摘要:

AbstractAutoradiographic and immunohistochemical methods were used to study the distributions of GABAA, GABABand benzodiazepine(BDZ) receptors in the pigeon fore‐ and midbrain. GABAA, GABABand BDZ binding sites were found to be abundant although heterogeneously distributed in the telencephalon. The primary sensory areas of the pallium of the avian telencephalon (Wulst and dorsal ventricular ridge) tended to be low in all three binding sites, while the surrounding second order belt regions of the pallium were typically high in all three. Finally, the outermost rind of the pallium (termed the pallium externum by us), which surrounds the belt regions and projects to the striatum of the basal ganglia, was intermediate in all three GABAergic receptors types. Although both GABAAand benzodiazepine receptors were abundant within the basal ganglia, GABAAbinding sites were densest in the striatum and BDZ binding sites were densest in the pallidum. Among the brainstem regions receiving GABAergic basal ganglia input, the anterior and posterior nuclei of the ansa lenticularis showed very low level of all three receptors, while the lateral spiriform nucleus and the ventral tegmental area/substantia nigra complex contained moderate abundance of the three binding sites. The dorsalmost part of the dorsal thalams (containing nonspecific nuclei) was rich all three binding sites, while the more ventral part of the dorsal thalamus (containig specific sensory nuclei), the ventral thalamus and the hypothalamus were poor in all three binding sites. The pretectum was also generally poor in all three, althrough some nuclei displayed higher level of one or more binding sites. The optic tectum, inferior colliculus, and central gray were rich in all three sites, while among the isthmic nuclei, the parvicellular isthmic was nucleus was conspicuously rich in BDZ sites. The REsults show a strong correlation of the regional abundance of GABA binding sites with previously described distributions of GABAergic fibers and terminals in the avaian forebrain and midbrain. The distribution of these binding sites is also remarkably similar to that in mammals, indicating a conservative evolution of forebrain and midbrain GABA systems systems among amniotes. © 1994 Wiley‐Liss,

ISSN:0092-7317    

DOI:10.1002/cne.903440202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe topographical relationships between cholinergic neurons, identified by their immuno‐reactivity for choline acetyltransferase (ChAT) or their staining for β‐nicotinamide ademine dinucleotide phosphate (NADPH)‐diaphorase, and dopaminergic, serotoninergic, Nonadrenergic, and glutamatergic neurons that occur in the mesopontine tegmentum, were studied in the squirrel monkey (Saimiri sciureus). The ChAT‐positive neurons in the pedunculopontine nucleus (PPN) form two distinct subpopulations, one that corresponds to PPN pars compacta(PPNc) and the other to PPN pars dissipata (PPNd). The ChAT‐positive neurons in PPNc are clustered along the dorsolateral border of the superior cerebellar peduncle (SP) at trochlear nucleus levels, whereas those in PPNd are scattered along the SP from midmesencephalic to midpontine levels. At levels caudal toe the trochlear nucleus, ChAT‐positive neurons corresponding to the laterodorsal tegmental nucleus (LDT) lie within the periaqueductal gray and extend caudally as far as locus coeruleus levels. All ChAT‐positive neurons in PPN and LDT stain for NADPH‐diaphorase; the majority of large neurons in PPN and LDT are cholinergic, but some large neurons devoid of NADPH‐diaphorase also occurnin these nuclei. Cholinergic neurons in the mesopontine tegmentum form clusters that are largely segregated from raphe serotonin immunoreactive neurons, as well as from nigral dopaminergic and coeruleal noradrenergic neurons, as revealed by tyrosine hydroxylase immunohistochemistry. Nevertheless, dendrites of cholinergic and noradrenergic neurons are clolinergic and noradrenergic neurons are closely intermingled, suggesting the possibility of dendrodendritic contacts. In addition, numerous large and medium‐sized glutamate‐immunoreactive neurons are intermingled among cholinergic neurons in PPN. Furthermore, at trochlear nucleus levels, about 40% of cholinergic neurons display glutamate immunoreactivity, whereas other neurons express glutamate or ChAT immunoreactivity only. This study demonstrates that (1) cholinergic neurons remain largely segregated from monoaminergic neurons throughout the mesopontine tegmentum and (2) PPN contains cholinergic and glutamatergic neurons as well as neurons coexpressing ChAT and Glutamate in primates.

