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Biomedical subjects

M Tohyama

Publications and source records attributed to M Tohyama.

612 records · Page 34Linked to original sources
PubMedDate not supplied

Immunohistochemical distribution of glucagon, substance P and vasoactive intestinal polypeptide in hepatic vasculature of the rat.

The distribution of immunoreactive glucagon, substance P (SP) and vasoactive intestinal polypeptide (VIP)-like structures was investigated in the rat liver, with special reference to the hepatic vasculature by means of the indirect immunofluorescence method. Immunoreactive structures of glucagon were seen in the walls of the portal vein, hepatic artery and hepatic vein, but not in the central vein. Immunoreactive glucagon was localized in the smooth muscle cells of these blood vessels. SP and VIP-like immunoreactive (SPI and VIPI) structures were seen in the neuronal elements. In the porta hepatis, thick, compact SPI and VIPI fibers, which were dissociated from their fiber bundles, reached the tunica adventitia where they were distributed. No SPI and VIPI structures were seen in the tunica media or the tunica interna. No SPI- and VIPI-containing cell bodies could be detected in the liver. These observations suggest that these peptides may have an important role in the neural regulation of hepatic hemodynamics.

Animals↗
PubMedDate not supplied

The distribution of alpha-melanocyte stimulating hormone (alpha-MSH) in the central nervous system of the rat: an immunohistochemical study. II. Lower brain stem.

The distribution of immunoreactive alpha-melanocyte stimulating hormone (alpha-MSHI) in the rat lower brain stem was examined by indirect immunofluorescence or peroxidase- anti-peroxidase immunohistochemical method using an antiserum against synthetic alpha-MSH. The results confirmed the presence of alpha-MSHI fibers in the midbrain central gray matter and parabrachial area, and demonstrated a much more extensive distribution of these fibers in various parts of the lower brain stem areas previously thought not contain alpha-MSHI fibers. In addition, the commissural nucleus was identified as a new alpha-MSHI neurons-containing site. No alpha-MSHI neurons were seen in other regions of the rat lower brain stem.

Animals↗
PubMedDate not supplied

CCK pathway from supramammillary region to the nucleus anterior ventralis thalami of the young rats.

The existence of cholecystokinin-8-like immunoreactive (CCKI) pathway from supramammillary region (SUM) to the nucleus anterior ventralis thalami (AVT) was demonstrated in this study by means of experimental immunohistochemical manipulations in very young rats, because destruction of unilateral SUM, which contains CCKI neurons, resulted in a disappearance of CCKI fibers in the ipsilateral AVT.

Animals↗
PubMedDate not supplied

Coexistence of substance P and neurotensin-like peptides in single neurons of the rat hypothalamus.

The coexistence of substance P with neurotensin-like immunoreactivity in certain neurons of the hypothalamus were demonstrated by the double immunofluorescence method. Substance P and neurotensin-like immunoreactivity coexisted within single neurons of some hypothalamic areas such as the medial preoptic area, perifornical area, anterior hypothalamic area, lateral hypothalamic area, periventricular nucleus and posterior hypothalamic nucleus, although they did not coexist in the majority of immunoreactive cells.

Animals↗
PubMedDate not supplied

Distribution and origin of vasoactive intestinal polypeptide-like immunoreactive fibers in the central amygdaloid nucleus of the rat: an immunocytochemical analysis.

We studied the distribution of vasoactive intestinal polypeptide-like immunoreactive (VIPLI) fibers in the central amygdaloid (AC) nucleus of the rat, using indirect immunofluorescence and the origins of such fibers using a combination of retrograde tracing with immunocytochemistry. VIPLI fibers formed a dense fiber plexus in the lateral subdivision of the AC nucleus, but other subdivisions showed little immunoreactivity. Destruction of the supramammillary (SuM) region and the adjacent lateral hypothalamus, both of which contained a group of VIPLI neurons, resulted in the marked reduction of VIPLI fibers in the ipsilateral AC nucleus, indicating that many of the fibers in the AC nucleus originate from these two areas. This assumption was supported by the finding that injection of fast blue dye into the AC nucleus labeled the VIPLI neurons in the SuM region and lateral hypothalamus.

Amygdala↗
PubMedDate not supplied

Relative sparing of calcitonin gene-related peptide-containing primary sensory neurons following neonatal capsaicin treatment in the rat.

Calcitonin gene-related peptide (CGRP)-containing sensory neurons projecting to viscera or skin were detected by immunocytochemistry combined with fluorescent tracer in the dorsal root ganglia (Th9-10) of rats 5-6 weeks old treated neonatally with capsaicin. The number of CGRP-like immunoreactive (IR) cells were reduced by 50-60% with capsaicin treatment. Visceral CGRP-IR sensory neurons were shown to be more sensitive than cutaneous ones, which was also supported by the fact that CGRP-IR fibers in the stomach were completely diminished while epidermal CGRP-IR fibers were spared.

Animals↗
PubMedDate not supplied

Purification and characterization of neurotensin receptor from rat brain with special reference to comparison between newborn and adult age rats.

