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Biomedical subjects

N Mizuno

Publications and source records attributed to N Mizuno.

At least 325 records · Page 18Linked to original sources
PubMed1989

Effects of pancreatic polypeptide on basal and meal stimulated secretion of gastrointestinal, pancreatic and adrenocortical hormones in the dog.

We have assessed the effects of intravenous infusion of bovine pancreatic polypeptide (PP) (1 microgram kg-1 h-1) on the basal and postprandial secretion of gastrointestinal, pancreatic and adrenocortical hormones in normal dogs. Bovine PP within the physiological range increased plasma cortisol levels transiently but significantly. PP elicited an inhibition of insulin response to a protein-rich meal, and tended to reduce the gastrin response. There were, however, no significant changes in basal or postprandial plasma concentrations of motilin and pancreatic glucagon during PP infusion. These results suggest that PP may have a role in controlling insulin secretion from the pancreas. The possible mechanisms are discussed mainly on the basis of vagal innervation.

Adrenal Cortex Hormones↗
PubMed1988

Direct projections of non-pyramidal neurons of Ammon's horn to the supramammillary region in the cat.

Non-pyramidal neurons in cat Ammon's horn were shown to send their axons to the supramammillary regions (SMR), i.e. the supramammillary nucleus and its vicinities including the supramammillary nucleus and the lateral, posterior and dorsal hypothalamic areas: wheat germ agglutinin-horseradish peroxidase (WGA-HRP) injection into Ammon's horn resulted in labeling of presumed axon terminals in the SMR; and after injecting HRP into the SMR, retrogradely labeled non-pyramidal neurons were seen in Ammon's horn.

Animals↗
PubMed1988

Metabolism of glutamate and ammonia in astrocyte: an immunocytochemical study.

Alpha-ketoglutarate (alpha-KG) reductive amination activity in rat brain was found to be mostly absorbed with an antibody against liver glutamate dehydrogenase. With this and anti-glutamine synthetase antibodies, alpha-KG reductive amination activity was immunocytochemically shown to coexist with glutamine synthetase activity in astrocytes. The results suggest that astrocytes de novo synthesize glutamate from alpha-KG and ammonia, and metabolize it to glutamine.

Amination↗
PubMed1988

Cingulate gyrus of the cat receives projection fibers from the thalamic region ventral to the ventral border of the ventrobasal complex.

Direct projections to the cingulate gyrus from the thalamic region lying just ventrally to the ventral border of the ventrobasal complex (VB) were found in the cat by two sets of experiments that used WGA-HRP (wheat germ agglutinin-horseradish peroxidase conjugate). In the first set of experiments, WGA-HRP was injected into the thalamic region around the ventral border of the VB. When the site of injection involved the thalamic region lying ventrally to the ventral border of the VB at the levels of the caudal two thirds of the VB, the cerebral cortex in the rostral part of the cingulate gyrus ipsilateral to the WGA-HRP injection contained fine HRP-positive granules, which indicated anterograde labeling of axon terminals. These labeled presumed axon terminals were mainly distributed to the superficial part of layer I, deep part of layer II, layer IV, and the most superficial part of layer V in the cingulate cortex. In the second set of experiments, WGA-HRP was injected into the cerebral cortex of the rostral part of the cingulate gyrus. When the site of injection involved the region of the cingulate gyrus, where presumed axon terminals had been labeled in the first set of experiments, the thalamic region just ventral to the ventral margin of the caudal two-thirds of the VB ipsilateral to the WGA-HRP injection contained neuronal cell bodies labeled retrogradely. The results indicate that some neurons that are located in the thalamic region just ventral to the ventral border of the caudal two-thirds of the VB send their axons to the cerebral cortex in the rostral part of the cingulate gyrus. The possible significance of the thalamocingulate projection found in the present study is discussed with relation to nociceptive behavior and function.

Animals↗
PubMed1988

The supramammillary region of the cat sends substance P-like immunoreactive axons to the hippocampal formation and the entorhinal cortex.

A combined method of the tracing of WGA-HRP (wheat germ agglutinin-conjugated horseradish peroxidase) and the immunohistochemistry of substance P (SP) showed that many SP-like immunoreactive neurons in the supramammillary nucleus of cat hypothalamus sent their axons to the hippocampal formation. SP-like immunoreactive axons in the hippocampal formation and entorhinal cortex were markedly reduced in number ipsilaterally after placing an electrothermic lesion in the supramammillary region of the hypothalamus.

Animals↗
PubMed1988

Somatosensory and auditory relay nucleus in the rostral part of the ventrolateral medulla: a morphological study in the cat.

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.

Afferent Pathways↗
PubMed1988

Direct projections from the subthalamic nucleus of Luys to the spinal cord in the Japanese monkey.

