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Y Smith

Publications and source records attributed to Y Smith.

At least 91 records · Page 5Linked to original sources
PubMed1989

Dopaminergic innervation of the basal ganglia in the squirrel monkey as revealed by tyrosine hydroxylase immunohistochemistry.

The organization of the dopaminergic mesostriatal fibers and their patterns of innervation of the basal ganglia in the squirrel monkey (Saimiri sciureus) were studied immunohistochemically with an antiserum raised against tyrosine hydroxylase (TH). Numerous fibers arose from midbrain TH-positive cell bodies of the substantia nigra pars compacta (group A9), the retrorubral area (group A8), and the lateral portion of the ventral tegmental area (group A10). These fibers accumulated dorsomedially to the rostral pole of the substantia nigra where they formed a massive bundle that coursed through the prerubral field and ascended along the laterodorsal aspect of the medial fore-brain bundle in the lateral hypothalamus. Some ventrally located fibers ran throughout the rostrocaudal extent of the lateral preopticohypothalamic area and could be followed up to the olfactory tubercle, whereas other fibers turned laterodorsally to invade the head of the caudate nucleus. At more dorsal levels in the lateral hypothalamus, many fiber fascicles detached themselves from the main bundle and swept laterally to reach the globus pallidus, the putamen, and the amygdala. Several TH-positive fibers coursed along the dorsal surface of the subthalamic nucleus, and some invaded the dorsomedial third of this structure. The remaining portion of the subthalamic nucleus contained relatively few TH-positive elements. In contrast, the globus pallidus received a dense dopaminergic innervation deriving mostly from two fascicles that coursed backward along the two major output pathways of the pallidum: the lenticular fasciculus caudodorsally and the ansa lenticularis rostroventrally. At the pallidal level, the labeled fibres merged within the medullary laminae and arborized profusely in the internal pallidal segment and less abundantly in the external pallidal segment. However, the caudoventral portion of the external pallidum displayed a dense field of TH-positive axonal varicosities. Other fibers ran through the dorsal two-thirds of the external pallidum en route to the putamen. The striatum contained a multitude of thin axonal varicosities among which a few long and varicosed fibers were scattered. These immunoreactive neuronal profiles were rather uniformly distributed along the rostrocaudal extent of the striatum but appeared slightly more numerous in the ventral striatum than in the dorsal striatum. The pattern of distribution of the TH-positive axonal varicosities in the dorsal striatum was markedly heterogeneous: it consisted of typical zones of poor TH immunoreactivity lying within a matrix of dense terminal labeling.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

Neurons of the substantia nigra reticulata receive a dense GABA-containing input from the globus pallidus in the rat.

The lectin Phaseolus vulgaris leucoagglutinin (PHA-L) was used as an anterograde tracer to study the topographical distribution and synaptic organization of pallidonigral fibres in the rat. Injections of PHA-L in the lateral part of the globus pallidus led to anterograde labelling of a rich plexus of varicose fibres that arborized profusely in the central core of the rostral three quarters of the substantia nigra pars reticulata (SNr). However, few fibres were detected in SNr after PHA-L injection restricted to the most medial part of the globus pallidus. A small number of fibres was seen in the substantia nigra pars compacta after each injection. The most characteristic feature of the pallidonigral terminals was the formation of baskets around the perikarya and primary dendrites of SNr cells. Electron microscopic analysis revealed that the pallidonigral terminals contain pleomorphic vesicles and a large number of mitochondria and that they form symmetrical synaptic contacts. Furthermore, postembedding immunocytochemistry for gamma-aminobutyric acid (GABA) showed that they display GABA immunoreactivity. These findings demonstrate that, in the rat, the pallidonigral projection is a major source of GABA-containing terminals innervating pars reticulata cells and that the pattern of innervation is such that they may exert a powerful inhibitory control over these cells.

Animals↗
PubMed1989

Evidence for a distinct nigropallidal dopaminergic projection in the squirrel monkey.

