bluuebunny/crossref_metadata_2025 huggingface dataset:
Parvalbumin‐ and calbindin D28K‐immunoreactive neurons in the hippocampal formation of the macaque monkey
Authors: Seress Láaszlóa , Gulyáas Attila I. , Freund Tamáas F.
Published: January 2005

Calcium‐binding proteins calbindin D28k (CaBP) and parvalbumin (PV) were localized in neurons of the monkey hippocampal formation. CaBP immunoreactivity is present in all granule cells and in a large proportion of CA1 and CA2 pyramidal neurons, as well as in a distinct population of local circuit neurons. In the dentate gyrus, CaBP‐immunoreactive nongranule cells are present in the molecular layer and in the hilar region, but they do not include the pyramidal basket cells at the hilar border. In the Ammon's horn, CaBP‐positive, nonpyramidal neurons are more frequent in the CA3 area than in any other parts of the hippocampal formation. They are concentrated in the strata oriens and pyramidale of areas CA1‐3, whereas only a few small neurons were found in the strata lucidum and radiatum of CA3 and in the stratum moleculare of the CA1 area.

PV is exclusively present in local circuit neurons both in the dentate gyrus and in Ammon's horn. In the dentate gyrus the presumed basket cells at the hilar border exhibit PV immunoreactivity. In the hilar region and molecular layer only a relatively small number of cells are immunoreactive for PV. Most of these PV‐positive cell bodies are located in the inner half of the molecular layer, with occasional horizontal cells at the hippocampal fissure. In Ammon's horn, strata oriens and pyramidale of areas CA1‐3 contain a large number of PV‐positive cells. There are no PV‐immunoreactive cells in the strata lucidum, radiatum, or lacunosum moleculare.

The CaBP‐ and PV‐containing neurons form different subpopulations of cells in the monkey hippocampal formation. With the exception of a basket cell type in the monkey dentate gyrus, the CaBP‐ and PV‐positive cell types were found, to be remarkably similar in rodents and primates.
Specific temporal and spatial distribution of JUN, FOS, and KROX‐24 proteins in spinal neurons following noxious transsynaptic stimulation
Authors: Herdegen Thomas , Kovary Karla , Leah John , Bravo Rodrigo
Published: January 2005

We present the first comparative investigation of the basal and transsynaptically induced expression of c‐JUN, JUN B, JUN D, c‐FOS, FOS B, and KROX‐24 proteins in the spinal cord, using immunocytochemistry with specific antibodies. We demonstrate that electrical stimulation of the sciatic nerve at Aδ/C‐fiber (not Aα/β‐fiber) intensity strongly induces the expression of these immediate‐early gene‐encoded proteins.

Basal immunoreactivity was found for c‐JUN in motoneurons, for JUN D in almost every cell of the gray matter, and for KROX‐24 in the superficial dorsal horn.

One hour after electrical stimulation of the sciatic nerve at Aδ/C‐fiber intensity, expression of all proteins except JUN D reached its maximum. Initially immunoreactivity was restricted to the ipsilateral dorsal horn, but after 4 hours appeared contralaterally. Expression of JUN D was increased only after 4 hours. Within the dorsal horn, the expression of c‐JUN, JUN B, FOS B, and KROX‐24 was mainly restricted to the superficial layers. Immunoreactivity decreased to basal levels between 8 and 16 hours. c‐FOS and JUN D were expressed in both the superficial and deep dorsal horn; in the latter, c‐FOS and JUN D persisted longer. Induced JUN D was present the longest and was still visible after 32 hours. In motoneurons of the ipsilateral ventral horn, c‐JUN, JUN D, and c‐FOS appeared after 8 hours.

Surgical exposure of the sciatic nerve evoked a strikingly prolonged expression of all proteins compared to that following electrical stimulation of the sciatic nerve.

Our results demonstrate that stimulation of nociceptive Aδ‐ and C‐fibers induces early and late expression of proteins encoded by immediate‐early genes with a specific temporal and spatial distribution of the expression of each protein. Furthermore, the extent of protein expression reflects the intensity of noxious stimulation.
Calcitonin‐gene related peptide is an evolutionarily conserved marker within the amniote thalamo‐telencephalic auditory pathway
Authors: Brauth Steven E. , Reiner Anton
Published: January 2005

The distribution of neurons and fibers containing calcitonin‐gene‐related peptide (CGRP) was mapped in the thalamo‐telencephalic auditory pathways of four amniote species, rats, pigeons (Columba livia), caiman (Caiman crocodilus), and turtles (Pseudemys scripta). In colchicine‐treated turtles and pigeons, numerous CGRP+ perikarya were observed in the auditory relay nucleus of the thalamus (n. reuniens of reptiles, and n. ovoidalis of birds). In pigeons, these neurons were most abundant in the outer circumference of the nucleus and were not observed without colchicine pretreatment. In the telencephalon of turtles, caiman, and pigeons, CGRP + fibers were observed within portions of the dorsal ventricular ridge previously shown to receive projections from the auditory thalamus, thus implying that the thalamic CGRP+ neurons observed here in fact project to these telencephalic areas. In colchicine treated rats, numerous CGRP+ perikarya were observed along the ventral margin of the medial geniculate nucleus extending into the posterior intralaminar and peripeduncular nuclei, as well as occasionally within the ventral subdivision of the medial geniculate nucleus. Injections of fluorogold into the auditory cortex combined with immunofluorescence labeling for CGRP revealed that CGRP+ cells in these areas do, in fact, project to the auditory cortices.
Tuberculoventral neurons project to the multipolar cell area but not to the octopus cell area of the posteroventral cochlear nucleus
Authors: Wickesberg Robert E. , Whitlon Donna , Oertel Donata
Published: January 2005

