bluuebunny/crossref_metadata_2025 huggingface dataset:
Developmental changes in the expression of γ‐aminobutyric acidA/benzodiazepine receptor subunit mRNAs in the inferior olivary complex
Authors: Chang C. C. Anne , Luntz‐Leybman Vera , Evans James E. , Rotter Andrej , Frostholm Adrienne
Published: January 2005

The pharmacological and physiological properties of ligand‐gated ion channels are dependent on their subunit composition; spontaneously occurring changes in subunit composition during neuronal development may result in dramatic functional differences between embryonic and adult forms of the receptor complex. In the present study, in situ hybridization with antisense cRNA probes was used to examine the subunit composition of the γ‐aminobutyric acidA/benzodiazepine (GABAA/BZ) receptor in the developing inferior olivary complex. This receptor is thought to be a pentameric chloride channel comprised of selected α, β, γ, δ, and ρ subunits, the majority of which have several isoforms: α1−6, β1−4, γ1−4 and ρ1, 2. Among the 13 subunit variants present in the mammalian central nervous system, α2−5 β3, and γ1, 2 mRNAs are expressed at significant levels in the inferior olivary complex. Two clearly different temporal patterns of GABAA/BZ receptor subunit mRNA expression were observed: The expression of α3, α5, β3, and γ2 mRNAs was at a peak during embryonic and early postnatal development followed by rapid down‐regulation thereafter. Conversely, α2, α4, and γ1 mRNA expression was very low or absent during early development, and a pronounced increase was observed at the end of postnatal week 1. These studies suggest that there are developmental changes in the subunit composition of the GABAA/BZ receptor in inferior olivary neurons. These changes in subunit expression, which occur during a period of major alterations in afferent and efferent synaptic connections, may subserve a change in the role of GABA from its function as a neurotrophic factor to that of an inhibitory neurotransmitter. © 1995 Wiley‐Liss, Inc.
Colocalization of gephyrin and GABAA‐receptor subunits in the rat retina
Authors: Sassoè‐Pognetto M. , Kirsch J. , Grünert U. , Greferath U. , Fritschy J. M. , Möhler H. , Betz H. , Wässle H.
Published: January 2005

Gephyrin is a protein that copurifies with the glycine receptor (GlyR) and is required for the clustering of GlyRs at postsynaptic sites. Previously, it was thought that antibody mAb 7a, directed against gephyrin, was a specific marker for GlyR. However, there is evidence that gephyrin can also be found at nonglycinergic synapses. Here, immunocytochemistry was applied to show this directly for the rat retina. Both gephyrin and different Subunits of the γ‐aminobutyric acid (GABA)A receptor were localized to discrete puncta in the inner plexiform layer, and these puncta were shown by electron microscopy to represent synaptic sites. Double immunocytochemistry revealed that GABAA receptors and GlyRs are not colocalized. However, gephyrin and different subunits of GABAA receptors were found to occur at the same synapses. The amount of colocalization varied with the GABAA receptor subunit composition and was most extensive for the α2 subunit, less for the α3 subunit, and minimal for the αl subunit. The gephyrin present at GABAergic synapses of the retina might also be involved with clustering of receptors at the postsynaptic sites. Hence, localization of gephyrin can no longer be considered as a unique marker of glycinergic synapses. © 1995 Wiley‐Liss, Inc.
Expression of the p150Glued component of the dynactin complex in developing and adult rat brain
Authors: Melloni Richard H. , Tokito Mariko K. , Holzbaur Erika L. F.
Published: January 2005

p150Glued is a component of the dynactin (Glued) complex that has been shown in vitro to be a required activator of cytoplasmic dyneinmediated transport of vesicles along microtubules and, thus, may be an essential component of retrograde axonal transport. In vivo, a dominant mutation in the Drosophila homologue of p150Glued induces aberrant neuronal development when heterozygous and is lethal when homozygous. In order to characterize the role of the dynactin complex in the development and function of vertebrate neurons, the distribution of the p150Glued message was examined via in situ hybridization to serial sections of adult rat brain and to a developmental series of sections. In the adult rat brain, the most intense hybridization observed with the p150Glued probe was in the pyramidal cells of the hippocampus proper, the dentate granule neurons, the cingulate and piriform cortices, the ventromedial hypothalamus, and the granular cell layer of the cerebellum. White‐matter fiber tracts and the neuropil were generally devoid of signal. The data indicate that the mRNA encoding p150Glued is highly enriched in the cell bodies of neurons within the central nervous system. In developing rat, p150Glued is expressed at very high levels in neural tissue from the earliest time points assayed. Particularly intense hybridization was observed in the multiple layers of the retina, which is consistent with the phenotype of the Drosophila mutation. Therefore, the distributions observed via in situ hybridization are consistent with an essential role for p150Glued in retrograde axonal transport. © 1995 Wiley‐Liss, Inc.
Localisation, quantitation, and characterisation of neuropeptide F‐ and FMRFamide‐immunoreactive peptides in turbellarians and a monogenean: A comparative study
Authors: Johnston R. N. , Shaw C. , Brennan G. P. , Maule A. G. , Halton D. W.
Published: January 2005

