bluuebunny/crossref_metadata_2025 huggingface dataset:
D2‐like dopamine receptors in amphibian retina: Localization with fluorescent ligands
Authors: Muresan Zoia , Besharse Joseph C.
Published: January 2005

Dopamine induces several light adaptive changes in amphibian retina via receptors with D2‐like pharmacology, but the identity of the primary target cells has not been determined. Using a fluorescent probe consisting of a selective D2 antagonist, N‐(p‐aminophenethyl)‐ spiperone (NAPS), derivatized with the fluorophore Bodipy (NAPS‐Bodipy), we identified the distribution of dopamine binding sites in the retina of two amphibians, post‐metamorphic Xenopus laevis and larval Ambystoma tigrinum. Specific labeling was defined as staining that was displaced by D2 selective ligands (eticlopride or sulpiride), but insensitve to D1 selective drugs (SCH 23390), adrenergic catecholamines (epinephrine or norepinephrine), or serotoninergic analogues (ketanserin). Both rod and cone cells showed specific dopamine D2‐like binding sites arranged in clustered arrays on discrete membrane domains of the inner segment. Labeling of photoreceptor outer segments was continuous and was not displaced by competition with D2 selective ligands; this labeling was considered nonspecific. In addition, in both species, clustered binding of the D2‐probe was found on Müller cells and on a subset of inner retinal cells with the morphology of amacrine/interplexiform cells. Our data provide direct evidence for D2 receptors on both rods and cones, and suggest that the receptors may be clustered into patches within a discrete cellular domain, the inner segment. © 1993 Wiley‐Liss, Inc.
Direct catecholaminergic innervation of spinal dorsal horn neurons with axons ascending the dorsal columns in cat
Authors: Doyle Christopher A. , Maxwell David J.
Published: January 2005

Previous ultrastructural studies have shown that catecholamine‐containing nerve terminals in the spinal dorsal horn form synaptic junctions with dendrites and somata, but the identity of the neurons giving rise to these structures is largely unknown. In this study we have investigated the possibility that spinomedullary neurons, which project through the dorsal columns to the dorsal column nuclei, are synaptic targets for descending catecholaminergic axons.

Neurons with axons ascending the dorsal columns were retrogradely labelled after uptake of horseradish peroxidase by their severed axons in the thoracic (T10–T12) or cervical (C2–C3) dorsal columns. After the retrogradely labelled neurons were visualized, the tissue was immunocytochemically stained with antisera raised against tyrosine hydroxylase or dopamine‐β‐hydroxylase.

Three hundred forty‐three retrogradely labelled neurons within laminae III–V of the lumbosacral dorsal horn were examined under high power with the light microscope. In Triton X‐100 treated material, over 60% of cells were found to have dopamine‐β‐hydroxylase‐immunoreactive varicosities closely apposed to their somata and proximal dendrites. The number of contacts per cell varied from 1 to 22, with a mean number of 4.5. Fewer cells (34%) received contacts from axons immunoreactive for tyrosine hydroxylase as a consequence of the weaker immunoreaction produced by this antiserum. Correlated light and electron microscopic analysis confirmed that many of these contacts were regions of synaptic specialization and that immunostained boutons contained pleomorphic (round to oval) agranular vesicles together with several dense core vesicles.

These observations suggest that catecholamines regulate sensory transmission through this spinomedullary pathway by a direct postsynaptic action upon its cells of origin. Such an action would be predicted to suppress transmission generally through this pathway. © 1993 Wiley‐Liss, Inc.
Propriospinal input to thoracolumbar sympathetic nuclei from cervical and lumbar lamina I neurons in the cat and the monkey
Authors: Craig A. D. (Bud)
Published: January 2005

The possibility that specific thermoreceptive and nociceptive influences on sympathetic outflow are conveyed directly to spinal sympathetic regions by lamina I neurons was investigated anatomically with the immunofluorescent PHA‐L technique in the cat and the cynomolgus monkey. Iontophoretic injections made with physiological guidance were restricted to lamina I or to laminae I–II in the cervical (C6–8) or lumbar (L6–7) enlargement. Bilateral (symmetric) terminal arborizations were observed (with an ipsilateral predominance) in the intermdiolateral, intermediomedial, and intervening regions of the thoracolumbar intermediate zone. In serial horizontal sections, patches of terminal labeling appeared at regular longitudinal intervals in the intermediolateral region. Longitudinally coursing fibers that had multiple varicosities and gave off small terminal branches were observed in the intermediolateral and the intermediomedial regions. Mediolateral strips of labeling that extended from labeling in the intermediolateral region to labeling in the intermediomedial region occurred at fairly regular longitudinal intervas. Because the longitudinal distribution of these terminations corresponds very well with the characteristic (ladder‐like) longitudinal pattern of organization of the neuropil of the thoracolumbar sympathetic nuclei, i.e., the principal part of the intermediolateral cell column, the central autonomic n., and the intervening n. intercalatus, it is inferred that these lamina I terminations occur within these nuclei. After cervical injections, the labeling was most dense in the upper thoracic T2–4 spinal cord segments in both the cat and the monkey; labeling was also present in the T10–12 segments. After lumbar injections, labeling in the cat was located in the L4 segment; labeling in the monkey was present in the T4–6 and T10–12 segments. The labeling obtained was much more dense in the monkey than in the cat.

