bluuebunny/crossref_metadata_2025 huggingface dataset:
Ramification pattern and ultrastructural characteristics of the serotonin‐immunoreactive neuron in the antennal lobe of the moth Manduca sexta: A laser scanning confocal and electron microscopic study
Authors: Sun X. J. , Tolbert L. P. , Hildebrand J. G.
Published: January 2005

The two antennal lobes, the primary olfactory centers of the brain, of the moth Manduca sexta each contain one neuron that displays serotonin immunoreactivity. The neuron projects out of the antennal lobe and sends branches into ipsi‐ and contralateral protocerebral areas. An axon‐like process extends from the contralateral protocerebrum to, and terminates in, the contralateral antennal lobe. In order to begin to investigate the possible role of this unique neuron in olfactory information processing, we have used laser scanning confocal microscopic and electron microscopic immunocytochemical techniques to study the ramification pattern, ultrastructural characteristics, and synaptic connections of the neuron in the antennal lobes of female adult Manduca sexta. The neuron ramifies extensively in the antennal lobe contralateral to the cell body. The ramifications, mainly in the base and center of each glomerulus, do not overlap with those of the sensory axons from the antenna. This finding suggests that the serotonin‐immunoreactive neuron may not receive direct input from sensory neurons, and that it may modulate the activity of the neurons of the antennal lobe rather than that of the sensory neurons. In the electron microscope, the neuron exhibits large dense‐cored vesicles and small, clear round vesicles. In the antennal lobe ipsilateral to the cell body, the primary neurite of the serotonin‐immunoreactive neuron is unbranched and lacks detectable synaptic connections. The ramifications in the contralateral antennal lobe, however, participate in synaptic connections. At very low frequency, contralateral branches form synapses onto unlabeled processes and also receive synapses from unidentified neurons in the glomeruli, indicating that the neuron may participate directly in synaptic processing of olfactory information. The high ratio of output to input synapses made by the serotonin‐immunoreactive processes in the contralateral antennal lobe is consistent with the idea that this neuron may receive synaptic input via its bilateral branches in the protocerebrum and then send information to the contralateral antennal lobe where the neuron may exert feedback or modulatory influences on olfactory information processing in the glomeruli. © 1993 Wiley‐Liss, Inc.
GABAergic innervation of the Mauthner cell and other reticulospinal neurons in the goldfish
Authors: Lee Robert K. K. , Finger Thomas E. , Eaton Robert C.
Published: January 2005

The Mauthner cells are pair of identifiable hindbrain neurons that participate in the escape response of fishes. Membrane excitability in these cells is regulated by inhibitory neurons that use glycine as a transmitter. We examined the possibility that the inhibitory transmitter gamma‐amino butyric acid (GABA) may also act on the Mauthner cells.

We used immunocytochemical methods involving an antibody against glutamic acid decarboxylase (GAD), the synthesizing enzyme for GABA. Our study revealed dense GAD immunoreactive terminals surrounding the Mauthner cells. Puncta counts showed that the distribution of GAD immunoreactivity was densest at the distal lateral dendrite of the Mauthner cells; the distribution of puncta tapers gradually in regions closer to the soma. The axon cap was devoid of GABAergic immunoreactivity.

We also performed unilateral lesions of the octaval nuclei to evaluate the origin of the GAD immunoreactive terminals. Following the lesions, we found marked decreases in GAD immunoreactive terminals on the proximal lateral dendrite, soma, and proximal ventral dendrite of both Mauthner cells. These results suggest that the octaval region contributes to bilateral inhibition of the Mauthner cells. The distal lateral dendrite of the ipsilateral Mauthner cell also showed a reduction in GAD immunoreactive terminals. This suggests that GABA mediates remote dendritic inhibition of this cell.

GAD immunoreactive puncta also surrounded other large reticulospinal neurons, some of which are serially reiterated along the anterior‐posterior axis of the hindbrain. Thus, GABA may also exert an influence not only on the Mauthner cells, but also on other reticulospinal neurons. © 1993 Wiley‐Liss, Inc.
Rapid increase in mitochondrial volume in nucleus magnocellularis neurons following cochlea removal
Authors: Hyde Gregory E. , Durham Dianne
Published: January 2005

Second‐order auditory neurons in nucleus magnocellularis (NM) of the chick brainstem undergo a series of rapid metabolic changes following unilateral cochlea removal, culminating in the death of 25% of NM neurons. Within hours of cochlea removal, ipsilateral NM neurons show marked increases in histochemical staining for the mitochondrial enzymes succinate dehydrogenase and cytochrome oxidase. We investigated corresponding ultrastructural changes in NM neurons by preparing animals undergoing unilateral cochlea removal for transmission electron microscopy. We quantified changes in NM mitochondrial volume by stereological methods and qualitatively compared mitochondrial morphology between NM neurons destined to survive and those destined to die after cochlea removal.