Over the past decade it has become clear that the nervous systems of platyhelminths are both complex and highly developed, particularly in peptidergic elements. The central position of an ancestral flatworm in the evolution of the Bilateria, has placed a greater importance on the study of modern flatworms. Using antisera generated to the C‐terminal region of platyhelminth neuropeptide F and the molluscan neuropeptide, FMRFamide, in immunocytochemistry at both light and ultrastructural levels, immunoreactivities have been localised within the nervous systems of three species of triclad turbellarians, Dugesia lugubris, Dendrocoelum lacteum, and Polycelis nigra, and one species of monogenean trematode, Diclidophora merlangi. Extensive immunostaining was obtained with both antisera throughout the central and peripheral nervous systems of all species studied, but intensity and abundance was significantly greater in the turbellarians. Indirect electron‐immunogold labeling demonstrated that immunoreactivity to both neuropeptides was often colocalised in neurosecretory vesicles, although discrete populations of vesicles were also observed. Radioimmunoassay of extracts of all species confirmed that neuropeptide F immunoreactivity was consistently more abundant than FMRFamide immunoreactivity, and that the levels of both in the three turbellarians were several orders of magnitude greater than those found in the monogenean. Chromatographic analyses of turbellarian extracts revealed that neuropeptide F and FMRFamide immunoreactivities were attributable to different peptides. These data imply that the neuropeptidergic systems of turbellarians are considerably more extensive than those of monogeneans, and would suggest that a regression has occurred in the latter as a consequence of the adoption of a more sedentbxy parasitic lifestyle. © 1995 Wiley‐Liss, Inc.
Spatial distribution of thalamic projections to the supplementary motor area and the primary motor cortex: A retrograde multiple labeling study in the macaque monkey
Authors: Shindo Katsuhiro , Shima Keisetsu , Tanji Jun
Published: January 2005

The exact knowledge on spatial organization of information sources from the thalamus to the supplementary motor area (SMA) and to the primary motor cortex (MI) has not been established. We investigated the distribution of thalamocortical neurons projecting to forelimb representations of the SMA and the MI using a multiple retrograde labeling technique in the monkey. The forelimb area of the SMA, and the distal and proximal forelimb areas of the MI were identified by electrophysiological techniques of intracortical microstimulation and single neuron recording. Injections were made into these three representations with three different dyes in the same animal (horseradish peroxidase conjugated to wheat germ agglutinin, diamidino yellow, and fast blue), and the thalamic neurons were retrogradely labeled. Injections into the SMA densely labeled thalamic neurons in nuclei ventralis lateralis pars oralis (VLo), ventralis lateralis pars medialis (VLm) and ventralis lateralis pars caudalis (VLc), but not in nucleus ventralis posterior lateralis pars oralis (VPLo). Injections into the MI labeled thalamic neurons primarily in VLo, VLc, and VPLo. We found that the distribution of projection neurons to the three areas was largely separate in the thalamus. However, in the middle part of VLo, and in a limited portion of VLc, thalamic neurons projecting to the SMA partially overlapped with those to the distal forelimb area of the MI. They overlapped little with those to the proximal forelimb area of the MI. We noted no overlap between the distributions of thalamic projection neurons to the distal and proximal forelimb areas of the MI. These findings suggest that the SMA and MI receive separate information from the thalamus, while sharing minor sources of common inputs. © 1995 Wiley‐Liss, Inc.
Cerebellar Purkinje cells from the Lurcher mutant and wild‐type mouse grown in vitro: A light and electron microscope study
Authors: Doughty Martin L. , Patterson Lilian , Caddy Keith W. T.
Published: January 2005

Lurcher is an autosomal semidominant murine mutation. Lurcher heterozygotes, (+/Lc) lose all their cerebellar Purkinje cells by adulthood. Explants from 2 days postnatal (P2) wild‐type (+/+) and +/Lc cerebellar cortex were grown in vitro to investigate the role of local neuronal environment and afferent input on the degenerating +/Lc Purkinje cell. In Lurcher explants, Purkinje cells were maintained for up to 25 days in vitro. No significant difference was observed between +/+ and +/Lc Purkinje cell numbers from 10 to 20 days in vitro, as revealed by calbindin‐D immunoreactivity. Growing +/Lc explants in association with + / + explants resulted in no significant difference in Purkinje cell survival (10–20 days in vitro). Image analysis of the gross morphology of calbindin‐D‐immunostained Purkinje cells from +/+ and +/Lc explants grown in vitro revealed a significant decrease in the total area and dendritic lengths of +/Lc Purkinje cells (15 and 20 days in vitro). The fine structure of +/Lc and +/+ Purkinje cells was examined under the electron microscope (10–25 days in vitro). No difference in ultrastructure was observed between +/Lc and +/+ Purkinje cells grown in vitro, and many features similar to normal Purkinje cell development in vivo were present. These included monosynaptic parallel fibre synapses with Purkinje cell dendritic spines, other interneuron synapses with Purkinje cell dendrites and soma, astroglial investment, and minimal extracellular space in the neuropil. Unusual features observed included a persistence of the perisomatic spines in some Purkinje cells, an absence of Nissl bodies in the Purkinje cell perikaryon, naked Purkinje cell dendritic spines, and occasional heterol, ogous synapses. The results are discussed in the light of previous chimeric analysis of the Lurcher mutation, and a hypothesis is put forward to explain the survival of + /Lc Purkinje cells in vitro. © 1995 Wiley‐Liss, Inc.
Nitric oxide‐synthesising neurons in the central subnucleus of the nucleus tractus solitarius provide a major innervation of the rostral nucleus ambiguus in the rabbit
Authors: Gai W.‐P. , Messenger J. P. , Yu Y.‐H. , Gieroba Z. J. , Blessing W. W.
Published: January 2005

