bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence for a GABAergic interface between cortical afferents and brainstem projection neurons in the rat central extended amygdala
Authors: Sun Ning , Yi Hong , Cassell Martin D.
Published: January 2005

The synaptic circuitry of the intrinsic GABAergic system of the central extended amygdala (CEA) in relation to efferent neurons and cortical afferents was examined in the present study. Neurons in the CEA projecting to the dorsal vagal complex and the parabrachial complex were identified by the retrograde transport of wheat germ agglutinin‐horseradish peroxidase (WGA‐HRP). Postembedding GABA‐immunocytochemistry revealed that GABA‐immunoreactive (GABA‐IR) terminals formed largely symmetrical synaptic contacts with the perikarya and proximal dendritic processes of almost all WGA‐HRP‐labeled neurons in the CEA. To determine the relationship between cortical afferents and CEA GABAergic neurons, WGA‐HRP was used to anterogradely label afferents from the insular cortex in combination with postembedding immunogold detection of GABA. Cortical afferents formed asymmetrical synaptic contacts predominantly on small dendrites and dendritic spines. Many of the dendrites postsynaptic to cortical terminals in the central nucleus were immunoreactive for GABA although only relatively few spines were GABA‐IR. Combining pre‐embedding GAD‐immunocytochemistry with cortical lesions resulted in approximately 40% of degenerating terminals of insular cortical origin in the central nucleus in contact with small, GAD‐IR dendrites and spines.

The present results demonstrate that the neurons providing the major CEA outputs to the brainstem receive an extensive GABAergic innervation, strongly supporting our proposal that CEA efferent neurons are under strong tonic inhibition by intrinsic GABAergic neurons. Further, our finding that the major cortical input to the central nucleus preferentially innervates intrinsic GABAergic neurons suggests that these neurons in the CEA may serve as an interface between the principal inputs and outputs of this forebrain region. © Wiley‐Liss, Inc.
New subdivision schema for the avian torus semicircularis: Neurochemical maps in the chick
Authors: Puelles Luis , Robles Carmen , Martínez‐de‐la‐Torre Margaret , Martínez Salvador
Published: January 2005

Chemoarchitectonic subdivisions in the chicken torus semicircularis were mapped by means of acetylcholinesterase histochemistry and immunocytochemical labeling of leucineenkephalin, choline acetyltransferase, neuropeptide Y, and calbindin/calretinin in adjacent sections. The torus semicircularis was found to consist of three main divisions: intercollicular area, torai nucleus, and preisthmic superficial area. All three appear variously subdivided. The intercollicular area is a mid‐mesencephalic ventral periventricular region and appears subdivided into core and shell intercollicular regions. The toral nucleus is formed by a large caudal periventricular cytoarchitectonic complex, consisting of a periventricular lamina subdivided into core and shell regions, a pericentral, diffuse external nucleus, a central nucleus subdivided into core and shell regions, a caudomedial shell nucleus, a paracentral nucleus, and a posterior hiliar nucleus, apart from other minor parcellations. The preisthmic superficial area extends superficially at the caudomedial end of the toral nucleus, reaching the paramedian dorsal brain surface just rostral to the isthmo‐optic nucleus. It is subdivided into core and shell regions. This previously unnoticed area is distinguished here from the intercollicular area and from the caudomedial shell and paracentral nuclei, all of which are frequently mixed in the literature under the concept “intercollicular nucleus.” The revised terminology and subdivision for the avian torus clarifies many chemoarchitectonic and hodological mappings reported in the literature. It also suggests new research subjects and eliminates some causes of confusion. © Wiley‐Liss, Inc.
NGF increases neuritic complexity of cholinergic interneurons in organotypic cultures of neonatal rat striatum
Authors: Studer Lorenz , Spenger Christian , Luthman Johan , Seiler Rolf Walter
Published: January 2005

The influence of NGF on cholinergic interneurons in organotypic roller tube cultures of 4 day postnatal rat striatum was examined after 13 to 16 days in vitro. Cultures were divided into four groups. The medium of the NGF treated group was supplemented with 5 ng/ml NGF, whereas control groups were cultured either without NGF, by adding 20 ng/ml neutralising anti‐NGF antibody, or by adding both NGF and anti‐NGF antibody to the medium. Two different cell populations were identified by an image analysis system which measured acetylcholinesterase staining intensity. It was demonstrated that NGF promotes survival of the large, intensely stained population. Eighty computer‐assisted reconstructions of intensely stained cells, 20 for each treatment group, were performed in a random order by means of a neuron tracing system. Axons and dendrites were analysed separately. © Wiley‐Liss, Inc.