Within hours of cochlea removal, ipsilateral NM neurons show striking increases in mitochondrial volume (84% at 12 hours and 236% at 12 hours after cochlea removal compared to unoperated, control animals). At 2 week survival times, ipsilateral NM neurons contain fewer mitochondria than contralateral neurons. Surprisingly, anesthesia alone causes short‐term increases in NM mitochondrial volume. Animals anesthetized with pentobarbital and ketamine and sacrificed 6 or 12 hours later showed a 45% increase in mitochondrial volume compared to previously unanesthetized animals. NM neurons destined to die within days of cochlea removal can be identified within several hours after deafferentation by the appearance of their ribosomes. We observed qualitative differences in mitochondrial morphology in dying neurons. Mitochondria in neurons destined to die consistently showed mitochondrial swelling and vacuolization indicative of metabolic dysfunction. Similar mitochondrial changes have been reported when mitochondria take up excess calcium. Ultrastructural changes in NM after cochlea removal display features of both programmed and pathological cell death, in which increased intracellular calcium is thought to play a role. © 1994 Wiley‐Liss, Inc.
The hippocampal CA3 network: An in vivo intracellular labeling study
Authors: Li X.‐G. , Somogyi P. , Ylinen A. , Buzsáki G.
Published: January 2005

The intrahippocampal distribution of axon collaterals of individual CA3 pyramidal cells was investigated in the rat. Pyramidal cells in the CA3 region of the hippocampus were physiologically characterized and filled with biocytin in anesthetized animals. Their axonal trees were reconstructed with the aid of a drawing tube. Single CA3 pyramidal cells arborized most extensively in the CA1 region, covering approximately two‐thirds of the longitudinal axis of the hippocampus. The total length of axon collaterals in the CA3 region was less than in CA1 and the axon branches tended to cluster in narrow bands (200–800 μm), usually several hundred microns anterior or posterior to the cell body. The majority of the recurrent collaterals of a given neuron remained in the same subfield (CA3a, b, or c) as the parent cell. CA3a neurons innervated predominantly the basal dendrites, whereas neurons located proximal to the hilus (CA3c) terminated predominantly on the apical dendrites of both CA1 and CA3 cells. Two cells, with horizontal dendrites and numerous thorny excrescences at the CA3c–hilus transitional zone, were also labeled and projected to both CA3 and CA1 regions. All CA3 neurons projected some collaterals to the hilar region. Proximal (CA3c) neurons had numerous collaterals in the hilus proper. One CA3c pyramidal cell in the dorsal hippocampus sent an axon collateral to the inner third of the molecular layer. CA3c pyramidal cells in the ventral hippocampus had extensive projections to the inner third of the dentate molecular layer, as well as numerous collaterals in the hilus, CA3, and CA1 areas, and several axon collaterals penetrated the subiculum. The total projected axon length of a single neuron ranged from 150 to 300 mm. On the basis of the projected axon length and bouton density (mean interbouton distance: 4.7 μm), we estimate that a single CA3 pyramidal cell can make synapses with 30,000–60,000 neurons in the ipsilateral hippocampus. The concentrated distribution of the axon collaterals (“patches”) indicates that subpopulations of neurons may receive disproportionately denser innervation, whereas innervation in the rest of the target zones is rather sparse. These observations offer new insights into the physiological organization of the CA3 pyramidal cell network. © 1994 Wiley‐Liss, Inc.
Substance P‐, calcitonin gene‐related peptide, growth‐associated protein‐43, and neurotrophin receptor‐like immunoreactivity associated with unmyelinated axons in feline ventral roots and pia mater
Authors: Risling M. , Dalsgaard C.‐J. , Frisén J. , Sjögren A.‐M. , Fried K.
Published: January 2005

The spinal pia mater receives a rich innervation of small sensory axons via the ventral roots. Other sensory axons enter the ventral roots but end blindly or turn abruptly in hairpin loop‐like formations and continue in a distal direction. In the present study, the content of substance P (SP)‐, calcitonin gene‐related peptide (CGRP)‐, growth‐associated protein (GAP‐43)‐, and low‐affinity neurotrophin receptor protein (p75NGFr)‐like immunoreactivity (‐LI) associated with these different types of sensory axons was assessed with light and electron microscopic immunohistochemical techniques. In addition, the binding of antibodies against synthetic peptides representing unique sequences of residues in the products of the trk and trkB protooncogenes was analyzed. These genes encode membrane spanning proteins, which have been shown to constitute specific high affinity binding sites for several members of the nerve growth factor family of neurotrophic factors.

The results of the present study imply that the ventral root afferents comprise several different types of sensory axons, which all contain SP‐, CGRP‐, GAP‐43‐, and p75NGFr‐like immunoreactivities. In addition, at least some of the presumed sensory fiber bundles in ventral roots and the pia mater were immunoreactive for the trkB gene product. Moreover, leptomenin‐geal cells and nonneuronal cells of the ventral roots were shown to bind antibodies to both the trk and trkB gene products. The ventral root afferents seem to share their immunohistochemical pattern with pain‐transducing axons at some other locations, such as the tooth pulp. The contents of SP‐ and CGRP‐LI in sensory axons that reach the central nervous system (CNS) through the ventral root indicate that ventral root afferents may be involved in sensory mechanisms, such as the ventral root pain reaction, as well as in the control of the pial blood vessels. The demonstration of GAP‐43 and neurotrophin receptor‐immunoreactivities associated with unmyelinated fibers in ventral roots and the pia mater is discussed in relation to previous reports on postnatal plasticity in these axonal populations. © 1994 Wiley‐Liss, Inc.
Topography of neurons expressing luteinizing hormone‐releasing hormone gene transcripts in the human hypothalamus and basal forebrain
Authors: Rance Naomi E. , Young W. Scott , McMullen Nathaniel T.
Published: January 2005