These observations reveal a spinal lamina I projection that could provide a direct pathway for the somatosympathetic reflex effects of thermal and noxious stimuli. Considered together with reports that lamina I and the sympathetic nuclei both receive descending input from certain key autonomic regions, this result emphasizes the importance of lamina I for homeostasis, in addition to its probable roles in behavioral arousal, affect, and sensation. These observations thus support the proposed concept that lamina I processes and distributes in a functionally specific manner the sensory input relevant to the physiological status of the tissues and organs of the entire organism. © 1993 Wiley‐Liss, Inc.
Crosstalk between the two sides of the thalamus through the reticular nucleus: A retrograde and anterograde tracing study in the rat
Authors: Rao's Vassilis , Bentivoglio Marina
Published: January 2005

In order to investigate the possible routes linking the thalamus in the two sides of the brain, the connections of the reticular nucleus (RT), the major component of the ventral thalamus, with contralateral dorsal thalamic nuclei were systematically investigated in the adult rat. This study was performed with several tract‐tracing techniques: single and double retrograde labeling with fluorescent tracers, and anterograde tracing with biocytin. Retrograde tracing was also combined with immunocytochemistry to provide additional criteria for the identification of labeled RT neurons.

The data obtained with the retrograde transport of one fluorescent tracer showed that RT neurons project to contralateral dorsal thalamic domains. In particular, retrograde labeling findings indicated that the anterior intralaminar nuclei, as well as the ventromedial (VM) nucleus, are preferential targets of the contralateral RT projections. Commissural neurons were concentrated in two portions of RT: its rostral part, including the rostral pole, which projects to the contralateral central lateral (CL) and paracentral (Pc) nuclei, and the ventromedial sector of the middle third of RT, which projects to the contralateral VM and posterior part of CL and Pc. The double retrograde labeling study of the bilateral RT–intralaminar connection indicated that at least part of the commissural RT cells bifurcate bilaterally to symmetrical portions of the anterior intralaminar nuclei.

The targets of the RT commissural system inferred from the retrograde labeling data were largely confirmed by anterograde tracing. Moreover, it was shown that RT fibers cross the midline in the intrathalamic commissure.

The present data demonstrate that bilateral RT connections with the dorsal thalamus provide a channel for interthalamic crosstalk. Through these bilateral connections with thalamic VM and intralaminar neurons, RT could influence the activity of wide territories of the cerebral cortex and basal ganglia of both hemispheres. © 1993 Wiley‐Liss, Inc.
NILE/L1 and NCAM‐polysialic acid expression on growing axons of isolated neurons
Authors: van den Pol Anthony N. , Kim Warren T.
Published: January 2005

The neuron adhesion molecules NILE/L1 and NCAM may be involved in axonal guidance and cell recognition. To investigate all exposed membrane domains of single neurons, something which has not previously been done for any adhesion molecule, we used digitally processed scanning electron microscopy with a high‐energy backscatter electron detector. This allowed a quantitative analysis of immunogold staining densities on all surfaces of isolated rat hippocampal neurons in culture to study NILE/L1 and NCAM expression independent of potentially inductive innervation.

During early stages of neuritic extension, all growth cones showed similar NILE/L1 expression, but as soon as a single process extended farther than the others (by 20 hours), this putative axon and its growth cone generally showed a stronger level of NILE/L1 immunogold labeling than the other neurites. This is the earliest evidence of plasma membrane differentiation between axons and dendrites. With further neuritic growth, the relative NILE/L1 expression on axons and their growth cones continued to increase. In contrast to some earlier reports, NILE/L1 was expressed on axonal growth cones growing on both polylysine‐coated glass and astrocyte substrates.

Strong immunostaining for NCAM‐related polysialic acid (PSA) was found on axonal growth cones and filopodia, suggesting that the homophilic adhesive action of NCAM may be reduced during axonal growth. PSA showed greater labeling on distal axons than on other areas of the neuron, indicating a variable NCAM‐mediated adhesion on different regions of the same cell. Neither NILE/L1, NCAM, nor PSA appeared to show regional differences in axons fasciculating or defasciculating on themselves. A strong intercellular heterogeneity of NILE/L1, NCAM, and PSA expression levels on neurons in the same culture dish was found, suggesting that subsets of cells from the hippocampus may express biologically relevant differences in adhesion molecules compared to neighboring neurons.