Injection of large amounts of a mixture of horseradish peroxidase and wheat germ agglutinin-horseradish peroxidase conjugate into the upper cervical segments of the spinal cord in the Japanese monkey (Macaca fuscata) led to the retrograde labeling of a small number of neuronal cell bodies within the rostral part of the subthalamic nucleus of Luys. Direct projection from the subthalamic nucleus to the spinal cord appeared to be much less prominent in the Japanese monkey than in the cat and rat.

Afferent Pathways↗
PubMed1988

Possible origins of cerebrovascular nerve fibers showing vasoactive intestinal polypeptide-like immunoreactivity: an immunohistochemical study in the dog.

Changes of vasoactive intestinal polypeptide-like immunoreactivity (VIP-LI) in perivascular nerve fibers of the major cerebral arteries were examined immunohistochemically in the dog. The density of cerebrovascular nerve fibers showing VIP-LI (the average number of nerve fibers with VIP-LI in a unit area of the major cerebral arteries) was estimated, by using whole-mount preparations after extirpation of the pterygopalatine, otic or superior cervical ganglion. After pterygopalatine ganglionectomy, the density was markedly decreased in major cerebral arteries of both anterior circulation (the anterior cerebral and middle cerebral arteries) and posterior circulation (the basilar, superior cerebellar, posterior cerebral and posterior communicating arteries). After otic ganglionectomy, the density was moderately reduced in the major arteries of the posterior circulation, but was not decreased in those of the anterior circulation. After superior cervical ganglionectomy, the density was decreased markedly in the major cerebral arteries of the posterior circulation, and moderately in those of the anterior circulation. The results also indicate that the pterygopalatine, otic and superior cervical ganglia supply perivascular nerve fibers showing VIP-LI to the major cerebral arteries bilaterally with an ipsilateral dominance.

Animals↗
PubMed1988

Distribution of axons exhibiting both enkephalin- and serotonin-like immunoreactivities in the lumbar cord segments: an immunohistochemical study in the cat.

Axons exhibiting both enkephalin- and serotonin-like immunoreactivities were observed by the double immunofluorescence method in the lumbar cord segments of the cat. Double-labeled axons were seen most frequently in laminae I, IIa and the lateral part of lamina V. They were also distributed in other parts of the dorsal horn and lamina X (especially in the dorsal part), but rarely found in laminae VII, VIII and IX. After cervical hemicordotomy the vast majority of double-labeled axons disappeared from the spinal gray ipsilateral to the lesion.

Animals↗
PubMed1988

Calcitonin gene-related peptide-like immunoreactivity in neuronal elements of the cat cerebellum.

Calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) was found in many mossy fiber endings in the cat cerebellum. Some fine varicose fibers within the cerebellar nuclei also showed CGRP-LI. By injecting colchicine into the lateral ventricle of the cerebrum, CGRP-LI was further visualized in perikarya of many granule cells and some small neurons in the dentate and interpositus nuclei. Among the brainstem precerebellar nuclei, the largest number of neuronal cell bodies with CGRP-LI was found in the pontine nuclei. When a lesion was placed in the pontine brachium, mossy fiber endings with CGRP-LI reduced in number in the cerebellar hemisphere of the posterior lobe ipsilateral to the lesion. Fine varicose fibers with CGRP-LI within the dentate nucleus were also decreased in number ipsilaterally to the lesion. Thus, the majority of fiber endings with CGRP-LI in the hemisphere of the posterior lobe and the dentate nucleus of the cerebellum were assumed to originate from the contralateral pontine nuclei.

Animals↗
PubMed1988

Immunohistochemical study of glutaminase-containing neurons in the cerebral cortex and thalamus of the rat.