We describe an intramedullary nitric oxide synthase (NOS) neural pathway that projects from the nucleus tractus solitarius (NTS) to the rostral nucleus ambiguus (NA) in the rabbit. With the use of NADPH diaphorase histochemistry and NOS immunohistochemistry, a compact group of NOS‐positive perikarya was identified in the central subnucleus of the NTS dorsomedial to the tractus solitarius and rostral to the obex. A dense network of NOS terminals was seen in the rostral NA. We investigated whether NOS terminals in the NA derive from NOS perikarya in the central NTS and whether the central NOS pathway links esophageal afferents and efferents. In some rabbits, the central NTS was unilaterally lesioned. In others, Phaseolus vulgaris‐leucoagglutinin (PHA‐L) was injected into the central NTS, or cholera toxin‐gold was injected into the NA, or cholera toxin‐horseradish peroxidase (HRP) was injected into the wall of the esophagus. The medulla was subsequently processed to demonstrate PHA‐L, cholera toxin‐gold, HRP, and NOS reactivity. Seven days after the NTS lesion, we observed a marked decrease in the density of NOS terminals in the ipsilateral NA. After injection of PHA‐L into the central NTS, a dense group of PHA‐L fibres was seen in the rostral NA, principally ipsilaterally. Afferent fibres from the esophagus were found around the NOS cell bodies in the central NTS, and many of these NOS neurons were double labeled with cholera toxin‐gold after injection of this tracer into the NA. NOS terminals were found around NA neurons that were retrogradely labelled from the esophagus. We conclude that the NOS neurons in the central NTS act as interneurons in a central pathway connecting esophageal afferents and efferents. © 1995 Wiley‐Liss, Inc.
Different climbing fibres innervate separate dendritic regions of the same purkinje cell in hypogranular cerebellum
Authors: Bravin Monica , Rossi Ferdinando , Strata Piergiorgio
Published: January 2005

Electrophysiological experiments have shown that in hypogranular cerebella the Purkinje cells are innervated by several climbing fibres. The aim of this paper is to provide morphological evidence for this multiple innervation and to describe the topographical distribution of the different climbing fibres onto the somadendritic region of the Purkinje cell.

Experiments have been performed in hypogranular adult Wistar rats lesioned during the first postnatal week by methylazoxymethanol (MAM) or by X‐irradiation. Purkinje cells were labelled by an anti‐calbindin antibody, whereas climbing fibres were visualised by means of Phaseolus vulgaris leucoagglutinin.

Purkinje cells showed variable degrees of abnormality and displacement. Climbing fibres made contact with the dendrites of all kinds of Purkinje cells, including those ectopically positioned whose dendrites branched in the white matter. This shows that Purkinje cells can develop dendritic branching in the absence of granule cells and maintain the capability of interacting with their proper afferents, even when they are severely affected and displaced. In four Purkinje cells we have been able to follow the course of two climbing fibre terminal arbourisations. Almost no terminal branches were present around the Purkinje cell soma, and the whole arbour covered the proximal two‐thirds of the Purkinje cell dendritic tree. These arbourisations, after an initial common course along the primary dendrite, distributed to separate dendritic regions. The observation of a single labelled climbing fibre covering a limited region of the dendritic tree was more common. As this finding is never observed in control material, it is concluded that the remaining region is covered by another unlabelled climbing fibre belonging to a different inferior olive neurone.

These results represent a morphological demonstration of multiple climbing fibre innervation of the adult Purkinje cell. The maintenance of polyinnervation in the adult, which is consequent to the loss of granule cells, is not associated with a defect in the peridendritic translocation of the olivary arbour. In addition, the strict segregation of the different climbing fibres to distinct territories of the Purkinje cell dendritic tree suggests that each terminal arbourisation acts as a functionally independent unit and prevents other competitors from invading its own target domain. © 1995 Wiley‐Liss, Inc.
Effect of vibrissae deprivation on follicle innervation, neuropeptide synthesis in the trigeminal ganglion, and S1 barrel cortex plasticity
Authors: Li Xinren , Glazewski Stanislaw , Lin Xiaoqln , Elde Robert , Fox Kevin
Published: January 2005

Deprivation of vibrissae from an early age causes plasticity in S1 barrel cortex. This method of deprivation is most likely to induce plasticity by altering the balance of primary afferent activity from the deprived and spared vibrissae. To study whether or not induction or expression of this type of plasticity might be affected by follicle nerve injury caused by the deprivation technique, three different methods of detecting nerve injury were used: counting axon numbers in the distal follicle nerve, quantifying morphological changes in axons, and measuring neuropeptide expression in the trigeminal ganglion cells. First, nerves innervating follicles chronically deprived of vibrissae from birth had the same number of myelinated and unmyelinated axons as nerves from normally reared animals. Second, axons innervating deprived follicles showed no morphological changes in myelination or mitochondria characteristic of damaged nerves. Third, the corresponding nerve cell bodies in the trigeminal ganglion did not show upregulation of galanin or neuropeptide Y expression. In contrast, animals receiving mild injury of the follicle nerve endings (by cauterization of the follicle) showed profound changes in axonal myelination and mitochondria and increases in neuropeptide expression. These results imply that vibrissae deprivation does not act by inducing injury of the follicular nerve, suggesting that changes in the balance of follicle nerve activity are the cause of cortical plasticity. Consistent with this notion, a fourth experiment demonstrated that trimming the vibrissae induces cortical plasticity comparable to that induced by complete vibrissae removal. © 1995 Wiley‐Liss, Inc.
The organization of the turtle inner retina. II. Analysis of color‐coded and directionally selective cells
Authors: Ammerüller Josef , Muller Jay F. , Kolb Helga
Published: January 2005