In light of the growing body of evidence pointing to the multifaceted array of homophilic and heterophilic binding interactions that NILE/L1 and NCAM may exhibit, and the functional importance of molecular densities, the quantitative data here support the hypothesis that sufficient cellular and subcellular heterogeneity exists for these molecules to be involved in some aspects of axonal guidance. © 1993 Wiley‐Liss, Inc.
Pre‐ and postnatal development of the primary visual cortex of the common marmoset. I. A changing space for synaptogenesis
Authors: Missler Markus , Eins Siegfried , Merker Hans‐Joachim , Rothe Hartmut , Wolff Joachim R.
Published: January 2005

The primary visual cortex of Callithrix jacchus occupies a large portion of the occipital neocortex and can be safely delineated from fetal stages onwards. In 20 animals ranging in age from fetal to adult age the morphological development of area 17 was evaluated and compared with the growth of whole brain, skull, and head size. Cortical thickness, surface area, and volume of the area were determined in addition to predominant growth directions. The volume of area 17 approximately doubles between birth (241 mm3) and three months of age (506 mm3). This maximum value marks an overshoot in growth (volume: 180%, surface area: 150%, thickness: 122%), which is followed by a considerable reduction before adult values (100%) are reached. Although these values seem to indicate that the overall reduction in size is fairly isometric, growth and regression are locally anisometric. For example, layers II–IVc contribute disproportionately to the overshoot; thickening is less pronounced than tangential growth and follows a slightly different time course. These data suggest that the developing visual cortex represents a highly dynamic distribution space for the developing synaptic junctions which should be taken into account in studies on synaptogenesis. By comparison it is suggested that this growth dynamic is not restricted to area 17 but also occurs in some other parts of the cerebral cortex. In contrast, most subcortical brain regions apparently do not undergo overshoot growth. Structural changes of the skull compensate the overshoot in cortex growth, so that head size increases steadily. © 1993 Wiley‐Liss, Inc.
Glia cells of the monkey retina. I. Astrocytes
Authors: Distler C. , Weigel H. , Hoffmann K.‐P.
Published: January 2005

Morphology and distribution of retinal astrocytes have been studied in macaque monkeys by immunocytochemical localization of glial fibrillary acidic protein (GFAP). With the exception of the fovea and the far periphery, astrocytes are ubiquitous in the nerve fiber layer (NFL) and the ganglion cell layer (GCL) of the monkey retina. The morphology of NFL astrocytes changes gradually, from star‐shaped in the periphery to bipolar close to the optic disc. By contrast, GCL astrocytes maintain their star‐shaped appearance throughout the retina. Astrocytes are unevenly distributed in the monkey retina, showing the highest concentration around the optic disc, and particularly low densities in the perifoveal region and the far periphery. The fovea proper is devoid of astrocytes. Employing high‐resolution confocal microscopy, we could demonstrate that astrocytes from manifold contacts to blood vessels. In addition, bundles of NFL astrocyte processes are co‐localized with axon bundles, individual astrocytes forming contacts to several axon bundles. In contrast, a similar affinity of astrocytes to ganglion cell somata was never observed. Thus, our data confirm and extend the current knowledge of morphology and putative function of astrocytes in mammalian and especially the primate retina. © 1993 Wiley‐Liss, Inc.
Distribution of transitory corpus callosum axons projecting to developing cat visual cortex revealed by DiI
Authors: Elberger Andrea J.
Published: January 2005

Functional studies of the development of the corpus callosum in the cat have shown that an intact callosum during postnatal month 1 is necessary for normal visual development. In vivo tracing techniques have not provided enough information on corpus callosum connectivity to fully evaluate the evidence for a morphological mechanism for the functional effects of neonatal callosum section. However, lipophilic in vitro membrane tracers permit a more detailed search for such evidence because the entire limit of many cells can be labeled simulatanously. To investigate the morphological basis for the observed functional results in cats, the corpus callosum was labeled in vitro with the carbocyanine dye, DiI. Crystals of DiI were placed in the midsagittal callosum in tissue from 2 to 277‐day‐old cats. Tissue was coronally sectioned 3–22 months later. Sections were photographed and reconstructed to show the overall distribution of corpus callosum projections, as well as the locations of individual corpus callosum axons and their presumed terminals.

The distribution of corpus callosum projections, examined in cortical areas 17–19, 7, and posterior medial lateral suprasylvian cortex, changes significantly during development. During postnatal week 1, callosal axons extend throughout these cortical areas to layer I. Numerous varicosities on callosal axons are located en passant and at axon terminals in layer I. During postnatal week 2, the density of callosal projections is reduced in all cortical areas, although many axons still extend to layer I. By postnatal month 2, the callosal axons extending to layer I are predominantly near the border with adjacent cortical areas; in the nonborder regions of these areas, many axons extend to layer VI while a much smaller number of axons extend to layers II–V. By postnatal month 3, the callosal projections to supragranular layers are almost exclusively restricted to cytoarchitectonic border regions; in the remaining regions, including medial area 17, there are occasional axons extending to the supragranular layers and only a moderate number of axons extending to infragranular layers.