In an attempt to identify glutamatergic neurons, the cerebral cortex and thalamus of the rat were examined immunohistochemically by using a monoclonal antibody against phosphate-activated glutaminase (PAG), a major synthetic enzyme of transmitter glutamate in the central nervous system. In both the neocortex and mesocortex, pyramidal cells in layers V and VI showed intense PAG-like immunoreactivity (PAG-LI), whereas neuronal cell bodies in layers I-IV showed weak PAG-LI. At the deep border of layer VI, neurons with horizontally elongated cell bodies showed PAG-LI. In the pyriform and entorhinal cortices, neurons with intense to moderate PAG-LI were seen in layer II as well as in the deeper layers. In the hippocampal formation, pyramidal cells in CA1, CA2, and CA3 and polymorphic cells in CA4 showed PAG-LI; PAG-LI was most intense in pyramidal cells of CA3. Fine granules with weak PAG-LI were also seen on and/or within the cell bodies of granule cells in the dentate gyrus. In the thalamus, neurons with PAG-LI were distributed in all nuclei, although regional differences were observed in the distribution pattern of neurons with PAG-LI and in the intensity of PAG-LI in individual neurons. The largest neurons in each thalamic nucleus showed intense PAG-LI; these were considered to be projection neurons. In addition to perikaryal labeling, many fine, PAG-like immunoreactive granules were distributed in the neuropil of both the cerebral cortex and thalamic nuclei. Some of these fine granules with PAG-LI in the neuropil were assumed to represent fiber terminals with PAG-LI, because the distribution pattern of the deposits in the primary somatosensory and primary visual cortices resembled that of thalamocortical fiber terminals. Glutamate is rather ubiquitous in the mammalian central nervous system, and it is still debatable whether the monoclonal antibody to PAG from brain mitochondria can distinguish transmitter-related glutaminase from the other metabolism-related ones. In the present study, however, large neurons in the thalamic nuclei, as well as pyramidal neurons in the cerebral cortex, showed PAG-LI most intensely, supporting the assumption that projection neurons of the cerebral cortex and thalamus are primarily glutamatergic.

Animals↗
PubMed1988

Peptide YY receptors in the brain.

Radiolabelled ligand binding studies demonstrated that specific receptors for peptide YY are present in the porcine as well as the canine brains. Peptide YY was bound to brain tissue membranes via high-affinity (dissociation constant, 1.39 X 10(-10)M) and low-affinity (dissociation constant, 3.72 X 10(-8)M) components. The binding sites showed a high specificity for peptide YY and neuropeptide Y, but not for pancreatic polypeptide or structurally unrelated peptides. The specific activity of peptide YY binding was highest in the hippocampus, followed by the pituitary gland, the hypothalamus, and the amygdala of the porcine brain, this pattern being similarly observed in the canine brain. The results suggest that peptide YY and neuropeptide Y may regulate the function of these regions of the brain through interaction with a common receptor site.

Amygdala↗
PubMed1988

The distribution of hypoglossal motoneurons in the dog, rabbit and rat.

The distribution of motoneurons innervating the extrinsic tongue muscles was studied in the dog, rabbit and rat using the horseradish peroxidase technique. In these mammals, hypoglossal motoneurons were clustered in roughly ventral (or medial) and dorsal (or lateral) groups. Axons of hypoglossal motoneurons in the ventral (or medial) group passed via the medial branch of the hypoglossal nerve, and those in the dorsal (or lateral) group by way of the lateral branch of the hypoglossal nerve. Motoneurons supplying the geniohyoid or genioglossus muscle were distributed, respectively, in the ventral or lateral aspect of the ventral (or medial) cluster of hypoglossal motoneurons. Hypoglossus and styloglossus motoneurons were located in the lateral aspect of the dorsal (or lateral) cluster. The area of distribution of hypoglossus motoneurons overlapped with that of styloglossus motoneurons. It seems likely that motoneurons innervating intrinsic tongue muscles form the remainder of the hypoglossal nucleus. The largest motoneurons in the hypoglossal nucleus were distributed in the cluster of geniohyoid motoneurons. Thus, in the present study a somatotopic arrangement of motoneurons innervating the extrinsic tongue muscles was found, in keeping with previous studies using the retrograde cell degeneration technique.

Animals↗
PubMed1988

The distribution of infrahyoid motoneurons in the cat: a retrograde horseradish peroxidase study.

The distribution of cell bodies and the peripheral course of axons of infrahyoid motoneurons were examined in the cat by the retrograde horseradish peroxidase method after application of the enzyme to the peripheral nerve branches supplying the infrahyoid muscles. Infrahyoid motoneurons were observed to constitute a slender cell column, which extended from a level of the caudal part of the hypoglossal nucleus usually to the most caudal level of the C1 cord segment, or occasionally to the lower levels of the C2 cord segment. The cell column was located immediately lateral to that of motoneurons of the spinal accessory nerve. In the cell column, thyrohyoid motoneurons were distributed in the medulla oblongata; sternohyoid motoneurons were located somewhat more cranially than sternothyroid motoneurons in the medulla oblongata and cervical cord. However, the level of craniocaudal distribution of thyrohyoid, sternohyoid or sternothyroid motoneurons highly overlapped. The experiments involving severance of the hypoglossal and/or cervical nerves indicated that axons of thyrohyoid and sternohyoid motoneurons passed via the roots of both hypoglossal and C1 nerves, that axons of sternohyoid motoneurons passed via the C1 nerve roots, and that axons of infrahyoid motoneurons innervating the conjugated part of the sternohyoid and sternothyroid muscles passed usually via the C1 nerve roots, or occasionally via the roots of both C1 and C2 nerves.

Animals↗