Color coding and directional selectivity (DS) of retinal neurons were studied in the Pseudemys turtle by using similar intracellular recording and staining techniques as in the preceding paper (J. Ammermüller and H. Kolb, 1995, J. Comp. Neurol. 358:1–34). Color‐coded responses were elicited by red (621 or 694 nm), green (525 or 514 nm), and blue (455 nm) light flashes. In addition to red/green and yellow/blue types of chromaticity horizontal cells, in our sample of 305 identified cells we found that 17% of bipolar cells, 6.5% of amacrine cells, and 18% of ganglion cells exhibit color‐coded responses. DS responses were found in 37% of the tested ganglion cells and 41% of the tested amacrine cells.

Two morphologically identified bipolar cell types, B10 and B11, were red‐ON/blue‐OFF and red‐OFF/green, blue‐ON, respectively. Of five identified amacrine cell types, three were red‐OFF blue‐ON center (Al, A3, A23b), one was red‐OFF/green‐ON center (A32), and one (A33) was double color‐opponent of red‐ON/blue‐OFF center: red‐OFF/blue‐ON surround. Five ganglion cell types had variously color‐coded centers (G14 and G24) or surrounds (G3 and G18), including one type, G6, that was double color‐opponent (red‐OFF/green‐ON center:red‐ON/ green‐OFF surround). Responses to colors were found primarily in the sustained responses of bipolar and ganglion cells. However, in amacrine cells, transient components of the response also showed color dependence. Red‐OFF‐center responses were found in ganglion cells that were in a position to make connections at the strata 2/3 border with the red‐OFF bipolar cell (B11); red‐ON‐center responses occurred in ganglion cells with branches in stratum 4 of the IPL where the red‐ON‐center bipolar (B10) ended. Blue‐ON‐center signals appeared to be processed mainly in strata 1–2/3, and blue‐OFF‐center signals in strata 3–5 of the IPL, with contributions of amacrine cells and bipolar cells.

Labeled DS amacrine cells could be identified as A9, A20, and A22, and ganglion cells as G19, G20, and G24. The latter type (G24) showed DS and color coding. All response types (ON‐center, OFF‐center, ON‐OFF) were encountered, DS amacrine cells were monostratified near the middle of the IPL, whereas DS ganglion cells were mono‐, bi‐, and multistratified, although all DS ganglion cells had one feature in common: they had dendrites in stratum 1 of the IPL. We discuss our findings in terms of the importance of color and motion discrimination tasks associated with complex ganglion cell physiology in the retina of this species. © 1995 Wiley‐Liss, Inc.
Inositol 1,4,5‐trisphosphate receptors: Immunocytochemical localization in the dorsal cochlear nucleus
Authors: Ryugo D. K. , Pongstaporn T. , Wright D. D. , Sharp A. H.
Published: January 2005

In the cochlear nucleus of mammals, the relatively homogeneous responses of auditory nerve fibers are transformed into a variety of different response patterns by the different classes of resident neurons. The spectrum of these responses is hypothesized to depend on the types and distribution of receptors, ion channels, G proteins, and second messengers that form the signaling capabilities in each cell class. In the present study, we examined the immunocytochemical distribution of the inositol 1,4,5‐trisphosphate (IP3) receptor in the dorsal cochlear nucleus to better understand how this second messenger might be involved in shaping the neural signals evoked by sound.

Affinity‐purified polyclonal antibodies directed against the IP3 receptor labeled a homogeneous population of neurons in the dorsal cochlear nucleus of rats, guinea pigs, mustache bats, cats, New World owl monkeys, rhesus monkeys, and humans. These cells were all darkly immunostained except in the human where the labeling was less intense. Immunoblots of dorsal cochlear nucleus tissue from the rat revealed a single band of protein of molecular weight ∼260 kD, which is the same size as the purified receptor, indicating that our antibodies reacted specifically with the IP3 receptor. These immunolabeled neurons were identified as cartwheel cells on the basis of shared characteristics across species, including cell body size and distribution, the presence of a highly invaginated. Nucleus, and a well‐developed systain of cisternae. Reaction product was localized along the membranes of rough and smooth endoplasmic reticulum, subsurface cisternae, and the nuclear envelope. This label was distributed throughout the cartwheel cell body and dendritic shafts but not within dendritic spines, axons, or axon terminals. The regular pattern of immunolabeling across mammals suggests that IP3 and cartwheel cells are conserved in evolution and that both play an important but as yet unknown role in hearing. © 1995 Wiley‐Liss, Inc.
Developmental time course of acidic and basic fibroblast growth factors' expression in distinct cellular populations of the rat central nervous system
Authors: Kuzis Karl , Reed Susan , Cherry Nicola J. , Woodward William R. , Eckenstein Felix P.
Published: January 2005