Thus, a substantial number of elaborately formed transitory corpus callosum axons, distributed throughout visual cortex, exist for several weeks during postnatal development; in area 17, these axons are found in central through peripheral visual field representations. The transitory callosal axons appear to have axon terminals in layer I as well as en passant terminals while extending through layers II–VI. If some of these terminals were to form synapses, there would be extensive opportunities for the corpus callosum to provide input to layers I–VI throughout visual cortex during the period of development in which cortical microcircuitry is being established. © 1993 Wiley‐Liss, Inc.
Quantitative autoradiographic localization of [125I]insulin‐like growth factor I, [125I]insulin‐like growth factor II, and [125I]insulin receptor binding sites in developing and adult rat brain
Authors: Kar S. , Chabot J.‐G. , Quirion R.
Published: January 2005

Insulin‐like growth factors I and II (IGF I and IGF II) and insulin itself, which are structurally related polypeptides, play an important role in regulating brain growth and development as well as in the maintenance of its normal functions during adulthood. In order to provide a substrate for the better understanding of the roles of these growth factors, we have investigated the anatomical distribution as well as the variation in the density of [125I]IGF I, [125I]IGF II, and [125I]insulin receptor binding sites in developing and adult rat brain by in vitro quantitative autoradiography. The distributional profile of [125I]IGF I, [125I]IGF II, and [125I]insulin receptor binding sites showed a widespread but selective regional localization throughout the brain at all stages of development. The neuroanatomic regions which exhibited relatively high density of binding sites with each of these radioligands include the olfactory bulb, cortex, hippocampus, choroid plexus, and cerebellum. However, in any given region, receptor binding sites for IGF I, IGF II, or insulin are concentrated in anatomically distinct areas. In the cerebellum, for example, [125I]IGF II receptor binding sites are concentrated in the granular cell layer, [125I]insulin binding sites are localized primarily in the molecular layer, whereas [125I]IGF I receptor binding sites are noted in relatively high amounts in granular as well as molecular cell layers. The apparent density of sites recognized by each radioligand also undergoes remarkable variation in most brain nuclei, being relatively high either during late embryonic (i.e., IGF I and IGF II) or early postnatal (i.e., insulin) stages and then declining gradually to adult levels around the third week of postnatal development. These results, taken together, suggest that each receptor‐ligand system is regulated differently during development and thus may have different roles in the process of cellular growth, differentiation, and maintenance of the nervous system. Furthermore, the localization of [125I]IGF I, [125I]IGF II, and [125I]insulin receptor binding sites over a wide variety of physiologically distinct brain regions suggests possible involvement of these growth factors in a variety of functions associated with specific neuronal pathways. © 1993 Wiley‐Liss, Inc.
Distribution of GAP‐43 mRNA in the adult rat brain
Authors: Kruger Lawrence , Bendotti Caterina , Rivolta Romano , Samanin Rosario
Published: January 2005

Regional distribution of gene expression of the axonal growth‐associated protein, GAP‐43, was studied in adult rat brains by in situ hybridization autoradiography to determine the features of mature neuronal populations that synthesize GAP‐43 protein. Such synthesis appears to correlate with axonal growth during maturation and regrowth after axotomy. In most adult neurons, the sharp decline in GAP‐43 gene expression implies a reduced capacity for axonal growth. Neurons capable of extending axonal knobs in the absence of injury may indicate a “plasticity” underlying dynamic processes of interaction between neurons and their synaptic targets.

Antisense and sense (control) riboprobes were used on serial sections in the three principal axes, and the magnitude of hybridization signal was examined to determine regional patterns. GAP‐43 mRNA levels are pronounced in diverse neuronal groups including the locus coeruleus, raphé nn., dopaminergic nigral and ventral tegmental nn., mitral cells, hippocampal CA3, inferior olivary n., vagal motor n. and other parasympathetic preganglionic neurons, select thalamic midline and intralaminar nn., several specific nn. of the hypothalamus and basal forebrain, the granular layer of cerebellar cortex, the infragranular neocortex, and the granular olfactory paleocortex; there is substantial range in the magnitude of expression. Regions revealing minimal signal include most thalamic sensory relay nuclei, the granule neurons of the olfactory bulb and dentate gyrus, and the caudate and putamen.

Possible concomitants of GAP‐43 expression include regulation of ion flux and neurotrans‐mitter release. Those neurons with long, extensively dispersed and numerous synaptic connections display the strongest signals and may possess the greatest propensity forcontinuous growthand turnover of their axon terminals, in contrast to short‐axon and specific projection neurons exhibiting minimal levels. These data may enable inferring which populations display normal or experimentally induced axonal growth. © 1993 Wiley‐Liss, Inc.
Imparied motor axon regeneration in the C57BL/Ola mouse
Authors: Chen S. , Bisby M. A.
Published: January 2005

The delayed Wallerian degeneration which occurs in the C57BL/Ola mouse is associated with impaired motor axon regeneration. Following sciatic nerve crush, recovery of the sciatic functional index was delayed and incomplete when compared with recovery in C57BL/6J mice. After facial nerve crush, recovery of whisker movement in Ola mice was also delayed, and there was a prolonged period of partial recovery, not seen in 6J mice. Regeneration rate of the motor axons was measured by the axonal transport technique in sciatic nerve and was approximately 0.7 mm/d for Ola mice, and 4.0 mm/d for 6J mice. Combining these results from our previous work, we conclude that regeneration of both sensory and motor axons is imparired when Wallerian degeneration does not follow its usual time course after injury. © 1993 Wiley‐Liss, Inc.
Immunohistochemical study of the pattern of rapid expression of c‐fos protein in the visual cortex of dark‐reared kittens following initial exposure to light
Authors: Beaver C. J. , Mitchell D. E. , Robertson H. A.
Published: January 2005

Brief alterations to the nature of the visual input during critical periods in the early life of cats and monkeys can result in rapid anatomical and physiological changes in the central visual pathways. The immediate early genes (IEGs) represent a possible way in which these changes could be mediated since the protein products of a number of these genes have been shown to be induced rapidly in neurons in response to a variety of transynaptic stimuli.

