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Mori T, Inoue S, Egawa M, Takamura Y, Minami S, Wakabayashi I. Impaired growth hormone secretion in VMH lesioned rats. INTERNATIONAL JOURNAL OF OBESITY AND RELATED METABOLIC DISORDERS : JOURNAL OF THE INTERNATIONAL ASSOCIATION FOR THE STUDY OF OBESITY 1993; 17:349-353. [PMID: 8101181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
To investigate impaired growth hormone (GH) secretion in ventromedial nuclei (VMH) lesioned rats, we examined spontaneous plasma GH secretion, and plasma GH responses to arginine, clonidine and growth hormone releasing factor (GRF) under unanaesthetized and unrestrained conditions. Spontaneous GH secretion was blunted with 75% decrease of peak value in VMH lesioned rats, while it clearly existed in control rats. When rats were pre-treated with chlorpromazine (1-2 mg/kg, i.v.) which eliminates pulsatile GH secretion, no difference was observed in the plasma GH response to arginine (1 g/kg, i.v.) or to clonidine (100 micrograms/kg, i.v.) between VMH lesioned and control rats, but response to GRF (10 micrograms/kg, i.v.) was enhanced in the former animals. Administration of antiserum against somatostatin (1 ml) plus chlorpromazine significantly elevated the basal plasma GH level and GH response to arginine in control rats, but did not elevate them in VMH lesioned rats. These results suggest that reduction of both hypothalamic GRF and somatostatin release contribute to the impaired GH secretion in VMH lesioned rats. Reduction of somatostatin caused enhanced GH response to GRF and no increase in basal GH level with pre-treatment of antiserum against somatostatin. Reduction of GRF resulted in a failure to restore GH response to arginine with pre-treatment of antiserum against somatostatin. Reduction of both GRF and somatostatin caused blunted spontaneous GH secretion and normal GH response to arginine and clonidine.
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Masui H, Wakabayashi I, Hatake K, Kurahashi M, Yoshimoto S, Hishida S, Sakamoto K. [Effect of ethanol on isometric tone of aorta from guinea pig]. ARUKORU KENKYU TO YAKUBUTSU IZON = JAPANESE JOURNAL OF ALCOHOL STUDIES & DRUG DEPENDENCE 1993; 28:79-94. [PMID: 8347104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Using aortic strips isolated from guinea pig, effects of ethanol on vascular smooth muscle tone were studied. Low concentrations (5, 50, 100 mM) of ethanol potentiated norepinephrine and serotonin-induced contractions, but not KCl-induced one. Ethanol (100 mM) potentiated calcium-induced contraction in the presence of norepinephrine, but not that in the presence of KCl. Ethanol (100 mM) showed no effects on norepinephrine-induced contraction in the calcium-free medium. Ethanol (100 mM) augmented 45Ca uptake stimulated with norepinephrine, but not that with KCl. Ethanol at the higher concentration of 600 mM by itself induced contraction, which was inhibited by trifluoperazine or in the calcium-free medium, but not by phentolamine, diphenhydramine, methysergide, indomethacin or nifedipine. Ethanol (600 mM) directly increased 45Ca uptake, which was not affected by nifedipine. These findings indicate that the low concentrations of ethanol potentiate receptor-mediated vascular smooth muscle contraction and the higher concentration of ethanol directly contracts it via facilitation of transmembranous calcium influx.
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Wakabayashi I. [Recent progress in growth hormone research]. NIHON IKA DAIGAKU ZASSHI 1993; 60:133-9. [PMID: 8331148 DOI: 10.1272/jnms1923.60.133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Adachi K, Kudo M, Chen MN, Nakazawa S, Wakabayashi I. Cerebral aneurysm associated with multiple endocrine neoplasia, type 1--case report. Neurol Med Chir (Tokyo) 1993; 33:309-11. [PMID: 7687038 DOI: 10.2176/nmc.33.309] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Cerebral aneurysm associated with pituitary adenoma and other endocrine dysfunctions occurred in a 45-year-old female suffering from multiple endocrine neoplasia, type 1 (Wermer's syndrome). She died of subarachnoid hemorrhage secondary to rupture of the aneurysm. Pituitary adenoma and/or other endocrine dysfunctions associated with multiple endocrine neoplasia, type 1 may be a factor in the aneurysm formation.