NGF enhanced complexity of neuritic, predominantly axonal trees by increasing the number of axonal segments by 91% to 100% (P < 0.01), the number of dendritic segments by 33% to 63% (P = 0.09 to P < 0.01), maximal axonal branch order by 37% to 50% (P < 0.05), and maximal dendritic branch order by 22% to 37% (P < 0.05). Further evidence of more complex neuritic trees was given by Sholl concentric sphere analysis. Anti‐NGF antibody could block all these effects. General rules of branching architecture were not affected by NGF treatment as shown by analysing mean segment length in relation to the branch order, branch point exit angles, total tortuosity, Rall's ratio, and tapering of neuritic trees. © Wiley‐Liss, Inc.
Expression of a keratan sulfate proteoglycan during development of the dorsal lateral geniculate nucleus in the ferret
Authors: Robson John A. , Geisert E. E.
Published: January 2005

ABAKAN is a keratan sulfate proteoglycan was identified in rat brain by monoclonal antibody TED15 (Geisert et al. [1992] Brain Res. 571:165–168). It blocks neuronal attachment and neurite outgrowth in culture, is associated with astrocytes, and marks the boundaries of areas in the developing rat brain (Geisert and Bidanset [1993] Dev. Brain Res., 75:163–173). In the present study TED15 was used to examine the distribution of ABAKAN during laminar development of the dorsal lateral geniculate nucleus in ferrets. This distribution was also compared with that of astrocytes as displayed with antibodies to GFAP. In the adult, TED15 and anti‐glial fibrillary acidic protein (GFAP) labeling are similar. Both are fairly uniform in the nucleus although somewhat elevated near the optic tract and in the interlaminar zone between laminae A and A1. During development the pattern is quite different. At postnatal day 1 (P1), before lamination is evident, TED15 and anti‐GFAP labeling are light in the nucleus. By P10, when laminae are emerging, both are elevated in the A‐A1 interlaminar zone and in the C laminae. At P18, when laminae are distinct, TED15 labels the A‐A1 interlaminar zone, and it marks the borders between the ON and OFF leaflets within A and A1 (Stryker and Zahs [1983] J. Neurosci. 3:1943–1951). In comparison, anti‐GFAP marks the interlaminar zone but not the ON/OFF leaflets. By 6 weeks the nucleus resembles the adult nucleus. These results show that ABAKAN marks the boundaries of the major functional subdivisions of the lateral geniculate nucleus in the developing ferret and suggest that it plays a role in lamination. © Wiley‐Liss, Inc.
The motor neurons innervating the direct flight muscles of Drosophila melanogaster are morphologically specialized
Authors: Trimarchi James R. , Schneiderman Anne M.
Published: January 2005

The anatomy of the motor neurons innervating six direct flight muscles in Drosophila melanogaster has been investigated by using a horseradish peroxidase backfilling technique. The somata of these motor neurons are arranged in two distinct clusters ipsilateral to the muscle they innervate. One cluster of cell bodies is located in the ventrolateral region between the prothoracic neuromere and the mesothoracic leg‐related neuropil and the other is situated dorsally and posteriorly to the mesothoracic leg‐related neuropil. Axons from somata in the ventrolateral cluster run in the anterior dorsal mesothoracic nerve, while axons from somata in the other cluster run in the mesothoracic accessory nerve. This distribution of somata and axons is discussed in the light of the morphological similarity and proximity of these functionally related muscles.

On the basis of the branching patterns of their neurites, direct flight muscle motor neurons can be classified as stubbly, fibrous or tufted. The terminal arborizations of the motor neurons over the direct flight muscles are also morphologically specialized. Both the central and the peripheral morphological specializations of the direct flight muscle motor neurons correlate with the activity patterns exhibited by their associated muscles during flight and courtship song. © Wiley‐Liss, Inc.
Immunohistochemical detection of calcium/calmodulin‐dependent protein kinase II in the spinal cord of the rat and monkey with special reference to the corticospinal tract
Authors: Terashima Toshio , Ochiishi Tomoyo , Yamauchi Takashi
Published: January 2005

Calcium/ calmodulin‐dependent protein kinase II is a prominent enzyme in the mammalian brain that phosphorylates a variety of substrate proteins. In the present study, monoclonal antibodies that specifically recognize either the α or the β isoforms of this enzyme were used to determine the distribution of these isoforms within the rat and monkey spinal cord. In the rat, the corticospinal tract consists of two components: the dorsal corticospinal tract, which occupies the ventralmost aspect of the dorsal funiculus; and the ventral corticospinal tract, which occupies an area adjacent to the ventral median fissure. Both dorsal and ventral corticospinal tract fibers were strongly immunopositive for the α‐antibody. Unilateral ablation of the sensorimotor cortex of the rat eliminated the α‐immunoreactive staining in the contralateral dorsal corticospinal tract. The neuropil in the superficial laminae of the dorsal horn (Rexed's laminae I and II) was densely stained with the α‐antibody, whereas the neuropil in laminae IV‐X was immunonegative. Dense α‐immunopositive neurons were also distributed in the head of the dorsal horn (laminae I‐IV). In contrast to the strong α‐immunoreactivity seen in the dorsal corticospinal tract fibers, only very weak β‐immunoreactivity was observed in this tract. Moderate β‐immunoreactive products were distributed homogenously throughout the neuropil of the gray matter, although the neuropil of the superficial laminae of the dorsal horn (laminae I and II) was stained more strongly than the other regions of the gray matter (laminae III‐X). Neuronal components in all laminae were immunopositive for the β‐antibody. Thus, motoneurons in the ventral horn, which were immunonegative for the α‐antibody, were immunopositive for the β‐antibody. This selective distribution pattern of immunoreactivity of α‐ and β‐antibodies in the rat was also present in the monkey spinal cord, although the α‐immunopositive corticospinal tract fibers in the monkey descended in the lateral funiculus as the lateral corticospinal tract instead of passing through the dorsal funiculus, as is the case in the rat. The differential distribution of immunoreactivity in the spinal cord suggests that these two isoforms of calcium/ calmodulin‐dependent protein kinase II may have different functional roles in the spinal cord. © Wiley‐Liss, Inc.
Morphological assessment of grafted rat and mouse cortical neurons: A light and electron microscopic study
Authors: Lübke Joachim , Wood Matthew J. A. , Clarke Deborah J.
Published: January 2005