Scatchard analysis of saturation curves was performed to compared newborn and adult rat neurotensin receptor using [3H] neurotensin as a tracer. The membrane fraction of newborn rat cerebral cortex has a single population of neurotensin receptor (Kd = 0.13 nM, Bmax = 710 fmol/mg protein), whereas adults have two distinct neurotensin binding sites (high affinity site, Kd1 = 0.13 nM; low affinity site, Kd2 = 20 nM). High affinity neurotensin receptor, solubilized with digitonin, was purified from newborn rat cortex by affinity chromatography. An overall purification of 14,000-fold was achieved. The binding of [3H] neurotensin to the purified receptor is saturable and specific, with a Kd of 0.45 nM. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in the presence of 2-mercaptoethanol revealed purified material of a single major band of Mr = 55,000.

Aging↗
PubMedDate not supplied

Cell size and cell type analysis of calcitonin gene-related peptide-containing cutaneous and splanchnic sensory neurons in the rat.

Cell size, cell type and calcitonin gene-related peptide (CGRP)-like immunoreactivity were compared between cutaneous and splanchnic sensory neurons by means of a combination of fluorescent tracer and immunohistochemistry. Nineteen percent of cutaneous sensory neurons and 88% of splanchnic sensory neurons were shown to contain CGRP. The former cells were larger than the latter ones, which was also confirmed by the finding that about a half of the former cells contained 200 kDa subunit of neurofilament protein, while only 8% of the latter ones were positively stained. These findings suggest that most of the visceral CGRP-IR sensory neurons are small type B.

Animals↗
PubMedDate not supplied

Orofacial pain increases mRNA level for galanin in the trigeminal nucleus caudalis of the rat.

The changes of preprogalanin mRNA levels in the superficial dorsal horn neurons (laminae I and II) of the trigeminal nucleus caudalis in response to orofacial pain induced by the injection of 5% formalin into the lips of rats was investigated and compared to those of preproenkephalin A mRNA and preprodynorphin mRNA in the same region by means of in situ hybridization histochemistry. Rapid and marked increases of preprogalanin and preprodynorphin mRNA were observed on the side of the injection, but the increase of preproenkephalin A mRNA level was less pronounced than that of the other two mRNAs, indicating that these peptides have different roles in the dorsal horn analgesic mechanism and that galanin, in addition to opioid peptides, may have a highly specific role in this mechanism.

Animals↗
PubMedDate not supplied

Are cerebrovascular factors involved in Alzheimer's disease?

Recent epidemiological studies have shown that vascular risk factors may be involved in Alzheimer's disease (AD) as well as dementia in general. To investigate the relation between a vascular disorder and AD pathology, current criteria are defective because most depend on exclusion of a cerebrovascular disorder. Epidemiological studies have indicated the possibilities that arteriosclerosis, abnormal blood pressure, diabetes mellitus and smoking may be related to the pathogenesis of AD. As for the mechanism that vascular disorders influence AD, it is presumed that amyloid deposition may be caused by a vascular disorder. Alternatively, a vascular event may cause progression of subclinical AD to a clinical stage. Insulin resistance and apolipoprotein E may also be involved in these mechanisms. Our studies show that ischemia-induced the Alzheimer-associated gene presenilin 1 (PS1) and endoplasmic reticulum-stress, generated from a vascular disorder, may unmask clinical AD symptoms caused by presenilin mutation, suggesting that a vascular factor might be involved in the onset of familial AD.

Alzheimer Disease↗
PubMedDate not supplied

Central dual innervation of arterioles and capillaries in the brain.

Fluorescence-and electron-microscopic studies were performed on nerve terminals close to intracerebral blood vessels in the rat. For the electron microscope subdural perfusion fixation with potassium permanganate was used. In the rat cerebral cortex deprived of the bilateral superior cervical ganglion some aminergic terminal boutons containing large and small core vesicles were observed contiguous to blood vessels. These terminals abutted on the capillary basement membrane. Since these terminals are found in the rat after bilateral superior cervical ganglion exision, they probably originate from central catecholaminergic neurons in the brain stem. These findings suggest that central aminergic neurons might play some role in cerebral blood flow regulation. In addition to aminergic terminal boutons, non-aminergic nerve terminals containing non-core vesicles also ended in the capillaries. Cerebral capillaries also have central dual innervation, aminergic and cholinergic, and dual peripheral innervation by sympathetic and parasympathetic fibers.

Adrenergic Fibers↗
PubMedDate not supplied

Calcitonin gene-related peptide containing sensory neurons innervating tooth pulp and buccal mucosa of the rat: an immunohistochemical analysis.

Differential peptidergic innervation of the rat buccal mucosa and incisor tooth pulp was demonstrated by experimental immunohistochemistry. In the buccal mucosa, calcitonin gene-related peptide (CGRP)-like immunoreactive (IR) nerve fibres were observed in both the epithelium and submucosal layer. Most of these fibres were also immunoreactive to substance P (SP). On the other hand, SP-IR fibres were less numerous than CGRP-IR fibres in the incisor tooth pulp. Fast blue (FB) was applied to the buccal mucosa and the incisor pulp chamber. Small (less than 20 microns) FB-labelled CGRP-IR neurons were more numerous in the buccal mucosa group, while medium to large neurons (20-50 microns) predominated in the incisor pulp. Following neonatal capsaicin treatment, CGRP- and SP-containing fibres in the buccal mucosa almost totally disappeared, but many CGRP-IR fibres remained in the incisor tooth pulp. The findings suggest that these two oral tissues are innervated by different subgroups of CGRP-IR neurons in the trigeminal ganglia.