Tuberculoventral neurons in the deep layer of the dorsal cochlear nucleus (DCN) provide frequency‐specific inhibition to neurons in the anteroventral cochlear nucleus (AVON) of the mouse (Wickesberg and Oertel, '88, '90). The present experiments examine the projection from the deep DCN to the posteroventral cochlear nucleus (PVCN). Horseradish peroxidase (HRP) injections into the PVCN reveal that the multipolar cell area, but not the octopus cell area, is innervated by neurons in the deep layer of the DCN. Injections into the multipolar cell area, in the rostral and ventral PVCN, labeled neurons across the entire rostrocaudal extent of the deep DCN. The labeled tuberculoventral neurons generally lay within the band of labeled auditory nerve terminals in the DCN. Injections of HRP into the octopus cell area, in the dorsal caudal PVCN, labeled almost no cells within the band of auditory nerve fiber terminals that were labeled by the same injection. The inhibition from tuberculoventral neurons onto ventral cochlear nucleus (VCN) neurons is likely to be mediated by glycine (Wickesberg and Oertel, '90). Slices of the cochlear nuclear complex were immunolabeled by an antibody against glycine conjugated with glutaraldehyde to bovine serum albumin (Wenthold et al., '87). Glycine‐like immunoreactivity was found throughout the DCN, the AVCN and the multipolar cell area, but there was little labeling in the octopus cell area. This finding provides independent evidence that tuberculoventral neurons do not innervate the octopus cell area and indicates that the octopus cell area is anatomically and functionally distinct.
Adrenal steroids regulate postnatal development of the rat dentate gyrus: II. Effects of glucocorticoids and mineralocorticoids on cell birth
Authors: Gould Elizabeth , Woolley Catherine S. , Cameron Heather A. , Daniels Deborah C. , McEwen Bruce S.
Published: January 2005

Unlike the majority of mammalian brain regions, the rat dentate gyrus undergoes maximal cell birth and cell death during the same developmental time period. Granule cell birth and death peak at the end of the first postnatal week. We have found that manipulations of glucocorticoid levels during the stress hyporesponsive period profoundly influence the density of pyknotic cells in the dentate gyrus while apparently not affecting the density of healthy cells. This raises the possibility that glucocorticoids are regulating processes in addition to cell death, i.e., cell birth. In order to determine whether increases in circulating glucocorticoids or mineralocorticoids affect the birth of cells in the developing dentate gyrus, 3H‐thymidine autoradiography was performed on brains of rat pups treated with either corticosterone or aldosterone during the first postnatal week. Quantitative analysis of 3H‐thymidine‐labelled cells revealed significant decreases in the density of labelled cells in the granule cell layers with both corticosterone and aldosterone treatment. In these same brains, significant decreases in the density of pyknotic cells were also observed in the granule cell layers. However, no changes in the numbers of 3H‐thymidine‐labelled pyknotic cells were observed with any treatment. Increases in circulating corticosterone or aldosterone resulted in significant increases in the density of both 3H‐thymidine‐labelled and pyknotic cells in the hilus. These results suggest that dentate gyrus cell birth and cell death are related and that these processes are regulated by adrenal steroids.
Relationships between neuronal birthdates and cytoarchitecture in the rat inferior olivary complex
Authors: Bourrat Franck , Sotelo Constantino
Published: January 2005

The correlation between birthdates of neurons and their ultimate location within the inferior olivary nucleus (ION) was investigated in the rat by the 5‐bromodeoxyuridine (BrdU) method. We performed injections every 4 hours throughout the ION generation period, and were thus able to demonstrate that (1) neurons are distributed in the adult ION following characteristic gradients that define subdivisions identical to those established by hodological studies; and (2) ION neurons born at the same time tend to be arrayed in small clusters in the adult structure. Implications of these findings for the mechanisms of olivary neuron migration, selective aggregation, and elaboration of projectional topography are discussed. This study provides direct evidence that one of the factors governing the elaboration of the cytoarchitecture of a neuronal nucleus is the temporal sequence of generation of its neurons.
Ultrastructure and synaptic organization of axon terminals from brainstem structures to the mediodorsal thalamic nucleus of the rat
Authors: Kuroda Masaru , Price Joseph L.
Published: January 2005

The ultrastructural characteristics and synaptic organization of afferent terminals from the brainstem to the mediodorsal thalamic nucleus (MD) of the rat have been studied with the electron microscope, by means of anterograde transport of wheat germ agglutinin‐horseradish peroxidase (WGA‐HRP).

Labeled fibers were seen predominantly in the lateral portion of MD after the injections of WGA‐HRP into the substantia nigra pars reticulata (SNr), the superior colliculus (SC), and the dorsal tegmental region (DT). The boutons arising from the SC were relatively small (< 1.5 μm in diameter), formed asymmetric synaptic contacts with small dendrites and dendritic spines, and contained round synaptic vesicles. The axon terminals from the DT were mostly large boutons (2–4.5 μm) with asymmetric synaptic specializations and round vesicles. These boutons and their postsynaptic targets formed synaptic glomeruli that were entirely or partially ensheathed by glial lamellae. The ultrastructural features are almost identical to those of boutons in the medial and central segments of MD that were previously shown to originate from the basal amygdaloid nucleus and the piriform cortex. The boutons from the SNr had a wide range in size, but the majority were medium‐sized to large (1.5–4 μm). The nigral boutons established symmetric synaptic contacts with dendritic shafts and occasionally with somata, and contained pleomorphic vesicles. However, like the DT terminals, they participated in glomerular formations. The nigral terminals closely resemble previously described terminals in the medial part of MD from the ventral pallidum, except that the nigral terminals formed en passant and axosomatic synapses as well as axodendritic synapses.