The distribution of neurons expressing luteinizing hormone‐releasing hormone (LHRH) gene transcripts was mapped in the human hypothalamus and basal forebrain by in situ hybridization and computer‐assisted microscopy. Hypothalamic blocks were dissected from five adult males and one adult female and snap frozen in isopentane. The blocks were serially sectioned either in the coronal or in the sagittal plane at a thickness of 20 μm. Approximately every twentieth section was incubated with a 35S‐labeled cDNA probe complementary to LHRH mRNA. Specificity was confirmed by hybridization of adjacent sections with a probe targeted to the gonadotropin‐associated protein (GAP) region of LHRH messenger ribonucleic acids (mRNA). Maps of neurons containing LHRH mRNA were manually digitized with the aid of an image‐combining computer microscope system. We report a much wider distribution and greater numbers of LHRH neurons than have been previously described in the human brain. Three morphological subtypes were observed based on cell size and labeling density: (1) small, heavily labeled, oval or fusiform neurons, located primarily in the medial basal hypothalamus, ventral preoptic area, and periventricular zone; (2) small, oval, sparsely labeled neurons located in the septum and dorsal preoptic region and scattered from the bed nucleus of the stria terminalis to the amygdala (“extended amygdala”); and 3) large round neurons (> 500 μm2 sectional profile area), intermediate in labeling density, scattered within the magnocellular basal forebrain complex, extended amygdala, ventral pallidum, and putamen. The pronounced differences in morphology, labeling density, and location of the three subtypes suggest that distinct functional subgroups of LHRH neurons exist in the human brain. © 1994 Wiley‐Liss, Inc.
Projections of the dorsal raphe nucleus to the brainstem: PHA‐L analysis in the rat
Authors: Vertes Robert P. , Kocsis Bernat
Published: January 2005

Early studies that used older tracing techniques reported exceedingly few projections from the dorsal raphe nucleus (DR) to the brainstem. The present report examined DR projections to the brainstem by use of the anterograde anatomical tracerPhaseolus vulgarisleucoagglutinin (PHA‐L). DR fibers were found to terminate relatively substantially in several structures of the midbrain, pons, and medulla. The following pontine and midbrain nuclei receive moderate to dense projections from the DR: pontomesencephalic central gray, mesencephalic reticular formation, pedunculopontine tegmental nucleus, medial and lateral parabrachial nuclei, nucleus pontis oralis, nucleus pontis caudalis, locus coeruleus, laterodorsal tegmental nucleus, and raphe nuclei, including the central linear nucleus, median raphe nucleus, and raphe pontis. The following nuclei of the medulla receive moderately dense projections from the DR: nucleus gigantocellularis, nucleus raphe magnus, nucleus raphe obscurus, facial nucleus, nucleus gigantocellularis‐pars alpha, and the rostral ventrolateral medullary area. DR fibers project lightly to nucleus cuneiformis, nucleus prepositus hypoglossi, nucleus paragigantocellularis, nucleus reticularis ventralis, and hypoglossal nucleus.

Some differences were observed in projections from rostral and caudal parts of the DR. The major difference was that fibers from the rostral DR distribute more widely and heavily than do those from the caudal DR to structures of the medulla, including raphe magnus and obscurus, nucleus gigantocellularis‐pars alpha, nucleus paragigantocellularis, facial nucleus, and the rostral ventrolateral medullary area. A role for the dorsal raphe nucleus in several brainstem controlled functions is discussed, including REM sleep and its events, nociception, and sensory motor control. © Wiley‐Liss, Inc.
Immunohistochemical localization of calbindin‐D28K and calretinin in the lamprey retina
Authors: Dalil‐Thiney Najet , Pochet Roland , Versaux‐Botteri Claudine , Vesselkin Nicolas , Repérant Jacques , Nguyen‐Legros Jeanine
Published: January 2005

Calbindin‐D28K and calretinin are homologous cytosolic calcium binding proteins localized in many retinal neurons from different species. In this report, location of cells immunoreactive to both proteins was investigated in the retina of the lamprey, Lampetra fluviatilis. This organism constitutes one of the older representative vertebrates and possesses a peculiar organization, probably unique: two‐thirds of the ganglion cells are in the classical amacrine cell layer and the nerve fiber layer is located in the scleral part of the inner plexiform layer. Calbindin‐like immunoreactivity was demonstrated in large bipolar cells and in cell bodies located in the inner retina. Although the distinction between labelled ganglion cells and labelled amacrine cells was rendered difficult, we hypothetized that the majority of calbindin‐immunoreactive cells observed in the inner retina are ganglion cells, because of the high number of labelled fibers in the nerve fiber layer. Calretinin‐like immunoreactivity was detected in both large and small bipolar cells, and also in cells located in the inner retina. Since few calretinin‐immunoreactive fibers were observed in the nerve fiber layer, we assume that the latter category of cells are amacrine cells. Horizontal cells were both negative for calbindin and calretinin‐like immunoreactivities. Calbindin and calretinin, which are present in cones from many species, could not be detected in the photoreceptor layer favouring the rod‐dominated lamprey retina. Although their distribution differs from those observed in most vertebrates, the present results indicate the good conservation of both calcium binding proteins in the retina during the vertebrate evolution. © Wiley‐Liss, Inc.
Behavior‐dependent activity labeling in the central complex of Drosophila during controlled visual stimulation
Authors: Bausenwein Bernhard , Müller Nicolas R. , Heisenberg Martin
Published: January 2005