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Kamegai J, Minami S, Sugihara H, Wakabayashi I. Barrel rotation evoked by intracerebroventricular injection of somatostatin and arginine-vasopressin is accompanied by the induction of c-fos gene expression in the granular cells of rat cerebellum. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1993; 18:115-20. [PMID: 8097547 DOI: 10.1016/0169-328x(93)90179-s] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Intracerebroventricular (i.c.v.) injection of somatostatin (SS) or arginine-vasopressin (AVP) elicits barrel rotation (BR) in rats. To identify the potential neuron structures involved in this characteristic behavior, the regional expression of the c-fos gene in rat brain after i.c.v. injection of SS (10 micrograms) or AVP (1 micrograms) was examined by hybridization histochemistry. The c-fos expression could serve as a marker of neuronal activity and/or neural transmission. Following SS-induced BR, c-fos gene expression was observed in the lingula, uvula, nodulus, simplex, centralis, and culmen of the cerebellum, while following AVP-induced BR, c-fos gene expression was observed in the first four of the above-mentioned regions of the cerebellum, but not in the centralis or culmen. In these regions, the c-fos mRNA signals were observed on the granular layer. Expression of the c-fos gene was immediately and transiently induced and was not observed in rats in which BR was not evoked after SS or AVP injection. In both control rats and SS- or AVP-injected rats, the c-fos gene expression was induced in the piriform cortex and the flocculus of the cerebellum. The findings suggest that BR is a manifestation of behavior induced by massive transsynaptic activation of the granular cells in the cerebellum.
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Okada K, Sugihara H, Minami S, Wakabayashi I. Effect of parenteral administration of selected nutrients and central injection of gamma-globulin from antiserum to neuropeptide Y on growth hormone secretory pattern in food-deprived rats. Neuroendocrinology 1993; 57:678-86. [PMID: 7690118 DOI: 10.1159/000126425] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Serial changes in growth hormone (GH) secretory pattern during 72 h food deprivation and in response to refeeding after 72 h food deprivation were observed in adult male Wistar rats. In addition, the effects of intravenous administration of glucose, fatty acids or amino acids and central injection of gamma-globulin from antiserum to human neuropeptide Y (NPY) on the GH secretory pattern were examined in 72 h food-deprived rats. Rats were provided with chronic indwelling right atrial cannula and serial blood specimens were withdrawn via the cannula every 10 min using an automatic blood-sampling device. The GH secretory pattern was analyzed using a Pulsar computer program. In fed rats, episodic GH secretion with an amplitude exceeding 350 ng/ml occurred at 170-min intervals and intervening trough GH levels were less than 10 ng/ml. During the 72 h food deprivation, the amplitude of pulsatile GH secretion decreased progressively without altering the pulse frequency. When 72 h food-deprived rats were refed lab chow, the pulse frequency and the pulse amplitude increased rapidly and lasted for 6-8 h. Normal pulsatile GH secretion resumed by 10-12 h after refeeding following the 72 h food deprivation. To identify the specific nutrient (i.e. glucose, fatty acids or amino acids) serving as the signal causing restoration of the central drive to GH secretion, glucose solution (2 or 6 kcal), lipid emulsion (2 or 6 kcal) or amino acid solution (2 kcal) was administered intravenously to the 72 h food-deprived rats.(ABSTRACT TRUNCATED AT 250 WORDS)
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Wakabayashi I. Involvement of nitric oxide in fading of 5-hydroxytryptamine-induced vasocontraction. PHARMACOLOGY & TOXICOLOGY 1993; 72:175-81. [PMID: 8390654 DOI: 10.1111/j.1600-0773.1993.tb00312.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