Injections of the retrograde fluorescent tracer fast blue in the striatum (STR) and nuclear yellow in the internal segment of the globus pallidus (GPi) in the squirrel monkey (Saimiri sciureus) revealed a nigropallidal projection whose cellular origin was largely distinct from that of the nigrostriatal pathway. Neurons containing the tracer injected in GPi were scattered throughout the substantia nigra-ventral tegmental area complex where they formed approximately 20-25% of the total number of retrogradely labeled cells. Only about 5-10% of all positive neurons were double-labeled after STR-GPi injections. In experiments combining the use of the fluorescent tracer propidium iodide with immunofluorescence, the majority of neurons projecting to GPi displayed tyrosine hydroxylase immunoreactivity. Hence, in addition to their important role at striatal level, midbrain dopaminergic neurons may influence directly the output neurons of the basal ganglia at pallidal level in primates.

Animals↗
PubMed1989

Distinct afferents to internal and external pallidal segments in the squirrel monkey.

The use of retrograde fluorescence double-labeling method has revealed that the internal (GPi) and external (GPe) segments of globus pallidus in squirrel monkey receive projections from different cell populations in striatum and subthalamic nucleus. Striatal neurons projecting either to GPi or GPe formed wide and nonoverlapping cell bands oriented obliquely and covering large portions of putamen and caudate nucleus. Subthalamic neurons projecting to GPe were more abundant and more laterally located than those projecting to GPi. A few cells branching to GPi and GPe were found in subthalamic nucleus but not in striatum. Thus, different striatal and subthalamic neuronal populations influence GPi and GPe in primates.

Animals↗
PubMed1988

Basal forebrain cholinergic and noncholinergic projections to the thalamus and brainstem in cats and monkeys.

The projections of basal forebrain neurons to the thalamus and the brainstem were investigated in cats and primates by using retrograde transport techniques and choline acetyltransferase (ChAT) immunohistochemistry. In a first series of experiments, the lectin wheat germ-agglutinin conjugated with horseradish peroxidase (WGA-HRP) was injected into all major sensory, motor, intralaminar, and reticular (RE) thalamic nuclei of cats and into the mediodorsal (MD) and pulvinar-lateroposterior thalamic nuclei of macaque monkeys. In cats numerous neurons of the vertical and horizontal limbs of the diagonal band nucleus and the substantia innominata (SI), including its rostromedial portion termed the ventral pallidum (VP), were retrogradely labeled after WGA-HRP injections in the rostral pole of the RE complex, the MD, and anteroventral/anteromedial (AV/AM) thalamic nuclei. Fewer retrogradely labeled cells were observed in the same areas after injections in the ventromedial (VM) thalamic nucleus, and none or very few after other thalamic injections. After RE, MD, and AV/AM injections, 7-20% of all retrogradely labeled cells in the basal forebrain were also ChAT positive, while none of the retrogradely labeled neurons following VM injections displayed ChAT immunoreactivity. The basal forebrain projection to the MD nucleus was shown to arise principally from VP in both cats and macaque monkeys. In a second series of experiments performed in cats, injections of WGA-HRP in the brainstem peribrachial (PB) area comprising the pedunculopontine nucleus led to retrograde labeling of a moderate number of neurons in the lateral part of the VP, SI, and preoptic area (POA), only a few of which displayed ChAT immunoreactivity. In addition, a large number of retrogradely labeled cells were observed in the bed nuclei of the anterior commissure and stria terminalis after PB injections. In a third series of experiments, the use of the retrograde double-labeling method with fluorescent tracers in squirrel monkeys allowed us to identify a significant number of basal forebrain neurons sending axon collaterals to both the RE thalamic nucleus and PB brainstem area, while no double-labeled neurons were disclosed after injections confined to the ventral anterior/ventral lateral (VA/VL) thalamic nuclei and PB area or following injections in the cerebral cortex and PB area. Our findings reveal the existence of cholinergic and noncholinergic basal forebrain projections to the thalamus and the brainstem in both cats and macaque monkeys. We suggest that these projections may play a crucial role in the control of thalamic functions in mammals.

Animals↗
PubMed1988

Neurons of the subthalamic nucleus in primates display glutamate but not GABA immunoreactivity.

Immunohistochemical studies undertaken with a highly specific antiserum raised against gamma-aminobutyric acid (GABA)-glutaraldehyde-lysyl-protein conjugate showed that cell bodies of the subthalamic nucleus in the squirrel monkey (Saimiri sciureus) were closely surrounded by several GABA-positive terminals but were not themselves immunoreactive. In contrast, after incubation with a monoclonal antibody directed against carbodiimide-fixed glutamate, virtually all cell bodies of the subthalamic nucleus displayed an intense immunoreactivity. They were surrounded by various neuronal processes that also stained for glutamate. These results suggest that the neurons of the subthalamic nucleus in primates utilize the excitatory neurotransmitter glutamate instead of the inhibitory neurotransmitter GABA.

