bluuebunny/crossref_metadata_2025 huggingface dataset:
Distinct patterns of activated neurons throughout the rat midbrain periaqueductal gray induced by chemical stimulation within its subdivisions
Authors: Sandkühler J. , Herdegen T.
Published: January 2005

This study provides a map of those neurons in the midbrain periaqueductal gray which are activated by chemical stimulation within different subdivisions of the periaqueductal gray. In pentobarbital anesthetized rats, the expression of the c‐FOS protein was detected by immunocytochemistry and was used as a marker of neuronal activity. Microinjections of the γ‐aminobutyric acid (GABAA) receptor antagonist bicuculline (200 pmol in 50 nl) were used to increase selectively the firing rate of neurons originating from the injection site. The pattern of c‐FOS immunoreactivity was highly specific for different injection sites. Dorsal injections were characterized by an extensive distribution of c‐FOS immunoreactivity along the entire rostrocaudal extent of the periaqueductal gray, while ventral injections produced a much more restricted labeling. Following injection into the dorsal subdivision of the rostral periaqueductal gray, c‐FOS immunoreactivity was present bilaterally in the dorsal and dorsolateral subdivisions of the rostral periaqueductal gray and was found in all subdivisions of the caudal periaqueductal gray. Dorsolateral injections at the level of the oculomotor nuclei produced strictly ipsilateral labeling in the dorsal and dorsolateral periaqueductal gray at the level of injection and throughout the ipsilateral half of the periaqueductal gray at more caudal levels. Stimulation in the ventrolateral periaqueductal gray induced FOS in the ventrolateral periaqueductal gray and the adjoining reticular formation. At rostral levels c‐FOS immunoreactivity was also seen in the lateral periaqueductal gray but was absent caudal to the injection site. The identified patterns of activity in the periaqueductal gray provide a new basis for the interpretation of the diverse functional consequences of stimulation at periaqueductal gray sites. © 1995 Wiley‐Liss, Inc.
Reduced nicotinamide adenine dinucleotide phosphate‐diaphorase/nitric oxide synthase profiles in the human hippocampal formation and perirhinal cortex
Authors: Sobreviela Teresa , Mufson Elliott J.
Published: January 2005

Nicotinamide adenine dinucleotide phosphate‐diaphorase (NADPH‐d)‐stained profiles were evaluated throughout the human hippocampal formation (i. e., dentate gyrus, Ammon's horn, subicular complex, entorhinal cortex) and perirhinal cortex. NADPH‐d staining revealed pleomorphic cells, fibers, and blood vessels. Within the entorhinal and the perirhinal cortices, darkly stained (type 1) NADPH‐d pyramidal, fusiform, bipolar, and multipolar neurons with extensive dendrites were scattered mainly within deep layers and subjacent white matter. Moderately stained (type 2) NADPH‐d round or oval neurons were seen mainly in layers II and III of the entorhinal and perirhinal cortices, in the dentate gyrus polymorphic layer, in the CA fields stratum pyramidal and radiatum, and in the subicular complex. The distribution of type 2 cells was more abundant in the perirhinal cortex compared to the hippocampal formation. Lightly stained (type 3) NADPH‐d pyramidal and oval neurons were distributed in CA4, the entorhinal cortex medial subfields, and the amygdalohippocampal transition area. Sections concurrently stained for NADPH‐d and nitric oxide synthase (NOS) revealed that all type 1 neurons coexpressed NOS, whereas types 2 and 3 were NOS immunonegative. NADPH‐d fibers were heterogeneously distributed within the different regions examined and were frequently in close apposition to reactive blood vessels. The greatest concentration of fibers was in layers III and V–VI of the entorhinal and perirhinal cortices, dentate gyrus polymorphic and molecular layers, and CA1 and CA4. A band of fibers coursing within CA1 divided into dorsal and ventral bundles to reach the presubiculum and entorhinal cortex, respectively. Although the distribution of NADPH‐d fibers was conserved across all ages examined (28–98 years), we observed an increase in the density of fiber staining in the aged cases. These results may be relevant to our understanding of selective vulnerability of neuronal systems within the human hippocampal formation in aging and in neurodegenerative diseases. © 1995 Wiley‐Liss, Inc.
Vasopressin in the brain of a desert hibernator, the jerboa (Jaculus orientalis): Presence of sexual dimorphism and seasonal variation
Authors: Lakhdar‐Ghazal N. , Dubois‐Dauphin M. , Hermes M. L. H. J. , Buijs R. M. , Bengelloun W. A. , Pévet P.
Published: January 2005

The distribution of vasopressin innervation in the brain of the jerboa (Jaculus orientalis)was investigated, with special attention to sex differences and seasonal variations. Vasopressin perikarya were observed in the paraventricular and supraoptic nuclei, the suprachiasmatic nucleus, the periventricular nucleus, the medial preoptic area, the bed nucleus of the stria terminalis, and the medial amygdaloid nucleus. In addition, vasopressin cell bodies were observed in the ventral retrochiasmatic area. After treatment with colchicine, vasopreasin perikarya were also observed around the organum vasculosum laminae terminalis, in the medial diagonal band of Broca, and in the dorsal medial preoptic nucleus.

Vasopressin fibers were also found to be more widespread in the jerboa brain than in other rodents. Fibers were observed in the medial diagonal band of Broca, the stria medullaris, the tuber cinerum, the area postrema, the medial vestibular nucleus, and the dorsal motor nucleus of the vagus.