3H‐2‐deoxyglucose (2‐DG) is used as a histological marker to study the spatial distribution of neuronal activity in the central brain of Drosophila melanogaster under controlled stimulus conditions. Tethered flies injected with the label are kept for 45–90 minutes in the center of a rotating drum carrying on its periphery a singe black vertical stripe or a periodic grating. In either stimulus situation, one‐half of the flies walk on top of a small black styrofoam ball floating on ajet of air, and one‐half are kept flying 1.5 mm above the ball. (1) During walking on the styrofoam ball little 2‐DG accumulates in the central brain. The area in and around the ellipsoid body as well as several tracts are weakly labeled. (2) After flight, labeling patterns are more distinct. The following labeled structures can be identified: ventral bodies, ring neurons of the ellipsoid body, the region of the inferior bridge, fiber tracts connecting the central complex to other parts of the protocerebrum, and tracts in the subesophageal and dorsal brain. These contrast with fan‐shaped body and protocerebral lobes, which are only weakly labeled. (3) Not only flight and walking lead to distinct staining patterns but also the two visual stimuli. With the single stripe, in most flies the caudal layers of the ellipsoid body accumulate more 2‐DG than the rostral ones. With the striped drum, the ellipsoid body is uniformly labeled. (4) Other stimulus‐related features are found less regularly: Unilateral distribution of 2‐DG in or around the noduli was observed in several flies that had been exposed to a rotating single stripe. In one preparation, two strongly marked individual neurons of the protocerebral bridge can be tentatively identified. The labeling patterns support earlier notions that the central complex is involved in the initiation and organization of behavior and that it integrates visual data of the two brain hemispheres. © Wiley‐Liss, Inc.
Complex expression of keratins in goldfish optic nerve
Authors: Druger Robert K. , Glasgow Eric , Fuchs Chana , Levine Edward M. , Matthews James P. , Park Chong‐Yon , Schechter Nisson
Published: January 2005

Keratins are the predominant intermediate filament proteins in the nonneuronal cells of the goldfish optic nerve. At least three different keratin pairs are expressed in this tissue, indicating an unexpected complexity. Expression of the type II keratin ON3 in goldfish opticnerve astrocytes predicts the expression of a type I keratin partner. Here we report the cDNA sequence and predicted amino acid sequence of two type I keratins from the goldfish optic nerve, designated GK48 and GK49. The GK48 protein is the goldfish equivalent of mammalian keratin 18 (K18) and is the most likely type I keratin partner to the ON3 protein. The GK49 protein is similar to the GK50 protein, a type I keratin characterized previously from the goldfish optic nerve. The GK48 and ON3 mRNAs are expressed in a variety of goldfish tissues, whereas the expression of GK49 mRNA has a more limited expression. In addition, in situ hybridization experiments show that the expression of the GK48 and ON3 mRNAs are evenly distributed throughout the optic nerve, while the GK49 mRNA is expressed along longitudinal lines. These results show that there is a diversity of keratin expression within different cell types in the goldfish optic nerve. © Wiley‐Liss, Inc.
The origin of serotoninergic afferents to the cat's cerebellar nuclei
Authors: Kitzman Patrick H. , Bishop Georgia A.
Published: January 2005

In the cat, serotoninergic (5HT) axons and terminals form a dense plexus that is present throughout the granule cell and Purkinje cell layers of the cerebellar cortex and all of the cerebellar nuclei. The intent of the present study was to identify the source of 5HT fibers in the cerebellar nuclei. The medial, interposed, and lateral cerebellar nuclei were selectively injected with either rhodamine or fluorescein‐labeled latex microspheres that were retrogradely transported to brainstem neurons. Transverse sections of the brainstem were processed with a primary antibody to 5HT and secondary antibody tagged with either rhodamine or fluorescein. The location of neurons containing both serotonin‐like immunoreactivity and retrogradely transported microspheres was plotted. All three of the cerebellar nuclei receive 5HT afferents from the nucleus locus coeruleus, the dorsal raphe nucleus, and the dorsal tegmental nucleus. In addition, the medial nucleus receives projections from the superior central nucleus, the nucleus raphe obscurus, the nucleus raphe magnus, and the periolivary reticular formation. The interposed nuclei receive additional projections from the nucleus raphe magnus, whereas the lateral nucleus receives additional projections from the superior central nucleus. In conclusion, the 5HT projections to the cerebellar nuclei do not appear to be collaterals of those projecting to the cortex (Kerr and Bishop, J Comp Neurol 304:502–515, 1991). These findings suggest that, although the cortex and nuclei are anatomically and physiologically related, they do not process all information in parallel. © Wiley‐Liss, Inc.
Cholinergic innervation of mouse forebrain structures
Authors: Kitt Cheryl A. , Höhmann Christine , Coyle Joseph T. , Price Donald L.
Published: January 2005

