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Y Tsuruo

Publications and source records attributed to Y Tsuruo.

At least 19 recordsLinked to original sources
PubMed1991

Hypophysiotrophic TRH-producing neurons identified by combining immunohistochemistry for pro-TRH and retrograde tracing.

To determine hypophysiotrophic thyrotropin-releasing hormone (TRH)-producing neurons in the rat hypothalamus, we employed a combination of the immunohistochemistry for TRH prohormone (pro-TRH) and the retrograde tracing of neurons that project to the median eminence (ME) by injecting biotinylated wheat germ agglutinin (WGA) into the ME. In intact rats, immunoreactive pro-TRH-positive neurons occurred in the parvicellular paraventricular nucleus (parvi-PVN), basal part of the anterior and lateral hypothalamus, perifornical area and dorsomedial nucleus, especially accumulating in the parvi-PVN. Twenty-four hours after injection of the WGA into the middle portion of the ME, we found neurons that incorporated the lectin in the anterior periventricular area, the PVN, and the arcuate nucleus. When we examined serial sections consecutively stained with anti-WGA, anti-pro-TRH, and anti-WGA, most of the pro-TRH-labeled neurons in the medial parvi-PVN and a part of the neurons in the anterior periventricular area and in the anterior, lateral, and dorsal parvi-PVN appeared to incorporate WGA. These neurons may correspond with the hypophysiotrophic TRH-synthesizing neurons in the rat hypothalamus.

Amino Acid Sequence↗
PubMed1991

Substance P-containing neurons innervating LHRH-containing neurons in the septo-preoptic area of rats.

Neuroanatomical attempts have been made to determine the synapses between luteinizing hormone-releasing hormone (LHRH)-containing neurons and substance P (SP)-containing neurons in the hypothalamus of female rats. Wheat germ agglutinin was injected into the septo-preoptic area (SPA) and found to be incorporated into certain SP-containing neurons within the arcuate nucleus and the ventrolateral portion of the anterior hypothalamus. Hence, we used a preembedding double immuno-staining technique in demonstrating LHRH and SP neurons in the SPA. In light-microscopic preparations LHRH was labeled with 3,3'-diaminobenzidine tetrahydrochloride (DAB) as chromogen while SP was labeled with silver-gold particles; brown LHRH cells appeared to be surrounded by black silver-gold dots. In electron-microscopic preparations, the labelings for LHRH and SP were made reversely; SP was localized with DAB chromogen, and SP-containing axonal terminals appeared to make synaptic contacts on silver-gold-labeled LHRH cell bodies and dendritic processes. The terminals contained numerous small clear vesicles and some large dense-cored vesicles, and the synaptic membrane specialization appeared to be symmetric and asymmetric. These findings indicate that certain SP neurons existing in the arcuate nucleus and the ventrolateral portion of the anterior hypothalamus may project fibers to make synaptic contact with LHRH neurons in the SPA in the rat.

Animals↗
PubMed1990

Immunohistochemical evidence for synaptic connections between neuropeptide Y-containing axons and periventricular somatostatin neurons in the anterior hypothalamus in rats.

By employing a pre-embedding double immunolabeling technique, we examined light and electron microscopically synaptic associations between neuropeptide Y (NPY)-containing axons and somatostatin (SRIH)-containing neurons in the anterior periventricular area (APV) of the rat hypothalamus. For light microscopy, the immunoreactions for NPY and SRIH were visualized with silver-gold and diaminobenzidine (DAB), respectively, and the reverse labeling was used for electron microscopy. Light microscopy disclosed many brown SRIH perikarya surrounded by several black beads of NPY fibers in the APV. In electron microscopy, immunoreactive SRIH neurons revealed silver-gold particles scattered throughout the cytoplasm and accumulated in the Golgi area and the secretory granules. SRIH perikarya and dendritic processes indicated synaptic associations with DAB-labeled NPY fiber terminals and immunonegative fibers. NPY presynaptic terminals possessed numerous small clear vesicles and a few dense core vesicles; vesicular membranes and cores were labeled with DAB chromogen. Both the pre- and postsynaptic membranes were thickened equally to be a symmetric synapse. These findings suggest that NPY neurons are involved in the regulation of growth hormone secretion from the pituitary by affecting periventricular SRIH neurons.