The morphology of cortical neurons grafted into (or near) the rat striatum was studied by means of intracellular Lucifer yellow injections in fixed slices. Rat donor syngeneic cortical tissue (from postnatal day 1 old rats; AO strain) as well as mouse donor xenogeneic cortical tissue (prenatal day 19; C3H/HE strain) were grafted as solid pieces into 8–12 week‐old rats (AO strain). Recipients of mouse xenografts were immunosuppressed with a monoclonal antibody against the interleukin‐2 receptor. After perfusion and sectioning of the graft‐containing areas, individual slices were incubated in the DNA stain 4.6‐diamidino‐2‐phenylindole (DAPI) to visualize the cell nuclei. Grafts could be easily identified by a surrounding rim of astrocytes which outline the border between grafted and host tissue. Grafted cortical neurons were intracellularly filled with Lucifer yellow, DAB‐photoconverted, and further processed for light and electron microscopy.

In general, no cortical lamination could be observed in the grafted rat and mouse cortical tissue, but neurons were loosely packed throughout the graft. Two major cell types could be identified in all grafts investigated so far. The majority resembled those described as spiny neurons (85%), which could be further classified into pyramid‐like, spiny stellate‐like or fusiform spiny neurons, with somata ranging between 15 and 25 μm in diameter. The remaining 15% resembled non‐spiny neurons with either a multipolar basket‐like or fusiform morphology. Dendrites of spiny and non‐spiny neurons, which could extend to distances up to 400 μm, were never seen to cross the astrocytic border, but some main axon and axonal collaterals of spiny neurons were found to leave the graft. On the basis of light microscopic observations no difference was found between mouse and rat grafted cortical neurons. The results of this study show that grafted cortical neurons retain some of the characteristic features of neurons in the intact adult cerebral cortex, although there appears to be a greater preponderance of spiny neurons in grafted tissue. This may reflect an immaturity of the grafted tissue or a response to the striatal environment.
Peptidergic neurons in the snail Helix pomatia: Distribution of neurons in the central and peripheral nervous systems that react with an Antibody raised to the insect neuropeptide, leucokinin I
Authors: Elekes K. , Hernádi L. , Muren J. E. , Nässel D. R.
Published: January 2005

In this study, antiserum raised against an insect myotropic peptide, leucokinin I (DPAFNSWGamide), was: used for mapping leucokinin‐like immunoreactive (LK‐LI) neurons in the gastropod mollusc, Helix pomatia. Immunocytochemistry performed on both whole‐mounts and cryostat sections demonstrated LK‐LI neurons in all ganglia of the central nervous system (CNS), except the visceral ganglion. Altogether about 700 immunolabelled neurons have been found, with nearly one‐half (46%) in the cerebral ganglia. A large proportion of the LK‐LI neurons have small cell bodies and are likely to be interneurons. The most prominent LK‐LI cell group is represented by the entire neuron population of the mesocerebri, which is the major source of a thick fiber bundle system, encircling and innervating the whole CNS. One single LK‐LI giant neuron was found, which is located in the left pedal ganglion and is termed GLPdLKC (giant left pedal leucokinin immunoreactive cell). This cell has not been identified previously. The ganglion neuropils are heavily innervated by varicose LK‐LI fiber arborizations. Some integrative centers, such as the medullary neuropil of the procerebri, reveal an extreme density of LK‐LI innervation. All major peripheral nerves contain a large number of LK‐LI axons, and LK‐LI innervation is found in the musculature of different peripheral organs (buccal mass, lip, tentacles, oviduct, intestine). Among the peripheral organs investigated, the intestine contains a rich varicose LK‐LI network, composed of both intrinsic and extrinsic elements. Radioimmunoassay (RIA) demonstrates a very high content of LK‐LI material in Helix ganglion extracts (about 50 pmol/CNS). This is the first report on the occurrence of a substance resembling the myotropic neuropeptide leucokinin I in a phylum outside arthropods. Based on our immunocytochemical observations, a role for leucokinin‐like peptides in both central and peripheral regulatory processes in Helix is suggested. According to double‐labelling experiments, only a small number of the LK‐LI neurons are labelled with an antibody to the vertebrate tachykinin substance P.
Nerve growth factor‐like immunoreactive profiles in the primate basal forebrain and hippocampal formation
Authors: Mufson Elliott J. , Conner James M. , Varon Silvio , Kordower Jeffrey H.
Published: January 2005