Acidic and basic fibroblast growth factors (aFGF and bFGF, respectively) are expressed in high levels in adult central nervous system (CNS). We report the time course of developmental appearance and distribution of these factors and of two FGF receptors, FGFR‐1 and FGFR‐2, in the CNS of rats ranging in age from embryonic day 16 to adult. Immunohistochemical analysis showed that sensory neurons in the midbrain were the first cells to contain detectable aFGF immunoreactivity at embryonic day 18. The next cell group to contain aFGF were motor neurons, which were found to be aFGF‐positive at the day of birth. A number of other subcortical neuronal populations were observed to contain aFGF immunoreactivity after postnatal day 7. Adult levels and distribution patterns of aFGF were reached in all CNS areas by postnatal day 28. Basic FGF immunoreactivity was observed at postnatal day 0 in neurons in the CA2 subfield of hippocampus. Astrocytes contained detectable bFGF immunoreactivity, starting at postnatal day 7. Adult levels and patterns of distribution of bFGF were reached in all CNS areas by postnatal day 28. These immunohistochemical observations were confirmed by using bioassay and Western blot techniques. FGFR‐1 and FGFR‐2 mRNA were expressed in significant levels in all CNS areas at all time points analyzed. The observation that aFGF and bFGF appear in specific and distinct cellular populaitions at relatively late developmental times suggests that these FGFs may be involved in spe6ific mechanisms of CNS maturation, maintenance, and repair. © 1995 Wiley‐Liss, Inc.
Sexual and seasonal differences in the vomeronasal epithelium of the red‐backed salamander (Plethodon cinereus)
Authors: Dawley Ellen M. , Crowder James
Published: January 2005

Sexually dimorphic behaviors often are associated with sexually dimorphic neural structures. Perinatal hormonal levels influence structural sexual dimorphism, and seasonal structural changes also can be the result of seasonal hormonal fluctuations. We compared the volume of vomeronasal organs of male and female red‐backed salamanders (Plethodon cinereus) throughout the year. Odorants are delivered to vomeronasal receptors through nasolabial grooves when salamanders touch the bases of these grooves to objects (nose tapping). Males may locate and identify potential mates through nose tapping during the prolonged breeding season that lasts from October through May. We compared vomeronasal organ data through multiple regression by using total body size, sex, and season as variables that may influence vomeronasal organ volume. Gonads also were examined as an indicator of reproductive status. Total body size and sex significantly affect vomeronasal organ volume; as body size increases, so does vomeronasal organ volume, and males have significantly larger vomeronasal organs than females at all times of the year. During the summer, both males and females have larger vomeronasal organs than at any other time of the year. Summer also is a period of intense foraging and the initiation of a new cycle of gametogenesis. Previous studies of circulating hormone levels in amphibians have shown that the initial stages of gametogenesis correspond to a period of low estradiol and testosterone levels but high gonadotropin‐releasing hormone levels. The functional significance of sexual and seasonal differences in the vomeronasal organs of P. cinereus may relate to the neurogenesis of specialized receptors for courtship and mating. © 1995 Wiley‐Liss, Inc.
Laminar distribution and sources of catecholaminergic input to the optic tectum of the pigeon (Columba livia)
Authors: Rodman Hillary R. , Karten Harvey J.
Published: January 2005

A combined immunohistochemical and retrograde tracing approach was used to characterize the catecholaminergic innervation of the optic tectum (TeO), the major target of retinal projections in many avian species. Giemsa counterstaining was employed to determine precisely the laminar localization of immunoreactive fibers and presumptive terminals. The TeO of the pigeon is densely innervated by fibers immunoreactive for tyrosine hydroxylase (TH), which are most heavily distributed to the superficial layers of its dorsal and anterior portions. Within the dorsal‐anterior tectum, TH‐immunoreactive processes are particularly dense in retinorecipient layers 4 and 7 and in layer 5a. As in the mammalian superior colliculus, the bulk of the catecholaminergic innervation of the pigeon TeO reflects inputs, presumably noradrenergic, originating in the locus coeruleus and nucleus subcoeruleus. However, the catecholaminergic innervation of the pigeon TeO shows several features distinct from those reported for the mammalian superior colliculus. These include an input from a pretectal TH‐positive cell group unknown in mammals and the presence of residual TH immunoreactivity after administration of the noradrenergic neurotoxin DSP‐4. Moreover, the pattern of TH‐immunoreactive fibers in pigeon TeO, indicates more laminar and regional specialization within this structure than has been reported for the catecholaminergic innervation of the superior colliculus in mammals. © 1995 Wiley‐Liss, Inc.
Developmental patterning of rod and cone photoreceptors in embryonic zebrafish
Authors: Raymond Pamela A. , Barthel Linda K. , Curran Gary A.
Published: January 2005