Animals↗
PubMed1988

Cholinergic and non-cholinergic projections from the upper brainstem core to the visual thalamus in the cat.

The projections of cholinergic and non-cholinergic neurons of the rostral brainstem reticular formation to the visual thalamic nuclei (dorsal lateral geniculate - LG, lateral posterior - LP, and perigeniculate - PG) were studied in cat by using the retrograde transport of horseradish peroxidase conjugated with wheat germ agglutinin (WGA-HRP) combined with choline acetyltransferase (ChAT) immunohistochemistry. After thalamic injections, less than 10% of all retrogradely labeled neurons in the upper brainstem reticular core were located at most rostral (perirubral) levels where there are virtually no cholinergic elements. Approximately 75-80% of all HRP-positive neurons in the reticular formation were found between stereotaxic planes anterior 1 and posterior 2, in the peribrachial (PB) area of the pedunculopontine nucleus and in the laterodorsal tegmental (LDT) nucleus. The brainstem afferents to LG and PG thalamic nuclei essentially derive from PB neurons, with a small contribution from LDT cells, whereas the LP thalamic nucleus receives massive inputs from both PB and LDT brainstem nuclei. Of all HRP-positive elements visualized in the PB nucleus after an LG or a PG injection, 87% and 73%, respectively, were also ChAT-positive. Of all HRP-positive elements in the PB and LDT nuclei after an LP injection, 82% and 92%, respectively, were also ChAT-positive. The numbers of labeled neurons in the contralateral brainstem reticular nuclei reach 30% to 50% of the numbers found in the ipsilateral reticular formation. These findings reveal the existence of a prominent cholinergic projection from the brainstem reticular formation to the visual thalamic nuclei. Such a chemospecific projection is probably involved in phasic and tonic events of activated behavioral states.

Animals↗
PubMed1988

Projections of cholinergic and non-cholinergic neurons of the brainstem core to relay and associational thalamic nuclei in the cat and macaque monkey.

The projections of brainstem core neurons to relay and associational thalamic nuclei were studied in the cat and macaque monkey by combining the retrograde transport of wheat germ agglutinin conjugated with horseradish peroxidase with choline acetyltransferase immunohistochemistry. All major sensory (medial geniculate, lateral geniculate, ventrobasal), motor (ventroanterior, ventrolateral, ventromedial), associational (mediodorsal, pulvinar, lateral posterior) and limbic (anteromedial, anteroventral) thalamic nuclei of the cat were found to receive projections from cholinergic neurons located in the peribrachial area of the pedunculopontine nucleus and in the laterodorsal tegmental nucleus as well as from non-cholinergic neurons in the rostral (perirubral) part of the central tegmental mesencephalic field. Specific relay nuclei receive less than 10% of their brainstem afferents from non-cholinergic neurons located at rostral midbrain levels and receive 85-96% of their brainstem innervation from a region at midbrain-pontine junction where the cholinergic peribrachial area and laterodorsal tegmental nucleus are maximally developed. Of the total number of horseradish peroxidase-positive brainstem neurons seen after injections in various specific relay nuclei, the double-labeled (horseradish peroxidase + choline acetyltransferase) neurons represent approximately 70-85%. Three to eight times more numerous horseradish peroxidase-labeled brainstem cells were found after injections in associational (mediodorsal and pulvinar-lateral posterior complex) and diffusely cortically-projecting (ventromedial) thalamic nuclei of cat than after injections in specific relay nuclei. The striking retrograde cell labeling observed after injections in nuclei with associative functions and widespread cortical projections was due to massive afferentation from non-cholinergic parts of the midbrain and pontine reticular formation, on both ipsi- and contralateral sides. After wheat germ agglutinin-horseradish peroxidase injections in the associative pulvinar-lateral posterior complex and mediodorsal nucleus of Macaca sylvana, 45-50% of horseradish peroxidase-positive brainstem peribrachial neurons were also choline acetyltransferase-positive. While cells in the medial part of the cholinergic peribrachial area were found to project especially towards the pulvinar-lateral posterior nuclear complex in monkey, the retrograde cell labeling seen after the mediodorsal injection was mostly confined to the lateral part of both dorsal and ventral aspects of the peribrachial area.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

Projections of brainstem core cholinergic and non-cholinergic neurons of cat to intralaminar and reticular thalamic nuclei.