Sexual dimorphism and seasonal variation in vasopressin immunoreactivity were observed in areas that not only showed a testosterone‐dependent vasopressin innervation in other rodents but also in the paratenial and mediodorsal thalamic nuclei, the tuber cinerum, the suprarnarnmillary complex, the zona incerta, the interpeduncular complex, and the dorsal and medial raphe nuclei. A denser vasopressin innervation was observed in spring/summer (sexual active period) than in autumn. Numerous brain structures contained vasopressin receptors (cerebral cortex, hypothalamus, substantia nigra, dentate gyrus, thalamic nuclei, superior colliculus, dorsal cochlear nucleus, and cerebellum); no sex‐ or season‐related differences were observed.

These data indicate a high level of vasopressin in the jerboa brain, which may reflect an adaptation to its harsh bioclimatic environment. © 1995 Wiley‐Liss, Inc.
Reconstitution of the rat olfactory epithelium after methyl bromide‐induced lesion
Authors: Schwob James E. , Youngentob Steven L. , Mezza Renee C.
Published: January 2005

The olfactory epithelium and its neuronal population are known to have a substantial capacity to recover after either direct injury or damage to the olfactory nerve. However, the mechanisms underlying that capacity for recovery, and indeed the limits on the recovery process, are not well understood. The aim of this study is to describe in detail the way in which the olfactory epithelium reconstitutes after direct injury. Adult male rats were exposed to 330 ppm methyl bromide (MeBr) gas for a single 6—hour period. The exposure destroys all of the neurons and sustentacular cells in over 95% of the olfactory epithelium of food‐restricted rats and in over 90% of the epithelium in ad‐libitum‐fed rats of the same weight, yet substantial recovery of the olfactory epithelium occurs. In response to the lesion, cellular proliferation increases markedly beginning between 24 and 48 hours, peaks at 1 week, and persists at levels higher than the control level for more than 4 weeks after MeBr exposure. Even though proliferation accelerates promptly, the beginning of neuronal reconstitution is delayed; only few immature neurons are observed 3 days after the lesion, yet they reappear in large numbers by the end of the first week. The first mature neurons emerge between 7 and 14 days after lesion and increase to near normal numbers by 4–6 weeks. In association with the restoration of neuronal population, basal cell proliferation returns to control levels between 4 and 6 weeks after damage. Likewise, sustentacular cells, identifiable by anticytokeratin 18 labeling, reappear rapidly and reform a distinct lamina in the superficial aspect of the epithelium. They closely resemble their counterparts in control epithelium with regard to disposition and shape by 3 weeks after lesion and with regard to expression of olfactory‐specific cytochrome P450s by 8 weeks. Thus, most areas of the epithelium are restored to a near normal appearance and cellular composition by the end of 8 weeks, suggesting that the MeBr paradigm for lesioning epithelium offers significant advantages over techniques such as Triton X‐100 or ZnSO4 irrigation. However, not all measures of epithelial status are normal even at 8 weeks. Immature neurons remain slightly more numerous than normal at this time. Furthermore, some areas of the olfactory epithelium do not recover after MeBr lesion and are replaced by respiratory epithelium. By documenting the events and the extent of olfactory epithelial reconstitution after direct injury, the present results serve as a foundation for future studies designed to identify the mechanisms underlying epithelial recovery and the difference between areas of epithelium that reconstitute fully after lesion and those where the recovery process fails. © 1995 Wiley‐Liss, Inc.
Increase in α‐CGRP and GAP‐43 in aged motoneurons: A study of peptides, growth factors, and ChAT mRNA in the lumbar spinal cord of senescent rats with symptoms of hindlimb incapacities
Authors: Johnson Hans , Mossberg Karin , Arvidsson Ulf , Piehl Fredrik , Hökfelt Tomas , Ulfhake Brun
Published: January 2005

Sprague‐Dawley rats develop progressive motor dysfunctions during the third year of life. We use this as a model to examine possible neuronal mechanism(s) that may cause motor impairments occuring during aging.

In this study we have used indirect immunofluorescence histochemistry (IF) and in situ hybridization histochemistry (ISH) to study quantitatively and qualitatively the staining pattern and mRNA expression of calcitonin gene‐related peptide (α‐CGRP), growth‐associated protein 43 (GAP‐43), and acidic fibroblast growth factor (aFGF) in spinal lumbar motoneurons of young adult (2–3 months) and aged (30 months) Sprague‐Dawley rats. In addition, mRNAs encoding choline acetyltrimsferase (ChAT), β‐CGRP, and cholecystokinin (CCK) were analyzed.

All aged rats used in this study disclosed symptoms of hindlimb incapacity, ranging from mild weight‐bearing insufficiency to paralysis of the hind limbs. The symptoms were confined to the musculature of the hindlimb and hip regions. Only a small number (∼ 15%) of the large motoneurons that innervate the hindlimb muscles were lost in those aged rats that had clinical symptoms of hindlimb motor incapacities. The remaining motoneurons expressed ChAT mRNA at levels similar to those of Young adult rats. The vast majority of these motoneurons showed increased mRNA levels for α‐CGRP and GAP‐43. Aged motoneurons contained more CGRP like immunoreactivity (LI), but the number of immunoreactive neurons was smaller than in adult rats. GAP‐43‐LI could be detected in motoneurons in aged, but not in adult, rats. GAP‐43‐LI was always colocalized with CGRP‐LI in aged motoneurons. Studies of individual aged rats revealed that the increase of GAP‐43 mRNA‐positive coll bodies occurred in cases with the most severe clinical symptoms, whereas the increase in α‐CGRP was even evident in rats with mild symptoms. No alterations in content of aFGF‐LI or aFGF mRNA could be detected in the aged rat, and the content of CCK and β‐CGRP mRNAs was also normal. The usefulness of this rat model for studies of neuromuscular aging and possible functional roles for GAP‐43 and CGRP in plastic and regenerative processes during aging are discussed. © 1995 Wiley‐Liss, Inc.
AMPA‐selective glutamate receptor subtype immunoreactivity in the aged human hippocampal formation
Authors: Ikonomovic Milos D. , Sheffield Roxanne , Armstrong David M.
Published: January 2005