The distribution of nerve growth factor (NGF), the prototypic neurotrophin, within the basal forebrain and hippocampal formation of young adult monkeys and aged humans was characterized with and affinity purified polyclonal β‐NGF antibody raised against mouse β‐NGF. In the basal forebrain of both primates, a granular NGF‐like immunoreactive (ir) reaction product was observed within neurons of the medial septum, nucleus of the diagonal band, and nucleus basalis of Meynert. NGF‐like immunoreactivity exclusively colocalized within p75 NGF receptor (NGFR) containing basal forebrain neurons. The intensity of NGF immunolabeling varied between cell bodies. Many NGF‐ir perikarya were highly immunoreactive. In other basal forebrain neurons, NGF‐like immunoreactivity was either undetectable or minimally expressed. In the hippocampus of both species, NGF‐like immunoreactivity was mainly localized within the hilus of the dentate gyrus and within CA3 and CA2 hippocampal subfields. A marked diminution in NGF‐like staining was seen in CA1. Within the hippocampal formation, NGF‐like immunoreactivity was heaviest within the neuropil of stratum radiatum, intermediate in stratum oriens, and lightest in stratum pyramidal. NGF‐like immunoreactivity was not found within the granule or pyramidal cells of the dentate gyrus and hippocampal formation, respectively. These findings demonstratre the presence of an NGF‐like antigen in association with monkey and human magnocellular basal forebrain neurons and within their hippocampal target sites. This lends support to the hypothesis that NGF is internalized from sources located within target regions of the primate cholinergic basal forebrain neurons and is retrogradely transported to these cell bodies where the NGF trophic effect likely occurs.
Morphogenesis of catecholaminergic interneurons in the frog spinal cord
Authors: Heathcote R. David , Chen Aileen
Published: January 2005

During embryonic and larval development of the frog Xenopus laevis, a bilateral population of cerebrospinal fluid‐contacting neurons matures in the ventral spinal cord. These cells are catecholaminergic and form a dispersed or nonrandom pattern of spacing within each of their spinal cord columns. In order to test the mechanisms underlying pattern formation of these neurons, it is first necessary to understand their normal morphogenesis. Morphogenetic changes were examined by using immunocytochemistry for tyrosine hydroxylase as a cell marker. Immunoreactivity in spinal cord cells was detected as early as 1.4 days (stage 28) of embryonic development. Subsequently, these cells underwent changes in shape, and rapid, regressive changes in cell size. The population emerges gradually during development, but the major characteristic of nonrandom spacing, their dispersion from other catecholaminergic cells, is apparent at early stages of differentiation. Increases in cell density occur over an extended period of time and can be divided into an initial phase of large, rapid changes and a subsequent plateau phase of gradual changes. The two longitudinal columns of catecholaminergic cells that are characteristic of older animals become apparent just before hatching, when density increases until cells on both sides of the midline are present in the same region. Although the dispersed pattern exists within each column, cross‐correlation analysis shows that there is a random relationship between cells in opposite columns. During larval development, the catecholaminergic cell domain expands in both a rostral and caudal direction. The morphogenetic changes of the catecholminergic cell population begin to show how the cells become partitioned within the floor plate region of the spinal cord. © 1994 Wiley‐Liss, Inc.
Age and damage induced changes in amyloid protein precursor immunohistochemistry in the rat brain
Authors: Beeson James G. , Shelton Earl R. , Chan Hardy W. , Gage Fred H.
Published: January 2005

Alzheimer's disease (AD) is characterized by the extensive deposition of the 42‐amino‐acid β‐amyloid or A4 protein in neuritic plaques and neurofibrillary tangles within the brain. This protein is liberated from the much larger amyloid protein precursor (APP). Multiple species of APP have been proposed, including several forms that contain a 56 amino acid insert sequence analogous to the Kunitz protease inhibitors. Although expression of APP mRNA is reportedly altered in AD brain and various roles for APP have been proposed, the pathogenesis of amyloid deposition and AD remains unclear. AD is also characterized by specific memory impairments associated with decreased cholinergic activity. While aging rats do not develop mature amyloid pathology, behaviorally impaired aged rats demonstrate an analogous cholinergic decline. In this study, we examined behaviorally characterized aged rats and normal young controls for changes in APP immunohistochemistry by using anti‐APP antibodies, which detect N‐ or C‐terminal regions and which distinguish APP species with or without the Kunitz protease inhibitor domain. The results show specific age‐ and behavior‐related changes in cortical APP immunoreactivity as well as limited numbers of APP immunoreactive deposits in the aged rats. Additionally, we found that lesions of the fimbria‐fornix pathway, which in part mimic the memory impairments and loss of cholinergic activity seen in AD, result in the marked accumulation of APP immunoreactive material in the region of cholinergic fiber degeneration in the hippocampus. These findings are discussed in relation to the pathogenesis of AD in humans. © 1994 Wiley‐Liss, Inc.
Efferent connections from the lateral hypothalamic region and the lateral preoptic area to the hypothalamic paraventricular nucleus of the rat
Authors: Larsen Philip J. , Hay‐Schmidt Anders , Mikkelsen Jens D.
Published: January 2005

The lateral preoptic and lateral hypothalamic regions contain the majority of the cell groups embedded in the fibre trajectories of the medial forebrain bundle on its course through the hypothalamus. Recent studies have extended considerably the parcellation of the lateral hypothalamic region, and, therefore, the need to emphasize new insights into the anatomical organisation of projections from the neurons of the lateral hypothalamic region. In the present study we describe the anatomical organisation of efferent projections from the lateral preoptic and lateral hypothalamic regions to the hypothalamic paraventricular nucleus (PVN) on the basis of retrograde‐ and anterograde‐tracing techniques. Iontophoretic injections of the retrograde tracer, cholera toxin subunit B, into the PVN revealed that most hypothalamic nuclei project to the PVN. Within the lateral hypothalamic region, retrogradely labelled cells were concentrated in the intermediate hypothalamic area, the lateral hypothalamic area, and the perifornical nucleus, whereas fewer retrogradely labelled cells were found in the lateral preoptic area.