Animals↗
PubMed1990

Vasopressin-deficient paraventricular magnocellular neurons of homozygous Brattleboro rats synthesize neuropeptide Y.

Immunohistochemical study was carried out to determine whether neuropeptide Y (NPY), which was only found in certain experimental procedures in arginine vasopressin (AVP)-containing neurons of the magnocellular paraventricular nucleus, might also be synthesized in AVP-deficient homozygous Brattleboro (BB) rats. After an intraventricular colchicine administration, NPY was found in many AVP-deficient non-oxytocinergic magnocellular neurons of the paraventricular and supraoptic nuclei in BB rats, but not in suprachiasmatic nucleus neurons. The results suggest that the NPY synthesis is a phenotype of magnocellular non-oxytocinergic neurosecretory neurons and occurs independently from the synthesis of AVP.

Animals↗
PubMed1990

Morphological evidence for neuronal regulation of luteinizing hormone-releasing hormone-containing neurons by neuropeptide Y in the rat septo-preoptic area.

Using a preembedding double immunolabeling technique, synaptic contacts were found between luteinizing hormone-releasing hormone (LHRH)-containing neurons and neuropeptide Y-containing axonal fibers in the rat septo-preoptic area. In demonstrating LHRH neurons, we used mainly an antiserum generated against rat gonadotrophic hormone-releasing hormone-associated peptide. Although many diaminobenzidine-labeled neuropeptide Y-containing fibers were seen around silver-gold-labeled LHRH cell bodies, synapses with synaptic membrane specialization were scarce. The fiber terminals usually contained many small clear vesicles and some large cored vesicles. The synapses were characterized with the presynaptic accumulation of the small clear vesicles and symmetric thickenings of the synaptic membranes.

Animals↗
PubMed1990

Intragranular co-storage of neuropeptide Y and arginine vasopressin in the paraventricular magnocellular neurons of the rat hypothalamus.

Certain populations of arginine vasopressin (AVP) neurons in the magnocellular paraventricular nucleus became immunoreactive for neuropeptide Y (NPY) when rats were treated with colchicine or monosodium glutamate (MSG). The co-storage of these peptides was examined by employing a post-embedding electron-microscopic immunohistochemistry technique using gold-labeled antibodies to the two peptides. In colchicine-treated rats, the neuronal perikarya contained numerous secretory granules showing co-storage of the two peptides. The cells of the MSG-treated rats were characterized by having well-developed Golgi bodies with the granular structures also co-storing the two peptides, although the secretory granules in the perikarya were rather fewer than in the colchicine-treated rats. It is concluded that the destruction of the arcuate nucleus by MSG-treatment may potentiate the synthesis of NPY in AVP neurons, the synthesis of which is latent in intact animals.

Animals↗
PubMed1989

Synaptic regulation of paraventricular arginine vasopressin-containing neurons by neuropeptide Y-containing monoaminergic neurons in rats. Electron-microscopic triple labeling.

Synaptic regulation of arginine vasopressin (AVP)-containing neurons by neuropeptide Y (NPY)-containing monoaminergic neurons was demonstrated in the paraventricular nucleus of the rat hypothalamus. NPY and AVP were immunolabeled in the pre- and the post-embedding procedures, respectively, and monoaminergic fibers were marked by incorporating 5-hydroxydopamine (5-OHDA), a false neurotransmitter. The immunoreaction for NPY was expressed by diaminobenzidine (DAB) chromogen, and that for AVP by gold particles. The DAB chromogen was localized on the surface of the membrane structures, such as vesicles or mitochondria, and on the core of large cored vesicles. Gold particles were located on the core of the secretory granules within the AVP cell bodies and processes. The incorporated 5-OHDA was found as dense cores within small or large vesicular structures. From these data, three types of nerve terminals were discernible: NPY-containing monoaminergic, NPY-containing non-aminergic, and monoaminergic fibers. The AVP cell bodies appeared to have synaptic junctions formed by these nerve terminals as well as by the unlabeled nerve terminals which have small clear vesicles and large cored vesicles. These different types of nerve terminals were frequently observed in a closely apposed position on the same AVP cell bodies. The functional relationships of these three types of neuronal terminals are discussed.