Cone photoreceptors in the zebrafish retina are arranged in a crystalline lattice, with each spectral subtype at a specific position in the array: rod photoreceptors are inserted around the cones. Patterning events and developmental mechanisms that lead to the formation of the cone mosaic are not known. To begin investigating this issue, we examined the initial stages of opsin expression in zebrafish embryos by in situ hybridization with goldfish opsin cRNA probes to determine how and when the cone mosaic pattern arises. We found both differences and similarities in the spatiotemporal patterns of rod and cone development, which suggest the following: (1) Expression of opsin message (including rod opsin, blue and red cone opsins) was initiated at 50–52 hours postfertilization by a few photoreceptors which were consistently found in a ventral patch of retina located nasal to the choroid fissure. (2) The cone mosaic pattern was generated by a crystallization‐like process initiated in the precocial ventral patch and secondarily in nasal retina, which then swept like a wave into dorsotemporal retina. (3) The pattern of differentiation of rods in the ventronasal patch differed substantially from that in the remainder of the retina, suggesting that these precocial rods might differ from typical rods. (4) Developmental maturation of rods in zebrafish, as reflected by expression of opsin, may be accelerated compared to cones, which are thought to become postmitotic before rods. These data are consistent with a model in which lateral inductive interactions among differentiating photoreceptors lead to patterning of the array. © 1995 Wiley‐Liss, Inc.
Platelet‐derived growth factor receptors of mouse central nervous system cells in vitro
Authors: Hutchins James B.
Published: January 2005

This study evaluates the distribution of receptors for platelet‐derived growth factor (PDGF) on central nervous cells maintained in vitro using colloidal gold‐labeled immunocytochemical markers at the electron microscopic level. Platelet‐derived growth factor receptors were found to be sparsely distributed over the surface of type 1 astrocytes, apparent type 2 astrocytes, and neurons. Receptors appeared to be preferentially associated with filopodia‐like extensions of the cell membrane. The existence of functional receptors was confirmed using the impermeant, water‐soluble affinity cross‐linking agent bis(sulfosuccinimidyl) suberate to covalently link radiolabeled PDGF to its receptor. The PDGF/receptor complexes could also be immunoprecipitated with the same antibody used in immunocytochemical experiments. The improved resolution of these techniques allows definitive identification of PDGF receptors on cultured mammalian central nervous system cells other than oligodendrocytes. These data expand the range of possible roles of PDGF during nervous system development. Receptors for PDGF are likely to play a key role in the differentiation of cells in the central nervous system. © 1995 Wiley‐Liss, Inc.
Neurotransmitter receptors in the proliferative zones of the developing primate occipital lobe
Authors: Lidow Michael S. , Rakic Pasko
Published: January 2005

Film autoradiography was used to investigate the expression of several neurotransmitter receptor subtypes in the transient ventricular and subventricular proliferative zones of the developing occipital lobe in two groups of macaque monkey fetuses. The first group of fetuses were between 60 and 93 days after conception (E60‐E93), when the ventricular and subventricular zones of the monkey occipital lobe produce neurons destined for the visual cortex. In the second group, fetuses were between E107 and E128, after generation of cortical neurons has ceased. In the E60–E93 group of fetuses, ventricular and subventricular zones displayed high densities of 5‐HT1‐serotonergic, D1‐dopaminergic, α1‐and α2‐adrenergic and high affinity kainate receptors. The activation of these receptors has previously been shown to stimulate cell proliferation in other cell systems. The possible involvement of these receptors in regulation of neuronal production is also supported by their absence in the deep laminae of the embryonic cerebral wall after E107, after cortical neurogenesis has been completed. The only exception is a high density of α2‐adrenergic receptors maintained near the ventricular surface long after all cortical neurons have been generated. We also found that during neurogenesis, proliferative zones in E66–E90 fetuses displayed virtually no 5‐HT2‐serotonergic, D2‐dopaminergic, β‐adrenergic, M1‐muscarinic cholinergic, gamma aminobutyric acid (GABA)A, N‐methyl‐D‐aspartate (NMDA), or β‐amino‐3‐hydroxy‐5‐menthy‐4‐isoxazole proprionate (AMPA) sites; most of these receptor subtypes have been reported to mediate the suppression of cell proliferation. The present findings suggest that dividing and/or newly generated cortical neurons are capable of receiving specific signals from multiple neurotransmitters present in their environment. © 1995 Wiley‐Liss, Inc.
Early olfactory enrichment and deprivation both decrease β‐adrenergic receptor density in the main olfactory bulb of the rat
Authors: Woo Cynthia C. , Leon Michael
Published: January 2005

The density of noradrenergic locus coeruleus projections and β‐adrenergic receptors in the main olfactory bulb of the rat increases with age. Both β1 and β2 receptor subtypes exhibit laminar distributions, with focal regions of high receptor density present within the neuropil of individual glomeruli. Since the first synaptic contacts between olfactory receptor neurons and bulbar neurons occur within the glomeruli, early olfactory experiences possibly could influence the density or distribution of β‐adrenergic receptors in the bulb. We therefore investigated the effects of olfactory deprivation and early olfactory enrichment on the density and distribution of β‐adrenergic receptors in the main olfactory bulb. Animals were subjected to either unilateral naris closure on postnatal day 1 or odor training from postnatal days 1–18. Bulbs were removed on postnatal day 19 and subjected to quantitative autoradiography using the β‐adrenergic receptor antagonist [125I]iodopindolol and specific receptor subtype antago nists ICI 118,551 (β2‐antagonist) and ICI 89,406 (β1‐antagonist). Unilateral naris occlusion decreased both the number of β2 glomerular foci and the density of β1 and β2 receptors in the deprived bulb compared to the nondeprived bulb. Early odor training resulted in a significant decrease in the number, area, and receptor density of 2 glomerular foci in the midlateral region of the bulb. The distribution of 2 glomerular foci also differs with these two sensory manipulations. Changes in β‐adrenergic receptor density in response to both early learning and olfactory deprivation may be induced by a transient increase in olfactory bulb norepinephrine. © 1995 Wiley‐Liss, Inc.
Tissue plasminogen activator mRNA expression in granule neurons coincides with their migration in the developing cerebellum
Authors: Freidman Glenn C. , Seeds Nicholas W.
Published: January 2005