A combined immunohistochemistry and WGA‐HRP tracing study revealed that the nigral inputs were immunoreactive for glutamic acid decarboxylase and the axon terminals from the DT were immunoreactive for choline acetyltransferase. In a separate study, the colliculothalamic fibers have been shown to take up and transport the transmitter specific tracer [3H]‐D‐aspartate, and are therefore putatively glutamatergic and/or aspartatergic. Taken together: with this, the present results suggest that the collicular afferents are excitatory and glutamatergic and/or aspartatergic, that the inputs from the DT are also excitatory and cholinergic, while the nigral inputs are inhibitory and GABAergic.
Receptor‐mediated retrograde transport in CNS neurons after intraventricular administration of NGF and growth factors
Authors: Ferguson Ian A. , Schweitzer John B. , Bartlett Perry F. , Johnson Eugene M.
Published: January 2005

Radiolabel tracer techniques were used to follow the distribution of nerve growth factor (NGF) and other neuromodulatory factors after intraventricular injection. Autoradiography showed that shortly after intraventricular injection of radio‐iodinated NGF (125I‐NGF), substantial amounts of radioactivity had penetrated the ventricular wall surfaces; this binding was transient and nonspecific. The 125I‐NGF was progressively cleared from the central nervous system (CNS), presumably via the flow of cerebrospinal fluid (CSF) into the blood. A relatively small proportion of the injected 125I‐NGF was taken up by NGF receptor‐positive neurons in the CNS. Retrograde accumulation of radiolabel was observed within the basal forebrain cholinergic neurons at 5 hours after intraventricular injection. Labeling intensity was maximal at 18 hours and much reduced by 30 hours. This labeling was blocked by co‐injection of an excess of unlabeled NGF. Specific and saturable retrograde labeling was also observed within other NGF receptor‐bearing neurons, including the prepositus hypoglossal nucleus and the raphe obscurus nucleus. When epidermal growth factor (EGF), transforming growth factor‐β1 (TGF‐β1), platelet‐derived growth factor‐AA (PDGF‐AA), PDGF‐BB, leukemia inhibitory factor (LIF), insulin‐like growth factor‐I (IGF‐I), or IGF‐II was radiolabeled and injected intraventricularly, specific labeling of neurons was observed for 125I‐IGF‐II and 125I‐LIF within separate subpopulations of the dorsal and medial raphe. No retrograde accumulation within neurons was observed for EGF, TGF‐β1, PDGF‐AA, PDGF‐BB, or IGF‐I. This study describes an in vivo method for identifying putative neuromodulatory factors and their responsive neurons.
Cholinergic neurons in the rat septal complex: Ultrastructural characterization and synaptic relations with catecholaminergic terminals
Authors: Milner Teresa A.
Published: January 2005

Physiological and pharmacological studies have suggested that catecholamines modulate cholinergic neurons in the medial septal and diagonal band nuclei (i.e., the septal complex). Thus, the ultrastructural morphology of neurons containing choline acetyltransferase (ChAT), the biosynthetic enzyme for acetylcholine, and their relation to catecholaminergic terminals exhibiting immunoreactivity for the catecholamine synthesizing enzyme tyrosine hydroxylase (TH) were examined in the rat septal complex. Dual immunoautoradiographic and peroxidase anti‐peroxidase labeling methods were used to simultaneously localize antibodies raised in rabbits against TH and from rat‐mouse hybridomas against ChAT in single sections. At least two types of perikarya with ChAT‐immunoreactivity (ChAT‐I) were observed. The first type were large (20–30 μm), elongated or round, and contained a small indented nucleus with an abundant cytoplasm and an occasional lamellar body. The second type was also either ovoid or round but was medium‐sized (15–20 μm) and contained a larger indented nucleus and a smaller amount of cytoplasm than the first type. Both types of perikarya as well as dendrites with ChAT‐I were surrounded by astrocytic processes apposed to most of their plasmalemmal surfaces. The distribution and types of terminal associations (i.e., asymmetric synapses, symmetric synapses and appositions which lacked a membrane specialization in the plane of section analyzed) with, ChAT‐labeled perikarya and dendrites were quantitatively evaluated. The majority (68% of 197) of the presynaptic terminals were unlabeled; the remaining terminals were immunoreactive for TH (25%) or ChAT (7%). All three types of terminals contacted primarily the shafts of small dendrites and more rarely ChAT‐labeled perikarya and large dendrites.

ChAT‐labeled terminals: (1) formed associations with unlabeled perikarya and dendrites (31% of 176); (2) formed associations with perikarya and dendrites with ChAT‐I (7%); (3) contacted the same unlabeled perikarya and dendrite as a TH‐containing terminal (21%); (4) were in apposition to TH‐labeled terminals (25%); or (5) were either in apposition to unlabeled or ChAT‐labeled terminals or lacked associations with any processes. The majority of associations formed by the terminals with ChAT‐I were on the shafts of small dendrites. Moreover, most of the associations formed were either symmetric synapses or appositions not separated by astrocytes in the plane of section analyzed.

