bluuebunny/crossref_metadata_2025 huggingface dataset:
Cholinergic neurons within the rat hippocampus: Response to fimbria‐fornix transection
Authors: Blaker S. N. , Armstrong D. M. , Gage F. H.
Published: May 2005

The distribution and morphologic characteristics of choline acetyltransferase (ChAT)‐containing neurons were studied throughout the rostrocaudal extent of the rat hippocampus and in a midline area just dorsal to the dorsal hippocampus. Peroxidase reaction product was observed with the aid of immunohistochemical methods and a high‐titer polyclonal antibody against ChAT, the acetylcholine biosynthetic enzyme. ChAT‐positive cells in the hippocampus were characterized by small, round or oval perikarya with two or more proximal processes. They were located within the caudal and temporal hippocampal formation, predominantly within the subiculum, in the stratum lacunosum moleculare, at the border of the stratum lacunosum moleculare and the stratum radiatum, and in the molecular layer of the dentate gyrus. The cells resembled in morphology the small, bipolar and multipolar neocortical ChAT‐immunoreactive cells. In addition to the hippocampus, ChAT‐positive neurons were observed caudally in a region just above the dorsal hippocampal commissure and rostrally in the columns of the fornix. These cells were large with an oval perikarya and darkly labeled compared to neurons in the hippocampus. They more closely resembled the ChAT‐positive neurons in the midline raphe of the medial septal nucleus.

Examination of the rat hippocampus 2 and 8 weeks following unilateral lesioning of the fimbria‐fornix and supracallosal striae revealed a sparse innervation of ChAT‐positive fibers in the hippocampus ipsilateral to the lesion. ChAT‐labeled neurons in the hippocampus did not appear to sprout in response to the lesion. In contrast, ChAT‐positive cells in the midline did appear to sprout into the medial dorsal subiculum and dorsal medial hippocampus. We conclude that these two populations of cells are distinct with respect to their response to hippocampal denervation and, furthermore, that this distinction may be attributed to a differential response to nerve growth factor.
CRF‐containing neuron systems in the rat hypothalamus: Retrograde tracing and immunohistochemical studies
Authors: Kawano Hitoshi , Daikoku Shigeo , Shibasaki Tamotsu
Published: May 2005

By employing a combination of the immunohistochemistry for rat corticotropin‐releasing factor (rCRF) and retrograde tracing with biotinylated wheat germ agglutinin (b‐WGA) injected into the posterior pituitary (group 1) or into the middle portion of the median eminence (group 2), functionally different populations of CRF neurons were identified in the rat hypothalamus. In the group 1 animals, WGA‐labeling was seen not only in the posterior lobe but also in the intermediate lobe, in which CRF fibers exist. In these animals, WGA‐labeling occurred for almost all large neurons in the anterior commissural, paraventricular (PV), and supraoptic (SO) nuclei, some of the neurons showing a slight immunoreactivity for anti‐rCRF. Conversely, CRF positive neurons appeared in large numbers, some being labeled with WGA, in the caudal periventricular region (CPR), and in the dorsomedial to lateral hypothalamic area (DLH), especially in the latter. In the group 2 animals, WGA was disparsed throughout the subependymal, internal, and external layers of the medial portion of the median eminence, and was taken up by many small cells in the PV, almost half of the cells being immunoreactive for CRF. Slight WGA‐labeling further occurred in some large neurons of the PV and SO, and in some cells of the DLH. It is concluded that hypophysiotropic CRF existing in the external layer of the median eminence originates from small neurons located in the PV, whereas CRF distributed in the posterior and intermediate pituitary originates from the magnocellular PV and SO, and from some neurons in the DLH and CPR.
Organization of the inner plexiform layer of the turtle retina: An electron microscopic study
Authors: Guiloff Gloria D. , Jones Jill , Kolb Helga
Published: May 2005

We have performed a serial‐section electron microscopic study of the inner plexiform layer (IPL) of the retina of the turtle Pseudemys scripta elegans. A qualitative and quantitative assessment of the neuropil of the IPL has been done from photomontages taken from the linear visual streak area and peripheral retina.

Counts of conventional, ribbon, serial, and reciprocal synapses, of ganglion cell dendrites, and of profiles containing large, dense‐cored vesicles were made in five equal‐thickness strata in each montage. Averages of these different features were plotted for each stratum in the linear visual streak and compared with peripheral retina. The trend was for stratum 2 to have the highest overall absolute number of amacrine and bipolar interactions, and also of serial synapses, both in the linear visual streak and in peripheral regions. Stratum 4 tended to have the second‐highest number of synapses. The total number of synapses for the entire thickness of the IPL, regardless of stratification, is higher in the streak than in the periphery. The total amacrine‐to‐bipolar‐synapse ratio in the IPL is the highest of any vertebrate studied to date (11.0 in the streak and 14.5 in the periphery) but the number of synapses\μm2 was found to be similar to that reported for other vertebrates. Amacrine‐to‐amacrine synaptic contacts greatly outnumber other types of synapses; amacrines constitute the principal input to ganglion cells, whereas bipolar output is mainly onto amacrines.