We combined the retrograde transport of wheat germ agglutinin conjugated with horseradish peroxidase with choline acetyltransferase immunohistochemistry to study the projections of cholinergic and non-cholinergic neurons of the upper brainstem core to rostral and caudal intralaminar thalamic nuclei, reticular thalamic complex and zona incerta in the cat. After wheat germ agglutinin-horseradish peroxidase injections in the rostral pole of the reticular thalamic nucleus, the distribution and amount of retrogradely labeled brainstem neurons were similar to those found after tracer injection in thalamic relay nuclei (see preceding paper). After wheat germ agglutinin-horseradish peroxidase injections in the caudal intralaminar centrum medianum-parafascicular complex, rostral intralaminar central lateral-paracentral wing, and zona incerta, the numbers of retrogradely labeled brainstem neurons were more than three times higher than those found after injections in thalamic relay nuclei. The larger numbers of horseradish peroxidase-positive brainstem reticular neurons after tracer injections in intralaminar or zona incerta injections results from a more substantial proportion of labeled neurons in the central tegmental field at rostral midbrain (perirubral) levels and in the ventromedial part of the pontine reticular formation, ipsi- and contralaterally to the injection site. Of all retrogradely labeled neurons in the caudal midbrain core at the level of the cholinergic peribrachial area and laterodorsal tegmental nucleus, 45-50% were also choline acetyltransferase-positive after the injections into central lateral-paracentral and reticular nuclei, while only 25% were also choline acetyltransferase-positive after the injection into the centrum medianum-parafascicular complex. These findings are discussed in the light of physiological evidence of brainstem cholinergic mechanisms involved in the blockade of synchronized oscillations and in activation processes of thalamocortical systems.

Animals↗
PubMed1987

Organization of efferent projections of the subthalamic nucleus in the squirrel monkey as revealed by retrograde labeling methods.

The cellular origin and degree of collateralization of the subthalamostriatal, subthalamonigral and subthalamopallidal projections in the squirrel monkey (Saimiri sciureus) were studied using lectin-conjugated horseradish peroxidase (WGA-HRP), Nuclear yellow (NY) and Fast blue (FB) as retrograde tracers. In a first experimental group, WGA-HRP was injected in the left putamen and the right caudate nucleus. Following these injections numerous retrogradely labeled neurons occurred in the dorsolateral two-thirds of the subthalamic nucleus on the putamen-injected side, whereas a smaller number of positive cells were found in the ventromedial third of the same nucleus on the caudate-injected side. In a second experimental group NY was injected in the putamen whereas FB was delivered in the substantia nigra on the same side of the brain. After putaminonigral injections subthalamic cells containing the tracer injected in the putamen (about 75-80% of all retrogradely labeled neurons) occurred in the dorsolateral two-thirds of the nucleus, whereas those containing the tracer injected in the substantia nigra (about 20-25% of all positive subthalamic cells) were confined to the ventromedial third of the structure. Approximately 5-10% of all subthalamic positive neurons were double-labeled following putaminonigral injections. In a third experimental group, NY was injected in the caudate nucleus and FB in the substantia nigra on the same side. After such injections cells retrogradely labeled with NY or FB were present in about equal number and appeared closely intermingled in the ventromedial third of the subthalamic nucleus. Less than 10% of all positive subthalamic neurons were double-labeled following caudatonigral injections. In a fourth experimental group, NY was delivered in the globus pallidus and FB in the substantia nigra on the same side. In these animal cells containing the tracer delivered in the pallidum were about 4 times more numerous than those labeled with the tracer injected in the substantia nigra, and approximately 10-20% of all positive subthalamic neurons were double-labeled following pallidonigral injections. Most of these double-labeled cells occurred in the zone where the two populations of single-labeled cells overlapped. Finally, in a last experimental group, NY was injected in the pedunculopontine nucleus on one side and in the substantia nigra on the other. Following these injections cells containing the tracer delivered in the pedunculopontine nucleus were found to be 5-6 times less numerous than those labeled after substantia nigra injections...

Animals↗
PubMed1987

Differential dopaminergic innervation of the two pallidal segments in the squirrel monkey (Saimiri sciureus).