3,3'-Diaminobenzidine↗
PubMed1989

Axons containing neuropeptide Y innervate arginine vasopressin-containing neurons in the rat paraventricular nucleus. Dual electron microscopic immunolabeling.

Synaptic connections between neurons immunoreactive for arginine vasopressin (AVP) and axon terminals immunoreactive for neuropeptide Y (NPY) were found in the magnocellular part of the paraventricular nucleus (PVN) in the rat hypothalamus. In pre-embedding double immunolabeling, NPY axon terminals labeled with diaminobenzidine (DAB) reaction product established synaptic junctions on the perikarya and neuronal processes of AVP neurons labeled with silver-gold particles. Ultrastructural morphology of the neurons was more suitably preserved by a combination of pre- and post-embedding procedures. The presynaptic NPY terminals contained many small clear vesicles and a few cored vesicles, and DAB chromogen (immunoreaction product) was located on the surface of the vesicular profiles and on the core. The postsynaptic AVP neurons possessed many large secretory granules labeled with gold particles. At the synaptic junctions, small clear vesicles were accumulated at the presynaptic membrane, and the postsynaptic membrane was coated with a dense accumulation of fine electron dense particles. The perikarya also received synapses made by immuno-negative axon terminals containing many small clear vesicles and a few cored vesicles. These terminals were found more frequently than those containing NPY.

Animals↗
PubMed1989

Development of the neuronal system containing neuropeptide Y in the rat hypothalamus.

In the rat hypothalamus, neuropeptide Y-containing neurons first appeared on day 14.5 of gestation in the arcuate nucleus and in the dorsolateral hypothalamic area. Until birth neuropeptide Y-containing cell bodies increased in number in the arcuate, dorsomedial-lateral and paraventricular nuclei, but disappeared thereafter, but some cells remaining in the arcuate nucleus. In animals treated neonatally with monosodium L-glutamate to destroy the arcuate nucleus, neuropeptide Y-immunoreactivity became evident in many cells scattered in the magnocellular paraventricular and dorsomedial-lateral hypothalamic nuclei on day 16 but not on days 60 and 12. These neuropeptide Y-immunoreactive neurons which appeared in the paraventricular nucleus were also vasopressin-positive. Neuropeptide Y fibers, on the contrary, remarkably diminished in number on day 16, particularly in the paraventricular and dorsomedial-lateral nuclei, and the medial preoptic area, but made a considerable recovery on days 60 and 120. Hence it is probable that, in normal ontogenetic progress, the development of the neuropeptide Y fibers in these areas is inhibitorily affected by that of arcuate neuropeptide Y neurons.

Aging↗
PubMed1989

Immunohistochemical approach to the functional morphology of the hypothalamic-hypophysial system.

Immunohistochemical studies at the light and electron microscopic levels have provided much information on functional morphology in the hypothalamic-hypophysial system. The present paper describes the immunohistochemical techniques available at present and their use to determine the localizations of neurons containing hypophysiotrophic substances, the co-storage of plural signals in these neurons, and the synaptic regulation of these neurons in rats.

Animals↗
PubMed1989

Distribution of TRH-like immunoreactivity with special reference to coexistence with other neuroactive compounds.