It has been hypothesized that, in Alzheimer's disease, glutamate‐mediated excitotoxicity contributes to the degeneration of selected populations of neurons. In the present study, immunocytochemical techniques were used to determine the distribution and anatomical features of GluR1‐ and GluR2/3‐immunolabeled cell bodies and processes within the hippocampal formation of normal (i.e., no pathology) elderly humans. The results of this study provide an essential baseline with which to compare the expression and distribution of glutamate receptor subunits within the brains of patients with Alzheimer's disease.

With respect to GluR1 immunoreactivity, the molecular layer of the dentate gyrus displays the most intense immunolabeling of any hippocampal structure. Contributing to this intense labeling are apical dendrites that arise from neurons within the adjacent granule cell layer. Interestingly, GluR1‐labeled neurons account for a relatively small percentage of the total number of neurons as revealed by Nissl staining in the granule cell layer. In contrast, GluR2/3‐labeled neurons are densely distributed throughout the granule cell layer, yet they provide relatively few processes to the adjacent molecular layer compared to GluR1‐positive processes.

GluRl labeling is also prominent within the CA fields of Ammon's horn, with CA2 > CA3 > CA1 ≥ CA4. Most prominent within the CA fields are the labeled dendrites of pyramidal neurons. In many instances, apical dendrites can be traced into the adjacent stratum radiatum, where they impart a deep striated appearance to this region of the hippocampus. Robust GluR2/3 labeling is also observed within the pyramidal layer of Ammon's horn, with an order of staining intensity similar to that observed for GluRl. However, unlike GluRl labeling, which is localized predominantly along dendrites, GluR2/3 labeling is observed primarily in association with ceh bodies. Collectively, these data suggest that the molecular composition of the AMPA receptor complex may differ between the dendrite and soma of granule and pyramidal neurons within the hippocampal formation, so functionally we may predict that these two regions of the neuron would respond differently following glutamate receptor stimulation. © 1995 Wiley‐Liss, Inc.
Dopamine transporter immunoreactivity in rat brain
Authors: Freed Curt , Revay Randall , Vaughan Roxanne A. , Kriek Evelyn , Grant Steven , Uhl George R. , Kuhar Michael J.
Published: January 2005

The dopamine transporter (DAT) is a primary site for the action of cocaine in inducing euphoria. Its action is necessary for the selectivities of dopaminergic neurotoxins that provide the best current experimental models of Parkinson's disease. In the present report, rat ddpamine transporter‐like immunoreactivity (iDAT) was assessed by immunohistochemistry using newly developed polyclonal antisera raised against conjugated peptides corresponding to sequences found in the dopainine transporter's carboxy‐ and amino‐termini. Dense iDAT was observed in patterns consistent with neural processes and terminals in the striatum, nucleus accumbens, olfactory tubercle, nigrostriatal bundle, and lateral habenula. Perikarya in the substantia nigra pars compacts, were immunostained with moderate intensity using one of two immunohistochemical methods, while scattered ventral tegmental area perikarya were stained with somewhat less intensity. Immunoreactive neuronal processes with axonal and dendritic morphologies were stained in the substantia nigra and the paranigral and parabrachialis pigmentosus nuclei of the ventral tegmental area, while sparser processes were noted more medially in the ventral tegmental area. Neuronal processes were found in several laminae in the cingulate cortex, with notable fiber densities in the superficial aspects of lamina I and laminae II/III. The intensities of immunoreactivities in striatum and cerebral cortex were dramatically attenuated ipsilateral to nigrostriatal bundle 6‐hydroxydopamine lesions. Specificity of immunostaining was supported by agreement of the results using sera directed against two distinct DAT segments, studies with preimmune and preadsorbed sera and studies of the extracted protein. These antisera identify and reveal details of the distribution of DAT immunoreactivity in rat brain and display ivariations in levels of DAT expression of likely functional significance. © 1995 Wiley‐Liss, Inc.
The process of reinnervation in the dentate gyrus of adult rats: Gene expression by neurons during the period of lesion‐induced growth
Authors: Steward Oswald
Published: January 2005

Neurons in the hippocampal dentate gyrus are extensively reinnervated following the destruction of their normal inputs from the ipsilateral entorhinal cortex (EC). The present study evaluates gene expression by dentate granule neurons and the neurons giving rise to the sprouting connections during the period of synapse growth.

Adult male rats were prepared for in situ hybridization at 2, 4, 6, 8, 10, 12, 14, 20, and 30 days following unilateral EC lesions. Sections were hybridized using 35S‐labeled cRNA probes for mRNAs that encode proteins thought to be important for neuronal structure and/or synapse function, including (1) mRNAs that are normally present in dendrites‐the mRNAs for the high molecular weight microtubule‐associated protein 2 (MAP2) and the α‐subunit of calcium/calmodulin‐dependent protein kinase Il (CAMII kinase), (2) mRNAs that are upregulated in neurons that are regenerating their axons (Tα1 tubulin and F1/GAP43) and (3) mRNAs for proteins that are the principal constituents of neurofilaments and microtubules (the low molecular weight neurofilament protein NF68 and β‐tubulin).

