摘要:

AbstractAccumulating evidence suggests that pigment‐dispersing hormone‐immunoreactive neurons with ramifications in the accessory medulla of the insect brain are involved in circadian pacemaking functions. We have used immunocytochemical techniques to investigate the neurochemical organization of the accessory medulla in the locustSchistocerca gregaria. Local neurons with arborizations largely restricted to the accessory medulla are immunoreactive with antisera against serotonin,Manduca sextaallatotropin, andDiploptera punctataallatostatin 7. Projection neurons with arborizations in the accessory medulla and fibers to the lamina and/or several areas in the midbrain including the posterior optic tubercles, the inferior and the superior protocerebrum show Phe‐Met‐Arg‐Phe (FMRF) amide‐, gastrin/cholecystokinin‐, crustacean cardioactive peptide‐, and substance P immunoreactivities. A unique neuron with tangential ramifications in the medulla and lamina and varicose terminals in the accessory medulla contains a peptide related to locustatachykinin I/II. Double‐label experiments show colocalization of pigment‐dispersing hormone‐immunoreactivity with substances related to gastrin/cholecystokinin, FMRFamide, substance P, or crustacean cardioactive peptide in certain projection neurons of the accessory medulla. The results suggest that neuropeptides and biogenic amines play major neuroactive roles in the accessory medulla of the locust. The abundance and extensive colocalization of neuropeptides in the locust accessory medulla is discussed with respect to the possible involvement of this brain area in circadian pacemaking functions.

ISSN:0092-7317    

DOI:10.1002/cne.903620302

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractIn the present study, we assessed the extent of the thyrotropin‐releasing hormone (TRH) input to motoneurons in the ambigual, facial, and hypoglossal nuclei of the rat using a combination of intracellular recording, dye filling, and immunohistochemistry. Twelve motoneurons in the rostral nucleus ambiguus were labelled by intracellular injection in vivo of Neurobiotin (Vector). Seven out of 12 ambigual motoneurons displayed rhythmic fluctuations of their membrane potential in phase with phrenic nerve discharge, whereas the other five had no modulations of any kind. Seven facial motoneurons and seven hypoglossal motoneurons were also filled with Neurobiotin. All three motor nuclei contained TRH‐immunoreactive varicosities, with the largest numbers found in the nucleus ambiguus. Close appositions were seen between TRH‐immunoreactive boutons and every labelled motoneuron. Respiratory‐ related motoneurons in the nucleus ambiguus received the largest number of TRH appositions with 74 ± 38 appositions/neuron (mean ± S. D.; n = 7). In contrast, nonrespiratory ambigual motoneurons received significantly fewer TRH appositions (11 ± 5; n = 5;P<0. 05; Mann‐Whitney U test). Facial motoneurons received about the same number of TRH appositions as nonrespiratory ambigual motoneurons, with 13 ± 4 (n = 7). Hypoglossal motoneurons received the fewest appositions from TRH‐containing boutons, with 8 ± 2 (n = 7). There were no differences in the TRH inputs to respiratory and nonrespiratory motoneurons in the facial and hypoglossal nuclei. These results demonstrate that, among motoneurons in the medulla, respiratory motoneurons in the rostral nucleus ambiguus are preferentially innervated by the TRH‐immunoreactive boutons. ©