These findings provide cellular substrates in the septal complex (1) for sparse synaptic input relative to astrocytic investment of cholinergic neurons and (2) for direct synaptic modulation of cholinergic and non‐cholinergic neurons by catecholamines and/or acetylcholine. These findings have direct relevance to catecholaminergic‐cholinergic interactions and to the neuropathological basis for Alzheimer's disease.
Development of the olfactory bulb in the clawed frog,Xenopus laevis: A morphological and quantitative analysis
Authors: Byrd Christine A. , Burd Gail D.
Published: January 2005

The relationship between olfactory axons and the cells of the olfactory bulb during normal development was analyzed to determine whether olfactory afferent axons could play a role in the induction of olfactory bulb formation. The morphology of the olfactory bulb in Xenopus larvae from stages 26 to 58 and in adult frogs was analyzed with light and electron microscopy. Axons were first observed beneath the basal lamina of the neural tube at stages 30 and 32; at stage 32, neurons in this area of the neural tube began to differentiate. Synapses of olfactory axons onto young neuronal processes were observed as early as stages 36 and 38. By stage 44, all of the layers of the olfactory bulb were present. The basic structure of the mature form of the olfactory bulb was apparent as early as stage 48/49 and remained constant throughout late larval life and even into adulthood, with only the size increasing.

To determine the numerical relationship between olfactory axons from both main and vomeronasal epithelia and mitral/tufted cells in the main and accessory olfactory bulbs, a quantitative study was also performed in which the number of olfactory axons and the number of mitral/tufted cells were estimated for larval stages (stages 50 to 58) and adults. The number of axons increased with stage, with a 16‐fold increase between stage 58 and adulthood. The number of mitral/tufted cells increased with stage, with only a 2.3‐fold increase between stage 58 and adults. There is a correlation between axon number and mitral/tufted cell number during larval development that is consistent with the hypothesis that olfactory axons influence olfactory bulb development. The convergence ratio of olfactory axons onto mitral/tufted cells was 5:1 in larvae and increased to 34:1 in adults; this increase probably results in increased olfactory sensitivity in adult frogs.
Major differences in CNS sulfonylurea receptor distribution between the rat (newborn, adult) and turtle
Authors: Xia Ying , Haddad Gabriel G.
Published: January 2005

Our previous results have shown that KATP channels play an important role in K+ efflux and extracellular K+ accumulation in the rat brain, and this role was quantitatively more important in the adult than in the newborn brain. The purpose of this study was to localize by autoradiographic techniques the binding sites of glibenclamide, a potent sulfonylurea ligand that targets KATP channels, in the adult and newborn fat central nervous system (CNS). Since the adult turtle is resistant to anoxia, we also compared the rat to the turtle brain sulfonylurea receptor distribution. In all three animal groups (newborn rat, adult rat, adult turtle), specific glibenclamide binding was saturable. Scatchard plots were curvilinear in the rat, thus suggesting that glibenclamide binds to two types of sites, i.e., high and low affinity sites. Scatchard analysis on turtle brain tissue showed evidence of one binding site only, We also found that the distribution of glibenclamide binding sites was heterogeneous in the adult rat CNS with a higher density in rostral than in caudal regions. The highest binding densities were seen in the cortex, hippocampus, cerebellum, substantia nigra, and a few thalamic nuclei; intermediate densities were observed in the basal ganglia, septum, thalamus, and the hypoglossal nucleus. There was a low density in most areas of the hypothalamus, midbrain, brainstem, and spinal cord. Compared with the adult rat, the newborn had a very homogeneous distribution of binding sites and densities were very low throughout the CNS; the level of binding density was even lower and in some regions undetectable in the adult turtle. Our results indicate that (1) there are high and low affinity sulfonylurea receptors in the rat CNS, (2) there is a striking heterogeneity in the distribution and density of sulfonylurea receptors in the adult rat CNS and this is in sharp contrast to the homogeneous distribution and low density in both newborn rat and adult turtle; (3) sulfonylurea receptors increase in number postnatally in the rat since binding density increases and the Kd in the newborn rat is similar to that in the adult rat. We speculate that KATP channels and sulfonylurea receptors are poorly developed in the turtle and develop mostly after birth in the rat, reaching highest density in adulthood.
Ramifications of the axons of AH‐neurons injected with the intracellular marker biocytin in the myenteric plexus of the guinea pig small intestine
Authors: Bornstein J. C. , Hendriks R. , Furness J. B. , Trussell D. C.
Published: January 2005