Using choline acetyltransferase (ChAT) immunocytochemistry and acetylcholinesterase (AChE) histochemistry, we investigated regional and laminar differences in cholinergic innervation in the cerebral cortex, hippocampus, amygdala, and thalamus of mice. In mice, unlike rats, the patterns of ChAT‐immunostained and AChE‐positive fibers are virtually identical in the cortex and are organized in a trilaminar pattern with cholinergic processes prominent in layers I and IV and within the lower portion of layer V and upper segment of layer VI. ChAT‐immunoreactive cells were not seen in cortex. In the amygdala, the basolateral nucleus showed the highest density of cholinergic processes. In the hippocampus, a thin, dense band of ChAT‐labeled processes was present in the inner segment of the molecular layer of the dentate gyrus and within the stratum oriens of CA1‐3, adjacent to the basal aspect of pyramidal cells. Within the thalamus, anteroventral, mediodorsal (lateral portion), intralaminar, and reticular nuclei showed high densities of cholinergic processes. The results of this study provide the basis for examining the effects of transgenes and age on forebrain cholinergic systems.
Electrical responses and synaptic connections of giant serotonin‐immunoreactive neurons in crayfish olfactory and accessory lobes
Authors: Sandeman D. C. , Sandeman R. E.
Published: January 2005

Five pairs of identified 5HT‐IR cells in the deutocerebrum of the crayfish Cherax are known to have their synaptic endings in the accessory and olfactory lobes. Two of these cells, one on each side of the brain, are significantly larger than the others. Dye fills of these “giant” cells reveal each to be an interneuron with its branches confined to, but distributed throughout, the olfactory and accessory lobes on the side of the brain ipsilateral to its cell body and with no branches to the contralateral side. Intracellular recordings from the giant cells were made while stimulating the olfactory afferents and tracts within the brain in an attempt to discover the inputs and outputs to the cells. Electrical stimulation of chemoreceptor sensilla on the outer branch of the antennule does not excite the giant 5HT neurons. Focal extracellular electrical stimulation of the olfactory globular tract containing the axons of projection neurons from the olfactory and accessory lobes produces excitatory synaptic potentials and action potentials in the giant cells. Focal extracellular electrical stimulation of the deutocerebral commissure, the axons of which terminate in the glomeruli of the accessory lobes, also results in excitation of the giant cells. We conclude that the input to the giant cells is via axons in the deutocerebral commissure and collaterals from the projection neurons, ending in the glomeruli of the accessory lobes. The output of the giant cells is to the olfactory lobes, where it may serve to modulate olfactory signals.
Dendritic architecture of rat somatosensory thalamocortical projection neurons
Authors: Ohara P. T. , Havton L. A.
Published: January 2005

This study examines dendrites from physiologically characterized and intracellularly labelled thalamocortical projection (TCP) neurons from the rat ventrobasal complex (VB) and posterior nucleus (POm). The goals were to provide quantitative descriptions of TCP neuron dendrites, examine underlying design principles of dendritic morphology, and determine correlations between dendritic size parameters. Forty‐four dendrites from seven VB neurons and 21 dendrites from three POm TCP neurons that responded to low‐threshold mechanical stimuli were reconstructed and quantitatively analyzed at the light microscopic level. The dendritic architecture of the neurons was remarkably similar in most parameters studied, including the percentage of dichotomous branching, contribution of terminal branches to total dendritic length, and branching symmetry. There was a positive correlation between stem dendrite diameter and the length of the entire dendrite arbor, making it possible to estimate the total length of a dendritic arbor by measuring the stem dendrite diameter. The correlations of the VB and POm dendrites had different slopes. The path distance (the distance from the soma to a dendritic end point) of individual dendrites showed only a small variation with large differences in the total dendritic length of an arbor. The constant diameter of distal dendrites shows that dendrite diameter is a poor predictor of synaptic location on the dendritic tree.

Although the morphology of neurons and their individual dendrites varied considerably in overall size and qualitative appearance, when examined qualitatively, many aspects of dendritic structure were similar within and between groups. We suggest that the rat somatosensory TCP neurons have a stereotyped dendritic architecture and present data which provide a base for future comparative, developmental, and plasticity studies.
Organization of the efferent projections from the pontine parabrachial area to the bed nucleus of the stria terminalis and neighboring regions: A PHA‐L study in the rat
Authors: Alden Marie , Besson Jean‐Marie , Bernard Jean‐François
Published: January 2005

The organization of efferent projections from the pontine parabrachial (pPB) area to the forebrain rostral to the central nucleus of the amygdala (Ce) was studied in the rat by using microinjections of Phaseolus vulgaris leucoagglutinin (PHA‐L), into subregions of the pPB area. The present study is a follow‐up of a former study (Bernard et al. [1993] J. Comp. Neurol. 329:201–229) which examines pPB projections onto the Ce.

The results demonstrate that: (1) the pPB(m) region (the medial, the ventral lateral subnuclei and the waist area) diffusely projects to the lateral division (BSTL) of the bed nucleus of the stria terminalis (BST), the Ce‐BSTL continuum (including, the dorsal portion of substantia innominata, the ventral portion of globus pallidus, the fundus striatum, and the substriatal area) and to a lesser extent the agranular insular cortex; (2) the pPB(1) region [the central lateral (pPBc1) and the outer portion of external lateral subnuclei] densely projects to the dorsal lateral subnucleus of BST (BSTdl); only the pPBcl subnucleus projects to the median, the anteroventral and the periventricular nuclei of the preoptic hypothalamus; and (3) the remaining pPB area (the dorsal lateral, part of the external lateral and the external medial subnuclei) projects to the nucleus of horizontal limb of diagonal band but does not project onto the BST and the preoptic hypothalamus.