Immunohistochemical studies with an antiserum raised against tyrosine hydroxylase have allowed us to demonstrate a dense dopaminergic innervation of the globus pallidus in the squirrel monkey. This innervation derived mostly from two fascicles that detached themselves from the major ascending dopaminergic bundle arising from midbrain dopamine cell bodies and running in the lateral hypothalamus. Dopaminergic fibers reached the globus pallidus by coursing along its two major output pathways: the lenticular fasciculus dorsally and the ansa lenticularis ventrally. At pallidal levels, dopaminergic fibers abounded in medullary laminae and arborized profusely within the internal pallidal segment, whereas the external pallidum displayed only few short fibers that prevailed in its dorsal portion. These findings provide the first evidence that the primate globus pallidus receives a massive and differentially distributed dopaminergic input.

Animals↗
PubMed1987

Quinolinic acid does not spare striatal neuropeptide Y-immunoreactive neurons.

When infused into the striatum of the rat, the excitotoxin quinolinic acid was found to eliminate neuropeptide Y (NPY)-immunoreactive nerve cell bodies and processes within the core of the injection area in a dose-dependent manner. This finding suggests that the NPY immunoreactivity in the striatum is entirely derived from a relatively small population of striatal NPY-producing interneurons. The striatal cholinergic neurons identified by means of the di-isopropylfluorophosphate (DFP)-pharmacohistochemical procedure for acetylcholinesterase were found to be more resistant than NPY-immunoreactive cells to the action of the neurotoxin. Similar results were also obtained following striatal injections of kainic acid. The fact that the striatal NPY-immunoreactive neurons are highly sensitive to quinolinic acid is not consistent with the recent proposal that this excitotoxin can be used as an experimental model of Huntington's disease where striatal NPY-positive neurons are selectively spared.

Acetylcholinesterase↗
PubMed1987

Distribution of GABA-immunoreactive neurons in the basal ganglia of the squirrel monkey (Saimiri sciureus).

The distribution of GABA-immunoreactive neurons was visualized in the basal ganglia of the squirrel monkey (Saimiri sciureus), by using a highly specific antiserum raised against GABA-glutaraldehyde-lysyl-protein conjugate and revealed by the indirect peroxidase-antiperoxidase immunohistochemical method. In the dorsal striatum, GABA-immunoreactive nerve cell bodies were small to medium in size (sectional area ranging from 90 to 125 microns2), but some larger ones (500-600 microns2) were also found. These cells displayed no obvious clustering but were significantly more numerous in the caudate nucleus than in the putamen; their number was also markedly greater at caudal than at rostral striatal levels. A moderate number of evenly distributed positive axon terminals were visible in both the caudate nucleus and the putamen. In the ventral striatum, GABA-immunoreactive nerve cell bodies and axon terminals were seen in fair number within the nucleus accumbens and in the deep layers of the olfactory tubercle. Many positive terminals but no somata were found in the islands of Calleja. In the globus pallidus, virtually all nerve cell bodies were GABA-immunoreactive and the neuropil exhibited a multitude of positive terminals. In the substantia innominata, clusters of small, globular GABA-immunoreactive somata were scattered among aggregates of larger, nonimmunoreactive neurons belonging to the nucleus basalis, and the whole region showed a low to moderate number of evenly spread GABA-positive terminals. In the subthalamic nucleus, nerve cell bodies were generally surrounded by several GABA-positive terminals but were not themselves immunoreactive. The substantia nigra showed many GABA-immunoreactive somata, which predominated in the pars lateralis and diminished progressively in number along the lateromedial axis of the pars reticulata. These cells formed a rather pleomorphic group comprising round, fusiform, or polygonal elements of relatively large size (sectional area ranging from 200 to 800 microns2). In the pars compacta and ventral tegmental area, a few GABA-immunoreactive neurons of small size were dispersed among larger, unreactive neurons. In both pars lateralis and pars reticulata of the substantia nigra, the number of GABA-positive terminals was high and their distribution was rather uniform; a smaller number were visible in the pars compacta of the substantia nigra and in the ventral tegmental area. The present results demonstrate that GABA-containing neurons are widely and heterogeneously distributed in the various components of the squirrel monkey's basal ganglia.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Distribution of GABA-immunoreactive neurons in the thalamus of the squirrel monkey (Saimiri sciureus).