The projections and terminal ramifications of electrophysiologically characterized myenteric neurons of the guinea pig small intestine were studied after intracellular injection of the marker substance biocytin. Myenteric neurons were impaled with microelectrodes containing 4% biocytin in 2 M KCl (pH 7.4) and characterized electrophysiologically as either AH‐neurons or S‐neurons. AH‐neurons were neurons in which action potentials were followed by prolonged after‐hyperpolarizations (lasting >4 seconds). S‐neurons were neurons in which such hyperpolarizations were not seen. Electrical stimulation of internodal strands evoked prominent fast excitatory synaptic potentials in S‐neurons, but not in AH‐neurons. Biocytin was injected electrophoretically into the impaled AH‐neurons by passage of hyperpolarizing current (0.6–0.8 nA for 5–15 minutes) through the recording electrode. The preparation was then fixed in Zamboni's fixative, dehydrated, and exposed to avidin coupled to horseradish peroxidase which allowed the injected biocytin to be visualised via a diaminobenzidine reaction. In many cases, the injected biocytin appeared to fill all the processes of injected AH‐neurons that ramified within the myenteric plexus. The filled processes included axons running up to 4 mm within the plexus and profuse varicose terminals ramifying within both the ganglion containing the injected cell body and nearby ganglia. Most (90%) cell bodies of the injected AH‐neurons had the morphology of Dogiel type II neurons; large, mostly smooth cell bodies with few short processes and several long processes. The other 10% of the AH‐neurons had similar cell bodies and long processes but also had prominent short filamentous processes. This population was termed dendritic AH‐neurons. The projections and terminals of 28 AH/Dogiel type II neurons and 7 dendritic AH‐neurons were analysed in detail. Both types of neurons project circumferentially to provide terminals to nearby ganglia, but the AH/Dogiel type II neurons also provide terminals to their own ganglia while the dendritic AH‐neurons typically do not. Although many of the injected AH‐neurons had projections orally or anally along the intestine no evidence for a preferential direction of projection was obtained. Analysis of the areas and distributions of the terminal fields of the AH/Dogiel type II neurons suggests that each may contact several other myenteric neurons and that each myenteric neuron may receive input from about ten AH/Dogiel type II neurons.
Receptive field properties of somatosensory neurons in the cat superior colliculus
Authors: Clemo H. Ruth , Stein Barry E.
Published: January 2005

In general, knowledge of the internal organization of receptive fields has played an important role in shaping current understanding of sensory physiology. Such knowledge is particularly important for understanding the function of the superior colliculus, since this structure is at once implicated in spatial localization and has relatively large receptive fields. While this issue has been addressed in the visual and auditory modalities represented in the superior colliculus, there are no previous studies of its somatosensory receptive field organization. Here, the properties of somatosendory receptive fields in the cat superior colliculus were studied quantitatively to determine whether they contain internal non‐homogeneities that might aid in the determination of stimulus detail. Of special interest was the possibility that these comparatively large receptive fields would contain areas of differential excitability that could aid in spatial resolution, that within‐field spatial summation and/or inhibition would be exhibited, and that the borders of the excitatory receptive field would be flanked by inhibitory regions. The data demonstrate that while inhibition beyond the receptive field borders is a rarity, these somatosensory receptive fields nearly always contain a well‐defined area of maximal sensitivity within which the size of the stimulus is a critical feature in determining the magnitude of the response. These best areas are systematically distributed across receptive fields as a function of their location in the structure, and indicate that the resolution of stimulus location and size may be greater than expected on the basis of receptive field size alone.
Organization of the superior olivary complex in the guinea pig. I. Cytoarchitecture, cytochrome oxidase histochemistry, and dendritic morphology
Authors: Schofield Brett R. , Cant Nell B.
Published: January 2005

The superior olivary complex is a prominent component of the auditory system. It consists of the lateral and medial superior olivary nuclei and a large number of smaller cell groups known as the periolivary nuclei, which are sources of both ascending and descending projections. The goal of this study was to establish criteria for identifying the periolivary nuclei in the guinea pig. Use of Nissl stains, the Golgi impregnation technique, and cytochrome oxidase histochemistry allowed us to distinguish eleven periolivary nuclei on the basis of differences in the types of cells they contain, in the distribution of cell types, and in the cytochrome oxidase staining characteristics of both the cells and the neuropil. The nuclei, named according to their position with respect to the lateral and medial superior olivary nuclei, can. be divided into four groups: (1) a lateral group comprising the lateral nucleus of the trapezoid body and the anterolateral and posteroventral periolivary nuclei, (2) a dorsal group comprising the dorsal and dorsolateral periolivary nuclei, (3) a ventral group comprising the ventral nucleus of the trapezoid body and the anteroventral, ventromedial and rostral periolivary nuclei, and (4) a medial group comprising the medial nucleus of the trapezoid body and the superior paraolivary nucleus. Cytological distinctions among the periolivary nuclei are consistent with other evidence that they serve different functions and highlight the need for detailed study of their connections, immunocytochemistry and physiological response properties.
Morphometric analysis of phrenic motoneurons in the cat during postnatal development
Authors: Cameron William E. , He F. , Kalipatnapu P. , Jodkowski J. S. , Guthrie R. D.
Published: January 2005

The dendritic geometry of 20 phrenic motoneurons from four postnatal ages (2 weeks, 1 and 2 months, and adult) was examined by using intracellular injection of horseradish peroxidase. The number of primary dendrites (∼ 11∼12) remained constant throughout postnatal development. In general, postnatal growth of the dendrites resulted from an increase in the branching and in the length and diameter of segments at all orders of the dendritic tree. There was one exception. Between 2 weeks and 1 month, the maximum extent of the dendrites increased in parallel with the growth of the spinal cord; however, there was no increase in either combined dendritic length or total membrane surface area. In addition, there was a significant decrease in the number of dendritic terminals per cell (59.8 ± 9.3 vs. 46.4 ± 7.4 for 2 weeks and 1 month, respectively).