Although there were small changes in the levels of labeling for the mRNAs that are normally present in dendrites, there were no dramatic increases in the levels of any of the mRNAs either in dentate granule cells or in neurons giving rise to the reinnervating fibers at any postlesion interval. These results indicate that neurons in mature animals can substantially remodel their synaptic terminals and their dendrites in the absence of large‐scale changes in gene expression (at least as measured by steady‐state mRNA levels at various time points). © 1995 Wiley‐Liss, Inc.
Distribution in the central nervous system of Aplysia of afferent fibers arising from cell bodies located in the periphery
Authors: Xin Yuanpei , Weiss Klaudiusz R. , Kupfermann Irving
Published: January 2005

The present study used autoradiography to determine the location of the projections of presumptive peripheral afferent neurons into the central nervous system of Aplysia. Selected peripheral tissues (with an empliasis on structures involved in feeding behavior) were exposed to radioactive amino acids, and the distribution of macromolecules transported into the nervous system via afferent fibers was determined by autoradiography. Different regions of the body exhibited different patterns of projections, and within the neuropil of the cerebral ganglion, there was a loose topographical prganization of projections from the head. For some regions of the body, the projection was largely limited to the ganglion from which the nerve enters; for other regions, the projection was very widespread. In some cases (e.g., rhinophore to eye), there was evidence of projections from one peripheral structure to another. Experiments with all peripheral tissues that were studied resulted in extensive labeling of central ganglia, indicating that afferents with peripheral cell bodies may provide a major source of sensory input to the central nervous system and suggesting that many or all of the numerous ultrafine axons visualized via electron microscopy in the nerves of Aplysia may originate from first‐ or second‐order sensory afferents whose cell bodies are located in the periphery. © 1995 Wiley‐Liss, Inc.
Electroreceptor development in the electric fish Eigenmannia: A histological and ultrastructural study
Authors: Vischer Heinrich A.
Published: January 2005

Developmental patterns of electroreceptors in the wealdy electric fish Eigenmannia were investigated by histological, histochemical, immunocytochemical, cell kinetic, ultrastructural, and computer‐assisted three‐dimensional reconstruction methods. The first cell of an electroreceptor primordium is embedded in the stratum germinativum of the epidermis. An unmyelinated, afferent nerve fiber ends near this cell below the basal lamina. Protrusions and vacuole‐like inclusions at the basal lamina above the nerve fiber ending suggest a mechanism of nervous induction. The receptor primordium cell subsequently divides into a single cell layer. Within 48 hours, a second apical cell layer forms from the first, and, thus, the primordium differentiates into an apical layer of presumptive receptor cells and a basal layer of presumptive supporting cells. While the two layers further differentiate into mature receptor and supporting cells, the afferent fiber penetrates the basal lamina, sprouts, and forms a synapse with each receptor cell. Transitory fibers also project along the receptor cells to the top of the developing electroreceptor but degenerate during development. Synapses are smaller in early developmental stages compared to older stages, and pre‐ and postsynaptic vesicles are more abundant and widely distributed in younger stages. Moreover, presynaptic ribbons are longer and are interconnected at their apical ends. Supporting cells continue to divide during further maturation and form new receptor cells. The number of receptor cells per tuberous organ increases during the first 4 days of electroreceptor development and plateaus when the fish are 9 days old. It declines again when organs begin to divide into clusters. © 1995 Wiley‐Liss, Inc.
Time‐course of neuropeptide changes in peri‐ischemic zone and amygdala following focal ischemia in rats
Authors: Cheung R. T. F. , Diab T. , Cechetto D. F.
Published: January 2005

Previously, using a middle cerebral artery occlusion model in Wistar rat, we showed autonomic disturbances similar to those seen clinically and observed striking neurochemical changes in cortical and subcortical sites at 5 days following stroke. The neurochemical changes may account for functional recovery and/or autonomic disturbances after focal ischemia. To understand the possible mechanisms and to facilitate future studies, it is necessary to define the time‐courses of these changes.

Using immunohistochemical staining with the peroxidase‐antiperoxidase reaction, the changes in several neuropeptides over the peri‐ischemic region and the ipsilateral central and basolateral nucleus of the amygdala were investigated at different times after middle cerebral artery occlusion. In the experimental group, neuropeptide Y immunoreactivity appeared to increase by 6 hours in the peri‐ischemic region. Using image analysis to quantify the staining intensity, the change became statistically significant at 1 day, peaked around 3 days, and subsided at 10 days. There was a delayed increase in neuropeptide Y in the ipsilateral basolateral nucleus of the amygdala with a peak around 3 days. Immunoreactive staining for leucine‐enkephalin, dynorphin, and neurotensin demonstrated an increase that was localized to the ipsilateral central nucleus of the amygdala with a peak around 3 days and a return to baseline levels by 10 days.