ISSN:0092-7317    

DOI:10.1002/cne.903620303

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractRetinal ganglion cells in the channel catfish (Ictalurus punctatus) were retrogradely labelled, and those with the largest somata and thickest primary dendrites were categorized by their levels of dendritic stratification. Three types were found, each forming a mosaic making up ∼ 1% of the ganglion cell population. Using a system based on established sublaminar terminology, we call these the alpha‐a (αa), alpha‐b (αb), and alpha‐c (αc) ganglion cell mosaics. Cells of the αamosaic had large, sparsely branched trees in sublamina a at 10–30% of the depth of the inner plexiform layer (IPL), sclerad to those of all other large ganglion cells. Some αasomata were displaced into the IPL or inner nuclear layer (INL) but belonged to the same mosaic as their orthotopic counterparts. Cells of the αamosaic had dendrites that branched a little more and arborized in sublamina b at 50–60% of the IPL depth. Many also sent fine branches into sublamina a, and some were fully bistratified in a and b. The αccells arborized in the most vitread sublamina, sublamina c, at 80–95% of the IPL depth. The soma areas of the three types in the largest retina studied ranged between 139 μm2and 670 μm2with significant differences in the order αa>αc≥ αb. Analyses based on nearest‐neighbour distance (NND) and on spatial auto‐ and cross‐correlograms showed that each mosaic was statistically regular and independent of the others. Mosaic spacings were similar for each type, giving mean NNDs of 242–279 μm in the largest retina and 153–159 μm in a smaller one. Correspondences between these mosaics, previously defined large ganglion cell types in catfish, and other mosaic‐forming large ganglion cells in fish and frogs are discussed along with their implications for neuronal classification, function, developm

ISSN:0092-7317    

DOI:10.1002/cne.903620304

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractAcetylcholine has been implicated in brainstem mechanisms of cardiac and ventilatory control, arousal, rapid eye movement (REM) sleep, and cranial nerve motor activity. Virtually nothing is known about the developmental profiles of cholinergic perikarya, fibers, terminals, and/or receptors in the brainstems of human fetuses and infants. This study provides baseline information about the quantitative distribution of muscarinic cholinergic receptors in fetal and infant brainstems. Brainstem sections were analyzed from 6 fetuses (median age: 21. 5 postconceptional weeks), 4 premature infants (median age: 26 postconceptional weeks), and 11 infants (median age: 53 postconceptional weeks). One child and three adult brainstems were examined as indices of maturity for comparison. The postmortem interval in all cases was less than or equal to 24 hours (median: 10 hours). Muscarinic receptors were localized by autoradiographic methods with the radiolabeled antagonist [3H] quinuclidinyl benzilate ([3H] QNB). Computer‐based methods permitted quantitation of [3H]QNB binding in specific nuclei and three‐dimensional reconstructions of binding patterns.By midgestation, muscarinic cholinergic receptor binding is already present and regionally distributed, with the highest binding levels in the interpeduncular nucleus, inferior colliculus, griseum pontis, nucleus of the solitary tract, motor cranial nerve nuclei, and reticular formation. During the last half of gestation, [3H]QNB binding decreases in most, but not all, of the nuclei sampled. The most substantial decline occurs in the reticular formation of the medulla and pons, a change that is not fully explained by progressive myelination and lipid quenching. Binding levels remain essentially constant in the inferior olive and griseum pontis. Around the time of birth or shortly thereafter, the relative distribution of binding becomes similar to that in the adult, with the highest levels in the interpeduncular nucleus and griseum pontis, although binding levels are higher overall in the infant. In the rostral pontine reticular formation, paramedian bands of high muscarinic binding are present which do not correspond to a cytoarchitectonically, defined nucleus. By analogy to animal studies, these bands may comprise a major cholinoreceptive region of the human rostral pontine reticular formation involved in REM sleep. In the human interpeduncular nucleus in all age periods examined, muscarinic binding localizes to the lateral portions bilaterally, indicative of a heterogeneous chemoarchitecture. Muscarinic binding is high in the arcuate nucleus, a component of the putative respiratory chemosensitive fields along the ventral surface of the infant medulla. This observation is consistent with the known effects of muscarinic agents on chemosensitivity and ventilatory responses applied to the ventral medullary surface in animal models. The nonuniform distribution of muscarinic binding in the caudorostral plane in individual brainstem nuclei, as illustrated by three‐dimensional reconstructions, underscores the need for rigorous sampling at precisely matched levels in quantitative studies. This study provides basic information toward understanding the neurochemical basis of brainstem disorders involving dysfunction of autonomic and ventilatory control, arousal, and REM sleep in preterm and full‐term newborns and infants and for developing cholinergic drugs for such disorders in the pediatric population. © 1995 Wiley