A light microscopic study of the cellular localization of GABA in the thalamus of the squirrel monkey (Saimiri sciureus) was undertaken by means of the indirect peroxidase-antiperoxidase method using a highly purified antiserum directed against GABA-glutaraldehyde-lysyl-protein conjugate. GABA-immunoreactive cell bodies and axon terminals were visualized in all thalamic nuclei in the squirrel monkey but their relative density varied from one nucleus to the other. At the level of the anterior nuclear group, GABA-positive cells and terminals abounded in the anterodorsal nucleus but were much less numerous in the anteromedial and anteroventral nuclei. In the nuclei of the ventral group, GABA-immunoreactive cells were found to be smaller and less numerous than nonimmunoreactive neurons. In the ventral anterior nucleus, GABA-positive neuronal profiles formed typical clusters, whereas they were more uniformly distributed in the posterior nuclei of the ventral group. In the intralaminar nuclei, GABA-immunoreactive cells and terminals abounded in the dorsal portion of the paracentral and centrolateral nuclei, whereas more caudally, GABA-positive terminals pervaded the entire parafascicular nucleus. In the mediodorsal nucleus, GABA-positive cell bodies and axon terminals formed typical clusters of various sizes scattered within the lateral parvocellular portion of the nucleus, while GABA-immunoreactive neuronal profiles were less numerous and more uniformly distributed in the medial portion of this structure. In the nuclei of the posterior group, GABA-immunoreactive neuronal profiles were uniformly distributed except in the pulvinar where they abounded in the inferior and oral parts but were scarce in the medial part. In the dorsal lateral geniculate nucleus, the magnocellular layers received the most massive GABA-positive innervation and contained the largest number of GABA-immunoreactive cell bodies. In the ventral lateral geniculate nucleus, GABA-positive cells occurred only ventrolaterally while GABA-immunoreactive terminals pervaded the entire structure. In the medial geniculate nucleus, GABA-immunoreactive cell bodies and terminals abounded particularly within the ventromedial third of the structure. In the habenula, a few GABA-immunoreactive cell bodies and numerous GABA-positive terminals were scattered throughout the lateral habenular nucleus, whereas only a few GABA-immunoreactive terminals surrounded the closely packed unreactive cells in the medial habenular nucleus. In contrast to other thalamic nuclei all neurons in the reticular nucleus displayed GABA immunoreactivity.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

Neuropeptide Y-immunoreactive neurons in the striatum of cat and monkey: morphological characteristics, intrinsic organization and co-localization with somatostatin.

A detailed study of the distribution of neuropeptide Y (NPY) in the striatum of squirrel monkey (Saimiri sciureus) and cat was undertaken by means of indirect immunofluorescence and peroxidase-antiperoxidase (PAP) methods. In monkey, the NPY-immunoreactivity is homogeneously distributed along the entire extent of the caudate nucleus (CD) and putamen (PUT), while in cat marked heterogeneities are noted. In the CD of cat, the NPY-immunoreactive fibers and cell bodies are concentrated in numerous patches of various sizes, which can be readily distinguished from zones of poor NPY-immunostaining. In the CD and PUT of squirrel monkey the NPY-positive neurons are either triangular, fusiform or globular, with long and smooth dendrites branching infrequently. The numerical density of NPY-immunoreactive cell bodies is greater in the CD than in the PUT, and it increases markedly along the rostrocaudal extent of the striatum. In the rostral CD and PUT the densities are 23 cells/mm2 and 14 cells/mm2, respectively, whereas the values for caudal CD and PUT are 35 cells/mm2 and 20 cells/mm2, respectively. Quantitative measurements reveal that these NPY-immunoreactive cells belong to a single subset of striatal neurons having a maximum diameter of 19.2 +/- 0.1 micron and a cross-sectional area of 145.5 +/- 0.6 micron2 (mean +/- S.E.M.; n = 1238 CD cells and 1169 PUT cells). Furthermore, experiments combining the use of lectin-conjugated HRP as retrograde tracer with PAP immunohistochemical method demonstrate that striatal NPY-immunoreactive neurons in squirrel monkey and cat do not project outside the striatum. Finally, co-localization studies in monkey reveal that the vast majority of striatal NPY-positive neurons also contains somatostatin. These results show that the NPY-immunoreactive neurons in mammalian striatum form a subpopulation of medium-sized interneurons containing somatostatin.

Animals↗
PubMed1986

Differential connections of caudate nucleus and putamen in the squirrel monkey (Saimiri sciureus).