Animals↗
PubMedDate not supplied

Demonstration of rat preprotachykinin A mRNA in the rat trigeminal ganglion by in situ hybridization histochemistry.

The localization of gamma-preprotachykinin A mRNAs in the rat trigeminal ganglion was demonstrated by in situ hybridization histochemistry using the 32P and 35S labelled gamma-preprotachykinin A complementary DNA. In situ hybridization using 32P allowed shorter exposure times, whereas higher resolution of the hybridization signal on both film and emulsion autoradiograms was obtained using 35S. Preprotachykinin A mRNA detected by the gamma-preprotachykinin A probe was localized in about 15 per cent of the trigeminal ganglion cells, most of which were small or medium sized. Immunohistochemical studies using anti-substance P antibodies demonstrated that 15-20 per cent of total trigeminal ganglion cells were positive. These cells were small or medium sized. The result of immunohistochemistry coincided well with that of in situ hybridization histochemistry. The present study showed that the cellular localization of preprotachykinin A mRNA could be analysed by in situ hybridization histochemistry.

Animals↗
PubMedDate not supplied

Geniculo-geniculate projection of enkephalin and neuropeptide Y containing neurons in the intergeniculate leaflet of the thalamus in the rat.

Geniculo-geniculate projections of immunoreactive neurons for gamma-aminobutyric acid (GABA), leucine-enkephalin (ENK), neuropeptide Y (NPY) and substance P (SP) in the intergeniculate leaflet (IGL) and ventral lateral geniculate nucleus (VLG) of the rat were examined by using a combination of retrograde tracing method and immunocytochemistry. After injection of the fast blue (FB) dye into the IGL and VLG, many ENK immunoreactive neurons, and some NPY immunoreactive neurons were labelled by FB dye in the contralateral IGL. However, GABA and SP immunoreactive neurons in the IGL and VLG were not labelled retrogradely by FB dye. A unilateral electrical lesion of the IGL and VLG caused a reduction of the ENK and NPY immunoreactive fibres in the contralateral IGL and VLG. These findings suggested that ENK is one major component of the neuroactive substances in the geniculo-geniculate projection, and NPY also contributes partly to this projection. Furthermore, the unilateral destruction of the IGL and VLG showed a marked loss of the NPY immunoreactive fibres and a slight loss of the ENK immunoreactive fibres in the bilateral suprachiasmatic nuclei.

Amidines↗
PubMedDate not supplied

Localization of neuroactive substances in the rat parabigeminal nucleus: an immunohistochemical study.

The distribution of neurons and fibres that contain substance P, cholecystokinin-8, vasoactive intestinal polypeptide, corticotropin-releasing factor, calcitonin-gene-related peptide, choline acetyltransferase, tyrosine hydroxylase, somatostatin, leucine-enkephalin, and neuropeptide Y was examined in the parabigeminal nucleus of the rat by immunohistochemistry. Many choline acetyltransferase-like immunoreactive or calcitonin-gene-related peptide-like immunoreactive neurons were observed in the dorsal, middle and ventral subdivisions of the parabigeminal nucleus. A few corticotropin-releasing factor-like immunoreactive neurons were also seen in these three subdivisions. The double-immunostaining demonstrated that some choline acetyltransferase-like immunoreactive neurons in the dorsal and ventral subdivisions contained calcitonin-gene-related peptide. Fibres containing cholecystokinin-8, substance P or vasoactive intestinal polypeptide were abundant in the parabigeminal nucleus. Fibres containing cholecystokinin-8 were concentrated in the dorsal and ventral subdivisions, and the lateral margin of the middle subdivision, whereas many fibres containing substance P or vasoactive intestinal polypeptide existed in the lateral half of each subdivision. Fibres containing calcitonin-gene-related peptide or corticotropin-releasing factor were mostly observed around the immunoreactive neurons. Tyrosine hydroxylase-like immunoreactive fibres were scattered in the parabigeminal nucleus.

Animals↗
PubMedDate not supplied

Localization and fine structure of calcitonin gene-related peptide (CGRP)-like immunoreactive nerve fibres in the organ of Corti of guinea pigs by immunohistochemistry.

The localization and fine structure of calcitonin gene-related peptide (CGRP)-like immunoreactive (CGRPI) fibres in the guinea pig cochlea were examined using immunohistochemistry. Numerous CGRPI fibres were located in the inner spiral bundle corresponding to the lateral system of the olivocochlear bundle. Immunoelectron microscopic analysis demonstrated that the CGRPI fibres belonged to the efferent terminals and some of them made synaptic contacts with peripheral neurites of the auditory nerve. These findings suggested that the olivocochlear CGRP neuron system influenced the neural activity of the auditory nerve, which conveys auditory information from the cochlea to the central nervous system.

Animals↗