ISSN:0092-7317    

DOI:10.1002/cne.903440203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe efferent projections of the pedunculopontine nucleus (PPN) to the ganglia have been studied in the squirrel monkey (Saimiri sciureus) with [3H]leucine andPhaseolus vulgaris‐leucoagglutinin (PHA‐L) as anterograde tracers. Following unilateral injections of [3H]leucine or PHA‐L in the central portion of the PPN, numerous autoradiographic linear profiles or PHA‐L‐labeled fibers ascend to the forebrain, both ipsilaterally and contralaterally. These fibers form a compact bundle that courses in the central portion of the mesopontine tegmentum. At rostral mesencephalic levels, theis bundle splits into ventromedial and dorsolateral fascicles that arborize in basal ganglia and thalamic nuclei, respectively. The substantia nigra and the subthalamic nucleus are by far the most densely innervated structures of the basal ganglia. In these two nuclei, labeled fibers arborize profusely ipsilaterally and less abundantly contralaterally. The labeled fibers in the substantia nigra are thin and varicose and arborize almost exclusively in the pars compacta, where they closely surround the soma and proximal dendrites of dopaminergic neurons. In the subthalamic nucleus labeled fibers are also thin and appear to contact more than one neuron along their course. Numerous labeled fibers also occur in the pallidal complex, where they arborize most profusely in the internal segment. Several thick, labeled fibers oriented dorsolaterally in the pallidal complex give rise to thinner fibers that closley surround the soma and proximal dendrites of pallidal neurons. Some labeled fibers are also scattered in the striatum. These fibers abound in the peripallidal and ventral portions of the putamen, are more sparsely distributed in the remaining portion of the putamen as well as in the caudate nucleus, and are virtually absent in the ventral striatum. These results reveal that the PPN gives rise to a massive and highly ordered innervation of the basal ganglia in the squirrel monkey. This nucleus may thus act as an important relay in the basal ganglia circuitry in primates. © 1994 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903440204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe distribution and chemospecificity of the pedunculonigral neurons have been studied in squirrel monkeys (Saimiri sciureus)with cholera toxin subunit B (CTb) and fluorogold (FG) as retrograde tracers combined with immunohistochemistry for choline acetyltransferase (ChAT), glutamate, and the calcuium binding protein calbindin D‐28k. The injection of either CTb or FG into the substantia nigra produces prominent retrograde cell labeling in the mesopontine tegmentum. Labeled neurons are particularly numerous at the level of the decussation of the superior cerebellar peduncle, where they abound principally in the pars dissipata of the pedunculopontine nucleus (PPN). A significant proportion of retrogradely labeled neurons in the PPN display ChAT immunoreactivity. Whithin the entire PPN, approximately 25% of the retrogradley labeled neurons express ChAT immunoreactivity, but proportions of doubly labeled neurons are about 35%, 25% in the rostral, middle, and caudal thirds of the PPn, respectively. These doubly labeled neurons are scattered among numerous retrogradely labeled neurons that are ChAT‐negative and whose number increases along the rostrocaudal extent of the PPN. Several retrogradely labeled neurons in the PPN display glutamate immunoreactivity, but very few express calbindin. This study provides the first direct evedence for the involvement of cholinergic and glutamatergic neurons in the pedunculonigral projection in primates. Furthermore, the fact that some neurons of the PPN display bothe ChAT and glutamate immunoreactivity indicates that single neurons in the mesopontine tegmentum may exert a two‐fold effect upon dopaminergic neurons of the substantia nigra. This dual cholinergic and glutamatergic pedunculonigral projection may play a crucial role in the functional organization of primate basal ganglia. © 1994 Wiley‐L

ISSN:0092-7317    

DOI:10.1002/cne.903440205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe locus coeruleus is a noradrenergic nucleus located in the isthmal tegmentum. In mammals, it contains several thousand neurons that have diverse projection patterns and contain various neuropentides. In fishes, this nucleus contains few neurons. This study attempts to define and quantify morphological types of locus coeruleus neurons, and search for neurochemical subpopulations in the zebrafish. In this fish, the locus coeruleus contains between 3 and 10neurons, and most nuclei contain between 5 and 8 cells. Nuclei in more inbred lines of fish have a narrower range of neurons. The difference in neuron number between the two sides of the same brain is small, but only 24% of the brains have identical numbers on both sides. These observations suggest that there is a two‐step control of neuron number: the genetic constitution of the fish determines the approximate number of cells, while epigenetic factors determine the final number. Based on dendritic orientation, three types of cells are identified: (1) V type, neurons with only ventrally projecting dendrites; (2)Ltypes, neurons with only laterally projecting dendrites; and (3)VLtype, neurons with both ventrally and laterally projecting dendrites. Over 65% of the neurons are of the V type; some nuclei haveVtype; some nuclei haveVtype cells only. There is a correlation between the total number of neurons and the ratio of each cell type. In nuclei with five cells or fewer, over 80% of the neurons areVtype; higher percentages of the other two types are seen in nuclei with 6 or more neurons. The dendritic morphology and orientation suggest that various types of neurons may receive different inputs. Cholinesterases are not detectable in locus coeruleus neurons. Immunocytochemical staining for a number of neuropeptides also fails to demonstrate detectable levels. Neuropeptide Y is present in some cell abutting the locus coeruleus, but these are probably not catecholamine‐containing neurons. Some neurons contain choline‐acetyltransferase. These observations suggest that locus coeruleus neurons of the zebradish may be morphologically and neurochemically heterogeneous. © 1994 Wiley‐L