To determine the distribution of terminating fibres in subnuclei of the heterogeneous PVN, iontophoretic injections of the anterograde tracer Phaseolus vulgaris‐leucoagglutinin were delivered into distinct areas of the lateral hypothalamic region. Neurons of the intermediate hypothalamic area projected mainly to the PVN subnuclei, which contained parvicellular neuroendocrine cells. In contrast, neurons of the rostral and tuberal parts of the lateral hypothalamic area and the perifornical nucleus projected to the PVN subnuclei, which contained parvicellular neurons that send descending projections to preganglionic cell groups in the medulla and spinal cord. The perifornical nucleus was the only area within the lateral hypothalamic region that consistently innervated magnocellular perikarya of the PVN. Finally, all areas of the lateral hypothalamic region contributed substantially to fibres terminating in the perinuclear shell of the PVN. These results demonstrate that anatomically distinct areas of the lateral hypothalamic region have distinct projections to subnuclei of the PVN and further substantiate the view that the lateral hypothalamic region as well as the PVN constitute anatomically and functionally heterogeneous structures. © 1994 Wiley‐Liss, Inc.
Neural network controlling feeding in Lymnaea stagnalis: Immunocytochemical localization of myomodulin, small cardioactive peptide, buccalin, and FMRFamide‐ related peptides
Authors: Santama Niovi , Brierley Matthew , Burke Julian F. , Benjamin Paul R.
Published: January 2005

This paper investigates the distribution of four classes of neuropeptides, myomodulin, small cardioactive peptide (SCP), buccalin, and FMRFamide, in central neurons forming the network that underlies feeding behavior in the snail Lymnaea stagnalis. Intracellular dye‐marking and immunocytochemical analysis, using antisera to the different classes of peptides, were applied to identified neurons of all three levels of the hierarchy of the circuitry: modulatory interneurons (cerebral giant cells, CGC; slow oscillator, SO), central pattern generator (CPG) interneurons (N1, N2, N3), motoneurons (B1–B10), and their peripheral target organs. Myomodulin immunoreactivity was detected in the CGC interneurons, in the SO, and in ventral N2‐type CPG interneurons. Several large buccal motoneurons, the paired B1, B2, B3, B7, and neurons located in the dorsal posterior area (putative B4 cluster types) were also myomodulin immunoreactive. Target organs of buccal motoneurons, the buccal mass, salivary glands, and oesophagus contained myomodulin‐immunopositive fibers. SCP appeared in N2‐type interneurons and was found colocalized with myomodulin in the B1 and B2 motoneurons. SCP‐containing neurons in the B4 cluster area were also detected. The buccal mass and salivary glands exhibited SCP‐immunoreactive fibers. Buccalin immunoreactivity was scarce in the buccal ganglia and was identified only in N1‐type interneurons and three pairs of dorsal posterior neurons. In the periphery, immunoreactive fibers were localized in the oesophagus only. None of the buccal neuronal types examined revealed immunoreactivity to SEQPDVDDYLRDVVLQSEEPLY (“SEEPLY”), a peptide encoded in the FMRFamide precursor protein of Lymnaea. SEEPLY immunoreactivity was confined to a pair of novel ventral neurons with projections to the laterobuccal nerve innervating the buccal mass. Immunoreactive fibers were also traced in this organ. © 1994 Wiley‐Liss, Inc.
A study of SMI 32‐stained pyramidal cells, parvalbumin‐immunoreactive chandelier cells, and presumptive thalamocortical axons in the human temproal neocortex
Authors: del Río María R. , DeFelipe Javier
Published: January 2005

Immunocytochemical studies in the primate neocortex have shown that particular populations of pyramidal cells can be identified by antibody SMI 32 that recognizes a nonphosphorylated epitope of neurofilament protein, while chandelier cells (a powerful type of cortical inhibitory interneuron) and presumptive thalamocortical axons can be identified by antibodies directed against the calcium‐binding protein parvalbumin (PV). We used these antibodies in correlative light and electron microscopic immunocytochemical studies to analyze certain aspects of the synaptic circuitry of human temporal neocortex. In sections cut in the tangential plane, many PV‐immunoreactive chandelier cell axon terminals and apical dendrites of SMI 32‐stained pyramidal cells were distributed in small clusters. Combination of immunocytochemistry for PV and SMI 32 revealed four subpopulations of pyramidal cells with regard to the immunocytochemical staining by SMI 32 and the innervation of their axon initial segments by PV‐positive or ‐negative chandelier cell axon terminals, but there were differences in the concentration and proportion of these subpopulations by layers. Furthermore, we present electron microscopic evidence suggesting that the characteristic layer III dense band of PV‐immunoreactive puncta is made up mainly of presumptive thalamocortical axon terminals. Besides, coincidence was found between the dense PV‐immunoreactive band and the dendritic plexus formed by the SMI 32‐stained pyramidal cells in the lower half of layer III, which leads us to think that they are probably a major target of PV‐immunoreactive thalamic terminations. © 1994 Wiley‐Liss, Inc.
Distribution of input synapses from processes exhibiting GABA‐ or glutamate‐like immunoreactivity onto terminals of prosternal filiform afferents in the locust
Authors: Watson A. H. D. , Pflüger H.‐J.
Published: January 2005