During the last years, several important advancements have been made that are of importance for our understanding of the distribution and localization of neurons and cells producing TRH-LI. As detailed in other chapters in this volume, the precursor for TRH has been characterized that has allowed production of antibodies raised against specific sequences of this precursor. This, in turn, has provided new tools for the immunohistochemical elucidation of TRH systems in the CNS. The TRH precursor has also been cloned, leading to possibilities for studying the localization of TRH mRNA with in situ hybridization. Finally, as shown in this paper, improvement of the fixation technique has made it possible to visualize extensive TRH-immunoreactive cell body and fiber systems with antiserum raised against the TRH tripeptide. The results from the latter studies and those with antisera directed to the TRH precursor and in situ hybridization are in good agreement, with some minor exceptions. It should be pointed out that some of the systems described here, for example TRH positive-cell bodies in cortical areas and the hippocampal formation, contain only a very weak immunoreactivity. As always with immunohistochemical techniques, the possibility of crossreactivity with TRH-like peptides or TRH-like sequences within larger proteins must be considered. The present results confirm the presence of TRH-LI in the insulin-producing beta cells of the pancreas, which with the improved technique can be demonstrated also in early adulthood in rats and guinea pigs. Moreover, it could be established that TRH-LI is present in neurons in the gastrointestinal tract as well as in a population of endocrine cells in the antrum of the stomach of the guinea pig. These cells seem at least partly to be identical to the well-known gastrin-producing cells. TRH-LI has been observed to occur in neurons already containing a classical transmitter and/or other peptides. Of particular importance here seems to be a descending bulbospinal system that in addition to TRH co-contains 5-HT, substance P-LI, galanin-LI, human growth hormone immunoreactive material, and proctolin-like material. The significance of this coexistence is not well understood, but interesting interactions have been observed. Attempts to manipulate the TRH phenotype in these medullary neurons by transplantation to other sites in the brain has so far shown that the expression of this peptide seems fairly stable.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

Hypothalamic neurons from a developmental aspect.

The development of hypothalamic neurons was examined in vivo and in transplanted grafts in rats. The neurons appeared in vivo in distinctive chronotopical schedules showing such morphological characteristics as synaptocrine or hemocrine neurons. These phenotypical properties seemed to be primed already by day 12.5 of gestation in rats, because the grafted hypothalamic primordia from 12.5-day-old embryonal rats differentiated neurons, which express these neuronal properties in the third ventricle of adult female rats. The synaptocrine neurons projected to other neurons, suggesting the establishment of synaptic contacts, and the hemocrine neurons projected to vasculatures developed in the grafts, suggesting the accomplishment of neurovascular associations.

Animals↗
PubMed1988

Thyrotropin-releasing hormone (TRH)-immunoreactive neuron populations in the rat olfactory bulb.

Thyrotropin-releasing hormone (TRH)-like immunoreactivity was examined in the rat olfactory bulb by an immunohistochemical method using antiserum against the tripeptide TRH. TRH-immunoreactive neurons and neuronal processes were localized in both main and accessory olfactory bulb, including the glomerular layer, external plexiform layer, mitral cell body layer, internal plexiform layer and granule cell layer. However, no TRH-positive structures were observed in the olfactory nerve layer. The present study demonstrates that TRH is located in several neuronal populations in the olfactory bulb, and that this peptide thus may be involved in the processing of information in the olfactory system.

Animals↗
PubMed1988

Some blood vessels in the rat median eminence are surrounded by a dense plexus of vasoactive intestinal polypeptide/peptide histidine isoleucine (VIP/PHI) immunoreactive nerves.

Using immunohistochemistry at the light and electron microscopic level some blood vessels along the median eminence were shown to be surrounded by dense networks of vasoactive intestinal polypeptide/peptide histidine isoleucine (VIP/PHI)-positive fibers. VIP and PHI released from these fibers may contribute to the elevated levels of these two peptides measured in portal blood as compared to peripheral blood by radioimmunoassay. VIP and PHI may also be important in the control of blood flow through the median eminence.

Animals↗
PubMed1988

TRH-like immunoreactivity in endocrine cells and neurons in the gastro-intestinal tract of the rat and guinea pig.

By use of the indirect immunofluorescence technique, the cellular localization of thyrotropin-releasing hormone (TRH) was studied in the gastrointestinal tract of rats and guinea pigs of different ages. TRH-like immunoreactivity (LI) was observed in many pancreatic islet cells of young rats and guinea pigs but only in single cells of 6-month-old rats. In aged guinea pigs, a reduction in the number of TRH-positive cells was evident; however, numerous strongly fluorescent cells were still present. In the guinea pig, TRH-LI was in addition observed in gastrin cells in the stomach. TRH-positive nerve fibers occurred in the myenteric plexus of the oesophagus, stomach and intestine of the rat, and in the muscle layers of the guinea pig. These results suggest a functional role of TRH both as hormone and neuroactive compound in various portions and sites of the gastro-intestinal tract of the rat and guinea pig.