The results support a specific time‐course for each of the neuropeptides studied and indicate that a survival time of 3 days after focal ischemia is the critical period for examining the relationship between neuropeptide responses and neuronal or functional recovery. © 1995 Wiley‐Liss, Inc.
Human intermediate reticular zone: A cyto and chemoarchitectonic study
Authors: Huang Xu‐Feng , Paxinos George
Published: January 2005

The primary aim of this study was to provide a comprehensive account of the morpholo topography, and frequency of tyrosine hydroxylase‐ and substance P‐like (TH‐LI, SP‐LI) immunoreactive neurons of the human intermediate reticular zone (IRt), the putative autonomic zone of the medullary reticular formation. A further aim is to examine the IRt from a three‐dimensional perspective using computer reconstruction techniques and compare its relationship with other structures in the rest of the medullary reticular formation.

Six adult human brains were obtained from individuals with no sign of cerebral disease and were perfusion fixed. Free‐floating transverse sections were immunostained with monoclonal antibodies against tyrosine hydroxylase and substance P by the avidin‐biotin‐peroxidase technique. The entire IRt displays TH‐LI cell bodies and fibers, and thus it is readily distinguishable from the neighbouring gigantocellular and parvicellular reticular nuclei. In contrast, SP‐LI cells are restricted to the external part of the IRt that is found in the open medulla, while SP‐LI fibers are more widely distributed. The IRt displays TH‐LI neurons which are fusiform, oval, and round in shape. The SP‐LI neurons of the IRt are primarily oval and fusiform. In preparations stained for Nissl substance, IRt cells were classified as pigmented and nonpigmented. A characteristic feature of the IRt is that its cells are larger (20 ± 4 μm) than those of the laterally adjoining parvicellular (12 ± 2 μm) and clearly smaller than those of the medially adjoining gigantocellular nuclei (33 ± 6 μm). The shape of the IRt is in keeping with the radial organization of the medulla with zones emanating from the fourth ventricle. Three‐dimensional computer recostructions of the cell plots show that (1) TH‐LI neurons extend through the entire IRt and densely packed in the rostral part of the ventrolateral IRt and (2) SP‐LI neurons are found only in the rostral half of the medulla oblongata. © 1995 Wiley‐Liss, Inc.
Immunocytochemical study of choline acetyltransferase in Drosophila melanogaster: An analysis of cis‐regulatory regions controlling expression in the brain of cDNA‐transformed flies
Authors: Yasuyama Kouji , Kitamoto Toshihiro , Salvaterra Paul M.
Published: January 2005

We have analyzed the cis‐regulatory regions in the 5′ flanking DNA of the Drosophila melanogaster choline acetyltransferase (ChAT; E.C. 2.3.1.6) gene by using germline transformants. These transformants are carrying wild‐type ChAT cDNA fused to different lengths of 5′ flanking sequence of the ChAT gene. Appropriate genetic crosses were used to introduce the transgene into animals with a presumptive null genetic background for endogenous ChAT. Expression of ChAT protein could thus be attributed exclusively to the transgene. Using a monoclonal antibody against Drosophila ChAT, we have investigated the spatial distribution of transgenic ChAT and compared it to the normal distribution of ChAT protein in wild‐type animals. The brains of 7.4 kb cDNA transformants showed a ChAT expression pattern similar to that of wild‐type anin in the first‐ and second‐order sensory neuropil but reduced expression in other highly ordered neuropil. Several lines that were transformed with 1.2 kb or 0.8 kb of 5′ flanking DNA demonstrated relatively normal expression in sensory neuropil. In addition, these lines also showed ectopic expression in higher order neuropil. In the optic lobe, the expression pattern directed by 7.4 kb of 5′ flanking DNA was very similar to that of wild‐type ChAT expression. In contrast, 1.2 kb or 0.8 kb transformants showed reduced levels of expression and a more limited pattern of distribution in the optic lobe. Our results suggest that the 5′ flanking DNA of the ChAT gene can be divided into several separable positive and negative regulatory regions, which define various subsets of cholinergic neurons in the nervous system. © 1995 Wiley‐Liss, Inc.
Central projections of the antennal cold receptor neurons and hygroreceptor neurons of the cockroach Periplaneta americana
Authors: Nishikawa Michiko , Yokohari Fumio , Ishibashi Takaaki
Published: January 2005

The central projections of the cold receptor axons were examined by filling two types of cold receptive sensilla with cobalt lysine—a cold and hygroreceptive (C/H) sensillum and a cold receptive and olfactory (C/O) sensillum—on the antennae of the cockroach, Periplaneta americana L. When the dye filled a single C/H sensillum, four axons were stained. Three of these axons terminate in the ipsilateral antennal lobe, while the other branches in the ipsilateral dorsal lobe. One of the branches passed through the tritocerebrum to terminate in the suboesophageal ganglion, while the other branches end in the lobe. When a single C/O sensillum is dye filled, all axons of the four receptor neurons terminate exclusively in the ipsilateral antennal lobe. One axon from the C/H sensillum and one axon from the C/O sensillum terminate in a particular glomerulus in the ventroposterior region of the antennal lobe. Each of these axons also has a tuft in separate giomeruli situated just dorsal to the glomerulus in which both axons terminate. This set of three glomeruli have indistinct boundaries and appear to form a complex of glomeruli similar to the macroglomerular complex of male moths. Assuming modality‐specific convergence of antennal afferents, these axons appear to belong to the cold receptor neurons, and the set of glomeruli appear to function in cold reception. Two other neurons stained from C/H sensilla always terminate in theglom‐eruli distinct from the set of glomeruli mentioned earlier. These neurons are assigned to the pair of hygroreceptor neurons, and their glomeruli are thought to function in hygroreception. © 1995 Wiley‐Liss, Inc.
Spinovestibular projections in the rat, with particular reference to projections from the central cervical nucleus to the lateral vestibular nucleus
Authors: Matsushita Matsuo , Gao Xiulai , Yaginuma Hiroyuki
Published: January 2005