It is suggested that the pPB(m)‐BSTL “diffuse pathway” is mainly implicated in motivational and autonomic aspects of taste. The pPB(1)‐BSTdl and hypothalamic “concentrated pathways” could be implicated in autonomic and nociceptive processes.
Neurotensin receptor expression in the rat forebrain and midbrain: A combined analysis by in situ hybridization and receptor autoradiography
Authors: Nicot Arnaud , Rostene William , Berod Anne
Published: January 2005

The aim of the present study was to examine the distribution of the levocabastine‐insensitive high‐affinity neurotensin binding sites in the rat forebrain and midbrain in relation to the distribution of the cloned neurotensin receptor mRNA by using a combination of both high‐resolution in vitro receptor autoradiography and in situ hybridization approaches. Groups of cells rich in neurotensin receptor mRNA were observed in the basal forebrain nuclei, the ventral tegmental area, the substantia nigra and in the interfascicular and caudal linear nuclei and the retrorubral field. Cells expressing lower levels of neurotensin receptor mRNA were found in several subdivisions of the cortex; the dentate gyrus; the septofimbrial, suprachias‐matic, medial habenular, and mammillary nuclei; the dorsal part of the lateral septum; the zona incerta; and the dorsomedial and perifornical hypothalamic areas. Most of the brain areas containing neurotensin receptor mRNA demonstrated a selective association of neurotensin binding sites with neuronal cell bodies. In contrast, in several telencephalic and diencephalic structures, the presence of neurotensin binding sites was not correlated with that of neurotensin receptor mRNA, suggesting that neurotensin receptors were mainly located on axon terminals.

This study provides a better understanding of the anatomical organization of neurotensin receptor expressing systems in the rat brain and gives further insight into the pre‐vs. postsynaptic location of neurotensin receptors in various brain regions. Moreover, it indicates that all neurons expressing the cloned neurotensin receptor harbour neurotensin binding sites on their perikaryal membrane.
The rostral dorsal cap and ventrolateral outgrowth of the rabbit inferior olive receive a GABAergic input from dorsal group Y and the ventral dentate nucleus
Authors: De Zeeuw C. I. , Gerrits N. M. , Voogd J. , Leonard C. S. , Simpson J. I.
Published: January 2005

The dorsal cap and ventrolateral outgrowth of the inferior olive are involved in the control of eye movements. The caudal dorsal cap is predominantly involved in the horizontal optokinetic reflex; it receives most of its GABAergic input from the nucleus prepositus hypoglossi. In the present study, we determined the source of a major inhibitory input to the rostral dorsal cap and the ventrolateral outgrowth, which are the olivary subnuclei mainly involved in the “vertical” optokinetic reflexes. We studied these subnuclei in the rabbit with the use of retrograde tracing of horseradish peroxidase and anterograde tracing of wheat germ agglutinin‐coupled horseradish peroxidase combined with postembedding immunocytochemistry. The ventral dentate nucleus of the cerebellum and dorsal group y project contralaterally to the rostral dorsal cap and ventrolateral outgrowth; this projection is entirely GABAergic. The terminals of this input form predominantly symmetric synapses with extraglomerular and intraglomerular dendrites; the remaining terminals are axosomatic. In addition, the dorsal cap and ventrolateral outgrowth contain significantly more crest synapses than any other olivary subnucleus. The terminals that form these crest synapses are derived from dorsal group y and/or the ventral dentate nucleus. None of the terminals in the dorsal cap or ventrolateral outgrowth was glycinergic.
Immunocytochemical localisation of hydroxyindole‐O‐methyltransferase in pineal photoreceptor cells of several fish species
Authors: Falcón Jack , Bégay Valérie , Goujon Jean Michel , Voisin Pierre , Guerlotté Jérome , Collin Jean‐Pierre
Published: January 2005

Melatonin is an internal “Zeitgeber,” involved in the timing and control of a number of rhythmic functions and behaviours. Its synthesising cells remain to be identified in the fish pineal. The last step in the melatonin biosynthetic pathway is catalysed by the enzyme hydroxyindole‐O‐methyltransferase. An affinity‐purified antibody, directed against chicken pineal hydroxyindole‐O‐methyltransferase, was used in the present study to identify the melatonin synthesising cells in four fish species: a primitive chondrostean (sturgeon), a saltwater teleost (dorado), and two freshwater teleosts (pike, trout). Western blot immunolabeling of pike and trout pineal proteins revealed a single band at 38 KDa, which corresponds to the known molecular weight of the enzyme in bovine, rat, and chicken pineal. Regardless of the species, a specific immunocytochemical labeling, visualised by means of the peroxidaseantiperoxidase method, was exclusively associated with the photoreceptor cells. These results provide evidence that photoreceptors of the fish pineal are responsible for the biosynthesis of 5‐methoxyindoles, including melatonin. In the pike, reactions were less intense in the distal portion of the pineal vesicle than in the other regions of the organ. It is questioned whether this might be related to the existence of a germinative zone, generating new photoreceptor cells in this distal portion. Hydroxyindole‐O‐methyltransferase has been previously demonstrated in mammalian pinealocytes, and modified photoreceptors of the avian pineal. It is now demonstrated in pineal photoreceptors of a primitive fish and of more evolved saltwater and freshwater fish. The results strengthen the view that these cells are related through phylogeny and that their well conserved melatoninergic function appears early in the course of evolution.
Biotin staining in the giant fiber systems of the lobster
Authors: Ma Pokay M.
Published: January 2005