This investigation was done to determine whether vascular nitric oxide is involved in the fading of 5-hydroxytryptamine (5-HT)-induced contraction of isolated aortic strips from rats. The 5-HT (100 microM)-induced contractile response showed a gradual decrease in tension after a plateau level had been attained. The degree of the fadeaway was less in strips without endothelium than in those with endothelium. Pretreatment with nitro-L-arginine (100 microM) or haemoglobin (10 microM) suppressed the fadeaway of 5-HT contraction in both types of strips, although the effect was less in strips without endothelium. In contrast to 5-HT contraction, phenylephrine (10 microM) contraction in the presence of endothelium did not begin fading away for at least 1 hr after stimulation. In strips precontracted with 5-HT (100 microM), relaxation induced by sodium nitroprusside (1-50 nM) was significantly higher than in those precontracted with phenylephrine (10 microM). There was no significant difference between the cyclic GMP levels at 1 hr after stimulation with phenylephrine (10 microM) and 5-HT (100 microM). These results suggest that decrease in vascular tone in rat aorta after the plateau of 5-HT contraction has been reached is in part due to nitric oxide derived from vascular endothelial and non-endothelial cells. The vascular tone decreases more quickly after the plateau in the case of 5-HT contraction than of phenylephrine contraction, which may be due to higher sensitivity of 5-HT contraction to nitric oxide.
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Sugihara H, Minami S, Okada K, Kamegai J, Hasegawa O, Wakabayashi I. Somatostatin reduces transcription of the growth hormone gene in rats. Endocrinology 1993; 132:1225-9. [PMID: 7679974 DOI: 10.1210/endo.132.3.7679974] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
To examine whether somatostatin (SS) exerts influences on the steady state levels of GH-releasing factor (GRF), the effect of SS on GH gene transcription was examined in rats. This approach was used because it has been shown that GRF stimulates GH gene transcription independent of GH release, and SS does not inhibit basal or GRF-stimulated GH gene transcription. Therefore, it is assumed that an effect of SS on GH gene transcription would be mediated by a change in GRF levels. Adult female Sprague-Dawley rats were provided with right atrial cannulae. Studies were performed using unanesthetized rats. Pituitary GH gene transcription was measured by transcription assay. An iv administration of antiserum to rat GRF 150 min previously significantly decreased GH gene transcription compared with that in control rats given normal goat serum. A continuous infusion of SS (300 micrograms/kg.h) via the cannula for 150 min significantly decreased GH gene transcription compared with that in control rats receiving 0.9% NaCl. When GRF (3 micrograms/kg.h) was given simultaneously with SS (300 micrograms/kg.h), GH gene transcription increased significantly compared with that in rats receiving SS infusion alone. After the withdrawal of SS infusion, GH gene transcription rapidly and significantly increased. The data suggest that SS reduces the steady state levels of GRF.
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Nakagawa K, Ishizuka T, Shimizu C, Ito Y, Wakabayashi I. Increased hypothalamic somatostatin mRNA following dexamethasone administration in rats. Eur J Endocrinol 1993; 127:416-9. [PMID: 1361705 DOI: 10.1530/acta.0.1270416] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
There is increasing evidence to suggest that supraphysiological doses of glucocorticoids suppress growth hormone secretion in vivo by augmenting somatostatin release from the hypothalamus; previously, we reported an increase in hypothalamic somatostatin content in dexamethasone-treated rats. To further examine whether the production of somatostatin really is augmented, hypothalamic somatostatin mRNA levels were determined by the Northern blot technique in female rats receiving 330 micrograms of dexamethasone daily for three days. In two series of experiments, hypothalamic somatostatin mRNA levels in dexamethasone-treated rats were significantly (p < 0.05) increased to 133 +/- 19 (mean +/- SD)% and 153 +/- 38% of the controls. In the dexamethasone-treated rats, plasma growth hormone levels were markedly suppressed compared with those of the controls. These results further support the hypothesis that pharmacological doses of glucocorticoids increase the production and release of somatostatin from the hypothalamus and thus inhibit growth hormone secretion, overriding the direct stimulatory effect of glucocorticoids on growth hormone production at the pituitary level.