The trend for higher numbers of synaptic interactions in strata 2 and 4 of the streak region of the turtle IPL can be correlated with the branching of small‐field amacrine and ganglion cells described in Golgi studies (Kolb: Philos. Trans. R. Soc. Lond. B 298:355–393, 82). In peripheral retina, branching of large‐field amacrines and a lower number of bipolar pathways may account for the trend for larger numbers of amacrine synapses in strata 2 and 4. Profiles having large, dense‐cored vesicles tend to occur most frequently in strata 1 and 5, which correlates well with the stratification in the IPL of the processes of immunoreactive amacrine cells described in other studies.
Neuropeptide‐ and neurotransmitter‐related immunoreactivities in the developing rat olfactory bulb
Authors: Matsutani Shinji , Senba Emiko , Tohyama Masaya
Published: May 2005

The development of neuropeptide and neurotransmitter‐related immunoreactivities in the rat olfactory bulb were investigated immunohistochemically by using antisera raised against substance P (SP), cholecystokinin‐8 (CCK), neurotensin (NT), leucine‐enkephalin or methionine‐enkephalin‐Arg6‐Gly7‐Leu8 (ENK), somatostatin (SOM), neuropeptide Y (NPY) and tyrosine hydroxylase (TH).

Results obtained for the adult olfactory bulb confirmed previous observations, except for SP‐like immunoreactive (SP‐IR) granule cells in the main olfactory bulb (MOB) and NT‐IR neurons around the modified glomerular complex (MGC) (Teicher et al., Brain Res. 194:530‐535, 1980).

SP‐, CCK‐ and NT‐IR neurons were observed in the MOB of the rat fetus. SP‐IR neurons also appeared in the accessory olfactory bulb (AOB). Among them, NT‐IR neurons in the MOB and SP‐IR neurons in the AOB were observed on embryonic day 16. SP‐ and CCK‐IR neurons in the MOB appeared on embryonic day 18. Most of these neurons were presumed to be projecting neurons. SOM‐, NPY‐, ENK‐ and TH‐IR neurons appeared in the newborn rats. The number and intensity of immunostaining of these neurons continued to increase with age, producing the adult pattern, except for NT‐IR neurons in the MGC and SP‐IR neurons in the mitral cell layer of the AOB, which were more numerous and intensely stained in young animals.
Synaptic organization of anomalous retinal projections to the somatosensory and auditory thalamus: Target‐controlled morphogenesis of axon terminals and synaptic glomeruli
Authors: Campbell Gregor , Frost Douglas O.
Published: May 2005

These experiments examine which morphological features of axon terminals and their synaptic glomeruli are determined by afferent axons, and which by their targets. In normal, adult hamsters, electron microscopy reveals that, with respect to multiple ultrastructural features, the terminals and synaptic glomeruli of retinal afferent axons in the dorsal lateral geniculate nucleus differ from those of ascending auditory and somatosensory afferents in the medial geniculate and ventrobasal nuclei, respectively. These features include: (1) the location of specific sensory axon terminals on the somata and dendrites of their targets neurons, (2) the constitutents of the glomeruli and their synaptic relationships, (3) the number of specific sensory terminal boutons per glomerulus, (4) bouton size, (5) the number of dendritic and somatic appendages contacted by each bouton, and (6) the mitochondrial morphology of the specific sensory afferent boutons.

In order to ascertain which of these features are determined by afferent axons and which by their targets, we subjected newborn Syrian hamsters to surgical procedures known to produce permanent, abnormal retinal projections to the main thalamic auditory (medial geniculate) and somatosensory (ventrobasal) nuclei. When the animals were adults, we examined the terminals and synaptic glomeruli of abnormal retino‐auditory and retino‐somatosensory axons that were anterogradely labeled by intraocular injection of horseradish peroxidase. With respect to all of the preceding features except mitochondrial morphology, the terminals and synaptic glomeruli of retino‐medial geniculate and retino‐ventrobasal axons more nearly resembled those of normal, auditory and somatosensory afferent axons, respectively, than they did those of normal, retino‐lateral geniculate axons.

These results demonstrate that the differentiation of all the features that we have examined, except mitochondrial morphology, is determined by factors in target neurons or their environment. This finding suggests that the differentiation of morphological features involved in contacts among neurons (including the type, number and size of interconnected neuronal elements and the loci at which they contact each other) is responsive to interactions among the connected elements, or between neural elements and their environment (e.g., glia, extracellular matrix), whereas the differentiation of structures reflecting intrinsic functions of individual neuronal elements is not responsive to such interactions.
Ventral striatopallidal parts of the basal ganglia in the rat: I. Neurochemical compartmentation as reflected by the distributions of neurotensin and substance P immunoreactivity
Authors: Zahm D. S. , Heimer L.
Published: May 2005

The distribution of neurotensin immunoreactivity in the basal ganglia of the adult rat was evaluated by studying alternate serial vibratome sections that were exposed to antiserum against neurotensin, substance P, or cholecystokinin. It was observed that a heterogeneous distribution of neurotensin‐immunoreactive fibers and terminals contributes to the neurochemical compartmentation of the ventral pallidum and ventral striatum, and that significant numbers of neurotensin‐immunoreactive neurons occupy striatal districts of the olfactory tubercle, nucleus accumbens, and ventromedial caudate‐putamen. An intense band of pallidal neurotensin immunoreactivity characterizes the medial part of the ventral pallidum adjacent to the nucleus accumbens, whose medial boundary is conveniently defined in sections incubated with cholecystokinin antiserum. Electron microscopic studies showed that the pallidal plexus of neurotensin‐immunoreactive elements consists primarily of boutons, which contact large dendrites in arrangements that in all respects appear to be of the classical striatopallidal variety. A gradual decrese in immunolabel was observed approaching the lateral parts of the ventral pallidum, which display sparse neurotensin immunoreactivity. The results thus indicate the existence of a significant neurotensinergic striatopallidal pathway confined primarily, if not exclusively, to the medial part of the ventral striatopallidal system. The contribution of neurotensin‐immunoreactive fibers and terminals to the compartmentation of ventral striatum is expressed most vividly in their exclusion from clusters of tightly packed medium‐sized neurons, many of which are intensely substance P immunoreactive. Such clusters appear identical with those previously described as rich in opiate receptors and poor in acetylcholinesterase activity. In the ventral striatal region where the nucleus accumbens and ventromedial caudate‐putamen merge, neurotensin‐immunoreactive neurons are organized in clusters. Further rostral in the nucleus accumbens, they are more evenly distributed. Few were found in the dorsolateral quadrant of the neostriatum.
Distribution and morphology of synapses on nonspiking local interneurones in the thoracic nervous system of the locust
Authors: Watson A. H. D. , Burrows M.
Published: May 2005

The structure and distribution of synapses on nonspiking local interneurones in the metathoracic ganglion of the locust was revealed by electron microscopy following intracellular injection of horseradish peroxidase (HRP). Before staining, each interneurone was characterized physiologically as nonspiking and its output effects on motor neurones innervating muscles in a hindleg were investigated. Three nonspiking interneurones of different morphologies, each typical of a previously described population, were selected for detailed study. The first has a dorsal soma and ipsilateral neuropilar branches, the second a ventral soma and ipsilateral branches, and the third a ventral soma and contralateral branches. The somata have few trophospongial invaginations, and most of their volume is occupied by the nucleus. The initial parts of the primary neurites are either wrapped in glia or isolated in tracts from the neuropile and thus do not participte in synaptic interactions. Some of the larger secondary neurites are also wrapped in glia, but others both make and receive synaptic contacts. Output synapses have an array of some 500–1,600 round, agranular vesicles (diameter 47.0 ± 5.7 nm; mean ± S.D., n = 97) associated with a bar‐shaped presynaptic density up to 0.3 μm long. Two postsynaptic processes, whose diameter can vary greatly, are usually associated with each presynaptic density. Processes making input synapses onto nonspiking local interneurones typically contain round, agranular vesicles and often make several contacts within a few microns. Serial reconstructions from one of the interneurones revealed input and output synapses intermingled on the larger processes with outputs dominating by a factor of 3:1, whereas on some of the thinner processes only input synapses are present. In the other two interneurones, however, both input and output synapses are present on the fine branches. No feature of the structure or distribution of synapses observed here on the nonspiking local interneurones distinguishes them from spiking neurones in the same ganglia.
Interstitial cells of cajal in the canine colon: A special communication network at the inner border of the circular muscle
Authors: Berezin I. , Huizinga J. D. , Daniel E. E.
Published: May 2005

The ultrastructure of the region shown to be essential for pacemaking activity of the circular muscle of the canine colon was studied. This region, at the inner border of the circular muscle, consists of a network of several layers of interstitial cells of Cajal type III. These are interconnected to one another and to the adjacent circular muscle cells by numerous gap junctions. Elsewhere in circular muscle, gap junctions are rare and small. In addition, interstitial cells are in close (often < 20 nm) contact with nerve varicosities containing large granular vesicles or sometimes small granular vesicles. The morphology of interstitial cells resembles that of others of type III. It is suggested that this arrangement of interstitial cells, circular smooth muscles, and nerves allows for a tightly coupled network of membrane oscillators to be subject to neural modulation.
Distribution of calcitonin gene‐related peptide immunoreactivity in relation to the rat central somatosensory projection
Authors: Kruger Lawrence , Sternini Catia , Brecha Nicholas C. , Mantyh Patrick W.
Published: May 2005

The distribution of the neuropeptide calcitonin gene‐related peptide (CGRP) was studied in relation to the known subcortical somatosensory pathways and contiguous systems in the central nervous system (CNS) of rats by using peroxidase histochemical methods in order to relate zones of immunoreactivity (IR) to cytoarchitecture. CGRP is the most ubiquitous peptide found to date in sensory ganglion cells: principally small and medium‐size neurons emitting thin axons inferred to be largely nociceptive in function on the basis of the peripheral distribution of their terminals. Its apparent absence in sympathetic axons provides an especially useful sensory marker.

The distribution of CGRP‐IR axons displays remarkable selectivity at each level of the CNS. The trigeminal root distributes axons primarily to the pericornual layers (laminae I and II) of spinal V nucleus caudalis and to subnucleus oralis, evading the subnucleus interpolaris and contributing only few axons to principal V. Although there are only a few CGRP‐IR somata at each level, heavily labeled axon trajectories can be traced to the nuclei of the solitary tract, the parabrachial nuclei, several sectors of the caudal medial thalamus, and the central nucleus of the amygdala. A sector of labeled neuron somata lies contiguous to each of these axon terminal zones, the largest of which is a thalamic nucleus containing cells of distinctive dendritic architecture extending from the periaqueductal gray across the posterior group nuclei to the peripeduncular nucleus, forming a linear array at the mesodiencephalic junction.

The relation of CGRP‐IR axonal distribution to spinothalamic, visceral, and gustatory systems is discussed in the context of a specialized „chemosensory”︁ component of the thin‐fiber somatosensory system.
Catecholaminergic neurons in the ventrolateral medulla and nucleus of the solitary tract in the human
Authors: Arango Victoria , Ruggiero David A. , Callaway Janie L. , Anwar Muhammad , Mann J. John , Reis Donald J.
Published: May 2005

Catecholaminergic neurons in the ventrolateral medulla (VLM) and nucleus of the solitary tract (NTS) are important because of their presumed roles in autonomic regulation, including the tonic and reflex control of arterial pressure, neuroendocrine functions, and the chemosensitivity associated with the ventral medullary surface. However, little is known about the connections of these neurons in the human brain. As a first step in analyzing the functional biochemical anatomy of catecholamine neurons in the human, we used antisera against tyrosine hydroxylase (TH) and phenylethanolamine N‐methyltransferase (PNMT) to localize medullary catecholamine‐containing neurons and processes in the VLM and the NTS.

Cells staining for TH were located throughout the VLM. Most cells staining for TH and PNMT, which are therefore adrenergic, occurred in an area of the VLM probably corresponding to the rostroventrolateral reticular nucleus. Axons of TH‐immunoreactive neurons in the VLM projected (1) dorsally, in a series of parallel transtegmental trajectories, toward the dorsomedial reticular formation, the NTS, and vagal motor nucleus, (2) longitudinally, through the central tegmental field, as fascicles running parallel to the neuraxis, (3) ventrolaterally toward the ventral surface (VS) of the rostral VLM where they appeared to terminate, and (4) medially into the raphe, where they arborized. Similar systems of fibers were labeled for PNMT; the longitudinal bundles of PNMT‐labeled axons were limited to the principal tegmental bundle and concentrated dorsally. Fibers containing PNMT were also identified in the medullary raphe, on the medullary ventral surface, and contacting intraparenchymal blood vessels. In the NTS, neurons exhibited immunoreactivity to both TH and PNMT: Four principal subgroups of TH‐immunoreactive neurons were seen: a ventral, an intermediate, a medial, and a dorsal group. Perikarya containing PNMT were restricted to the dorsolateral aspect of the NTS. Processes containing TH and PNMT immunoreactivity were identified in the medial and dorsolateral NTS; others appeared to project between the NTS and the VLM and within the solitary tract.

The presence of catecholaminergic fibers of the VLM interconnecting with the NTS, raphe, intraparenchymal microvessels, VS, and possibly the spinal cord suggests that the autonomic and chemoreceptor functions attributed to these neurons also may apply to the human.
Distribution of monoamine‐synthesizing neurons in the human medulla oblongata
Authors: Halliday G. M. , Li Y. W. , Joh T. H. , Cotton R. G. H. , Howe P. R. C. , Geffen L. B. , Blessing W. W.
Published: May 2005

We have employed immunohistochemical and morphometric procedures to study the distribution of monoamine‐synthesizing neurons in the medulla oblongata of the adult human, utilizing antibodies to tyrosine hydroxylase (TH), phenylethanolamine N‐methyltransferase (PNMT), and phenylalanine hydroxylase (PH8). In the human brain, the antigen with which PH8 reacts occurs within neurons that presumably synthesize serotonin (Haan et al., ′87). Neurons containing these antigens were mapped and counted in successive coronal sections with the aid of a computer‐assisted procedure. The results indicate that monoamine‐synthesizing neurons are distributed in the human brain in patterns broadly similar to those described for other species.

TH‐immunoreactive cells extended caudorostrally for approximately 32 mm commencing at the spinomedullary junction and ending 8 mm caudal to the pontomedullary junction. In coronal sections these TH‐immunoreactive neurons were seen in the lateral medulla dorsal to the inferior olive extending in a continuous band to the dorsomedial medulla. Above the obex the majority of these cells apparently synthesize adrenaline since many PNMT‐immunoreactive cells were also found in this region. There were few or no PNMT‐immunoreactive cells caudal to the obex, indicating that the TH‐immunoreactive cells in this region synthesize either noradrenaline or dopamine. Approximately 65% of these TH‐immunoreactive neurons contained melanin pigment, whereas few or no PNMT‐immunoreactive cells contained melanin pigment.

PH8‐immunoreactive cells extended throughout the rostrocaudal extent of the medulla oblongata (approximately 40 mm). In coronal sections the majority were found in the medullary raphe nuclei. However, many cells throughout the rostrocaudal extent of the medulla were found laterally intermingled with catecholamine‐synthesizing neurons. Occasional neurons in the lateral medulla appeared to contain both PH8‐ and TH‐immunoreactivity.
Immunocytochemical studies of the distribution of acetylcholine in the crayfish brain
Authors: Wang‐Bennett Lolin T. , Sovan Marie‐Laure , Glantz Raymon M.
Published: May 2005

A number of studies indicate that acetylcholine is an important transmitter in most crustacean primary afferents and in at least several central pathways. Little is known, however, regarding the structure or distribution of cholinergio pathways in the central nervous system. The recent introduction of antibodies to choline‐protein conjugates provides a potentially powerful means for localizing putative cholinergic neurons and pathways in the nervous system. Acetylcholine was localized with immunocytochemical procedures in the axons and terminals of cephalic primary afferents and in interneurons of the crayfish brain. The most intensely reactive loci were the primary sensory neuropiles, which contain the terminals of the statocyst afferents (parolfactory lobes) and antennal afferents (antennal lobe). These results are generally in accord with previous findings based upon choline uptake and enzyme assay in lobster cephalic nerves. We also found evidence consistent with the presence of acetylcholine in the globular interneurons of the accessory lobe and in descending interneurons which originate in the dorsal medial and anterior clusters of the protocerebrum. The axons of several neurons in the circumesophageal connective (descending interneurons and primary afferents) are also reactive to the choline antibody.
Putative cholinergic projections from the nucleus isthmi and the nucleus reticularis mesencephali to the optic tectum in the goldfish (Carassius auratus)
Authors: Zottoli Steven J. , Rhodes Kenneth J. , Corrodi J. Gregory , Mufson Elliott J.
Published: May 2005

The nucleus isthmi of fish and amphibians has reciprocal connections with the optic tectum, and biochemical studies suggest that it may provide a major cholinergic input to the tectum. In goldfish, we have combined immunohistochemical staining for choline acetyltransferase with retrograde labeling of nucleus isthmi neurons after tectal injections of horseradish peroxidase.

Seven fish received tectal horseradish peroxidase injections, and brain tissue from these animals was subsequently processed for the simultaneous visualization of horseradish peroxidase and choline acetyltransferase. In many nucleus isthmi neurons the dense horseradish peroxidase label obscured the choline acetyltransferase reaction product but horseradish peroxidase and choline acetyltransferase were colocalized in 54 cells from nine nuclei isthmi.

The somata of nucleus reticularis mesencephali neurons stained so intensely for choline acetyltransferase that we could not determine whether they were labelled also with horseradish peroxidase. However, the large choline acetyltransferase‐immunoreactive axons of nucleus reticularis mesencephali neurons stained intensely enough for us to follow them rostrally; the axons are clustered together until the level of the rostral tectum where two groupings form: one travels into the tectum and the other travels rostroventrally to cross the midline and enter the contralateral diencephalic preoptic area.

We conclude therefore that cholinergic neurons project to the optic tectum from the nucleus isthmi as well as nucleus reticularis mesencephali in goldfish.
Somatosensory and auditory relay nucleus in the rostral part of the ventrolateral medulla: A morphological study in the cat
Authors: Kamiya Hiroto , Itoh Kazuo , Yasui Yukihiko , Ino Tadashi , Mizuno Noboru
Published: May 2005

A nucleus that possibly relays both somatosensory and auditory information was identified in the well‐known autonomic control region in the rostral part of the ventrolateral medulla (RVL) of the cat by four sets of experiments using the WGA‐HRP (wheat germ agglutinin—horseradish peroxidase conjugate) method. First, after injecting WGA‐HRP into the dorsal column nuclei (DCN), anterograde and retrograde labeling was found bilaterally within and around a small cluster of medium‐sized neurons in the RVL; more labeled neuronal cell bodies were seen in the cluster ipsilateral to the injection than in the contralateral cluster, whereas labeled axon terminals were distributed more densely on the contralateral side than on the ipsilateral side. The neuronal cluster in the RVL was located close to the ventrolateral surface of the medulla oblongata, constituting a short, slender column extending from a caudal level of the facial nucleus to the level of the rostral one‐third of the inferior olive. This cluster of neurons was named the ventrolateral medullary nucleus (VLMN).

In the second set of experiments, WGA‐HRP was injected into the VLMN. Labeled neuronal cell bodies were seen in the reticular zone of the DCN bilaterally, with a slight dominance on the side contralateral to the injection, and further in the anteroventral division of the cochlear nuclei (CN) bilaterally, with a predominantly contralateral distribution. Labeled presumed axon terminals were seen bilaterally not only in the DCN and granular layer of the CN but also in the intercollicular region (IcR), lateral division of the posterior group of the thalamus (Pol), and medial geniculate nuclei (MG). Labeled terminals in the DCN were more numerous on the side ipsilateral to the injection than on the contralateral side, whereas those in other regions were distributed with a clear‐cut contralateral dominance.

In the third set of experiments, WGA‐HRP injection into the CN resulted in anterograde and retrograde labeling in the VLMN. The labeling was bilateral, but more marked in the VLMN contralateral to the injection.

In the fourth set of experiments, after WGA‐HRP injection into the IcR, Pol, or MG, labeled neuronal cell bodies were located in the VLMN bilaterally with a dominant contralateral distribution.

The results indicate that the VLMN possibly relays somatosensory and auditory information from the reticular zone of the DCN and anteroventral division of the CN to the IcR, Pol, and MG.
Immunocytochemical localization of glutamate decarboxylase in the rat basolateral amygdaloid nucleus, with special reference to GABAergic innervation of amygdalostriatal projection neurons
Authors: Carlsen Jørn
Published: May 2005

Glutamate decarboxylase (GAD) immunohistochemistry was employed at the light and electron microscopic levels to localize GABAergic structures in the basolateral amygdaloid nucleus (BL).

The GAD‐immunoreactive (GAD‐IR) staining pattern consisted of punctate structures and a morphologically diverse group of GAD‐IR neurons. At the electron microscopic level many of these punctate structures were found to make symmetrical synaptic contacts with cell bodies as well as distal parts of unlabeled, presumably projection and nonprojection, neurons. In addition, GAD‐immunoreactive neurons were identified in the BL, and they had the ultrastructural characteristics of local circuit or intrinsic neurons and were not retrogradely labeled with HRP following ventral striatal injections. Some of these GAD‐immunoreactive neurons were contacted by GABAergic boutons, forming symmetrical synaptic contacts.

GABAergic innervation of amygdaloid projection neurons in the BL was identified by combining GAD immunohistochemistry with Golgi impregnation and retrograde tracing of horseradish peroxidase (HRP) following injections of the tracer in the olfactory‐tubercle‐related parts of the ventral striatum. Amygdalostriatal projection neurons in the BL were observed to be in continuity with neurons in the piriform cortex which project to the ventral striatum. The results provide direct evidence for the presence of GAD‐IR boutons in the BL making synaptic contacts with identified amygdalostriatal projection neurons.

The present study provides direct anatomical evidence for the physiological observation that GABA exhibits a powerful regulation of the amygdaloid projection neurons in the BL and lends further support to the concept of a corticallike functional organization of the basolateral amygdala.
Galanin hyperinnervates surviving neurons of the human basal nucleus of meynert in dementias of alzheimer's and parkinson's disease: A hypothesis for the role of galanin in accentuating cholinergic dysfunction in dementia
Authors: Chan‐Palay V.
Published: May 2005

This study summarizes the findings from postmortem examination of the brains of 22 control cases without neurological deficit, 12 cases of senile dementia of the Alzheimer type (SDAT), and nine cases of Parkinson's disease (three without signs of intellectual deterioration, four with dementia, and two atypical with dementia nonresponsive to L‐dopa treatment). The aim of this study was to find the similarities and differences in galanin innervation of the cholinergic basal nucleus neurons in these dementing disorders as compared with controls. Immunocytochemistry with antibodies against galanin peptide and against choline acetyltransferase was applied on perfused brain preparations. Galanin peptide is present in the basal nucleus of Meynert neuron networks in the normal human brain: in local circuit neurons, in a number of galanin/cholinergic neurons, and in a feedback circuit (via collaterals) that terminate upon the cholinergic neuronal somata and dendrites. Thus, peptide galanin circuits could function as powerful modulators of the activities of basal nucleus cholinergic neurons, both within the basal forebrain and in their wider projections to the neocortex and amygdala. As galanin has been shown to inhibit cholinergic activity, this galanin network could suppress the activity of cholinergic neurons. In SDAT, there is a primary loss of cholinergic neurons compounded by a secondary reaction of the remaining cholinergic neurons to the terminal degeneration in the cortex. Galanin networks demonstrate an inverse relationship to the cholinergic cell loss. Galanin axons hypertrophy and hyperinnervate the remaining cholinergic neurons. In Parkinson's disease the loss of cholinergic neurons is accentuated by the presence of dementia: the hypertrophy of the galanin axonal networks on cholinergic neurons is dramatic in Parkinson's disease with dementia.

These observations throw new light on the neurotransmitter bases for these dementias. Galanin controls cholinergic mechanisms in the basal nucleus of Meynert, and dementia is accompanied by augmentation of galanin innervation onto an already depressed population of cholinergic neurons, thus demonstrating an appreciable amount of plasticity even in aged brain. These findings suggest that the present therapy of cholinergic enhancement as a means to retard intellectual deterioration can by itself have little effect at best, in these dementias. The suppressive effect of galanin peptide has to be reduced or curtailed, perhaps concurrently with the treatment of the cholinergic deficit. It is suggested that the curtailment of galanin activity might be achieved by galanin peptide antagonists or by small organic compounds that react with the galanin receptor and that these may constitute new therapeutic approaches toward dementia.
Neuronal localization of prosomatostatin mRNA in the rat brain with in situ hybridization histochemistry
Authors: Fitzpatrick‐MceElligott Sandra , Card J. Patrick , Lewis Michael E. , Baldino Frank
Published: May 2005

Individual neurons containing prosomatostatin mRNA were identified with in situ hybridization histochemistry. Our results demonstrate a widespread distribution of prosomatostatin mRNA in several regions of the rat central nervous system. Neurons containing this transcript were most abundant in the anterior olfactory nucleus, hypothalamus, hippocampus, and amygdala as well as in all regions of the cerebral cortex. Moreover, the distribution of mRNA‐containing perikarya was coextensive with the location of neurons containing somatostatin‐like immunoreactivity in all areas of the brain examined. Somatostatin neurons varied in their morphology and amount of hybridization signal from region to region. The widespread distribution and regional variations in neuronal morphology and the amount of hybridization signal are consistent with a neurotransmitter and/or a neuromodulator role for somatostatin in addition to its well‐established neuroendocrine role. These results demonstrate that both the peptide and its mRNA are found in perikarya in the same areas and that they are therefore the sites of synthesis for somatostatin.
Connections of the superior olivary complex in the rufous horseshoe bat Rhinolophus rouxi
Authors: Casseday J. H. , Covey E. , Vater M.
Published: May 2005

In the rufous horseshoe bat (Rhinolophus rouxi), the superior olivary complex contains four main divisions. In comparison with other species, the most lateral division is clearly homologous to the lateral superior olive (LSO); the most medial division is homologous to the medial nucleus of the trapezoid body (MNTB). Lying between these landmarks, in approximately the position of the medial superior olive (MSO) of other mammals, are two additional divisions that are cytoarchitecturally distinct from one another yet do not greatly resemble the MSO of nonecholocating mammals such as the cat. We refer to these nuclei as the dorsal medial superior olive (DMSO) and the ventral medial superior olive (VMSO). We examined the afferent and efferent connections of all of these cell groups with retrograde and anterograde transport of WGA‐HRP from the superior olivary complex. In the same animals we recorded the binaural response properties of single units in the superior olivary complex. Virtually all units recorded in LSO were excitatory to the ipsilateral ear and inhibitory to the contralateral ear (EI); all of the units sampled in the MNTB and most of those sampled in the VMSO responded only to the contralateral ear (OE). In DMSO the binaural properties of units were varied: the number of units that were inhibitory to the ipsilateral ear and excitatory to the contralateral ear (IE) was about equal to the number of units excitatory to both ears (EE); a few units had OE responses; no units had EI responses. Connectional correlates for these binaural response properties are seen in the patterns of retrograde transport from WGA‐HRP injections in the divisions of the superior olive. The LSO receives projections from the ipsilateral cochlear nucleus and MNTB; MNTB receives projections from the contralateral cochlear nucleus. The DMSO and VMSO both receive bilateral projections from the cochlear nuclei. The results of retrograde and anterograde transport suggest that VMSO, in addition, receives projections from the ipsilateral MNTB. The LSO, DMSO, and VMSO all project to the ventral two‐thirds of the central nucleus of the inferior colliculus, and their targets are approximately coextensive. However, the LSO projects bilaterally to the inferior colliculus, whereas the medial cell groups project mainly ipsilaterally.
Effects of hydroxyurea parallel the effects of radiation in developing olfactory glomeruli in insects
Authors: Oland Lynne A. , Tolbert Leslie P.
Published: May 2005

Previous observations (Oland and Tolbert: J. Comp. Neurol. 255:196–207, '87, Soc. Neurosci. Abstr. 13:1144, '87; Oland et al.: J. Neurosci. 8:353–367, '88) have provided evidence that the afferent‐axon‐induced development of synaptic glomeruli in the antennal lobe of the moth Manduca sexta depends upon an interaction between ingrowing sensory axons and the glial cells of the antennal lobe. In order to differentiate between the roles of glial cells and of afferent axons on the partitioning of the lobe into glomeruli, we have used the antimitotic agent hydroxyurea to produce lobes deficient in glial cells but retaining sensory input. The resulting lobes were analyzed in the light and electron microscopes, and the integrity of their antennal input was evaluated by examining the gross and microscopic structure of the antennae, the number of antennal afferent axons, and electroantennogram responses to odors. Our results with hydroxyurea show that in treated animals with adequate antennal input the degree to which the antennallobe neuropil becomes glomerular varies with the number of glial cells remaining in the lobe; when less than approximately one‐quarter of the normal glial complement is present, glomeruli do not develop at all. These experiments complement and extend previous experiments in which the number of glial cells was reduced with radiation (Oland et al.: J. Neurosci. 8:353–367, '88). The fact that the present results mimic the previous results with radiation strongly suggest that glial cells do mediate the afferent‐axon‐induced formation of olfactory glomeruli in the moth.
Ultrastructural organization of the retino‐pretecto‐olivary pathway in the rabbit: A combined WGA‐HRP tracing and gaba immunocytochemical study
Authors: Cardozo Bob Nunes , Van Der Want Johannes
Published: May 2005

The ultrastructural organization of the pretecto‐olivary projection neurons within the nucleus of the optic tract and dorsal terminal accessory optic nucleus of rabbits was studied by using anti‐GABA immunolabelling and retrograde transport of WGA‐HRP. GABA‐like immunoreactivity was determined with a postembedding colloidal gold technique. WGA‐HRP was injected in the dorsal cap of the inferior olive. The WGA‐HRP‐labelled neurons were incubated with gold‐substituted silver peroxidase.

Neurons projecting to the inferior olive had large to medium‐sized cell bodies and were GABA negative. In the nucleus of the optic tract, projection neurons are found in the rostral parts, while the majority of the local GABAergic interneurons are mainly found in the caudal parts. In the dorsal terminal nucleus both types of neurons are intermingled. The projection neurons were frequently in synaptic contact by GABAergic terminals. These neurons also receive retinal afferents indicating the existence of a two‐step synaptic connection from the retina to the inferior olive. It is suggested that this class of projection neurons forms the “direction‐selective” neurons that can be antidromically stimulated from the inferior olive.

The GABAergic terminals on the identified projection neurons are of axonal origin (F‐terminals), whereas presynaptic dendrites of interneurons (P‐terminals) were seldom observed to be in synaptic contact with retrogradely labelled profiles. The strong input of GABA on direction‐selective neurons indicates that GABA is directly involved in modulating retinal signals to the inferior olive.
Ocular dominance plasticity and developmental changes of 5′‐nucleotidase distributions in the kitten visual cortex
Authors: Schoen Siegfried W. , Leutenecker Bärbel , Kreutzberg Georg W. , Singer Wolf
Published: May 2005

The distribution of the adenosine‐producing ecto‐enzyme 5′‐nucleotidase was investigated histochemically in the visual cortex of normally reared and monocularly deprived kittens and cats.

In normally reared kittens aged between 11 to 44 days, 5′‐nucleotidase activity formed a band of intense neuropil staining throughout conical layer IV of areas 17 and 18. The other layers were almost devoid of reaction product. Between the 4th and 6th week, this band had a patchy appearance in area 17, the center‐to‐center spacing of 5′‐nucleotidase patches being approximately 1 mm.

Monocular enucleation accentuated these patches of enhanced 5′‐nucleotidase activity or made them reappear at developmental stages at which they had normally faded. Simultaneous visualization of ocular dominance columns by transneuronal transport of intraocularly injected 3H‐proline showed that the patches of enhanced 5′‐nucleotidase activity coincided with the territories of afferents from the intact eye.

With increasing age and normal visual development, the patches disappeared and 5′‐nucleotidase activity spread to the supra‐ and infragranular layers. The adult pattern was characterized by dense staining of all cortical laminae in both areas 17 and 18 and was established at about 8 weeks of age. At approximately 7 weeks of age, when the patches in layer IV had disappeared in the course of normal development, monocular enucleation caused a reappearance of the discontinuous pattern of 5′‐nucleotidase activity in layer IV.

These results reveal a close relation between the distribution of 5′‐nucleotidase and the time course of the developmental phase during which the visual cortex is susceptible to experience‐dependent alterations. As suggested by the correlation between sites of enzyme activity and eye dominance columns, the expression of 5′‐nucleotidase patches in layer IV appears to be associated with the remodelling of ocular dominance territories that occurs both in normal development and after manipulation of afferent retinal input Thus, 5′‐nucleotidase is likely to serve a function in activity‐dependent modifications of cortical circuitry. Moreover, 5′‐nucleotidase activity is the only endogenous marker known to date that exhibits a columnar pattern in cat visual cortex.
Retrograde transport of [3H]glycine from the cochlear nucleus to the superior olive in the guinea pig
Authors: Benson C. G. , Potashner S. J.
Published: May 2005

The origins of descending glycinergic projections to the guinea pig cochlear nucleus were investigated using retrograde labelling techniques. To identify the cell groups that provide descending projections to the cochlear nucleus, horseradish peroxidase, a nonspecific retrograde neuronal marker, was injected into the cochlear nucleus. After 24 or 48 hours, labelled cell bodies were evident bilaterally in all of the periolivary nuclei that surround the lateral and medial superior olive. The largest numbers of labelled neurons were located in the ventral nucleus of the trapezoid body bilaterally and in the lateral nucleus of the trapezoid body and dorsal periolivary nucleus ipsilaterally. Labelled cells were also present in the inferior colliculus bilaterally and in the contralateral cochlear nucleus. [3H]Glycine was employed as a retrograde tracer to identify the cell groups providing descending glycinergic projections to the cochlear nucleus. Three to 48 hours after injection of 19, 190, or 380 μM [3H]glycine into the cochlear nucleus, retrogradely labelled cell bodies were observed ipsilaterally in all of the periolivary nuclei. No labelled neurons were found in the inferior colliculus. After injections of the highest concentration of [3H]glycine, labelled cells were also found contralaterally in the ventral and lateral nuclei of the trapezoid body and also in the contralateral cochlear nucleus. We conclude that descending glycinergic projections to the cochlear nucleus originate mostly in ipsilateral periolivary cell groups. Minor glycinergic projections originate from the contralateral cochlear nucleus and also from the contralateral ventral and lateral nuclei of the trapezoid body.
Projections of the medial cerebellar nucleus to oculomotor‐related midbrain areas in the rat: An anterograde and retrograde HRP study
Authors: Gonzalo‐Ruiz A. , Leichnetz G. R. , Hardy S. G. P.
Published: May 2005

The mesencephalic projections of the medial cerebellar nucleus (MCN) were studied in the rat by using the method of anterograde transport of wheat germ agglutinin/horseradish peroxidase to establish connections of the nucleus with oculomotor‐related nuclei as a basis for its proposed role in eye movement. The principal targets of projections were the supraoculomotor ventral periaqueductal gray (PAG) and lateral PAG, and paraoculomotor cell groups (nucleus of Darkschewitsch and medial accessory nucleus of Bechterew). Lesser projections were observed to the intermediate layer of the superior colliculus, nucleus of the posterior commissure, and prerubral field. Following transcannular HRP gel implants into the oculomotor complex that included adjacent paraoculomotor nuclei, the largest number of retrogradely labeled cells was found in the caudal MCN. The findings suggest that the caudal MCN in the rat, like the primate fastigial nucleus, is involved in the control of eye movement.
Light microscope study of the coexistence of GABA‐like and glycine‐like immunoreactivities in the spinal cord of the rat
Authors: Todd Andrew J. , Sullivan Anne C.
Published: May 2005

The distributions of GABA‐like and glycine‐like immunoreactivities in the rat spinal cord were compared by using postembedding immunohistochemistry on semithin sections. In laminae I, II, and III, the proportions of GABA immunoreactive cells were 28%, 31%, and 46%, respectively, whereas for glycine immunoreactive cells the proportions were 9%,14%, and 30% Nearly all of the glycine immunoreactive cells in this area were also immunoreactive with the anti‐GABA antiserum. In lamina II, some Golgi‐stained islet cells were glycine immunoreactive, whereas others were not.

Immunoreactive cell bodies were also present in the remainder of the grey matter. Some of these reacted with anti‐GABA or antiglycine antiserum; others showed immunoreactivity with both antisera. Immunoreactive axons were found in the ventral and lateral funiculi of the white matter. Many large axons reacted with antiglycine antiserum, whereas GABA‐immunoreactive axons were mostly of small diameter. Some large and small axons showed both types of immunoreactivity.

These results suggest that the inhibitory neurotransmitters GABA and glycine coexist within cell bodies and axons in the rat spinal cord.