Projections from the spinal cord to the vestibular nuclei were examined following injections of Phaseolus vulgaris–leucoagglutinin, cholera toxin subunit B, or biotinylated dextran at various levels of the spinal cord in the rat. Labeled terminals were abundant after injections of the tracers into the C2 and C3 segments containing the central cervical nucleus. Labeled terminals were seen in the descending vestibular nucleus and the parvocellular, magnocellular, and caudal parts of the medial vestibular nucleus throughout its rostrocaudal extent. Labeled terminals were most numerous in the lateral vestibular nucleus throughout its rostrocaudal extent. The projections from the central cervical nucleus to the vestibular nuclei were exclusively contralateral to the cells of origin because the axons of the central cervical nucleus neurons cross in the spinal cord. Following tracer injections in the cervical enlargement, many labeled terminals were seen in the magnocellular part of the medial vestibular nucleus, but a few were seen in the lateral and the descending vestibular nucleus. Injections into more caudal segments resulted in sporadic terminal labeling in the magnocellular part of the medial vestibular nucleus, the descending vestibular nucleus, and the caudal part of the lateral vestibular nucleus.

The results indicate that primary neck afferent input relayed at the central cervical nucleus is mediated directly to the contralateral vestibular nuclei. It is suggested that this projection serves as an important linkage from the upper cervical segments to the lateral vestibulospinal tract in the tonic neck reflex. © 1995 Wiley‐Liss, Inc.
The glutamate‐enriched cortical and thalamic input to neurons in the subthalamic nucleus of the rat: Convergence with GABA‐positive terminals
Authors: Bevan Mark D. , Francis C. M. , Bolam J. P.
Published: January 2005

Neurons of the subthalamic nucleus play a key role in the normal physiology and the pathophysiology of the basal ganglia. In order to understand better how the activity of subthalamic neurons and hence the output of the basal ganglia are controlled, we have reexamined the topography and examined in detail the synaptology and neurochemical nature of the two major excitatory projections to the subthalamic nucleus, that from the cortex and from the parafascicular nucleus of the thalamus. The approach was to use anterograde neuronal tracing and postembedding immunocytochemistry for amino acid transmitters.

In confirmation of previous findings the cortical and thalamic projections were topographically organized, although the topography was more finely organized, and the projections more extensive, than previously demonstrated. Cortical and thalamic terminals made asymmetrical synaptic contacts with the dendrites and spines of subthalamic neurons. The thalamic terminals contacted larger postsynaptic targets, and therefore presumably more proximal regions of subthalamic neurons, than did the cortical terminals. Quantitative analysis of the postembedding immunolabelled sections revealed that the cortical and thalamic terminals were significantly enriched in glutamate‐immunoreactivity when compared to identified γ‐aminobutyric acid (GABA)‐positive terminals, supporting physiological studies that suggest that these projections use glutamate as their neurotransmitter. In addition a small population of nonanterogradely labelled terminals that formed asymmetrical synapses and were immunopositive for GABA were identified. A larger population of terminals that formed symmetrical synapses were also immunbpositive for GABA and were probably derived from the globus pallidus. The latter type of terminal was found to make convergent synaptic input with cortical or thalamic terminals on this dendrites and spines of subthalamic neurons, indicating that the “indirect pathways” by which information flows through the basal ganglia converge at the level of individual neurons in the subthalamic nucleus. © 1995 Wiley‐Liss, Inc.
Embryonic development of gonadotropin‐releasing hormone neurons in the sockeye salmon
Authors: Parhar Ishwar S. , Iwata Munehico , Pfaff Donald W. , Schwanzel‐Fukuda Marlene
Published: January 2005

Immunocytochemistry and in situ hybridization were used to test the hypothesis that gonadotropin‐releasing hormone (GnRH) neurons are formed in the olfactory placode during embryonic development in a salmonid, Oncorhynchus nerka. The development of GnRH neurons and the pituitary cell types was examined from 19 through 910 days after fertilization. Immunoreactive GnRH was first detected at 19 days in the cells of the olfactory placode. GnRH immunoreactivity was not detected in any other structure of the central nervous system at this age. By day 24, GnRH‐immunoreactive neurons were seen in the apical, intermediate, and basal layers of the olfactory placode. From days 30 through 51, GnRH neurons were seen emerging from the epithelium, along the olfactory nerve, and at the rostral olfactory bulb. By day 41, GnRH immunoreactivity was lost in the nasal epithelium. In the 72–day‐old fish, most of the GnRH neuronal population was found in ganglia of the nervus terminalis, at the cribriform bone (gCB), and at the rostral olfactory bulb (gROB).

On day 293, a decrease in GnRH‐immunoreactive neurons in the gCB and gROB was concomitant with an initial appearance of GnRH‐immunoreactive neurons and fibers along the caudoventral olfactory bulb. By day 462, the distribution of GnRH neurons and fibers was almost similar to adults. In maturing adults (910 days), GnRH‐immunoreactive neurons were rarely seen in the nasal regions, but were primarily found in the basal forebrain. GnRH fibers were widespread in the brain, proximal pars distalis, and in the pars intermedia of the pituitary.