ISSN:0092-7317    

DOI:10.1002/cne.903620305

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractA comprehensive survey of class I α‐tubulin (αl) and class II β‐tubulin (βII) mRNAs was performed using in situ hybridization in order to determine the extent of continued expression of these immature tubulin isotype mRNAs in the adult rat brain. Qualitatively similar distributions of the two isotype mRNAs were observed, with marked variations in hybridization intensity of both probes apparent across different brain regions. Neurons in a wide variety of structures throughout the brain exhibited intense hybridization signals. While the presence of large numbers of neurons with a moderate hybridization intensity could account for the relatively high level of total binding in some regions such as the cerebellar and dentate granule layers, in most cases higher regional mRNA levels reflected greater hybridization intensity per neuron. Little variability in hybridization intensity was typically seen between individual cells within specific nuclei throughout the brain. The presence of occasional intensely labeled neurons scattered throughout the basal ganglia provided the most striking exception to this pattern. While no qualitative differences between the distributions of αl‐tubulin and βII‐tubulin mRNAs were observed, consistent differences in the relative intensity of hybridization for α1‐tubulin versus βII‐tubulin mRNA were apparent in a few brain regions. Expression by glia did not appear to contribute significantly to detectable levels of either α1‐tubulin or βII‐tubulin mRNA. These findings suggest that continued expression of growth‐associated tubulin isotype mRNAs may have functional significance in specific neuronal populations of the adult brain. Partial overlap between the distributions of α1‐ and βII‐tubulin mRNAs and that of GAP‐43 mRNA is discussed, as are potential roles for growth‐associated tubulin gene expression in supporting cytoskeletal turnover, reactive axonal growth, and dendritic remodeling in t

ISSN:0092-7317    

DOI:10.1002/cne.903620306

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractMany septohippocampal neurons are GABAergic and are affected by transection of the fimbria‐fornix, like the septohippocampal cholinergic cells. Here we have studied the changes that occur in GABAergic septohippocampal neurons following fimbria‐fornix transection. For labeling of septohippocampal projection neurons, adult Sprague‐Dawley rats received injections of the fluorescent tracer Fluoro‐Gold into the hippocampus 1 week prior to bilateral transection of the fimbria‐fornix. After axotomy, rats were allowed to survive for varying periods ranging from 3 weeks to 18 months. Following fixation of the animals, sections through the septal region were either stained by in situ hybridization for glutamate decarboxylase (GAD) mRNA or immunostained for parvalbumin (PARV) which is known to be present in GABAergic septohippocampal neurons.In situ hybridization for GAD mRNA revealed no statistically significant changes in cell number 3 weeks and 6 months postlesion. In contrast, PARV‐immunoreactive neurons were reduced to 35% of control 3 weeks postlesion. This value increased to 66% after 6 months of survival. As seen in the electron microscope, axotomized PARV‐positive neurons exhibited characteristics of vital cells. Most neurons contained lysosomes associated with Fluoro‐Gold, resulting from retrograde labeling prior to fimbria‐fornix transection.We conclude that mainly PARV‐containing GABAergic neurons in the medial septal nucleus (MS) project to the hippocampus and are thus heavily affected by the lesion but are able to survive and restore the synthesis of PARV. The lack of significant changes in the number of GAD mRNA‐expressing cells is explained by the presence of numerous GABAergic MS neurons not projecting to the hippocampus.

ISSN:0092-7317    

DOI:10.1002/cne.903620307

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe midbrain dopamine system can be divided into two groups of cells based on chemical characteristics and connectivity. The dorsal tier neurons, which include the dorsal pars compacta and the ventral tegmental area, are calbindin positive, and project to the shell of the nucleus accumbens. The ventral tier neurons are calbindin‐negative and project to the sensonmotor striatum. This study examined the distribution of the mRNAs for the dopamine transporter molecule (DAT) and the D2receptor in the midbrain of monkeys by using in situ hybridization. The distribution patterns were compared to that of tyrosine hydroxylase and calbindin immunohistochemistry. The results show that high levels of hybridization for DAT and the D2receptor mRNA are found in the ventral tier, calbindin‐negative neurons and relatively low levels are found in the dorsal, calbindin‐positive tier. Within the dorsal tier, the dorsal substantia nigra pars compacta has the least amount of both messages. These results show that in monkeys, the ventral tegmental area and the dorsal pars compacta form a dorsal continuum of dopamine neurons which express lower levels of mRNA for DAT and D2receptor than the ventral tier. DAT has been shown to be involved in the selective neurotoxicity of N‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP). Different levels of DAT mRNA and calbindin may explain the differential effects of MPTP neurotoxicity. © 199