The organization of the subcortical connections of caudate nucleus and putamen in the squirrel monkey was studied using horseradish peroxidase conjugated to wheat germ agglutinin as anterograde and retrograde neuronal tracer. The tracer was injected in similar quantities in the putamen on the left side and in the caudate nucleus on the right side in 10 monkeys, and its presence was revealed by means of the tetramethylbenzidine method. The study of anterogradely labeled fibers visualized after such injections shows that putaminofugal fibers terminate massively in the ventral two-thirds of the globus pallidus, where they display a band-like arrangement, and much less abundantly in the caudal third of the substantia nigra. In contrast, caudatofugal fibers occupy only the dorsal third of globus pallidus but arborize profusely in the rostral two-thirds of substantia nigra. In the pars reticulata of the substantia nigra the caudatonigral fibers form a highly complex network composed of fiber trabeculae while the putaminonigral fibers occur as more discrete fascicles confined to the dorsolateral region of the structure. In the pars compacta of the substantia nigra the retrogradely labeled cells occur in the form of clusters that are closely intermingled with clusters of unlabeled neurons. The labeled-cell clusters are particularly dense on the putamen-injected side and more loosely organized on the caudate-injected side. On both sides, however, the striatonigral fibers that reach the substantia nigra pars compacta can be seen to terminate almost exclusively upon clusters composed of retrogradely labeled cells, suggesting the existence of a precise reciprocal link between nigral and striatal neuronal aggregates. At thalamic levels the retrogradely labeled cells are distributed according to a strikingly asymmetric pattern. For instance, a prominent labeling of neurons in the central superior lateral nucleus is seen only on the caudate-injected side. Furthermore, in the centromedian/parafascicular complex retrograde cell labeling is seen exclusively in parafascicular nucleus on the caudate-injected side and only in the centromedian nucleus, except its lateralmost portion, on the putamen-injected side. Control experiments involving injection of the tracer in cerebral cortex overlying the striatum reveal that the neurons in the lateral segment of the centromedian, which do not project to striatum, are in fact reciprocally connected with the cerebral cortex. In addition, our data show that some of the so-called "specific" thalamic nuclei contribute significantly to the thalamostriatal projection in monkey.(ABSTRACT TRUNCATED AT 400 WORDS)

Amygdala↗
PubMed1985

Distribution of neuropeptide Y immunoreactivity in the basal forebrain and upper brainstem of the squirrel monkey (Saimiri sciureus).

The distribution of neuropeptide Y (NPY) immunoreactivity in the brain of the squirrel monkey (Saimiri sciureus) was studied by means of the indirect immunofluorescence, peroxidase-antiperoxidase, and avidin-biotin-complex methods. The antiserum used was raised in rabbits and did not show any significant crossreactivity with related peptides including peptide YY and avian pancreatic polypeptide. In the upper brainstem of the squirrel monkey a dense NPY-immunoreactive terminal field is seen in lateral parabrachial area, locus coeruleus, and interpeduncular nucleus. A small group of NPY-immunoreactive cell bodies is present in the lateral habenula and a moderate number of NPY-immunoreactive fibers occurs in periaqueductal gray and nucleus raphe pallidus. The substantia nigra (SN) appears mostly devoid of NPY immunoreactivity whereas the ventral tegmental area contains a few reactive fibers. In the hypothalamus the medial preoptic area as well as the arcuate and paraventricular nuclei receive a strikingly dense NPY innervation. In addition, numerous NPY-positive cell bodies are found within the dorsomedial half of the supraoptic nucleus but very few are seen in paraventricular nucleus. A large number of NPY-immunoreactive cell bodies is also present in arcuate nucleus. In the basal telencephalon NPY-immunoreactive cells abound mostly in striatum, but some are also found in the amygdala (particularly basal, central, and lateral amygdaloid nuclei), the claustrum, and in the bed nucleus of the stria terminalis. Intensely reactive network of NPY-immunoreactive fibers is also present in all of these structures. In striatum, the numerous, fine and non-varicose NPY-immunoreactive fibers, as well as the NPY-positive cell bodies, are slightly more abundant in caudate nucleus than in putamen. The globus pallidus (GP) is mostly devoid of NPY-immunoreactive fibers and terminals. The fact that the two major recipient structures of striatal outflow (SN and GP) do not receive significant NPY input suggests that the striatal NPY-containing neurons are intrinsically organized.

Animals↗