The distance from the soma, where the peak number of dendritic terminals per cell occurred, ranged from 700–900 μm at 2 weeks and 2 months to 1,300–1,700 μm in the adult. The diameter of dendrites as a function of distance from the soma along the dendritic path increased with age. The process of maturation tended to increase the distance from the soma over which the surface area and dendritic trunk parameter (∑d1.5/D1.5) remained constant. The three‐dimensional distribution of dendrites was analyzed by dividing space into six equal volumes or hexants. This analysis revealed that the postnatal growth in surface area in the rostral and caudal hexants was proportionately larger than that in either the medial, lateral, dorsal, or ventral hexants. Strong linear correlations were found between the diameter of the primary dendrite and the combined length, surface area, volume, and number of terminals of the dendrite at all ages studied.
Nerve cables formed in silicone chambers reconstitute a perineurial but not a vascular endoneurial permeability barrier
Authors: Azzam Nabil A. , Zalewski Andrew A. , Williams Lawrence R. , Azzam Rita N.
Published: January 2005

The passage of molecules into the endoneurial environment of the axons of normal peripheral nerve is regulated by two permeability barriers, the perineurial‐nerve barrier and the endoneurial blood‐nerve barrier. These barriers exist because of the presence of tight junctions between adjacent perineurial cells and adjacent endothelial cells. In the present study we investigated whether permeability barriers form in nerve cables, which develop inside silicone chambers. The sciatic nerves of adult rats were cut, and the proximal and distal ends sutured into opposite ends of silicone chambers that were filled with dialyzed plasma. The presence of barriers was determined with the tracer horseradish peroxidase (HRP), which was injected intravenously and detected histochemically in tissues by light and electron microscopy. At four weeks, a regenerated nerve cable extended across the 10 mm length of each chamber. However, no permeability barriers were present since the reaction product for HRP was visible throughout the cable. At twenty‐six weeks, all the axons in cables were gathered into minifascicles. Each minifascicle of axons was surrounded by perineurial cells. Blood vessels were excluded from the minifascicles by the perineurial cells and the vessels were permeable to HRP, thus indicating that their endothelial cells had not formed tight junctions. Despite the leakage of HRP from the excluded vessels, the tracer did not reach the axons because the perineurial cells encircling the minifascicles developed tight junctions. In some animals, the chambers were removed at four weeks to determine whether the chamber influenced barrier development. This manipulation had no effect since cables, with or without chambers, exhibited similar findings at twenty‐six weeks. Our results indicate that nerve cables regenerate a perineurial but not an endoneurial permeability barrier. We conclude that axons in long‐term cables are protected by only a perineurial permeability barrier.
Efferent connections of the centromedian and parafascicular thalamic nuclei in the squirrel monkey: A PHA‐L study of subcortical projections
Authors: Sadikot A. F. , Parent A. , François C.
Published: January 2005

The subcortical projections of the centromedian (CM) and the parafascicular (Pf) thalamic nuclei were examined in the squirrel monkey (Saimiri sciureus) by using the lectinPhaseolus vulgaris‐leucoagglutinin (PHA‐L) as an anterograde tracer. Both CM and Pf project massively to the striatum where they arborize in a complementary fashion. On the one hand, CM innervates most of the putamen caudal to the anterior commissure, a dorsolateral rim of the putamen rostral to the anterior commissure, discrete areas of the head of the caudate nucleus close to the internal capsule, and a lateral sector of the body of the caudate nucleus. On the other hand, Pf provides a heavy input to the head, body, and tail of the caudate nucleus, and to the rostral putamen, excluding the areas innervated by CM. In addition, Pf projects more discretely to the nucleus accumbens and the olfactory tubercle. Therefore, the projections from both CM and Pf cover the entire striatum, with those from CM arborizing into the “sensorimotor” striatal territory and the ones from Pf innervating the “associative‐limbic” striatal territory. Furthermore, CM and Pf project to extrastriatal subcortical structures, such as the globus pallidus, the subthalamic nucleus, and the substantia nigra, where they also terminate in a complementary fashion. Topographically and cytologically, Pf is closely related to the subparafascicular nucleus (sPf). The Pf‐sPf complex projects to the hypothalamus, the substantia innominata, the peripeduncular nucleus, and the amygdala. It also gives rise to descending efferents arborizing in various brainstem structures, including the inferior olivary complex. Additional studies with retrograde double‐labeling methods show that distinct cell groups within CM project to the motor cortex and the striatum. Likewise, separate neuronal populations within the CM‐Pf‐sPf complex give rise to striatal and brainstem projections, the former arising from CM and Pf and the latter mainly from sPf. The complementary nature of CM and Pf projections to the striatum and other basal ganglia components suggests that this thalamic complex participates in a highly ordered manner in the parallel processing of the information that flows through the basal ganglia.
Connections of the retrosplenial dysgranular cortex in the rat
Authors: van Groen Thomas , Wyss J. Michael
Published: January 2005