Immunohistochemical methods were employed to examine the tempo and pattern of expression of Fos, the protein product of the c‐fos gene, induced in the visual cortex of kittens dark‐reared from birth to 30 days of age by brief periods of binocular visual exposure. In visual cortical area 17, the number of Fos immunoreactive cells increased rapidly from virtually zero in control kittens that received no visual exposure, to reach high levels in animals that received between 1 and 2 hours of visual experience. Immunoreactive cells were absent in the dorsal lateral geniculate nucleus, but were numerous in the ventral lateral geniculate nucleus, and in area 17, were most numerous in the extragranular layer (2, 3 and 6) but sparse in lower layer 4 and layer 5, and virtually absent in layer 1. Substantial constitutive Fos immunoreactivity was observed in area 17 of normal 30‐day‐old kittens but very few immunopositive cells were evident in adult animals. However, Fos immunoreactivity was observed in the visual cortex of a dark‐reared (for 30 days) adult animal following a brief period of visual exposure, a finding that suggests that Fos might serve other roles in the visual cortex in addition to those it might play uniquely during development. It is suggested that Fos, in combination with the protein products of a select number of other IEGs, may mediate a variety of rapid changes in the visual cortex including those that underlie visual system plasticity during early postnatal life. © 1993 Wiley‐Liss, Inc.
Distribution of acetylcholine receptors in the central nervous system of adult locusts
Authors: Leitch Beulah , Watkins Branwen L. , Burrows Malcolm
Published: January 2005

A polyclonal antibody raised against nicotinic acetylcholine receptor protein from purified locust neuronal membrane was used to analyse the distribution of antigenic sites within the central nervous system of adult Schistocerca gregaria. Light microscopic examination showed that all principal neuropiles in the thoracic ganglia label with the antibody but that the major tracts and commissures do not. Analysis of this pattern of staining in the electron microscope reveals that the receptor is present on specific synaptic and extrajunctional neuronal membranes in the neuropile. Antigenic sites are also evident on the plasma membranes and within the cytoplasm adjacent to Golgi complexes of some neuronal somata, suggesting that these neurones synthesise nicotinic acetylcholine receptors. In addition to neuronal labelling, there is evidence that the receptor is also present on the membranes of three types of glial cells. The implications of this pattern of receptor distribution are discussed. © 1993 Wiley‐Liss, Inc.
Cloning and characteristics of fish glial fibrillary acidic protein: Implications for optic nerve regeneration
Authors: Cohen Ilana , Shani Yael , Schwartz Michal
Published: January 2005

Mammalian central nervous system neurons do not regenerate after axonal injury, unlike their counterparts in fish and amphibians. After axonal injury, glial cells in mammals do not support regrowth of axons, while in fish they support the regeneration process. Controversy exists as to whether or not the intact fish optic nerve expresses glial fibrillary acidic protein, a well‐known marker for mature astrocytes, and thus whether its astrocytes differ in this respect from those of the brain and spinal cord, as well as from optic nerve astrocytes of other species. In an attempt to resolve this question we cloned fish glial fibrillary acidic protein. Two different complementary DNA clones were isolated from a carp brain complementary DNA library, each encoding a different form of glial fibrillary acidic protein apparently originating from different genes. Monospecific polyclonal antibodies were raised against a peptide synthesized according to the predicted amino acid sequence, and used to identify and localize the fish glial fibrillary acidic protein. Two glial fibrillary acidic proteins (of 49 kDa and 51 kDa) were identified by the antibodies in all tested fish central nervous system tissues. The antibodies were then used to examine glial fibrillary acidic protein immunoreactivity in sections taken from uninjured and injured optic nerves of goldfish. Injury was followed by an elevation in glial fibrillary acidic protein immunoreactivity along the whole length of the nerve, except at the site of the injury, where—as in the case of vimentin—no immunoreactivity was detectable. However, in contrast to vimentin‐positive glial cells, which repopulate the site of the injury soon after the optic nerve is injured, glial fibrillary acidic protein‐positive glial cells remained outside the injury site for as long as 6 weeks after the injury. Despite the injury‐induced changes in glial fibrillary acidic protein immunoreactivity, no change was observed in the level of transcript encoding glial fibrillary acidic protein after injury, while there was an increase in the amount of glial fibrillary acidic protein associated with the cytoskeleton and a reduction in the soluble form. These results suggest that the injury‐induced changes in immunoreactivity on sections involve changes not in transcription or translation of glial fibrillary acidic protein, but in glial fibrillary acidic protein compartmentalization. © 1993 Wiley‐Liss, Inc.
Ultrastructure of synapses from the pretectum in the A‐laminae of the cat's lateral geniculate nucleus
Authors: Cucchiaro Josephine B. , Uhlrich Daniel J. , Sherman S. Murray
Published: January 2005