The locust prosternum carries a population of long filiform hairs that are very sensitive to air currents. The sensory afferent neurons that innervate the hairs make strong monosynaptic connections with an identified intersegmental interneuron (A4I1) which is known to contact motor neurons that supply muscles controlling wing angle during flight. In order discover how the synapse between the afferents and interneuron A4I1 might be modulated, the afferents were labelled intracellularly by backfilling with horseradish peroxidase to reveal their central terminals which lie in the prothoracic ganglion. A postembedding immunogold method was used to make a quantitative assessment of the prevalence of immunoreactivity for GABA and glutamate in processes presynaptic to the afferent terminals. In one afferent neuron, where 77 synapses were examined, 40 (52%) of the presynaptic processes were immunoreactive for GABA. When adjacent sections through the same terminal branches were labelled with the two antibodies, it was demonstrated that GABA‐ and glutamate‐like immunoreactivity was present in different populations of presynaptic processes. A series of 110 ultrathin sections was cut through one set of afferent terminal branches and alternate grids were stained with GABA and glutamate antibodies. From these sections, the terminals were reconstructed and the position of 35 input and 21 output synapses mapped. Of the 35 input synapses, 18 (51%) were immunoreactive for GABA, 14 (40%) were immunoreactive for glutamate and 3 (9%) were unlabelled by either antibody. On these terminals, the different classes of input synapses appeared to be intermingled at random with the output synapses made by the afferent, and no pattern govering synapse distribution could be discerned. © 1994 Wiley‐Liss, Inc.
GABAergic projection from the intercalated cell masses of the amygdala to the basal forebrain in cats
Authors: Paré D. , Smith Y.
Published: January 2005

The intercalated cell masses (ICMs) are dense clusters of small GABAergic cells interposed between the basolateral and centromedial nucles groups of the amygdala. Until now, the ICMs have been largely ignored in anatomical studies of the amygdaloid complex. Thus, this study was undertaken to ientify some of their targets by means of tract‐tracing methods combined with immunohistochemical teniques.

Wheat‐germ agglutinin conjegated to horseradish peroxidase (WGA‐HRP) was injected into numerous cortical areas and dorsal thalamic nuclei, in the anterior commissure and/or stria terminalis nuclei, and in the caudate nucleus, as wel as into latera and preoptic hypothalamic areas. Very few retrogradely labeled cells were seen in the ICMs following these injections. In contrast, massive retrograde labeling was found in the rostral groups of ICMs after WGA‐HRP injections involving the substantia innominata and horizontal limb of the diagonal band. Furthermore, these retrogradely labeled intercalated cells were also GABA immunoreactive. Results of iontophoretic injections of Phaseolus vulgaris‐leucoagglutinin (PHA‐L) in the rostral ICMs confirmed that they contribute a massive projection to the entire extent of the substance innominata and horizontal limb of the diagonal band. Electron microscopic observations of ultrathin sections prepared for postembedding GABA or glutamate immunocytochemistry revealed that the ICM terminals labeled with PHA‐L displayed GABA, but not glutamate immunoreactivity, and formed symmetric synapses with dendritic profiles.

The present findings constitue the first direct demonstration of an amygdalofgal GABAergic projection to the basal forebrain. Considering that the basal forebrain contains a group of cholinergic and GABAergic neurons collectively projecting to the entire cortical mantle, this GABAergic projection of the ICMs could allow the amygdaloid complex to influence the activity of widespread cortical regions to which it is not directly connected, at least in the cat. © 1994 Wiley‐Liss, Inc.
Dopamine in the lobster Homarus gammarus. I. Comparative analysis of dopamine and tyrosine hydroxylase immunoreactivites in the nervous system of the juvenile
Authors: Cournil Isabelle , Helluy Simone M. , Beltz Barbara S.
Published: January 2005

As a catecholamine, depamine belogs to a class of molecules that have multiple transmitter and hhormonal functions in vertebrate and invertebrate nervous systems. However, in the lobster, where many central beurons have been identified and the peripheral innervation pattern is well known, the distribution of dopamine‐containing neurons has not been examined in detail. Therefore, immunocytochemical methods were used to identify neurons likey to contain dopamine and tyrosine hydroxylase in the central nervous system of the juvenile lobster Homarus gammarus.Approximately 100 neuronal somata stain for the catecholamine and/or its synthetic enzyme in the brain and ventral nerve cord. The systems of neurons labeled with dopamine and tyrosine hydroxylase natibodies have the following characteristic: (1) the two systems are nearly identical; (2) every segmental ganglion contains at least one pair of labeled neurons; (3)the positions and numbers of cell bodies labeled with each antiserum are similar in the various segmental ganglia; (4) six labeled neurons are anatomically identified; two interneurons from the brain project within the ventral cord to reach the last abdominal ganglion, two neurons from the commissural ganglia are presumably neurosecretory neurons, and two anterior unpaired medial abdominal neurons project to the hindgut muscles; and (5) nocell bodies are labeled in the stomatogastric ganglion, but fibers and terminals in the neuropil are stained. The remarkably small numbers of labeled neurons and the presence of very large labeled somata with far‐reaching projections are distinctive features consistent with other modulatory aminergic systems in both vertebrates and invertebrates. © 1994 Wiley‐Liss, Inc.
Evidence for prenatal competition among Ahe central arbors of trigeminal primary afferent neurons: Single axon analysis
Authors: Chiaia Nicolas L. , Zhang Shujie , King Tod D. , Rhoades Robert W.
Published: January 2005