Although the retrosplenial dysgranular cortex (Rdg) is situated both physically and connectionally between the hippocampal formation and the neocortex, few studies have focused on the connections of Rdg. The present study employs retrograde and anterograde anatomical tracing methods to delineate the connections of Rdg. Each projection to Rdg terminates in distinct layers of the cortex. The thalamic projections to Rdg originate in the anterior (primarily the anteromedial), lateral (primarily the laterodorsal), and reunions nuclei. Those from the anteromedial nucleus terminate predominately in layers I and IV‐VI, whereas the axons arising from the laterodorsal nucleus have a dense terminal plexus in layers I and III‐IV. The cortical projections to Rdg originate primarily in the infraradiata, retrosplenial, postsubicular, and areas 17 and 18b cortices. The projections arising from visual areas 18b and 17 predominantly terminate in layer I of Rdg, axons from contralateral Rdg form a dense terminal plexus in layers I‐IV, with a smaller number of terminals in layers V and VI, afferents from postsubiculum terminate in layers I and III‐V, and the projection from infraradiata cortex terminates in layers I and V‐VI. The efferent projections from Rdg are widespread. The major cortical projections from Rdg are to infraradiata, retrosplenial granular, area 18b, and postsubicular cortices, Subcortical projections from Rdg terminate primarily in the ipsilateral caudate and lateral thalamic nuclei and bilaterally in the anterior thalamic nuclei. The efferent projections from Rdg are topographically organized. Rostral Rdg projects to the dorsal infraradiata cortex and the rostral postsubiculum, while caudal Rdg axons terminate predominately in the ventral infraradiata and the caudal postsubicular cortices. Caudal but not rostral Rdg projects to areas 17 and 18b of the cortex. The Rdg projections to the lateral and anterior nuclei also are organized along the rostral‐caudal axis. Together, these data suggest that Rdg integrates thalamic, hippocampal, and neocortical information.
Immunocytochemical localization of the N‐acetyl‐aspartyl‐glutamate (NAAG) hydrolyzing enzyme N‐acetylated α‐linked acidic dipeptidase (NAALADase)
Authors: Stauch Slusher Barbara , Tsai Guochuan , Yoo Grace , Coyle Joseph T.
Published: January 2005

N‐acetylated α‐linked acidic dipeptidase (NAALADase) is a membrane bound enzyme that cleaves glutamate from the endogenous neuropeptide N‐acetyl‐aspartyl‐glutamate (NAAG). We report the immunocytochemical localization of NAALADase in rat brain and kidney by using specific anti‐NAALADase antiserum. NAALADase‐immunoreactivity (NAALADase‐IR) was widely distributed, abundant in neuropil, absent from neuronal cytoplasm, and displayed regional heterogeneity. Staining was selectively enriched in several structures previously reported to contain NAAG‐immunoreactivity (NAAG‐IR) including the amygdala, caudate‐putamen, central gray, dorsal raphe, globus pallidus, hippocampus, hypothalamus, locus coerulus, medial and lateral geniculate, olfactory bulb, periaqueductal gray, solitary nucleus, spinal trigeminal nucleus, substantia nigra, superior colliculus, and thalamus. Staining within these structures was enriched in neuropil; no intracellular staining was detected, even after colchicine treatment. In addition, NAALADase‐IR was observed in some NAAG‐containing fiber tracts including the corpus callosum, fornix, habenular commissure, solitary tract, stria medularis, and stria terminals. The co‐localization of NAALADase‐IR and NAAG‐IR support the hypothesis that NAALADase is responsible for the catabolism of NAAG in vivo. NAALADase‐IR was also detected in brain regions that, to date, have not revealed NAAG‐IR, including the bed nucleus of the stria terminalis and the median eminence. In addition, NAALADase‐IR was detected in the rat kidney cortex, specifically in the brush border of the proximal convoluted tubules. The observation that NAALADase‐IR was more widespread than NAAG‐IR suggests that NAALADase may also be involved in the catabolism of other structurally related neural and renal peptides.
Morphine or U‐50,488 suppresses fos protein‐like immunoreactivity in the spinal cord and nucleus tractus solitarii evoked by a noxious visceral stimulus in the rat
Authors: Hammond Donna L. , Presley Robert , Gogas K. R. , Basbaum Allan I.
Published: January 2005

Immunohistochemical visualization of Fos protein, the nuclear phosphoprotein product of the early‐immediate gene c‐fos, permits identification of populations of neurons that are activated in response to a variety of stimuli. This study examined the distribution of Fos‐like immunoreactive (FLI) neurons in the spinal cord and the nucleus tractus solitarii (NTS) of the caudal medulla evoked by a noxious visceral stimulus in the unanesthetized rat. It also compared the inhibition of pain behavior and Fos expression by a m̈‐selective opioid agonist, morphine, and a k‐selective opioid agonist, U‐50,488. Intraperitoneal injection of 3.5% acetic acid in the unanesthetized rat evoked the expression of FLI in a discrete population of spinal cord neurons, the distribution of which closely mirrored the spinal terminations of visceral primary afferents. Specifically, FLI neurons were concentrated in laminae I, IIo, V, VII, and X. Large numbers of Fos‐immunoreactive neurons were also present in the NTS of the caudal medulla, most likely as a result of spinosolitary tract and vagal afferent input. The number of labeled neurons in both the spinal cord and the NTS was significantly correlated with the number of abdominal stretches, a pain behavior measure. Both morphine (1–10 mg/kg s.c.) and U‐50,488 (3–30 mg/kg s.c.) produced a dose‐dependent inhibition of the pain behavior in these animals and a dose‐dependent suppression of the number of FLI neurons in both the spinal cord and in the NTS; complete suppression of FLI neurons was, however, not necessary for the production of antinociception. Furthermore, although equianalgesic doses of morphine and U‐50,488 reduced the number of labelled neurons in the spinal cord to a comparable extent, morphine reduced the number of immunoreactive neurons in the NTS to a greater extent than did U‐50,488. These results suggest that morphine and U‐50,488 have comparable effects on the transmission of visceral nociceptive messages by spinal neurons, but differentially affect the autonomic response to noxious visceral stimuli.
Localization of GABA, glycine, glutamate and tyrosine hydroxylase in the human retina
Authors: Crooks Jill , Kolb Helga
Published: January 2005