ISSN:0092-7317    

DOI:10.1002/cne.903620308

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe topography of neurons containing nitric oxide synthase (NOS) and monoamines was investigated in the guinea pig mesopontine tegmentum. NOS‐containing neurons were identified with NADPH‐diaphorase (NADPH‐d) histochemistry, and monoamine‐containing neurons were identified with tyrosine hydroxylase (TH) and serotonin (5‐HT) immunocytochemistry. The distribution of NADPH‐d positive cells was centered on the laterodorsal tegmental (LDT) and pedunculopontine tegmental (PPT) nuclei. Diaphorase‐containing cells had a mean soma diameter of 23.0 ± 4.1 μm (n = 160) and were distributed inhomogeneously, with numerous cells found within densely packed clusters. A nearest‐neighbor analysis revealed that these cells were closely spaced, with up to 20% within one cell diameter and more than 50% within two cell diameters of a neighboring NADPH‐d cell. Within the LDT and PPT, NADPH‐d positive cells were mixed with smaller, diaphorase‐negative cells (diam: 12.8 ± 3.3 μm; n = 182;P<0.01). TH‐containing cells were not organized into a compact LC as in rat and their distribution more closely resembled that observed in cat. On average, TH‐containing cells (diam: 21.2 ± 4.8 μm;n =160) were smaller than NADPH‐d cells (P<0.01). 5‐HT‐containing cells were mainly located in the raphe nuclei, as in other species. 5‐HT‐containing cells (diam: 18.2 ± 4.4 μm; n = 161) were smaller on average than both the NADPH‐d (P<0.01) and TH‐containing cells (P<0.01). An analysis of the overlap in soma distributions revealed that TH‐containing cells were largely interdigitated with NADPH‐d‐containing cells. As much as 78% of the area occupied by the NADPH‐d cells of LDT was contained within the area occupied by TH cells. Substantial numbers of TH and 5‐HT immunoreactive processes were seen in both LDT and PPT. Varicose 5‐HP and TH‐containing fibers, as well as thicker, possibly dendritic processes containing TH were often seen in close apposition to NADPH‐d containing somata and proximal dendrites. These results support the hypothesis that NADPH‐d cells of both the PPT and LDT receive input from TH and 5‐HT cells. Moreover, the clustered substructure of LDT and PPT and the extensive overlap of NADPH‐d and TH‐containing somata raise the possibility that the membrane permeable messenger nitric oxide plays a role in modulating TH‐containing somata and their processes as we

ISSN:0092-7317    

DOI:10.1002/cne.903620309

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe myelin proteolipid proteins are a vital component of the vertebrate central nervous system (CNS), contributing essential functions to the development of the myelinating cells of the CNS and to the structure of CNS myelin. Alternative splicing of the proteolipid protein (PLP) gene to produce two related isoforms occurs in Mammalia, Ayes, and Reptilia, but not Amphibia. As part of a long‐term investigation into the function of the different isoforms of PLP, embryonic development, myelination, and PLP gene expression in reptilian CNS were examined. PLP gene expression was already substantial by day 19 (stage 39) of the 27‐dayEumeces fasciatusegg incubation period. By day 21 of incubation, also stage 39, PLP mRNA was at peak levels; there was a significant amount of CNS myelination as demonstrated by electron microscopy of the spinal cord; and the reflexive motor response was evident. Although most axons were myelinated by the time of hatching, myelin sheaths continued to increase in size and compactness after hatching. The correlation of physiological development, CNS myelination, and expression of the PLP gene in the lizard corresponded well with the developmental pattern seen in mammals. © 1995 Wiley‐Li

ISSN:0092-7317    

DOI:10.1002/cne.903620310

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY

ISSN:0092-7317    

DOI:10.1002/cne.903620301

出版商:Wiley‐Liss, Inc.    

年代:1995

数据来源: WILEY