently diffuse pattern, several areas contained dense clusters of preterminal 5-HT processes: area 29e, dorsal presubiculum (layer II), lateral entorhinal area (layer III and ventral layer II) and the transitional zone of the ventral entorhinal area. The 5-HT fibers were found to enter the retrohippocampal region primarily by three different routes; from the ventral and dorsal aspects and from the piriform and lateral neocortex (via the perirhinal area). Most of the fibers enter the region by the ventral route and these were found to ascend in all layers but predominantly in layer I. The location of the 5-HT cells giving rise to the innervation of the entorhinal area was studied by combining retrograde transport of fluorescent tracers with immunohistochemistry on the same tissue section. Both ipsi- and contralaterally located cells in the dorsal and median raphe nuclei were found to project to the entorhinal area. Most, but not all, of these retrogradely labeled cell bodies also contain 5-HT immunoreactivity.

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The nucleus paragigantocellularis lateralis in the rat. Conformation and cytology.

The nucleus paragigantocellularis lateralis (PGCL) is located in the ventral portion of the rostral medulla. Serial sections of the rat brainstem were examined in the three cardinal planes and the boundaries of the PGCL were determined. In order to visualize the shape and extent of the nucleus, a three-dimensional reconstruction of the PGCL was made from a series of coronal sections. Measurements of neuronal areas, lengths, and widths indicate that a number of neuronal types are present. Small neurons measure less than 150 micron2 and large neurons greater than 250 micron2. Some neuronal types are distributed preferentially throughout the PGCL, and on this basis the nucleus may be divided into caudal and rostral subgroups. Most large neurons (greater than 250 micron2) are found in the caudal portion. Certain neurons contain intranuclear rods, and these neurons are often disposed in small groups, especially common the caudal PGCL. Two morphologically distinct neuronal types incorporate 3H-serotonin when this marker is infused into the ventricular system; the other neurons not marked by this method probably contain other, different transmitters. On the basis of neuronal measurements and staining qualities, it is ascertained that the PGCL is a parvocellular reticular nucleus characterized by many neuronal types.

Animals↗

The nucleus paragigantocellularis lateralis in the rat. Demonstration of afferents by the retrograde transport of horseradish peroxidase.

Injections of horseradish peroxidase (HRP) were placed in the middle or caudal portion of the nucleus paragigantocellularis lateralis (PGCL) and 24 h later the entire spinal cord and brain were processed and examined for labeled neurons. Spinal afferents arise from all levels of the cord. Rexed's lamination scheme was adapted to the spinal cord of the rat and labelled neurons were localized to laminae IV, V, VII, VIII and X mainly on the side contralateral to the injection. At cervical levels, labeled neurons were consistently found bilaterally. The medial reticular nuclei of the medulla and pons contained HRP-labelled perikarya, which were concentrated most heavily in the nuclei reticularis medullae oblongatae ventralis, gigantocellularis, and pontis caudalis predominantly ipsilateral to the injection. The medial vestibular nucleus was consistently labeled. HRP-labeled perikarya were found bilaterally within the commissural portion and in the medial part of the nucleus of the solitary tract on the side of the injection. The rostral portion of the PGCL receives afferents from some secondary auditory nuclei: the ipsilateral inferior colliculus and the posterior ventral cochlear nucleus bilaterally. Thus, the rostral PGCL may be involved in auditory feedback loops. The caudal raphe nuclei are a major source of afferents to the caudal PGCL. The lateral hypothalamic area, paraventricular nucleus, and zona incerta also contain labeled neurons when injections are centered in the caudal portion of the nucleus.

Animals↗

Chemical heterogeneity in cerebellar Purkinje cells: existence and coexistence of glutamic acid decarboxylase-like and motilin-like immunoreactivities.