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Kurahashi M, Masui H, Yoshimoto S, Wakabayashi I, Sakamoto K. Effect of diethyldithiocarbamate on diabetogenic action of alloxan in rats. Diabetes Res Clin Pract 1993; 19:39-47. [PMID: 8386078 DOI: 10.1016/0168-8227(93)90143-s] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
To determine whether alloxan action is mediated by hydroxyl radicals in vivo, we assayed methane sulfinic acid (MSA), a product of the trapping reaction of dimethyl sulfoxide (DMSO) with hydroxyl radicals. In DMSO-treated rats, the plasma levels of MSA were increased after injection of alloxan (75 mg/kg). This supports the hypothesis that the diabetogenic action of alloxan is mediated by hydroxyl radicals in vivo. The role of cytosolic superoxide dismutase (SOD) in protecting B cells against chemically induced diabetes was studied in rats injected intraperitoneally with diethyldithiocarbamate (DDC). When rats were injected intraperitoneally with DDC (750 mg/kg), the SOD activity at 2.5 h was decreased by 44% in the whole pancreas. The decreased SOD activity was affected by DDC but not by alloxan. Intraperitoneal injection of rats with DDC (750 mg/kg) increased diabetogenic susceptibility to a nondiabetogenic dose of alloxan (20 mg/kg). Subcutaneous injection of vitamin E, prior to administration of both DDC and alloxan, provided partial protection to the rats against the diabetogenic action. These findings suggest that the susceptibility to diabetogenic action of alloxan in B cells is augmented when the cellular SOD activity is inhibited. Thus, cellular SOD may play an important role in the maintenance of B cell function.
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Shuto Y, Okazaki T, Wakabayashi I. Transcriptional activity of a mutant thyroid hormone receptor beta in a family with generalized resistance to thyroid hormone. Mol Cell Endocrinol 1992; 90:111-5. [PMID: 1301392 DOI: 10.1016/0303-7207(92)90108-i] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We previously reported a family with generalized resistance to thyroid hormone (GRTH) which had a point mutation with codon 448 CCT (proline) being converted to ACT (threonine) in the thyroid hormone receptor (TR) beta. To characterize functional properties of the mutant TR beta, transient expression studies were performed in COS cells. A double stranded oligonucleotide encompassing thyroid hormone response element (TRE) derived from the rat GH gene was synthesized. We constructed chloramphenicol acetyl transferase (CAT) plasmid containing the thymidine kinase promoter under the control of the rat GH TRE. T3 induction of CAT activity by the mutant TR beta was significantly reduced as compared with that of the normal TR beta. This was observed in the presence of 0.5-50 nM T3, but not at 500 nM T3. When the normal and mutant TR beta were cotransfected, the mutant TR beta inhibited gene activation regulated by the normal TR beta. However, a high molar excess was necessary to significantly inhibit the function of the normal receptor. Additionally, the binding of in vitro synthesized mutant TR beta to TRE was preserved.
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Wakabayashi I, Hatake K, Sakamoto K. Ammonium ion increases the tone of rat portal vein. GENERAL PHARMACOLOGY 1992; 23:1189-92. [PMID: 1487128 DOI: 10.1016/0306-3623(92)90310-g] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
1. The effect of ammonium ion on vascular tone was investigated using the portal vein isolated from rat. 2. Ammonium chloride at 10-90 mM induced a contractile response. 3. Spontaneous twitch contraction of portal strips was augmented by ammonium chloride at 10-60 mM. 4. Ammonium chloride-induced contraction was abolished in calcium-free solution or in the presence of 1 microM nifedipine. 5. Methylamine (60 mM) also induced a contractile response and augmented the spontaneous twitch contraction in rat portal vein. 6. After withdrawal of ammonium chloride or methylamine from the organ bath solution, the spontaneous twitch contraction was strongly inhibited. 7. These results suggest that ammonium compounds increase vascular tone by causing influx of extracellular calcium through the voltage-dependent calcium channel and intracellular alkalinization is involved in this process.