Our study supports the notion that neurons expressing salmon‐GnRH mRNA and peptide originate in the medial olfactory placode and migrate into the basal forebrain during development. The midbrain neurons did not express salmon‐GnRH mRNA or peptide in the larval and juvenile fish. © Wiley‐Liss, Inc.
Permanent neuronal cell loss in the cerebellum of rats exposed to continuous low blood alcohol levels during the brain growth spurt: A stereological investigation
Authors: Napper Ruth M. A. , West James R.
Published: January 2005

This study demonstrates that exposure to an alcohol regimen that resulted in low, uniform blood alcohol concentrations during a period of rapid brain growth can lead to a permanent deficit in the number of Purkinje cells and granule cells in the floccular‐parafloccular region of the cerebellum. Sprague‐Dawley rat pups were artificially reared and were administered alcohol over postnatal days 4 through 9, a period of brain development similar to that of the human third trimester. Two groups received a daily alcohol dose of 4.5 g/kg, administered either as a 10.2% solution in two of the 12 daily feedings (10.2% group) or as a 5.1% solution in four of the 12 feedings (5.1% group). A third group received a daily dose of 6.6 g/kg administered as a 2.5% solution in every feeding (2.5% group). The condensed patterns of alcohol administration resulted in high peak blood alcohol concentrations with near total clearance while the higher daily dose (6.6 g/kg), administered continuously, resulted in low but continuous blood alcohol concentrations. Pups were allowed to grow to adulthood and killed on postnatal day 115. The total number of Purkinje cells and granule cells in the floccular‐parafioccular region of the cerebellum was estimated using unbiased stereological methods. Exposure to alcohol resulted in significant deficits in the number of both Purkinje cells and granule cells at 115 days of age in all three treatment groups. Most importantly a significant deficit of Purkinje cells and granule cells was found following continuous exposure to low blood alcohol concentrations, i.e., in the 2.5% group. The total number of Purkinje cells in the 2.5% group was 2.33 ± 0.31 x 104 compared with 3.18 ± 0.30 x 104 in the artificially reared controls. The total number of granule cells in the 2.5% group and the controls was 1.24 ± 0.10 x 107 and 1.64 ± 0.19 x 107 respectively.

These results support the hypothesis that exposure to a continuous, low blood alcohol concentration can result in the death of developing neurons and lead to permanent neuronal deficits. The degree of neuronal loss does not correlate with the magnitude of the peaks of blood alcohol concentration © Wiley‐Liss, Inc.
Morphology of higher‐order ocellar interneurons in the cockroach brain
Authors: Mizunami Makoto
Published: January 2005

Most species of insects have two or three ocelli, in addition to a pair of compound eyes. In the cockroach ocellus, a large number of photoreceptors converge upon four second‐order neurons, which exit the ocellus and project into the ocellar tract neuropil of the brain, where they form synapses with at least 15 third‐order neurons. Third‐order neurons project into a variety of neuropils in the brain, including the posterior slope, a premotor center from which descending neurons originate. I examined the morphology and ocellar response of neurons in the posterior slope of the cockroach, using intracellular recording and stainings. Most ocellar neurons of the posterior slope exhibited transient depolarizations at the cessation of ocellar illumination, which seem to reflect sign‐conserving synaptic input from third‐order neurons. Ocellar neurons of the posterior slope project into various areas of the brain, including (1) the central complex, a higher center implicated in higher locomotory control, (2) the pedunculus of the mushroom body, an associative center, (3) the lamina (the first neuropil of the optic lobe), (4) the antennal lobe (olfactory center), (5) the tritocerebrum (mechanosensory center), and (6) the subesophageal and thoracic motor centers. These results suggest that the posterior slope is a high‐order ocellar center from which ocellar signals are transmitted to various target neuropils of the brain, as well as a premotor center to form descending motor commands. © 1995 Wiley‐Liss Inc.
Immunocytochemical mapping of serotonin and neuropeptides in the accessory medulla of the locust, Schistocerca gregaria
Authors: Würden Stefan , Homberg Uwe
Published: January 2005

Accumulating evidence suggests that pigment‐dispersing hormone‐immunoreactive neurons with ramifications in the accessory medulla of the insect brain are involved in circadian pacemaking functions. We have used immunocytochemical techniques to investigate the neurochemical organization of the accessory medulla in the locust Schistocerca gregaria. Local neurons with arborizations largely restricted to the accessory medulla are immunoreactive with antisera against serotonin, Manduca sexta allatotropin, and Diploptera punctata allatostatin 7. Projection neurons with arborizations in the accessory medulla and fibers to the lamina and/or several areas in the midbrain including the posterior optic tubercles, the inferior and the superior protocerebrum show Phe‐Met‐Arg‐Phe (FMRF) amide‐, gastrin/cholecystokinin‐, crustacean cardioactive peptide‐, and substance P immunoreactivities. A unique neuron with tangential ramifications in the medulla and lamina and varicose terminals in the accessory medulla contains a peptide related to locustatachykinin I/II. Double‐label experiments show colocalization of pigment‐dispersing hormone‐immunoreactivity with substances related to gastrin/cholecystokinin, FMRFamide, substance P, or crustacean cardioactive peptide in certain projection neurons of the accessory medulla. The results suggest that neuropeptides and biogenic amines play major neuroactive roles in the accessory medulla of the locust. The abundance and extensive colocalization of neuropeptides in the locust accessory medulla is discussed with respect to the possible involvement of this brain area in circadian pacemaking functions. © 1995 Wiley‐Liss Inc.
Heterogeneity of astrocytes in human optic nerve head
Authors: Ye Hongqing , Hernandez M. Rosario
Published: January 2005