ISSN:0092-7317    

DOI:10.1002/cne.903440206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe locus coeruleus is a widely projecting isthmal noradrenergic nucleus. In the zebrafish, it consists of between three and ten neurons, most of which have multiple, bilaterally projecting axons. Immunohodolgical studies show that the locus coeruleus provides most, if not all, of the noradrenergic innervation of the brain rostral to the isthmus. The pathways and targets in the zebrafish are similar to ascending coeruleal projections of other vertebrates. Axons ascend through two amin pathways: the longitudinal catecholamine bundle and the periventricular catecholamine pathway. The former is a dense meshwork of varicosity‐bearing axons which ascends along the lateral longitudinal fasciculus into the mesencephalon. In the posterior tuberal area, this bundle dives ventrally and assumes a lateral position. In the diencephalon, it takes up a position ventral to the medial forebrain bundle, and follows this bundle into the telencephalon, where it joins the medial olfactory tract to enter the olfactory bulb. The periventricular catecholamine pathway is a diffuse pathway consisting of thick, smooth axons. It is associated with the medial longitudianl fasciculus. Rostral to the nucleus of the medial longitudinal fasciculus, this pathway joins the longitudinal catecholamine bundle around the medial forebrain bundle. The Periventricular pathway gives rise to coarse terminal arbors with large but sparse varicosities, whereas the longitudinal catecholamine bundle gives rise to terminal plexuses with fine and dense fibers and varicosities. Among the more densely innervated regions are the raphé nucleus, the interpeduncular nucleus, the torus semicircularis, parts of the hypothalamus, and the suprachiasmatic and preoptic areas. The tours longitudinalis, optic tectum, cerebellum, habenular complex, the dorsomedial zone of area dorsalis telencephali, and the olfactory bulb are moderately innervated. The nucleus glomerulosus, the torus lateralis and lateral subnuclei of the nucleus diffusus, and the anterior tuberal nucleus are devoid of noradrenergic innervation. © 1994 Wiley‐Liss

ISSN:0092-7317    

DOI:10.1002/cne.903440207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractCorticospinal projections in adult rodents arise exlusively from layer V neurons in the sensorimotor cortex. These neurons are topographically organized in their connections to spinal cord targets. Previous studies in rodents have shown that the mature distribution pattern of corticospinal neurons develops during the first 2 weeks postnatal from an initial widespread pattern that includes the visual cortex to a distribution restricted to the sensorimotor cortex. To determine whether specificity in corticospinal connections also emerges from an intially diffuse set of projections, we have studied the outgrowth of corticospinal axons and the formation of terminal arbors in developing hamsters. The sensitive fluorescent tracer 1, 1′, dioctadecyl‐3, 3, 3′, 3′‐tetramethylindocarbocyanine perchlorat (DiI) was used to label corticospinal axons from the visual cortex or from small regions of the forelimb or hindlimb sensorimotor cortex in living animals at 4–17 days postnatal. Initially axon outgrowth was imprecise. Some visual cortical axons extended transiently beyond their permanent targets in the pontine nuclei, by growing through the pyramidal decussation and in some cases extending as far caudally as the lumbar enlargement. Forelimb sensorimotor axons also extended past their targets in the cervical enlargement, in many cases growing in the corticospinal tract to lumbar levels of the cord. By about 17 days postnatal these misdirected axons or axon segments were withdrawn from the tract. Despite these errors in axon trajectories within the corticospinal tract, terminal arbors branching into targets in the spinal gray matter were topographically appropriate from the earliest stages of innervation. Thus visula cortical axons never formed connections in the spinal cord, forelimb sensorimotor axons arborized only in the cervical enlargement, and hindlimb cortical axons terminated only in the lumbar cord at all stages of development examined. Corticospinal arbors formed from collaterals that extended at right angles from the shafts of primary axons, most likely by the process of interstitial branching after the primary growth cone had extended past the target. Once collaterals extended into the spinal gray matter, highly branched terminal arbors formed within 2–4 days, beginning at about 4 and 8 days postnatal for the cervical and lumbar enlargements, respectively. These results show that specificity in connectivity is achieved by selectivty growth of axon collaterals in to appropriate spinal targets from the beginning and not by the later remodeling of intially diffuse connections. In contrast, errors occur in the initial outgrowth of axons in the corticospinal tract, which are subsequently corrected. Copyright © 1994 W