Animals↗
PubMed1988

Further analysis of presence of peptides in dopamine neurons. Cholecystokinin, peptide histidine-isoleucine/vasoactive intestinal polypeptide and substance P in rat supramammillary region and mesencephalon.

Double-labeling combined with elution-restaining immunofluorescence techniques were used to analyze the extent of coexistence among the peptides cholecystokinin (CCK), peptide histidine-isoleucine (PHI)/vasoactive intestinal polypeptide (VIP), substance P and the catecholamine-synthesizing enzyme tyrosine hydroxylase in neurons of the supramammillary region and mesencephalon of the rat. Approximately 50% of the PHI/VIP-containing perikarya and about 25% of the CCK-positive cell bodies in the supramammillary region exhibited coexistence of both peptides. Only a very minor portion of these double-labeled neurons were also found to contain immunostaining for tyrosine hydroxylase (indicative of dopamine in these cells). A low percentage of the neurons contained the enzyme plus either CCK- or PHI/VIP-like immunoreactivity. A low proportion of the tyrosine hydroxylase-positive neurons in this region contained substance P-like immunoreactivity and vice versa. In other areas, small numbers of neurons in periventricular and periaqueductal regions were found to be immunostained for CCK, PHI/VIP and tyrosine hydroxylase. Single examples of triple-labeled (CCK-PHI/VIP-TH) somata were infrequently observed in the ventral tegmental area. These data provide further evidence of peptide/peptide and peptide/monoamine coexistence in the central nervous system. The demonstration of CCK-PHI/VIP colocalization (possibly including a minor dopaminergic component) and of substance P and tyrosine hydroxylase coexistence within neurons of the supramammillary region, which has widespread projections to many areas of the forebrain, suggests that these neuropeptides may coexist in some of these pathways and perhaps be co-released in several different regions of the brain.

Animals↗
PubMed1988

DARPP-32, a dopamine- and cyclic AMP-regulated phosphoprotein in tanycytes of the mediobasal hypothalamus: distribution and relation to dopamine and luteinizing hormone-releasing hormone neurons and other glial elements.

The distribution of a dopamine- and cyclic adenosine-3':5'-monophosphate (cAMP)-regulated phosphoprotein with an apparent molecular weight of 32,000 (DARPP-32) was investigated in the rat diencephalon and monkey hypothalamus by use of immunohistochemical techniques. In addition to single cells located peri- and paraventricularly in hypothalamus and thalamus in the rat, and ependymal cells, DARPP-32-immunoreactivity was found to be present in a subpopulation of ependymal tanycytes. These DARPP-32-positive tanycytes lined the walls and floor of the third ventricle, sending processes towards the arcuate nucleus, surrounding blood vessels in this nucleus, and continuing towards the median eminence, where they abutted on portal vessels. A second group of DARPP-32-positive tanycytes with cell bodies within the median eminence was also observed. Simultaneous labeling with antiserum against tyrosine hydroxylase, a presumptive marker for tuberoinfundibular dopamine neurons, revealed a close relation to DARPP-32-containing tanycytes in several anatomical locations. Thus, in the periventricular area DARPP-32-positive tanycytes ensheathed tyrosine hydroxylase-positive processes. These processes, presumably representing dopaminergic dendrites, virtually penetrated between the ependymal cells to the ventricular space and thus perhaps established direct contact with the cerebrospinal fluid. Tyrosine hydroxylase-terminals were also observed in close association with DARPP-32-immunoreactive tanycytes in the rat median eminence. However, in view of the density of DARPP-32-positive processes in the external layer of the median eminence, the DARPP-32 processes may be related to a number of other types of nerve endings, including luteinizing hormone-releasing hormone, as shown in this study. The close association of DARPP-32-immunoreactive processes with tyrosine hydroxylase- and luteinizing hormone-releasing hormone-immunoreactive nerve endings in the rat was directly visualized at the ultrastructural level using triple-labeling immunocytochemistry. Both the ultrastructural analysis and immunohistochemistry at the light microscopic level, comparing the distribution of DARPP-32 and glial fibrillary acidic protein, indicated the presence of two types of glial processes in the median eminence. The electron microscopic studies also suggested the presence of both DARPP-32-positive and DARPP-32-negative glial processes in the external layer of the median eminence.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