The avidin‐biotin‐complex method is a popular immunocytochemical technique. This method labels consistently a group of neurons in the lobster ventral nerve cord in the absence of primary antibodies. The specific staining is due to a relatively high level of endogenous biotin (or biocytin) in these neurons. These biotin‐positive neurons are located in the supraesophageal, thoracic, and abdominal ganglia. Intraaxonal injection of Lucifer yellow followed by Texas red‐conjugated streptavidin staining reveals that the neurons are members of the medial giant (MG) and lateral giant (LG) systems, which are important in mediating rapid tail flipping during escape maneuvers. In neuronal somata, staining is restricted to the cytoplasm. Within MG axons, staining appears as punctate, subaxolemmal structures. Preincubating nerve cords in biocytin or direct intraaxonal injection of biocytin enhances staining of these punctate organelles. In LG axons, staining is localized to fragments of braided filamentous structures that also appear to be associated with the axolemma. Preincubation of ventral nerve cords in various concentrations of biocytin results in the appearance of additional groups of stained neurons, suggesting that there are subsets of neurons with specific biocytin‐uptake orretention mechanisms. In the crayfish, biotin‐positive staining is confined to the MG neurons; the LG neurons are not stained. In the earthworm, no staining is observed in the MG and LG axon escape systems. In the goldfish, no biotin‐staining is seen in the Mauthner neurons and their axons.

The significance of specific localization of biotin or biocytin to subsets of neurons is unclear. It may reflect the presence of high levels of biocytin moieties on biotin‐dependent enzymes. Biotin is an important cofactor in the catalytic functions of several decarboxylases crucial in energy production and lipogenesis. Axons of the giant fiber systems in lobsters and crayfish may have high energy and fatty acid synthesis requirements. Increased levels of biotin accumulation may also be related to other functions of the giant axon systems, such as the formation of electrical synapses among themselves and with phasic motoneurons.
Evidence that sympathetic preganglionic neurones are arranged in target‐specific columns in the thoracic spinal cord of the rat
Authors: Pyner S. , Coote J. H.
Published: January 2005

It is recognised that selective activation of different target‐specific sympathetic preganglionic neurones forms the basis of many autonomic responses. The anatomical basis for this could be the spatial arrangement of these neurones in the spinal cord nuclei. The present study tested this possibility in the rat by determining the location in single animals of three distinct groups of sympathetic preganglionic neurones, one group projecting to the superior cervical ganglion, another to the stellate ganglion and one to the adrenal medulla. Sympathetic preganglionic neurones to each of these targets were simultaneously labeled with fluorescent dyes, either Fluorogold, Fast Blue, or Diamidino Yellow. The numbers and general morphology of the neurones were similar to previous descriptions, and they were distributed in four subnuclei, the nucleus intermediolateralis pars principalis, the nucleus intermediolateralis pars funiculus, the nucleus intercalatus spinalis, and the nucleus intercalatus spinalis pars paraependymalis. It was shown that all three groups of neurones were represented in the more medial sympathetic nuclei, but in the nuclei at the lateral border of the intermediate grey matter each one of the three groups of neurones occupied a discrete location. Adrenal medullary sympathetic preganglionic neurones occupied a lateral aspect, the superior cervical ganglion sympathetic preganglionic neurones a medial aspect, and the stellate ganglion sympathetic preganglionic neurones a space between. Some sympathetic preganglionic neurones were double labeled after dye injections into the superior cervical and stellate ganglion thus indicating that they projected to both ganglia. It is concluded that there are populations of sympathetic preganglionic neurones arranged in horizontal columns which only send axonal projections to the superior cervical, stellate ganglia, or adrenal medulla, respectively, and hence are target specified for each structure. This arrangement is likely to be of importance in understanding selective activation of autonomic effectors, a feature of different types of behaviour. © 1994 Wiley‐Liss, Inc.
Topographical distribution of reduced nicotinamide adenine dinucleotide phosphate‐diaphorase in the brain of the Japanese quail
Authors: Panzica G. C. , Arévalo R. , Sánchez F. , Alonso J. R. , Aste N. , Viglietti‐Panzica C. , Aijón J. , Vázquez R.
Published: January 2005

The distribution of reduced nicotinamide adenine dinucleotide phosphate (NADPH)‐diaphorase activity was histochemically investigated in the Japanese quail brain. This enzyme is now considered responsible for the synthesis of nitric oxide, a novel neural messenger whose distribution has not been described in the avian brain until now. The histochemical technique provides a simple and reliable method for staining selected populations of neurons throughout the avian brain. In the telencephalon several regions showed heavily stained NADPH‐diaphorase positive neurons and processes. In particular the paleostriatal‐paraolfactory lobe complex showed the greatest presence of both positive cells and processes. Neurons and processes were also observed in several regions of the hyperstriatum as well as in the archistriatal nucleus taeniae. Some regions, such as the ectostriatum and the hippocampus, had no positive elements. In the diencephalon, the magnocellular hypothalamic system, which in mammals shows NADPH‐diaphorase activity, did not show any particular accumulation of reaction product. On the contrary, retinorecipient areas, such as the visual suprachiasmatic nucleus and the lateral geniculate complex, displayed a composite structure of both positive neurons and processes. The brainstem revealed a large NADPH‐diaphorase positive population extending through the tegmental nuclei to the locus coeruleus and subcoeruleus. A complex organization was also observed in the optic lobe, where fusiform elements were distributed within the stratum griseum and superficialis of the tectum. In the medulla, a dense terminal field was observed at the level of the nucleus of the solitary tract, whereas scattered neurons were located within the reticular nuclei. Although the staining of neurons and tracts was highly selective, the positive cells did not correspond to any single known neurotransmitter, neuropeptide, or neuroactive molecule system. Several sensory pathways were heavily stained for the NADPH‐diaphorase, including part of the olfactory, visual, and auditory pathways. The findings of the present study reveal that the NADPH‐diaphorase‐containing systems in the avian brain are organized according to a pattern comparable, because of its complexity, to that observed in mammals. However, important interspecific differences suggest that this novel neural system might be involved in diverse tasks. © 1994 Wiley‐Liss, Inc.
Antibody to neural cell adhesion molecule can disrupt the migration of luteinizing hormone‐releasing hormone neurons into the mouse brain
Authors: Schwanzel‐Fukuda M. , Reinhard G. R. , Abraham S. , Crossin K. L. , Edelman G. M. , Pfaff D. W.
Published: January 2005