Purkinje neurons of the cerebellar cortex from a chemically and morphologically heterogeneous population containing some members that have gamma-aminobutyric acid (GABA), others that have immunoreactivity for motilin, and a small number that have both. The remaining 30-40% of all Purkinje cells have neither of these two neuroactive substances, leaving possibilities for other transmitter candidates. The evidence was compiled from double-staining immunocytochemical procedures performed on single sections of the cerebellum and brain stem in rat, mouse, and monkey. Two polyclonal antibodies were applied in succession, one directed against the midregion and COOH terminus of the 22-amino acid polypeptide motilin and the other against glutamic acid decarboxylase (glutamate decarboxylase; L-glutamate 1-carboxy-lyase, EC 4.1.1.15), the rate-limiting enzyme in the synthesis of the neurotransmitter GABA. The staining combinations employed the immunoperoxidase method, with different chromogens for distinguishing the motilin-like immunoreactivity from glutamic acid decarboxylase immunoreactivity by different colors, or the immunoperoxidase method for one antiserum and immunofluorescence for the other. The locations of both motilin and GABA cell types were mapped. The recognition of motilin in Purkinje cells calls for experimental definition of the role of this substance in the cerebellum and for reevaluation of the roles of Purkinje cells and of GABA in cerebellar function. The significant motilin representation in the flocculus, paraflocculus, and vermis suggests that it may be the Purkinje cell mediative chemical in the vestibular parts of the cerebellum. However, the presence of GABA as well in the same regions indicates that the chemical preference may be at least bimodal.

Animals↗

Immunohistochemical localization of serotonin nerve terminals in the lateral entorhinal cortex of the rat: demonstration of two separate patterns of innervation from the midbrain raphe.

The distribution of serotonin (5-hydroxytryptamine, 5HT) containing nerve terminals in the lateral entorhinal cortex (LEC) has been studied using antibodies against 5-HT in combination with fluorescence histochemistry. Thin, varicose, branching fibers were found to be distributed in a relatively even, diffuse pattern throughout all layers of the LEC. The largest amount of this type of 5HT innervation was in Layer I. This diffuse pattern of 5-HT terminals was supplemented by a dense network of 5HT terminals restricted to Layer III of a small (approximately 1 mm) strip of the LEC. The fibers in this layer were thicker and more convoluted and contained larger varicosities than fibers in any other layer. The existence of a distinct innervation by 5-HT terminals of only a small portion of the LEC demonstrates a hitherto unrecognized and important principle of heterogeneity in 5-HT innervation of cortex. It suggests that 5-5HT neurons in the raphe can selectively influence specific, narrow regions of the lateral perforant path system, which, in turn, affect the intrinsic hippocampal circuits.

Animals↗

Autoradiographic experiments to examine uptake, anterograde and retrograde transport of tritiated serotonin in the mammalian brain.

In an attempt to define the potential application of neurotransmitter-specific transport as a method of tracing fiber connections, we have examined the uptake and subsequent ortho- and retrograde transport of tritium-labeled serotonin (3H-5HT) in the cerebellum-raphe pallidus system. Injection of various concentrations of 3H-5HT followed by different post-injection survival times revealed different labeling patterns in the injected sites and different patterns of transport. The most striking feature is that nonseroitonin neurons as well as serotonin cells were able to take up and transport the tritium label in both otho- and retrograde fashion. The non-sertonin-specific nature of this uptake and transport is more obvious at higher concentrations of 3H-5HT (more than 9 X 10(-5) M), with longer survival times and following pretreatment with monoamine oxidase inhibitors. At a concentration of 9 X 10(-6) M 3H-5HT, only specific uptake seems to take place as evidenced by label in known serotinin cells and fiber systems; however, it was impossible to detect by autoradiography any ortho- or retrograde transport at this low concentration. Non-specific uptake and transport were observed following injection into the vestibular nuclei and oculomotor complex. This suggests that non-specific uptake and the transport of 3H-5HT or metabolites may also occur in other regions of the central nervous system.

Animals↗