Previous studies from this laboratory have demonstrated that prenatal damage to vibrissae follicles results in significant increases in the brainstem representations of the remaining vibrissae as demonstrated by staining for the mitochondrial enzyme cytochrome oxidase (CO). Because CO is primarily a postsynaptic marker, these results do not directly address the question of whether there were changes in the projections of primary afferent fibers. To address this issue, we made intra‐axonal recordings from individual vibrissa‐related primary afferents in rats that sustained damage to vibrissae follicles oil embryonic day 17, and then injected horseradish peroxidase (HRP) into these axons to visualize their terminal arbors in the brainstem at the level of trigeminal subnucleus interpolaris (SpI). All vibrissae‐related primary afferents responded to deflection of one and only one vibrissa, and the terminal arbors of axons (N = 47) recovered from animals that sustained fetal peripheral lesions were significantly larger than those (N = 23) from normal rats. Fibers from fetally damaged animals had increased total fiber lengths and numbers of branch points. These results indicate that reduced competition among primary afferent axons results in increases in the terminal arbors that remain. These increases occur without any significant alteration in their peripheral receptive fields. © 1994 Wiley‐Liss, Inc.
Programmed cell death during the earliest stages of spinal cord development in the chick embryo: A possible means of early phenotypic selection
Authors: Homma Shunsaku , Yaginuma Hiroyuki , Oppenheim Ronald W.
Published: January 2005

The spatiotemporal distribution of cell death in the chick embryo neural tube and spinal cord (brachial region) was examined between stage (St.) 12 and 22, in plastic semithin sections. Between St. 12 and 16, the total number of pycnotic cells per segment was low, whereas after St. 16 the number of pycnotil cells was substantially increased. Between St. 17 and 19 three cell death foci or regions could be recognized. One region, the dorsal pycnotic zone, was located in the most dorsal part of the spinal cord, including the neural crest, with the highest number of pycnotic cells observed at St. 18. The second region, or ventral pyenotic zone, was located between motoneurons and the floor plate and had the highest number of dying cells at St. 17. The third region, the floor plate pycnotic zone, was located in the midportion of the floor plate and had the greatest amount of cell death at St. 19. Although low numbers of pycnotic cells were also observed in other regions between St. 17 and 19, no pycnotic cells were found in the ventrolateral region that gives rise to motoneurons. Ultrastructural observations as well as data from in situ nick end labeling indicate that the pycnotic cells observed in the neural tube die by apoptosis and that the debris from the dead cells is phagocytized primarily by adjacent healthy neuroepithelial cells.

Although the spatiotem poral distribution of pycnotic cells suggests that cell death at these early stages could play a role in establishing the pioneer axonal pathway for spinal commissural neurons, preliminary observations following perturbations of cell death do not support this notion. Alternatively, early cell death may be involved in the regulation of cellular patterning along the dorsoventral axis of the neural tube by a kind of negative selection of specific progenitor cells. © 1994 Wiley‐Liss, Inc.
Homogeneity of intracellular electrophysiological properties in different neuronal subtypes in medial preoptic slices containing the sexually dimorphic nucleus of the rat
Authors: Hoffman Neil W. , Kim Yang I. , Gorski Roger A. , Dude F. Edward
Published: January 2005

The sexually dimorphic nucleus of the preoptic area (SDN‐POA) is larger in male than in female rats, the male phenotype requiring the presence of circulating androgens perinatally. These experiments investigated the intracellular electrophysiology and morphology of SDN‐POA neurons and compared these properties with those of other medial preoptic area (MPOA) neurons. Biocytin‐injected cells in the SDN‐POA either had one or two primary dendrites, or they had multipolar dendritic arrays; dendrites were aspiny or sparsely spiny and displayed limited branching. Neurons in other parts of the MPOA were similar morphologically. Regardless of morphology, neurons situated in either the SDN‐POA or surrounding MPOA had low‐threshold potentials and linear or nearly linear current‐voltage relations. In most (73%) cells, stimulation of the dorsal preoptic region evoked a fast excitatory postsynaptic potential followed by a fast inhibitory postsynaptic potential (IPSP). Bicuculline blocked the fast IPSPs, which reversed near the Cl2 equilibrium potential (‐71 ± 5mV), indicating their mediation by gamma‐aminobutyric acid (GABA)A receptors.