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Wakabayashi I, Yoshimoto S, Masui H, Sakamoto K, Kinoshita H. [A study of factors affecting the concentration of serum lipid peroxide in the elderly inhabitants in a rural area]. Nihon Ronen Igakkai Zasshi 1992; 29:783-9. [PMID: 1460784 DOI: 10.3143/geriatrics.29.783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Among 16 male (mean age of 66.6 years) and 51 female (mean age of 65.3 years) inhabitants of a rural area, the concentration of serum lipid peroxide measured as malondialdehyde (MDA) by Yagi's method was analyzed by physicochemical and food intake items. The MDA level in serum showed a peak of 6.2 nmol/ml at fifties years old in females and showed constant values of 4.6 and 6.1 nmol/ml for females and males, respectively, in those aged 60 more. The MDA level significantly correlated positively to total- or LDL-cholesterol level and urinary K/Cr, thus MDA level seemed to be a risk factor of arteriosclerosis. Fruit intake significantly positively correlated to MDA level in male. The MDA level showed a significantly higher level in the group with both higher total-cholesterol and urinary K/Cr levels, than in the other groups. It is suggested that a high intake of potassium increases the MDA level in the group with higher total-cholesterol level.
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Wakabayashi I, Sakamoto K, Yoshimoto S, Masui H. Relation of serum sialic acid to lipid concentrations. BMJ (CLINICAL RESEARCH ED.) 1992; 305:562-3. [PMID: 1393037 PMCID: PMC1883271 DOI: 10.1136/bmj.305.6853.562] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Hatake K, Wakabayashi I, Kakishita E, Hishida S. Impairment of endothelium-dependent relaxation in human basilar artery after subarachnoid hemorrhage. Stroke 1992; 23:1111-6; discussion 1116-7. [PMID: 1636187 DOI: 10.1161/01.str.23.8.1111] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
BACKGROUND AND PURPOSE The goal of this study was to determine the alterations in vascular reactivity of human basilar artery after subarachnoid hemorrhage. METHODS Human basilar arteries were obtained from subjects who died within 1 day after subarachnoid hemorrhage and control subjects who died from causes other than brain involvement. Basilar artery strips were suspended for isometric tension recording in Krebs-Ringer solution. Morphometric study was also carried out on paraffin-embedded sections stained with van Gieson's elastica stain of preselected sites from the basilar arteries. The intimal and medial area and the intimal index ([intimal area/area circumscribed by internal elastic lamina] x 100) were evaluated. RESULTS Contractile responses to KCl, norepinephrine, and 5-hydroxytryptamine did not differ between subarachnoid hemorrhage and control groups. The endothelium-dependent relaxation responses to thrombin, bradykinin, and calcium ionophore A23187 were less for the subarachnoid hemorrhage group than for the control group. However, the endothelium-independent response to sodium nitroprusside of the subarachnoid hemorrhage group did not differ from that of the control group. Morphometric measurements were comparable between the two groups. CONCLUSIONS These results suggest that the decreased relaxation responses to thrombin and bradykinin occur at the level of endothelial cells and not smooth muscle cells and that decreased relaxation may be involved in delayed vasospasm after subarachnoid hemorrhage. Although the decreased relaxation was observed within 1 day after subarachnoid hemorrhage, a period in which delayed spasm does not occur, this time difference may be dependent on the severity of bleeding after rupture of an aneurysm.