A light microscope study using postembedding immunocytochemistry techniques to demonstrate the common neurotransmitter candidates gamma‐aminobutyric acid (GABA), glycine, glutamate, and tyrosine hydroxylase for dopamine has been done on human retina. By using an antiserum to GABA, we found GABA‐immunoreactivity (GABA‐IR) to be primarily in amacrine cells lying in the inner nuclear layer (INL) or displaced to the ganglion cell layer (GCL). A few stained cells in the INL, which are probably interplexiform cells, were observed to project thin processes towards the outer plexiform layer (OPL). There were heavily stained bands of immunoreactivity in strata 1, 3 and 5 of the inner plexiform layer (IPL). An occasional ganglion cell was also GABA‐IR.

By using an antiserum to glycine, stained cells were observed at all levels of the INL. Most of these were amacrines, but a few bipolar cells were also glycine‐IR. Displaced amacrine cells and large‐bodied cells, which are probably ganglion cells, stained in the GCL. The bipolar cells that stained appeared to include both diffuse and midget varieties. The AII amacrine cell of the rod pathway was clearly stained in our material but at a lower intensity than two other amacrine cell types tentatively identified as A8 and A3 or A4. Again, there was stratified staining in the IPL, with strata 2 and 4 being most immunoreactive.

An antiserum to glutamate revealed that most of the neurons of the vertical pathways in the human retina were glutamate‐IR. Rod and cone photoreceptor synaptic endings labeled as did the majority of bipolar and ganglion cells. The rod photoreceptor stained more heavily than the cone photoreceptor in our material. While both midget and diffuse cone bipolar cell types were clearly glutamate‐IR, rod bipolars were not noticeably stained. The most strongly staining glutamate‐IR processes of the IPL lay in the outer half, in sublamina a.

The antiserum to tyrosine hydroxylase (TOH) revealed two different amacrine cell types. Strongly immunoreactive cells (TOH1) had their cell bodies in the INL and their dendrites ramified in a dense plexus in stratum 1 of the IPL. Fine processes arising from their cell bodies or from the stratum 1 plexus passed through the INL to reach the OPL but did not produce long‐ranging ramifications therein. The less immunoreactive amacrines (TOH2) lay in the INL, the center of the IPL or the GCL and emitted thick dendrites that were monostratified in stratum 3 of the IPL.
Postnatal development of type I retinal ganglion cells in hamsters: A lucifer yellow study
Authors: Lau Kam Cheung , So Kwok‐fai , Tay David
Published: January 2005

The postnatal development of a population of superior colliculus projecting retinal ganglion cells with large somata in hamsters aged from postnatal day (P) 4 to adult was studied by the intracellular injection of Lucifer Yellow. This population of cells was interpreted as Type I cells based on their large soma sizes and dendritic morphology resembling that of mature Type I cells.

In addition to the growth of the soma and the dendritic field, transient morphological features such as intraretinal axon collaterals and exuberant dendritic spines, but not somatic spines, were frequently observed on this population of cells in hamsters during development. None of them exhibited any intraretinal axon collaterals after P7. The number of transient spine‐like processes on dendrites increased from P4 onwards to reach a peak at P16, decreased abruptly within a few days after the peak, and stabilised to reach the adult level by P30. These developing cells attained the maximum number of dendritic branches by P16 and there seems to be little, if any, reduction in the number of branch points after this time point. In addition, the length of individual branches of dendrites was not increased excessively during development and then shortened during maturation. Thus, the dendritic remodeling of these cells after P16 seems to be mainly the increase of the length of dendrites and the removal of exuberant dendritic spines.
Central projections of axons from taste hairs on the labellum and tarsi of the blowfly, Phormia regina Meigen
Authors: Edgecomb R. S. , Murdock L. L.
Published: January 2005

Taste hairs are located on the labellum and tarsi of blowflies. These multimodal hairs consist of four functionally distinct chemoreceptors and a mechanoreceptor. By staining selected multimodal hairs, we sought to identify the central projection patterns of multiple and single axons from those hairs. On each side of the labellum there are 11 “largest” hairs (LH). The neurons associated with the anteriormost (LH‐1), posteriormost (LH‐11), and one lateral (LH‐6) hair on the labellum were stained selectively with cobaltous sulfide. The overall projection pattern in the central nervous system (CNS) for axons from LH‐1 and LH‐11 is similar and differs markedly from axons from LH‐6. At least three individual axon‐projection patterns were determined for each labellar hair filled, indicating a partial functional organization for axons from multimodal hairs. One identified axon, the dorsalmost axon, has terminal arborizations that do not differ with the location of its associated hair. Another axon, thicker than the others, projects to a region that is distinct from the four thin axons. Within this region the arborizations of the thick axons occupy different areas depending on the location of their associated hair. Neurons from the largest hairs on the distalmost tarsomere (D5) of each leg were also stained and consisted of one thick and four thin axons. All axons except one thin axon from tarsal D5 hairs terminate in their respective leg neuromeres. The remaining thin axon projects to the suboesophageal ganglion ipsilateral to the hair filled and terminates in the same region as a branch of the labellar dorsalmost axon. These data suggest that axonal arbors from multimodal hairs have a limited functional and somatotopic organization in the blowfly CNS.