Neurons in the SDN‐POA have electrophysiological properties similar to those of other medial preoptic cells. When compared with the hypothalamic paraventricular nucleus, the MPOA appears relatively homogeneous electrophysiologically. This is despite the morphological variability within this population of neurons and heterogeneities that are also apparent at other levels of analysis. Finally, GABA‐mediated, inhibitory synaptic contacts are widespread among medial preoptic neurons, consistent with indications from earlier reports that GABA provides a link in the feedback actions of gonadal steroids on the release of gonadotropic hormones. © 1994 Wiley‐Liss, Inc.
Motor neurons in onuf's nucleus and its rat homologues express the p75 nerve growth factor receptor: Sexual dimorphism and regulation by axotomy
Authors: Koliatsos Vassilis E. , Price Donald L. , Clatterbuck Richard E.
Published: January 2005

The present study establishes that populations of neurons in the lumbosacral cord, which innervate pelvic striated muscles, express p75NGFR throughout their life spans. These neuronal groups comprise the Onuf's nucleus in humans and its principal rat homologues, dorsolateral (DL) and dorsomedial (DM) nuclei, as well as the cremasteric (CRE) nucleus. The p75NGFR in these neurons is localized in the rough endoplasmic reticulum, Golgi complex, and lysosomes. Almost all neurons that project to striated perineal muscles in the male rat express p75NGFR; very low levels of p75NGFR are detected in neurons that innervate perineal sphincters of the female. In the female rat, p75NGFR expression is masculinized with perinatal androgen treatment. In addition, the expression of p75NGFR in DM and DL neurons in the adult is up‐regulated by injury (i. e., pudendal axotomy) but is not influenced by gonadectomy. The results of this study establish that neurons of Onuf s nucleus and its rat homologues differ from general somatic motor neurons in that they express p75NGFR from early postnatal life (i. e., when all motor neurons express p75NGFR) into the adult (when the former, but not the latter, express the receptor). In view of growing evidence for the role of neurotrophins in the physiology of motor neurons, the above differentiating feature between general somatic and sexually dimorphic motor neurons suggests that p75NGFR may be involved in motor neuron plasticity and may participate in mechanisms by which neurons can protect themselves from degenerative insults. © 1994 Wiley‐Liss, Inc.
A physiological and structural study of neuron types in the cochlear nucleus. I. Intracellular responses to acoustic stimulation and current injection
Authors: Feng Jane J. , Kuwada Shigeyuki , Ostapoff E.‐Michael , Batra Ranjan , Morest D. Kent
Published: January 2005

Neurons in the cochlear nucleus differ in their discharge patterns when stimulated by tones. They also differ in their responses to depolarizing current injection in vitro. We made intracellular recordings from neurons in the cochlear nucleus of gerbils and chinchillas. The responses to tones and to depolarizing current were compared for the same neurons. Three categories of response patterns to tones were observed: chopper, primary‐like, and onset. Chopper neurons responded with regularly spaced action potentials to stimulation with tones and to injections of depolarizing current. Their response rate rose with increasing levels of current to a maximum, which was comparable to that evoked by suprathreshold tones. These observations suggest that the regularity and maximal firing rate of these neurons are determined by voltage‐dependent membrane properties. Primary‐like neurons responded with irregularly spaced action potentials to tones. Injection of depolarizing current into these neurons produced a single action potential at current onset, which could be followed by a few irregularly spaced action potentials. The response rate showed little relation to current level. These suggest that the membrane characteristics of primary‐like neurons are different from those of chopper neurons. Onset neurons produced action potentials only at the beginning of the stimulus for both tones and depolarizing current, even though there was a sustained depolarization throughout the duration of the tone. The findings suggest that cochlear nucleus neurons have different membrane properties and that these properties may play a critical role in a neuron's temporal response pattern to acoustic stimulation. © 1994 Wiley‐Liss, Inc.
Innervation of footpads of normal and mutant mice lacking sweat glands
Authors: Rao M. S. , Jaszczak E. , Landis S. C.
Published: January 2005

Footpads of normal adult mice are innervated by sympathetic and sensory fibers. The sympathetic fibers associated with sweat glands contain acetylcholinesterase and immunoreactivity for vasoactive intestinal peptide. Although catecholamine histofluorescence is absent, the gland innervation exhibits immunoreactivity for tyrosine hydroxylase. A distinct population of sympathetic fibers, which possess catecholamines and neuropeptide Y as well as tyrosinehydroxylase immunoreactivity, innervates blood vessels. Sensory fibers containing immunoreactivity for substance P and calcitonin gene‐related peptide course beneath the epidermis and some form endings in it. Treatment of neonatal mice with the adrenergic neurotoxin, 6‐hydroxydopamine, results in loss of sympathetic innervation of sweat glands and blood vessels, permits growth of sensory axons into sweat glands, but does not alter the peptidergic sensory innervation of the dermis and epidermis. Three mouse mutations, Tabby (Ta), crinkled (cr), and downless (dl), disrupt the interactions between the mesenchyme and epidermis that are required for normal development of specific epidermal derivatives, including sweat glands. The sympathetic innervation of blood vessels and sensory innervation of footpad skin of the three mutant mice that lack sweat glands is indistinguishable from normal. The sympathetic fibers that normally innervate sweat glands, however, are not present. These results indicate that in the absence of their normal target, the sympathetic fibers that innervate sweat glands are lacking. Furthermore, they suggest that, although sensory fibers may sprout into sympathetic targets in the footpad, the domains occupied by sensory fibers are not normally accessible to sympathetic axons. © 1994 Wiley‐Liss, Inc.