The neurons which synthesize and release luteinizing hormone‐releasing hormone (LHRH), are hypothesized to originate in the epithelium of the medial olfactory pit and to migrate into the brain along a scaffolding made up of neural cell adhesion molecule (NCAM)‐immunoreactive branches of the terminal and vomeronasal nerves. These LHRH neurons, studied by immunocytochemical and autoradiographic procedures, were found to originate within a very short period of embryogenesis, specifically day 10, in mice, and to follow a remarkably ordered spatiotemporal course along the migration route into the brain.

The purpose of the present experiments was to determine whether perturbation of the NCAM‐immunoreactive migration route, at a particular time in development, would arrest the migration of LHRH neurons into the brain. We found that a 1 μl injection of antiserum to NCAM into the area of the olfactory pit, on day 10 of embryogenesis, significantly reduced the number of LHRH‐immunoreactive neurons seen in the epithelium of the medial olfactory pit, with a concomitant significant reduction in the number of LHRH‐immunoreactive cells seen outside of the placode, on the migration route. These results confirm our initial hypothesis that LHRH neurons migrate from the epithelium of the olfactory pit to the brain and indicate that NCAM plays a causal role in this phenomenon. © 1994 Wiley‐Liss, Inc.
Persistence of rubrospinal projections following spinal cord injury in the rat
Authors: Theriault Elizabeth , Tator Charles H.
Published: January 2005

Recent neurophysiological and magnetic resonance imaging studies of clinically “complete” human spinal cord injuries indicate that some patients have considerable subclinical function and substantial morphological integrity of descending spinal tracts. In contrast, extensive histopathological changes, including cell death, have been described in central nervous system nuclei projecting to the cord following experimental transection or hemisection of the spinal cord in animal models. We have used a rodent model of severe compression cord injury that more closely resembles the clinical pathophysiology to investigate the extent of the persistence of the rubrospinal projection. Counts of red nucleus neurons retrogradely labelled with Fluorogold demonstrate that in contrast to the results obtained with transection models, compression injuries of the spinal cord donotresult in massive loss of rubrospinal projections, at least up to 8 weeks postinjury. The results also suggest that many of the axons persist distal to the lesion site and that they are functionally intact with respect to retrograde transport capabilities. © 1994 Wiley‐Liss, Inc.
Reduced cortical inhibitory synaptogenesis in organotypic cerebellar cultures developing in the absence of neuronal activity
Authors: Seil Fredrick J. , Drake‐Baumann Rosemarie
Published: January 2005

Organotypic cerebellar cultures derived from newborn mice were continuously exposed to medium containing tetrodotoxin and elevated levels of magnesium to block all electrical activity. After 2 weeks in vitro, no activity was evident during the first 15–20 minutes following transfer to a recording medium without blocking agents. Thereafter, cortical discharge rates increased until a state of sustained hyperactivity was reached. Ultrastructural examination of such cultures revealed a reduction of inhibitory Purkinje cell somatic synapses to half the control value along with an even greater reduction of axodendritic synapses (largely inhibitory) in the cortical neuropil. No loss of axospinous synapses (excitatory) was evident. These results support the concept that spontaneous neuronal activity is necessary for the full development of inhibitory circuitry. © 1994 Wiley‐Liss, Inc.
Undernutrition of rats during early life does not affect the total number of cortical neurons
Authors: Bedi K. S.
Published: January 2005

Undernutrition during early life is known to cause deficits and distortions in brain structure. However, it remains uncertain whether this includes a diminution of the total numbers of neurons. Recent advances in stereological techniques have made it possible to obtain unbiased estimates of total numbers of cells in well‐defined biological structures. Rats were undernourished from day 16 of gestation to 30 postnatal days of age by standardized procedures. These rats and well‐fed control rats were anaesthetized and killed by intracardiac perfusion with fixatives at 70 days of age. The left cerebral hemisphere from each animal was embedded in Paraplast and serially sectioned. The sections were analyzed via the Cavalieri principle to obtain the total cortical volume and by the “disector” method to estimate the numerical density of neurons in the cortex. These values were later used to compute estimates of the total number of cortical neurons for each animal. Well‐fed control rats had 26.9 million cortical neurons, while the previously undernourished animals had 24.8 million. The difference between these two groups was not statistically significant. It therefore appears that undernutrition of rats during early postnatal life does not affect the total numbers of neurons in the cerebral cortex. © 1994 Wiley‐Liss, Inc.