Tissue plasminogen activator activity in the developing cerebellum, as quantified by zymography of cerebellar homogenates from embryonic day (E) 17 to adult mice, shows a peak of activity at postnatal day (P) 7, followed by a steady 75% decrease into adulthood. Northern blot analysis reveals a similar pattern for tissue plasminogen activator mRNA levels, which are low at E17 but increase dramatically, reaching their highest levels of specific mRNA/μg RNA in P1–P7 mice and declining about threefold in the adult mouse. In situ hybridization of whole mouse brain sections with a tissue plasminogen activator antisense cRNA probe shows pronounced reactivity in the cerebellum. Although some binding is associated with the cerebellar meninges, the external granule layer is devoid of tissue plasminogen activator mRNA at all ages. However, highly labeled elongated cells, which also bind antibody to neuronal nuclear antigen and are adjacent to Bergmann glial fibers (i.e., migrating granule neurons), are readily visible throughout the molecular and Purkinje layers at P7 and P14. In the adult mouse cerebellum, tissue plasminogen activator mRNA labeling is restricted to cells in the Purkinje/internal granule layers. Thus, tissue plasminogen activator gene expression is induced as granule neurons leave the external granule layer and begin their inward migration. © 1995 Wiley‐Liss, Inc.
Development of cairetinin immunoreactivity in the neocortex of the rat
Authors: Fonseca Montserrat , Del Río José A. , Martínez Albert , Gómez Sonia , Soriano Eduardo
Published: January 2005

The prenatal and postnatal development of calretinin (CR)‐containing elements in the neocortex of the rat was analyzed using immunohistochemistry. CR immunoreactivity in the cortical anlage appeared early at embryonic day 14 (E14), with CR‐positive neurons located in the primitive plexiform layer and in the emerging subplate and marginal zones. At later prenatal and early postnatal stages, these two layers showed the highest CR immunostaining in the cortex, and large numbers of cell bodies and fibers were immunostained. From postnatal day 3 (P3) onwards, CR immunostaining disappeared progressively from the subplate‐layer VIb and the marginal zone‐layer I, so that very few cells remained stained in these layers in the adult. In the cortical plate and prospective layers VIa to II–III, CR‐positive neurons were seen at prenatal stages, their numbers increasing markedly during the first postnatal week. Most neurons showed undifferentiated nonpyramidal shapes, and matured during the second and third postnatal weeks, when the adult pattern of CR immunostaining was achieved. In addition, some pyramidal‐like neurons in the infragranular layers and in layer II–III transiently expressed CR during the postnatal period, most notably between P3 and P12. Colocalization experiments performed at P0–P3 with antibodies against the neurotransmitter γ‐aminobutyricacid (GABA) showed that most nonpyramidal CR‐positive neurons in the derivates of the cortical plate were also GABAergic during development. In contrast, large numbers of CR‐containing neurons in the subplate and marginal zone were GABA‐negative. The present results show that in addition to recording the early development of a subset of nonpyramidal neurons, CR is transiently expressed in certain GABA‐negative populations of the subplate and marginal zone, and most likely in pyramidal neurons. © 1995 Wiley‐Liss, Inc.
Molecular basis of interactions between regenerating adult rat thalamic axons and Schwann cells in peripheral nerve grafts II. Tenascin‐C
Authors: Zhang Y. , Campbell G. , Anderson P. N. , Martini R. , Schachner M. , Lieberman A. R.
Published: January 2005

Tenascin‐C is a developmentally regulated extracellular matrix component. There is evidence that it may be involved in axon growth and regeneration in peripheral nerves. We have used in situ hybridization and immunocytochemistry to investigate the association of tenascin‐C with central nervous system axons regenerating through a peripheral nerve autograft inserted into the thalamus of adult rats. Between 3 days and 4 weeks after implantation, tenascin‐C immunoreactivity was increased in the grafts, first at the graft/brain interface, then in the endoneurium of the graft, and finally within the Schwann cell columns of the graft. By electron microscopy, reaction product was present around collagen fibrils and basal laminae in the endoneurium, but the heaviest deposits were found at the surface of regenerating thalamic axons within Schwann cell columns. Schwann cell surfaces were not associated with tenascin‐C reaction product except where they faced the tenascin‐rich basal lamina or were immediately opposite axons surrounded by tenascin‐C. By 8 weeks after graft implantation tenascin‐C in the endoneurium and around axons of the graft was decreased. In the brain parenchyma aroundthe proximal part of the graft, axonal sprouts associated with tenascin‐C could not be identified earlier than 2 weeks after grafting and were sparse at this stage. Larger numbers of such axons were present at 8–13 weeks after grafting and were located predominantly where the glia limitans between brain and graft appeared to be incomplete, suggesting that the tenascin‐C may have penetrated the brain parenchyma from the graft. By in situ hybridization, cells expressing tenascin‐C mRNA (probably Schwann cells) appeared first at the brain/graft interface 3 days after grafting and thereafter were mainly located within the grafts. Lightly labelled cells containing tenascin‐C mRNA (probably glial cells) were scattered in the thalamic parenchyma both ipsilateral and contralateral to the graft and a few heavily labelled cells were located very close to the tip of the graft. These results show that regenerating adult thalamic axons, unlike regenerating peripheral axons, become intimately associated with peripheral nerve graft‐derived tenascin‐C, suggesting that they express a tenascin‐C receptor, as many neurons do during development, and that tenascin‐C derived from Schwann cells may play a role in the regenerative growth of such axons through the grafts. © 1995 Wiley‐Liss, Inc.
Cell and molecular analysis of the developing and adult mouse subventricular zone of the cerebral hemispheres
Authors: Gates Monte A. , Thomas L. Brannon , Howard Eugene M. , Laywell Eric D. , Sajin Boris , Faissner Andreas , Götz Bernhard , Silver Jerry , Steindler Dennis A.
Published: January 2005