We have recently shown in cats that many neurons projecting to the lateral geniculate nucleus from the pretectum use γ‐amino butyric acid (GABA) as their neurotransmitter. We sought to determine the morphology of synaptic terminals and synapses formed by these pretectal axons and the extent to which they resemble other GABAergic terminals found in the geniculate neuropil (i.e., from geniculate interneurons and cells of the nearby perigeniculate nucleus). To do this, we labeled a population of pretectal axons with the anterograde tracer Phaseolus vulgaris leucoagglutinin and analyzed the morphology and synaptology of labeled pretectal terminals in the A laminae of the cat's lateral geniculate nucleus. The pretectal projection, which arises primarily from the nucleus of the optic tract (NOT), provides synaptic innervation to elements in the geniculate neuropil. The labeled NOT terminals are densely packed with vesicles, contain dark mitochondria, and form symmetrical synaptic contacts. These are characteristics of the F1 type of terminal, and we know from other studies that GABAergic axon terminals from interneurons and perigeniculate cells also give rise to F1 terminals. We compared our population of NOT terminals with labeled perigeniculate and unlabeled F1 terminals selected from the geniculate neuropil and found that all three populations share many morphological characteristics. Both qualitative and quantitative assessments of the pretectal terminals suggest that these are a type of F1 terminal. Most pretectal terminals selectively form synapses onto geniculate profiles that contain irregularly distributed vesicles and dark mitochondria and that are postsynaptic to other types of terminals. These postsynaptic targets thus exhibit features of another class of inhibitory, GABAergic terminal known as F2 terminals, which are the specialized appendages of geniculate interneurons. Pretectal inputs, being GABAergic, may thus serve to inhibit local interneuronal outputs. Pretectal axons also innervate the perigeniculate nucleus, in which the only targets are the other main type of inhibitory, GABAergic neurons. These results suggest that the pretectum may facilitate retinal transmission through the lateral geniculate nucleus by providing inhibition to the local inhibitory cells: the interneurons and probably perigeniculate cells. This would serve to release geniculate relay cells from inhibition. © 1993 Wiley‐Liss, Inc.
Ipsilateral cortical projections to areas 3a, 3b, and 4 in the macaque monkey
Authors: Darian‐Smith Corinna , Darian‐Smith Ian , Burman Kathleen , Ratcliffe Neil
Published: January 2005

In the macaque monkey area 3a of the cerebral cortex separates area 4, a primary motor cortical field, from somatosensory area 3b, which has a subcortical input mainly from cutaneous mechanoreceptive neurons. That each of these cortical areas has a unique thalamic input was illustrated in the preceding paper. In the present experiments the cortical afferent projections to these 3 areas of the sensorimotor cortex monkey were visualized and compared, using 4 differentiable fluorescent dyes as axonal retrogradely transported labels. The cortical projection patterns to areas 3a, 3b, and 4 were similar in that they each consisted of (a) a “halo” of input from the immediately surrounding cortex, and (b) discrete projections from one or more remote cortical areas. However, the pattern of remote inputs from precentral, mesial, and posterior parietal cortex was different for each of the 3 cortical target areas. The cortical input configuration was least complex for area 3b, its remote input projecting mainly from insular cortex. The pattern of discrete cortical inputs to the motor area 4, however, was more complex, with projections from the cingulate motor area (24c/d), the supplementary motor area, postarcuate cortex, insular cortex, and postcentral areas 2/5. Area 3a, in addition to the proximal projections from the immediately surrounding cortex, also received input from the supplementary motor area, cingulate motor cortex, insular cortex, and areas 2/5. Thus, this pattern of cortical input to area 3a resembled more closely that of the adjacent motor rather than that of the somatosensory area 3b. Contrasting with this, however, the thalamic input to area 3a was largely from somatosensory VPLc (abbreviations from Olszewski [1952] The Thalamus of the Macaca mulatta. Basel: Karger) and not from VPLo (with input from cerebellum, and projecting to precentral motor areas). © 1993 Wiley‐Liss, Inc.
Distribution of the mRNA for a metabotropic glutamate receptor (mGluR3) in the rat brain: An in situ hybridization study
Authors: Ohishi Hitoshi , Shigemoto Ryuichi , Nakanishi Shigetada , Mizuno Noboru
Published: January 2005