ISSN:0092-7317    

DOI:10.1002/cne.903440208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractCells of glial origin are involved in the morphogenesis of the mammalian central nervous system (CNS). Characterization of glial‐associated proteins during neurogensis and differentiation may aid in understanding the complexity of CNS development. We have utilized immunoblotting and immunohistochemistry to characterize the developmental profiles of glial fibrillary acidic protein (GFAP) and vimentin (VIM) in the brain of the Brazilian opossum,Monodelphis domestica.Typical of marsupials, CNS morphogenesis and neurogenesis in the opossum extend well into the postnatal period. Opossum GFAP and VIM were found as single bands at molecular weights consistent with those reported for other species, thus indicating conservation of the VIM and GFAO proteinns through mammalian evolution. Differential developmental trends were observed for both proteins with relative VIM levels decreasing and GFAP levels increasing with age. Vimentin‐like immunoreactivity (VIM‐IR) was present at day 1 of postnatal life throughout the brain. The density of VIM‐IR was maximal at 10 and 15 days postnatal (especially in radial glial elements) and decreased slightly by 25 days postnatal. In the adult brain, VIM‐IR was markedly reduced compared to that of younger ages. In contrast, GFAP‐like immunoreactivity (GFAP‐IR) in the brain ofMonodelphisincreased dramatically with age. No GFAP‐IR was observed in the 1 and 5 day postnatal brains. By 25 days postnatal, the pattern of GFAP‐IR in the brainstem resembled that of the adult. In the forebrain, more GFAP‐IR was present than at younger ages. The adult distribution of GFAP‐IR was very similar to that reported for other mammalian species. These results indicate that GFAP and VIM are reciprocally related during periods of morphogenesis and differentiation of the opossum brain.

ISSN:0092-7317    

DOI:10.1002/cne.903440209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractClipping of mystacial vibrissae on one side of the rat's snout result in sensorimotor asymmetries in normal behavior and in behavior induced by the dopamine receptor agonist, apomorphine. Immediate‐carly gene expression, a marker for short‐term changes in neuron function, was used to examine wheter this sensory deprivation leads to functional changes in the somatosensory barrel cortex under experimental conditions which reveal behavioral asymmetries. The expression ofc‐fosandzif 268immediate‐early genes was assessed with in situ hybridization histochemistry. Four hours after unilateral clipping of the mystacial vibrissae, the level ofzif 268mRNA was reduced in the corresponding part of the contralateral barrel field. Injection of apoorphine (5 mg/kg) resulted in increased expression of bothc‐fosandzif 268immediate‐early genes in cortex and striatum. This apomorphine‐induced increase was blocked in the sensory‐deprived somatosensory corted. Laminar analysis of gene regulation shwoed that vibrissae removal affected immediate‐early expression in all layers of the barrel cortex. These results demonstrate that: (1) basalzif 268gene expression in neurons of the somatosensory cortex is dependent on sensory input, (2) cortical immediate‐early gene expression is increased after dopamine receptor activation, and (3) in the barrel cortex, this increase is also dependent on sensory input. We suggest that the observed reduction in gene expression after vibrissae removal reflects decreased activation of neurons in the barrel column by removal of sensory input. ©

ISSN:0092-7317    

DOI:10.1002/cne.903440210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe pattern of arborization of the striatonigral fibers in the squirrel monkey (Saimiri Sciureus) was studied withPhaseolus vulgaris‐leucoagglutinin (PHA‐L) and biocytin as anterograde tracers. Single, small injections of PHA‐L or biocytin in either the caudate nucleus or the putamen give rise to at least four distinct, nonoverlapping but interconnected fiber plexuses that are distributed throughout the rostrocaudal extent of the substantia nigra pars reticulata (SNr) according to a strikingly precise and constant sequence. These plexuses, which comprise numerous fibers that closely entwine unlabeled dendrites of SNr neurons (woolly fibers), often lie at the base of dopaminergic cell columns of the substantia nigra pars compacta (SNc). Long and varicose fibers emerge dorsally from SNr plexuses and climb along the ventrally oriented denarites of dopaminergic SNc neurons, as visualized with tyrosine hydroxylase immunohistochemistry. These fibers appear to contact en passant both dendrites and cell bodies of dopaminergic neurons belonging to the ventral tier of SNc. Anterograde double‐labeling experiments involving small deposits of PHA‐L and biocytin in adjacent areas of the caudate nucleus and the putamen reveal that neighboring striatonigral cell populations form two distinct sets of terminal plexuses that remain well segregated throughout SNr. Plexuses from the two sources interdigitate in some parts of SNr, but never intermix. Furthermore, the wooly fibers in these plexuses are composed exclusively of either PHA‐L‐or biocytin‐labeled elements; none of them display both types of labeling. These results reveal that the striatonigral projection in primates is highly divergent and that the striatum has multiple representations at nigral levels. They also indicate that striatal information is conveyed to the substantia nigra in a highly ordered fashion through multiple segregated channels. © 1994

ISSN:0092-7317    

DOI:10.1002/cne.903440211

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY