bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vasoactive intestinal peptide in the hypothalamohypophysial system of the mongolian gerbil
Authors: Mikkelsen Jens D. , Møller Morten 
Published: May 2005

AbstractBy use of the indirect peroxidase‐antiperoxidase immunohistochemical technique the location of perikarya and fibers exhibiting vasoactive intestinal peptide (VIP)‐like immunoreactivity was investigated in the hypothalamus and the posterior pituitary of the Mongolian gerbil (Meriones unguiculatus), because of the involvement of VIP in several neuroendocrine functions.In the hypothalamus, a large number of VIP‐immunoreactive perikarya were seen in the ventromedial part of the suprachiasmatic nucleus. Few VIP‐positive perikarya were present in the periventricular, paraventricular, and supraoptic nuclei and in the medial preoptic area close to the third ventricle. The perikarya in the paraventricular nucleus projected fibers in the direction of the median eminence. In the median eminence VIP‐immunoreactive fibers were present especially in the external layer, concentrated in the perivascular spaces surrounding the portal vessels. Scattered VIP‐immunoreactive fibers were also located in the internal layer of the median eminence as well as in the posterior pituitary lobe. In the latter, large VIP‐positive Herring‐like bodies were observed.With receptor autoradiography a large number of grains were demonstrated in the anterior pituitary lobe in contrast to the neural lobe.Many VIP‐positive fibers and some perikarya were observed within the ependyma covering the rostroventral part of the third ventricle. Finally, fibers exhibiting VIP immunoreactivity were also seen in the organum vasculosum laminae terminalis (OVLT).These results support the concept that VIP is released into the portal vascular system and plays a role in the regulation of the activity of the anterior pituitary. In addition, VIP might be secreted into the cerebrospinal fluid of the third ventricle.
Organization of spinocerebellar projection map in three types of agranular cerebellum: Purkinje cells vs. granule cells as organizer element
Authors: Nunes M. L. Arsénio , Sotelo C. , Wehrlé R. 
Published: May 2005

AbstractThe organization of the spinocerebellar projection was analysed by the anterograde axonal WGA‐HRP (horseradish peroxidase‐wheat germ agglutinin conjugate) tracing method in three different types of agranular cerebellar cortex either induced experimentally by X‐irradiation or occurring spontaneously in weaver (wv/wv) and staggerer (sg/sg) mutant mice.The results of this study show that in the X‐irradiated rat and weaver mouse, in both of which the granule cells are directly affected and die early in development, the spinal axons reproduce, with few differences, the normal spinocerebellar pattern. Conversely, in staggerer mouse, in which the Purkinje cells are intrinsically affected and granule neurons do not seem to be primarily perturbed by the staggerer gene action, the spinocerebellar organization is severely modified. These findings appear somewhat paradoxical because if granule cells, the synaptic targets of mossy spinocerebellar fibers, were necessary for the organization of spinocerebellar projection, the staggerer cerebellum would exhibit a much more normal projectional map than the weaver and the X‐irradiated cerebella. It is, therefore, obvious that granule cells, and even specific synaptogenesis, are not essential for the establishment of the normal spinocerebellar topography. On the other hand, the fact that the Purkinje cells are primarily affected in the unique agranular cortex in which the spinocerebellar organization is severely modified suggests that these neurons could be the main element in the organization of the spinocerebellar projection map. This hypothesis is discussed in correlation with already‐reported findings on the zonation of the cerebellar cortex by biochemically different clusters of Purkinje cells.
Physiological and morphological characterization of OFF‐center amacrine cells in the turtle retina
Authors: Ammermüller Josef , Weiler Reto 
Published: May 2005

AbstractOFF‐center amacrine cells were intracellularly recorded and stained with Lucifer yellow to investigate the cell correlations between photoresponses and morphological features.All OFF‐amacrine cells were monostratified and branched within the outer half of the inner plexiform layer. In the flat‐mounted retina, however, three distinct morphological classes were distinguishable, which correlated with observed physiological differences.Class 1 consisted of wide‐field, stellate amacrine cells with long, thin processes, which branched only close to the soma. The diameter of the circular dendritic field ranged from 0.8 mm to 2.0 mm. Their photoresponse to spot stimulation was a hyperpolarization during light‐ON and a small depolarization after light‐OFF. They showed strong antagonistic center‐surround organization of the receptive field. Its size was approximately equal to the dendritic field size.Class 2 consisted of wide‐field, giant amacrine cells with a „central”︁ dendritic field formed by thick dendrites, and a „peripheral”︁ dendritic field formed by a few long and thin, „axonlike”︁ processes. The shape of the dendritic field was elongated, with the long axis parallel to the visual streak. Their receptive field size was considerably smaller than their dendritic field size, which was several millimeters of diameter along the long axis. Their photoresponse to spot stimulation was a fast depolarization after light‐OFF, and about 50% of these cells showed strong antagonistic center‐surround receptive field organization.Class 3 consisted of small‐ or medium‐field, „starburstlike”︁ amacrine cells with circular dendritic fields of 0.1 mm to 0.6 mm diameter. Their fine, beaded dendrites branched predominantly in the distal parts of the dendritic field. Their photoresponses to light were similar to the of the giant amacrine cells; however, their receptive field size exceeded the dendritic field size.Radial sections of the retinas with labeled cells were incubated in antisera to reveal the putative transmitters GABA, serotonin, neurotensin, met‐enkephalin and glucagon. No immunoreactivity with these antisera was detected within the stained OFF‐center amacrine cells.
The histaminergic system in the guinea pig central nervous system: An immunocytochemical mapping study using an antiserum against histamine
Authors: Airaksinen Matti S. , Panula Pertti 
Published: May 2005

AbstractUsing an antiserum against conjugated histamine we mapped the histaminergic somata and their fiber projection areas in carbodiimide‐fixed guinea pig central nervous system. The neurons were large and they were found exclusively in the posterior hypothalamus, as in the rat, but in the guinea pig they were more numerous and distributed more widely in a thin layer around the posterior mammillary nucleus, scattered between and within the medial mammillary nuclei, and in a dense cell cluster emerging from the caudal magnocellular nucleus and extending to the medial preoptic area.The density of histamine‐immunopositive fibers was very high in the olfactory tubercle, diagonal band of Broca, nucleus accumbens, medial and cortical amygdaloid nuclei, periventricular and lateral basal hypothalamus, paraventricular thalamus, and in a region from the medial central gray to the locus coeruleus and the parabrachial nucleus. Dense fiber networks were found in the piriform and entorhinal cortex, septum, dentate gyrus, and subiculum, in most parts of amygdala, and in many areas of the hypothalamus, thalamus, substantia nigra, raphe nuclei, inferior olivary, solitary tract and medial vestibular nuclei, and neurohypophysis. Medium fiber density was observed in the internal layers of the olfactory bulb, anterior olfactory nuclei, neocortex, zone CA1 of hippocampus, and many midbrain and hindbrainregions. Low density was present in the outer layers of the olfactory bulb, other parts of hippocampus, the globus pallidus, most of the caudatus‐putamen, the cerebellar cortex, and the dorsal horn of the spinal cord. The retina and most of the myelinated white matter had single or no histaminergic fibers.It may be concluded from the results that most fibers seem to follow a ventromedial route to the forebrain, reaching the amygdala ventral to the medial forebrain bundle, the hippocampus via subiculum, and the hindbrain structures via the medial central gray. As compared to the rat, the fiber projections in the guinea pig brain were denser, particularly in the hippocampus, thalamus, pons‐medulla, and neurohypophysis. The fiber densities in various regions of the guinea pig brain are compared to histamine receptor densities and the possible functions of histamine are discussed.
GABA‐immunoreactive synaptic boutons in the rat basal forebrain: Comparison of neurons that project to the neocortex with pallidosubthalamic neurons
Authors: Ingham C. A. , Bolam J. P. , Smith A. D. 
Published: May 2005

AbstractAlthough the basal forebrain, including the globus pallidus, contains a high concentration of gamma‐aminobutyric acid (GABA), it is not known whether all types of neuron in the globus pallidus receive GABAergic synaptic input. We have studied two types of neuron: typical pallidal neurons that project to the subthalamic nucleus and magnocellular neurons which are found in the medial and ventral borders of the globus and project to the sensorimotor cortex.The postembedding immunogold staining of endogenous GABA revealed many preterminal axons and synaptic boutons that contained GABA immunoreactivity. Neurons that projected to the neocortex were postsynaptic to some of the GABA‐immunoreactive boutons, the majority of which formed symmetrical membrane specializations. From a series of random electron micrographs through the perikarya and proximal dendrites of such retrogradely labelled neurons the density of GABA‐containing afferent synaptic boutons was estimated to be 0.58 GABA‐containing boutons per 100 μm of neuronal membrane. The GABA‐containing boutons accounted for 72% of the total afferent input in the proximal regions of the pallidocortical neurons examined. The pallidosubthalamic neurons received many more afferent boutons than did the cortically projecting neurons, a high proportion (80.4%) of which were immunoreactive for GABA. The density of GABA‐containing boutons in contact with pallidosubthalamic neurons was 8.9 boutons per 100 μm.It is concluded that cortically projecting basal forebrain neurons, that are probably cholinergic, are innervated by GABA‐containing afferent boutons. However, pallidosubthalamic neurons in the same part of the basal forebrain are much more densely innervated by GABA‐containing boutons.
Ultrastructure and synaptic organization of luteinizing hormone‐releasing hormone (LHRH) neurons in the anestrous ewe
Authors: Lehman Michael N. , Karsch Fred J. , Robinson Jane E. , Silverman Ann‐Judith 
Published: May 2005

AbstractElectron microscopic immunocytochemistry was employed to examine the ultrastructure of luteinizing hormone‐releasing hormone (LHRH) neurons and their projections to the median eminence in the sheep brain. LHRH perikarya in the preoptic area of anestrous ewes are less innervated than nonimmunoreactive cells in the same sections, but still receive numerous synaptic inputs, primarily onto distal dendrites and small somatic protuberances. Axon terminals synapsing upon LHRH cells contain a combination of clear spherical vesicles and larger dense‐core vesicles. Interestingly, LHRH cell bodies and dendrites are almost entirely surrounded by glial processes. These processes intervene between immunoreactive elements that at a light microscopic level appear to be in contact with each other. Thus no evidence was obtained at the ultrastructural level for contacts among adjacent LHRH cells or dendrites in the preoptic area. Synaptic inputs onto LHRH cell bodies and dendrites appear to penetrate this glial sheath. In contrast to the absence of contacts among LHRH cells in the preoptic area, individual LHRH terminals in the median eminence are often clustered in direct plasma membrane contact. Comparisons between animals of differing reproductive status are needed to determine whether alterations in synaptic inputs, glial ensheathment, or LHRH‐LHRH appositions, may underlie seasonal changes in the activity of LHRH neurons.
Localization of glycine‐containing neurons in the Macaca monkey retina
Authors: Hendrickson Anita E. , Koontz Margaret A. , Pourcho Roberta G. , Sarthy P. Vijay , Goebel Dennis J. 
Published: May 2005

AbstractAutoradiography following 3H‐glycine (Gly) uptake and immunocytochemistry with a Gly‐specific antiserum were used to identify neurons in Macaca monkey retina that contain a high level of this neurotransmitter. High‐affinity uptake of Gly was shown to be sodium dependent whereas release of both endogenous and accumulated Gly was calcium dependent. Neurons labeling for Gly included 40‐46% of the amacrine cells and nearly 40% of the bipolars. Synaptic labeling was seen throughout the inner plexiform layer (IPL) but with a preferential distribution in the inner half. Bands of labeled puncta occurred in S2, S4, and S5.Both light and postembedding electron microscopic (EM) immunocytochemistry identified different types of amacrine and bipolar cell bodies and their synaptic terminals. The most heavily labeled Gly+ cell bodies typically were amacrine cells having a single, thick, basal dendrite extending deep into the IPL and, at the EM level, electron‐dense cytoplasm and prominent nuclear infoldings. This cell type may be homologous with the Gly2 cell in human retina (Marc and Liu: J. Comp. Neurol. 232:241‐260, ′85) and the AII/ Gly2 of cat retina (Famiglietti and Kolb: Brain Res. 84:293‐300, ′75; Pourcho and Goebel: J. Comp. Neurol. 233:473‐480, ′85a). Gly+ amacrines synapse most frequently onto Gly− amacrines and both Gly− and Gly+ bipolars. Gly+ bipolar cells appeared to be cone bipolars because their labeled dendrites could be traced only to cone pedicles. The pattern of these labeled dendritic trees indicated that both diffuse and midget types of bipolars were Gly+. The EM distribution of labeled synapses showed Gly+ amacrine synapses throughout the IPL, but these composed only 11‐23% of the amacrine population. Most of the Gly+ bipolar terminals were in the inner IPL, where 70% of all bipolar terminals were labeled. These findings are consistent with previous data from cats and humans and suggest that both amacrine and bipolar cells contribute to glycine‐mediated neurotransmission in the monkey retina.
Origins of brainstem‐spinal projections in the duck and goose
Authors: Webster Deirdre M. S. , Steeves John D. 
Published: May 2005

AbstractThe purpose of this study was to determine the location of neuronal cell bodies with projections to the cervical or lumbar spinal cord in the adult duck and goose. Bilateral or unilateral injections (5‐10 μl) of the retrograde tracer dye True Blue (TB:5%) were made into the high cervical or high lumbar levels of the spinal cord. Similar results were obtained in both species. First, we found no evidence of retrogradely labelled cells in the telencephalon. In the brainstem, the distribution of TB cells was similar to those previously reported for the pigeon; however, the present study now demonstrates that some of these descending pathways project as far as the lumbar cord. We also discovered that there is a topographical representation of spinal projecting neurons within the avian medullary‐pontine reticular formation.
Control of tectal cell number during larval development in Rana pipiens
Authors: Kollros Jerry J. , Thiesse Mary L. 
Published: May 2005

AbstractCell production and cell deaths were determined in larval Rana pipiens both in control tecta and in tecta following unilateral eyeball removal in embryos and larvae. Such enucleations produce significantly reduced rates of cell division in the contralateral tecta for virtually the entire larval period (confirming studies with enucleation almost exclusively performed in embryos—Kollros: J. Exp. Zool. 123:153–187, '53, and J. Comp. Neurol. 205:171–178, '82). Significant numbers of cell deaths in all nonependymal tectal cell layers were also observed. Control cell division rates peak at stage X, while cell death peaks are reached in stages XIII–XX. Overall, about 106 nonependymal cells are produced in control tecta, and about 350,000 of them die by the end of metamorphosis. Control of cell numbers following enucleation is shown to depend mainly on reductions in cell division rates when the operation occurs early in development and mainly on increases in cell death rates are invariably present within 1 day of the operation whereas the reduced division rates ordinarily require several more days to be seen. The modified rates, both of cell divisions and cell death, are limited to tectal areas to which optic nerve fibers have already extended. Maps of the positions of tectal cell divisions in many larval stages provide the basis for modifying the current dogma that tectal formation occurs as a series of newly formed mediocaudal wedges pushing previously produced wedges rostrolaterad. All such “old” wedges receive substantial cell additions for many stages, with the rate of addition decreasing rostrad earlier than caudad.
Serotonin‐immunoreactive neurons in the cnidarian Renilla koellikeri
Authors: Umbriaco Denis , Anctil Michel , Descarries Laurent 
Published: May 2005

AbstractThe cellular localization of 5‐hydroxytryptamine (5‐HT) was investigated in the pennatulid anthozoan Renilla koellikeri by means of peroxidase‐antiperoxidase‐immunohistochemistry with an antiserum against 5‐HT‐formaldehyde‐protein conjugate. In many colonies, strong 5‐HT‐immunoreactivity was displayed by the cell bodies and beaded processes of relatively small neuronlike elements predominating in the outer ectoderm or scattered in the underlying mesoglea. The immunostained neurons of the mesoglea were generally bipolar and their relatively short processes extended toward myoepithelial cells. In the ectoderm, most immunostained neurons appeared pseudounipolar. These cell bodies were endowed with a small, superficially directed, conical appendage reaching the outer surface of the epithelium. Their neurites emerged from the inner pole of the perikarya and branched toward other immunopositive ectodermal and mesogleal nerve cells, or nematocytes in the tentacles. The networklike distribution of the presumed 5‐HT ectodermal neurons varied between the different regions of colonies and along the autozooid column. In the context of earlier observations in cnidarians, these cytological features suggest a sensory as well as a modulatory function for 5‐HT in Renilla koellikeri.
Angiotensin converting enzyme in the human basal forebrain and midbrain visualized by in vitro autoradiography
Authors: Chai Siew Yeen , McKenzie John S. , McKinley Michael J. , Mendelsohn Frederick A. O. 
Published: May 2005

AbstractAngiotensin converting enzyme converts angiotensin I to angiotensin II, a peptide that plays an important role in the central regulation of blood pressure and fluid and electrolyte homeostasis. However, the distribution of this enzyme in the human brain has not been well described. In this study, angiotensin converting enzyme was mapped in the human basal forebrain and midbrain by using quantitative in vitro autoradiography employing a derivative of a potent converting enzyme inhibitor, 125I‐351A, as radioligand. This radioligand binds specifically and with high affinty to angiotensin converting enzyme and also exhibited these properties in binding to slide‐mounted sections of human basal ganglia.In the basal ganglia, high levels of binding of 125I‐351A are found in the caudate nucleus, putamen, nucleus accumbens, both divisions of the globus pallidus, and substantia nigra pars reticulata. High densities of labelling also occur in the ventral pallidum. In the hypothalamus, a moderate level occurs in the paraventricular and supraoptic nuclei, and a diffuse, low level of binding is found throughout the periventricular region.The organum vasculosum of the lamina terminalis, one of the circumventricular organs, displays the highest concentration of binding. The choroid plexus contains only moderate density of labelling in contrast to other mammalian species previously studied. Major fibre tracts are devoid of activity except for the posterior limb of the internal capsule, which contains fascicles of intense activity.In the midbrain, a moderate density of binding is detected in the periaqueductal gray. The dorsal, central linear, and, more caudally, the centralis superior medialis raphe nuclei also contain moderate densities of labelling.Angiotensin converting enzyme is heterogeneously distributed in the caudate nucleus and putamen, with distinct patches of high concentrations surrounded by a matrix of diffuse, lower levels. In the caudate nucleus, these patches of high binding corresponded to striosomes since they register with acetylcholinesterase‐poor zones.The high concentration of angiotensin converting enzyme found in the basal ganglia suggests that the enzyme may be involved in processing neuropeptides that occur in high concentrations in these structures. Possible substance P and enkephalins, which are also concentrated in striosomes.
GABA‐ergic and glycinergic pathways in the inner plexiform layer of the goldfish retina
Authors: Muller Jay F. , Marc Robert E. 
Published: May 2005

AbstractGABA‐ergic and glycinergic circuitry in the inner plexiform layer of the goldfish retina was evaluated by electron microscopic autoradiography of 3H‐GABA and 3H‐glycine uptake, combined with retrograde horseradish peroxidase (HRP) labeling of ganglion cells. GABA‐ergic and glycinergic synapses were found on labeled ganglion cells throughout the inner plexiform layer. This reinforces the idea that physiological evidence of GABA‐ergic and glycinergic influence on a variety of ganglion cells in goldfish and carp often reflects direct inputs. Double‐labeled synapses are presented as evidence of direct type Ab amacrine cell input to on‐center ganglion cells. At least one population of type Aa sustained‐off GABA‐ergic amacrine cell is proposed, on the basis of profuse GABA‐ergic inputs onto bipolar cells in sublamina a. Similar GABA‐labeled profiles are shown to synapse onto HRP‐labeled probable offcenter ganglion cells. Thus GABA‐ergic amacrine cells not only provide the predominant feedback to depolarizing (on‐center) and hyperpolarizing (offcenter) bipolar cells but also provide feed‐forward inputs to on‐ and off‐center ganglion cells. Large‐caliber GABA‐ergic dendrites present in both sublaminae a and b resemble those expected of a previously described bistratified, transient amacrine cell. These processes synapse onto HRP‐labeled ganglion cell profiles in both sublaminae. Two morphologies of glycinergic amacrine cell are proposed on the basis of light microscopic autoradiography, (1) the previously described small pyriform cell and (2) a multipolar cell. The differential connectivity of the glycinergic neurons described, however, remains indistinguishable. Whereas abundant glycinergic inputs to ganglion cells occur throughout the inner plexiform layer, contacts between glycinergic profiles and bipolar cells are extremely rare. Therefore, interpreting the meaning of glycinergic input to ganglion cells will require further study of amacrine cell circuitry.