Distribution of the mRNA for a metabotropic glutamate receptor, mGluR3, which is coupled to the inhibitory cAMP cascade, was examined in the central nervous system of the adult albino rat by in situ hybridization. The hybridization signals of mGluR3 were detected not only on neuronal cells but also on many glial cells throughout the brain and spinal cord. In the neuronal cells, prominent expression of mGluR3 mRNA was seen in the thalamic reticular nucleus. Moderately labeled neurons were seen in the anterior olfactory nucleus, cerebral neo and mesocortical regions, lateral amygdaloid nucleus, ventral part of the basolateral amygdaloid nucleus, dorsal endopiriform nucleus, supraoptic nucleus, superficial layers of the superior colliculus, inferior colliculus, interpeduncular nucleus, superior olivary nuclei, and Golgi cells in the cerebellar cortex. Weakly labeled neurons were observed in the striatum, nucleus accumbens, ventral pallidum, globus pallidus, entopeduncular nucleus, lateral hypothalamic area, hypothalamic paraventricular nucleus, medial habenular nucleus, anterior pretectal nucleus, Barrington's nucleus, Nucleus O, paragenual nucleus, trigeminal sensory complex, cochlear nuclei, dorsal motor nucleus of the trigeminal nerve, dorsal cap of the inferior olive, spinal dorsal horn, and lamina X of the spinal cord. The stellate cells in the cerebellar cortex, and neurons in the deep cerebellar nuclei were also labeled weakly. The granule cell layer of the dentate gyrus, as a whole, appeared to be labeled intensely, but each of the granule cells was labeled only weakly. No significant labeling was detected in the mitral and tufted cells in the olfactory bulb, hippocampal pyramidal cells, Purkinje and granule cells in the cerebellar cortex, or somatic motoneurons. The distribution of mGluR3 mRNA in particular neurons and glial cells indicates specific roles of mGluR3 in the glutamatergic system of the central nervous system. © 1993 Wiley‐Liss, Inc.
Vibrissal stimulation affects glucose utilization in the trigeminal/somatosensory system of normal rats and rats prenatally exposed to ethanol
Authors: Miller Michael W. , Dow‐Edwards Diana L.
Published: January 2005

The effect of gestational ethanol exposure on stimulus‐induced sensory activity in the trigeminal/somatosensory System was determined. The mature offspring of mothers fed an ethanol‐containing diet (Et) or pair‐fed a nutritionally matched control diet (Ct) were examined. The C‐row mystacial whiskers were stimulated. Glucose utilization in the principal sensory nucleus of the trigeminal nerve (PSN), ventrobasal thalamus, and somatosensory cortex was determined with [14C]2‐deoxyglucose autoradiography.

In Ct‐ and Et‐treated rats, whisker stimulation increased glucose utilization in C‐row barrel(oid)s in the left PSN, the right ventrobasal thalamus, and the right somatosensory cortex. The rate of glucose utilization in the C‐row barrel(oid)s and in nonstimulated regions was lower in the Et‐treated rats than in controls. In the cortices of Ct‐treated rats, the activity in the C‐row barrels on the right side was greater than in the right nonbarrel somatosensory cortex. Et‐treated rats also exhibited an increase in glucose utilization, albeit smaller than that in the Ct‐treated rats. In contrast, the glucose utilization in the left B‐ and C‐row barrels of Ct‐treated rats was decreased. No such decrease was evident in the left cortices of Et‐treated rats.

Thus, stroking whiskers stimulates the activity of sites in the trigeminal/somatosensory system. In cortex, the definition of these sites is emphasized by depressed activity, i.e., “surround” inhibition, in sites connected via callosal or corticocortical projections. Prenatal exposure to ethanol depresses the metabolic activity regardless of the physiological state; however, the “surround” inhibition of cortical activity is eliminated by prenatal exposure to ethanol through an exuberant projection. © 1993 Wiley‐Liss, Inc.
Localization of cholinergic neurons in the forebrain and brainstem that project to the suprachiasmatic nucleus of the hypothalamus in rat
Authors: Bina Keshavan G. , Rusak Benjamin , Semba Kazue
Published: January 2005

In mammals, the suprachiasmatic nucleus is responsible for the generation of most circadian rhythms and their entrainment to environmental cues. Cholinergic agents can alter circadian rhythm phase, and fibres immunoreactive for choline acetyltransferase, the biosynthetic enzyme for acetylcholine, are present in the suprachiasmatic nucleus. Since there are no cholinergic somata in the suprachiasmatic nucleus, these fibres must represent the terminals of cholinergic neurons whose cell bodies are located elsewhere in the brain. This study was aimed at locating the cholinergic neurons that project to the suprachiasmatic nucleus by retrograde and anterograde tract‐tracing and immunohistochemistry for choline acetyltransferase in the rat. After injection of fluorogold, a retrograde tracer, into the suprachiasmatic nucleus, retrogradely labelled neurons that were immunopositive for choline acetyltransferase were located throughout the rostrocaudal extent of the cholinergic basal nuclear complex, with highest densities in the substantia innominata and the nucleus basalis magnocellularis. A few cells were also located in the medial septum and in the vertical and horizontal limbs ofthe diagonal band of Broca. In the brainstem, double‐labelled neurons were located in the laterodorsal tegmental nucleus, pedunculopontine tegmental nucleus and the parabigeminal nucleus. Injections of the anterograde tracer biocytin in these three brainstem nuclei resulted in fibre labelling in the suprachiasmatic nucleus, consistent with the retrograde findings. No clearly double‐labelled cells were located in the retina. These results suggest that the suprachiasmatic nucleus receives cholinergic afferents from both the basal forebrain and mesopontine tegmentum which may mediate cholinergic effects on circadian rhythms. © 1993 Wiley‐Liss, Inc.
Long‐term consequences of impaired regeneration on facial motoneurons in the C57BL/Ola mouse
Authors: Chen S. , Bisby M. A.
Published: January 2005