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Minami S, Kamegai J, Sugihara H, Hasegawa O, Wakabayashi I. Systemic administration of recombinant human growth hormone induces expression of the c-fos gene in the hypothalamic arcuate and periventricular nuclei in hypophysectomized rats. Endocrinology 1992; 131:247-53. [PMID: 1612002 DOI: 10.1210/endo.131.1.1612002] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The neuronal expression of the protooncogene c-fos could serve as a marker of neural activity. To identify the brain sites responding to GH, rat brains after systemic administration of recombinant human GH (rhGH) were processed for hybridization histochemistry for c-fos mRNA. Adult male Wistar rats were hypophysectomized 10 days before rhGH administration. After hypophysectomy, rats received sc cortisone acetate (0.5 mg/kg BW) and L-T4 (20 microgram/kg BW) daily. Four international units (1.33 mg) of rhGH were given iv through an indwelling right atrial cannula. Vehicle was administered to control animals. The rhGH treatment was accompanied by expression of the c-fos gene in the arcuate nucleus (ARC) of the hypothalamus. The accumulation of the c-fos mRNA was transient, reaching maximum values at 60 min and decreasing thereafter to reach control levels within 120 min after rhGH injection. Among control animals, c-fos gene expression was not detected in the ARC. The c-fos mRNA was also detected in the paraventricular nucleus after rhGH administration; however, it was comparable to that in control animals. When rhGH was administered twice at 40-min intervals, c-fos gene expression was induced in the periventricular nucleus (PeV) as well as the ARC 40 min after the second rhGH injection. Throughout the studies, c-fos mRNA was not detected other than in the ARC, paraventricular nucleus, and PeV in the hypothalamus. In the ARC, distribution of the cells expressing the c-fos gene appears to overlap at least in part with somatostatin (SS) mRNA-containing cells. In the PeV, it appeared to correlate generally with the distribution of SS mRNA-containing cells. The data suggest that GH feeds back on neurons of hypothalamic PeV and ARC expressing SS mRNA, and that c-fos expression is involved in the feedback mechanism.
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Shuto Y, Wakabayashi I, Amuro N, Minami S, Okazaki T. A point mutation in the 3,5,3'-triiodothyronine-binding domain of thyroid hormone receptor-beta associated with a family with generalized resistance to thyroid hormone. J Clin Endocrinol Metab 1992; 75:213-7. [PMID: 1619012 DOI: 10.1210/jcem.75.1.1619012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A tight linkage between generalized resistance to thyroid hormone (GRTH) and the thyroid hormone receptor-beta (TR beta) gene is indicated. We evaluated a family with GRTH for the TR beta gene. We found that a new point mutation, consisting of a cytosine to adenine replacement at nucleotide position 1642, resulted in substitution in codon 448 in the T3-binding domain of TR beta. This base substitution was found in only one allele of affected members, but not in unaffected members of the family. The in vitro translation products of this mutant TR beta gene demonstrated significantly reduced T3-binding affinity. Previously, others have reported a kindred with GRTH, in that the same codon was subjected to proline to histidine replacement due to a mutation consisting of a cytosine to adenine replacement at nucleotide position 1643. There appeared to be a significant phenotypic difference between our kindred and that described by others.
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Yoshimoto S, Sakamoto K, Wakabayashi I, Masui H. Effect of chromium administration on glucose tolerance in stroke-prone spontaneously hypertensive rats with streptozotocin-induced diabetes. Metabolism 1992; 41:636-42. [PMID: 1640849 DOI: 10.1016/0026-0495(92)90056-g] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The present study was conducted to assess the effect of chromium (Cr) administration on glucose tolerance in insulin-dependent diabetes that accompanies hypertension. Four rat groups were used: stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar Kyoto rats (WKY) with and without streptozotocin (SZ, 40 mg/kg)-induced diabetes. Each group of rats was subdivided to the Cr-dose group and the control group. The Cr-dose group, which was intraperitoneally administered Cr solution (20 micrograms trivalent chromium/kg body weight/d for 4 weeks), and the control group (saline) were studied for plasma glucose and plasma insulin during intraperitoneal glucose tolerance test (IPGTT) and insulin action by isolated adipocytes. For diabetic SHRSP showing the highest plasma glucose and lowest plasma insulin among the four groups, Cr administration led to the greatest reduction in plasma glucose without a significant effect on plasma insulin during IPGTT. For each diabetic WKY and normal SHRSP and WKY, those given Cr showed lower levels of plasma glucose with lower levels of plasma insulin than the controls. For diabetic SHRSP, glucose uptake by isolated adipocytes in the Cr-dose group was higher than that in the control group. This effect of Cr administration involved enhancement of insulin responsiveness and sensitivity, attributed to enhanced affinity of the insulin receptor. A similar tendency was observed for diabetic WKY. However, for normal SHRSP and WKY, the increase in glucose uptake due to Cr administration coincided only with enhanced insulin responsiveness.(ABSTRACT TRUNCATED AT 250 WORDS)
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Hatake K, Wakabayashi I, Kakishita E, Hishida S. Effect of aging on contractile response to KCl, norepinephrine and 5-hydroxytryptamine in isolated human basilar artery. GENERAL PHARMACOLOGY 1992; 23:417-20. [PMID: 1511850 DOI: 10.1016/0306-3623(92)90104-r] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
1. We investigated the effect of aging on contractile response in human basilar artery. 2. The maximal contraction caused by KCl, norepinephrine and 5-hydroxytryptamine decreased with age. 3. ED50 value for norepinephrine or 5-hydroxytryptamine did not correlate with age. 4. These results suggest that the decrease in contractile response is due to nonspecific changes in the medial structure of the artery.