Previous studies demonstrated regional differences in the synthesis of extracellular matrix by astrocytes during optic nerve head (ONH) maturation and in glaucomatous optic neuro pathy, suggesting heterogeneity of astrocytes. To characterize different types of glial cells in human fetal and adult ONH, we used a variety of neural cell markers such as HNK‐1/N‐CAM, A2B5, galactocerebroside (GalC), myelin basic protein (MBP), and glial fibrillary acidic protein (GFAP). Cryostat or paraffin sections were prepared from fetal (16–25 weeks) and mature (8 months to 75 years old) ONH and processed for standard single/double immunocytochemistry. Two subpopulations of type 1 astrocytes were present in the mature prelaminar and laminar regions. Glial celia expressing only GFAP were identified as type 1A astrocytes at the edges of the cribriform plates. Cells forming the glial columns and lining the cribriform plates expressed both GFAP and fINK‐1/N‐CAM and were identified as type lB astrocytes. In the myelinated nerve, type 1A astrocytes form the glial limiting membrane. Cells labeled with GFAP and A2B5 were identified as type 2 astrocytes, and GFAP‐negative cells labeled with GaIC, MBP, and HNK‐1/N‐CAM were identified as oligodendrocytes. In fetal ONH, all glial cells expressed HNK‐1/N‐CAM. In older fetal ONH, some glial cells also expressed GFAP. No type 2 astrocytes or oligodendrocytes were present in the fetal ONH. In conclusion, at least two subpopulations of type 1 astrocytes exist in human ONH: Type 1A astrocytes may serve as structural support for a type lB astrocytes, which retain the developmental neural marker HNK‐1/N‐CAM, may have a more complex function by interfacing between blood vessels and other connective tissue surfaces. These findings demonstrate the heterogeneity of astrocytes in the human ONH and suggest differential regional responses to changes in their microenvironment. © 1995 Wiley‐Liss Inc.
Neuropeptide changes following excitotoxic lesion of the insular cortex in rats
Authors: Cheung R. T. F. , Cechetto D. F.
Published: January 2005

Following middle cerebral artery occlusion in Wistar rats, the immunoreactivity of neuropeptide Y increased ipsilaterally in the insular cortex and basolateral nucleus of the amygdala. In addition, the immunoreactivity of leucine‐enkephalin, dynorphin, and neurotensin increased in the ipsilateral central nucleus of the amygdala. The amygdalar neurochemical changes are likely the result of damage to the insular cortex, although other cortical areas were also affected by the ischemia. To investigate whether damage to the insular cortex is essential in eliciting these changes, a localized lesion of the right or left insular cortex was produced by microinjection of D,L‐homocysteic acid. Control animals received injections of vehicle into the right or left insular cortex or D,L‐homocysteic acid into the right primary somatosensory cortex. Neurochemical changes were examined immunohistochemically with the peroxidase antiperoxidase reaction 5 lays after the injection. The immunoreactivity of neuropeptide Y increased locally after excitotoxic damage to the insular cortex or primary somatosenaory cortex. The amygdalar neurochemical changes, including neuropeptide Y increase in the basolateral nucleus and leucine‐enkephalin, dynorphin, and neurotensin increase in the central nucleus, were seen only when the ipsilateral insular cortex was lesioned. These neurochemical changes were similar to those seen 5 days after middle cerebral artery occlusion.

Our findings indicat that damage to the insular cortex is essential in eliciting the neurochemical changes in the ipsilateral amygdala. In addition, the change in neuropeptide Y in the cortex appears to be a local reaction occurring irrespective of location of the lesion and glutamate receptor activation may be involved. © 1995 Wiley‐Liss Inc.
Projection of individual axons from the pretectum to the dorsal lateral geniculate complex in the cat
Authors: Uhlrich Daniel J. , Manning Karen A.
Published: January 2005

The dorsal lateral geniculate nucleus of the thalamus transmits visual signals from the retina to the cortex. Within the lateral geniculate nucleus, the ascending visual signals are modified by the actions of a number of afferent pathways. One such projection originates in the pretectum and appears to be active in association with oculomotor activity. Much remains unknown about the pretectal‐geniculate projection. Our purpose was to examine for the first time individual axon arbors from the pretectum that project to the lateral gesticulate nucleus, describing their topography and nuclear and laminar targets.

We made injections of the anterograde tracer Phaseolus vulgaris leucoagglutinin into the cat pretectum, targeting the nucleus of the optic tract. Serial 40 μm coronal sections were processed by using immunohistochemiatry to reveal labeled axons that were then serially reconstructed using light microscopy. Pretectal‐geniculate axons appeared morphologically heterogeneous in terms of swelling size, branching patterns, and laminar target. Most axons innervated the geniculate A laminae. A separate, smaller population innervated the C laminae. All axons exhibited substantially greater spread medial‐laterally than rostral‐caudally in the lateral gesticulate nucleus, displaying a topographical organization for visual field elevation, but not azimuth. Many pretectal axons that projected to the LGN also innervated adjacent structures, including the medial interlaminar nucleus, the perigeniculate nucleus, and/or the pulvinar. These results indicate that the projection from the pretectum to the dorsal lateral geniculate nucleus is heterogeneous, is semitopographical, and may coordinate neural activity in the lateral geniculate nucleus and in neighboring visual thalamic structures in association with oculomotor events. © 1995 Wiley‐Liss, Inc.