Peripheral nerves of the C57BL/Ola mouse mutant undergo markedly slowed Wallerian degeneration following injury. This is associated with impaired regeneration of both sensory and motor axons. Following a crush lesion of the facial nerve, there was no cell loss in facial nuclei of normal (C57BL/6J) adult mice, but 40% cell loss occurred in Ola mice and the survivors increased in size during the period when functional reinnervation was established. These results are interpreted as a result, first, of prolonged deprivation of target‐derived trophic factor in the slowly regenerating Ola motoneurons and second, increased peripheral field size of the survivors. Within the regenerated facial nerve, there was marked heterogeneity of myelinated fibre size in Ola mice. Some Ola axons, both proximal and distal to the lesion site, had areas over twice as great as the largest 6J axons when measured 1 year following injury. A population of small diameter fibres, not observed in 6J nerves, persisted distal to the crush site in Ola nerves, and this was associated with an increase in the total number of myelinated axons in the distal nerve: on average, each parent Ola axon retained three persistent daughter axons. The delayed Wallerian degeneration in Ola mice not only impairs immediate axon regrowth, but also results in a breakdown of the normal mechanisms which regulate axon number and size in regenerating nerve.
Antigenic compartmentation in the mouse cerebellar cortex: Zebrin and HNK‐1 reveal a complex, overlapping molecular topography
Authors: Eisenman Leonard M. , Hawkes Richard
Published: January 2005

Two monoclonal antibodies‐anti‐zebrin I and anti‐HNK‐1‐have been used to study the compartmentation of the mouse cerebellar cortex. As in other species, the pattern of localization of the Purkinje cell specific antigen zebrin I is confined to a subset of Purkinje cells that are organized into parasagittal bands. The basic pattern consists of two abutting paramedian bands (P1+) and up to three additional vermal bands on either side (P2+P4+) This patern is altered in the vermal regions of lobules X and VI‐VII where all Purkinje cells are immunoreactive. In the hemisphere there are three additional bands present (P5+P7+) plus two shorter bands in the paravermal area (P4b+ and P5a+) that extend from the paramedian lobule through the lobulus simplex. This pattern is very similar, but perhaps not identical, to that previously described for the rat. These results suggest a common mammalian plan for the expression and localization of zebrin I.

By using a monoclonal antibody to an epitope associated with HNK‐1, we have now identified a novel pattern of compartmentation in mouse cerebellum. The HNK‐1 epitope is expressed most notably on Purkinje cells and Golgi cells. The molecular layer immunoreactivity associated with the Purkinje cell dendrites varies in intensity in a systematic and reproducible fashion. This reveals a novel cerebellar compartmentation that is sometimes complementary, sometimes overlapping, to that revealed by anti‐zebrin. As a result, it is now possible to subdivide the cerebellar cortex into a still finer mosaic of antigenic patches and bands than was possible by using zebrins alone.© 1993 Wiley‐Liss, Inc.
Amphibian‐specific regulation of polysialic acid and the neural cell adhesion molecule in development and regeneration of the retinotectal system of the salamander Pleurodeles waltl
Authors: Becker Thomas , Becker Catherina G. , Niemann Ulrike , Naujoks‐Manteuffel Christiane , Gerardy‐Schahn Rita , Roth Gerhard
Published: January 2005

Antibodies specific to the neural cell adhesion molecule (NCAM‐total), the 180 × 103 My component of NCAM (NCAM‐180) and polysialic acid (PSA) were used in immunohistochemistry and Western blots to detect the spatiotemporal dynamics of these molecules in development and regeneration of the retinotectal system of Pleurodeles waltl. NCAM‐total and NCAM‐180 are continuously expressed in the retina, optic nerve, and tectum of the developing and adult salamander. This is also found for the 140 × 103 My component of NCAM in Western blots of the retina. In the larval retina, PSA is present in the inner plexiform layer (IPL) and a few cells in all nuclear layers. At metamorphosis, PSA expression in the retina strongly increases in the layer of cone photoreceptor somata. Several cells in the inner nuclear layer and Muller cell processes also begin to express PSA. This pattern persists into adulthood. The optic nerve and the tectum are strongly PSA‐immunoreactive throughout development. In the adult optic nerve and optic fiber pathway in the brain, PSA expression is selectively downregulated. In the crush‐lesioned adult optic nerve, regenerating fibers are NCAM‐180‐positive but PSA‐negative. This demonstrates a molecular difference between growing nerve fibers of Pleurodeles in development and in regeneration. PSA regulation is closely correlated with metamorphosis, thus suggesting that PSA expression may be under hormonal control. Some aspects of PSA and NCAM isoform expression patterns in the retinotectal system of salamanders differ considerably from that of other vertebrates. The substained expression of NCAM isoforms in adult salamanders might be due to secondary simplification (paedomorphosis). © 1993 Wiley‐Liss, Inc.