The subventricular zone (SVZ) of the lateral ventricle remains mitotically active in the adult mammalian central nervous system (CNS). Recent studies have suggested that this region may contain neuroñal precursors (neural stem cells) in adult rodents. A variety of neuronal and glial markers as well as three extracellular matrix (ECM) markers were examined with the hope of understanding factors that may affect the growth and migration of neurons from this region throughout development and in the adult. This study has characterized the subventricular zone of late embryonic, postnatal, and adult mice using several neuronal markers [TuJ1, nicotinamide adenine dinucleotide phosphate diaphorase (NADPH‐d), neuron‐ specific enolase (NSE)], glial markers [RC‐2, vimentin, glial fibrillary acidic protein (GFAP), galactocerebroside (Gal‐C)], ECM markers [tenascin‐C (TN‐C), chondroitin sulfate, a chondroi tin sulfate proteoglycan termed dermatan sulfate‐dependent proteoglycan‐1 (DSD‐1‐PG)], stem‐cell marker (nestin), and proliferation‐specific marker [bromodeoxyuridine (BrdU)]. TuJ1+ and nestin+ cells (neurons and stem cells, respectively) persist in the region into adulthood, although the numbers of these cells become more sparse as the animal develops, and they appear to be immature compared to the cells in surrounding forebrain structures (e. g., not expressing NSE and having few, if any, processes). Likewise, NADPH‐d+ cells are found in and around the SVZ during early postnatal development but become more sparse in the prolifera tive zone through maturity, and, by adulthood, only a few labeled cells can be found at the border between the SVZ and surrounding forebrain structures (e. g., the striatum), and even smaller numbers of positive cells can be found within the adult SVZ proper. BrdU labeling also seems to decrease significantly after the first postnatal week, but it still persists in the SVZ of adult animals. The disappearance of RC‐2+ (radial) glia during postnatal development and the persistence of glial‐derived ECM molecules such as tenascin and chondroitin sulfate proteoglycans (as well as other “boundary” molecules) in the adult SVZ may be associated with a persistence of immaturity, cell death, and a lack of cell emigration from the SVZ in the adult. © 1995 Wiley‐Liss, Inc.
Thyrotropin‐releasing hormone inputs are preferentially directed towards respiratory motoneurons in rat nucleus ambiguus
Authors: Sun Qi‐Jian , Pilowsky Paul , Llewellyn‐Smith Ida J.
Published: January 2005

In the present study, we assessed the extent of the thyrotropin‐releasing hormone (TRH) input to motoneurons in the ambigual, facial, and hypoglossal nuclei of the rat using a combination of intracellular recording, dye filling, and immunohistochemistry. Twelve motoneurons in the rostral nucleus ambiguus were labelled by intracellular injection in vivo of Neurobiotin (Vector). Seven out of 12 ambigual motoneurons displayed rhythmic fluctuations of their membrane potential in phase with phrenic nerve discharge, whereas the other five had no modulations of any kind. Seven facial motoneurons and seven hypoglossal motoneurons were also filled with Neurobiotin. All three motor nuclei contained TRH‐immunoreactive varicosities, with the largest numbers found in the nucleus ambiguus. Close appositions were seen between TRH‐immunoreactive boutons and every labelled motoneuron. Respiratory‐ related motoneurons in the nucleus ambiguus received the largest number of TRH appositions with 74 ± 38 appositions/neuron (mean ± S. D.; n = 7). In contrast, nonrespiratory ambigual motoneurons received significantly fewer TRH appositions (11 ± 5; n = 5;P< 0. 05; Mann‐Whitney U test). Facial motoneurons received about the same number of TRH appositions as nonrespiratory ambigual motoneurons, with 13 ± 4 (n = 7). Hypoglossal motoneurons received the fewest appositions from TRH‐containing boutons, with 8 ± 2 (n = 7). There were no differences in the TRH inputs to respiratory and nonrespiratory motoneurons in the facial and hypoglossal nuclei. These results demonstrate that, among motoneurons in the medulla, respiratory motoneurons in the rostral nucleus ambiguus are preferentially innervated by the TRH‐immunoreactive boutons. © 1995 Wiley‐Liss Inc.