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Hasegawa O, Sugihara H, Minami S, Wakabayashi I. Masculinization of growth hormone (GH) secretory pattern by dihydrotestosterone is associated with augmentation of hypothalamic somatostatin and GH-releasing hormone mRNA levels in ovariectomized adult rats. Peptides 1992; 13:475-81. [PMID: 1381827 DOI: 10.1016/0196-9781(92)90077-g] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The role of androgen in the sexual dimorphism in hypothalamic growth hormone (GH)-releasing hormone (GHRH) and somatostatin (SS) gene expression was examined in rats. In the first study, the SS and GHRH mRNA levels were measured in both male and female rats at 4, 6, 8, and 10 weeks of age. A significant sex-related difference in the SS and GHRH mRNA levels was observed after 8 weeks of age, when sexual maturation is fully attained. Male rats had higher SS and GHRH mRNA levels than the female rats. In the second study, adult ovariectomized rats received daily injection of dihydrotestosterone (DHT), nonaromatizable testosterone, at a dose of 2 mg/rat for 21 days. The DHT treatment masculinized the GH secretory pattern, which was indistinguishable from that of intact male rats, and simultaneously augmented the SS and GHRH mRNA levels. The DHT treatment of ovariectomized rats after hypophysectomy significantly raised the level of SS mRNA, but not that of GHRH mRNA compared to the control animals. These findings suggest that the activation of the SS gene expression through androgen receptor plays an important role in the maintenance of sexual dimorphism in GH secretion in rats.
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Wakabayashi I, Inokuchi K, Hasegawa O, Sugihara H, Minami S. Expression of growth hormone (GH)-releasing factor gene in GH-producing pituitary adenoma. J Clin Endocrinol Metab 1992; 74:357-61. [PMID: 1730814 DOI: 10.1210/jcem.74.2.1730814] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Pituitary cells synthesize various neuropeptides that influence pituitary hormone secretion. GH-releasing factor (GRF) may also be produced by normal or pituitary tumor cells. We examined GRF gene expression in pituitary tumors. Standard techniques for the analysis of GRF gene expression did not appear to be suitable. Highly sensitive reverse transcription coupled to polymerase chain reaction was used. Specimens of pituitary adenoma were obtained by transsphenoidal adenomectomy from six patients with acromegaly and three patients with no clinical evidence of pituitary hormone overproduction; non-functioning adenoma. Pituitary glands were collected at autopsy from three patients who died from nonendocrine disorders. A specific GRF gene transcript was detected in five out of six GH-producing pituitary adenomas, whereas this was not found in three separate specimens of nonfunctioning pituitary adenoma or anterior and posterior pituitary tissue. The data suggest that GRF is synthesized as an intrinsic product in human GH-producing pituitary adenoma.
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147
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Wakabayashi I, Sakamoto K, Hatake K, Masui H, Yoshimoto S. Potentiating effect of NH4Cl on vasoconstriction in rat aorta. Biochem Biophys Res Commun 1991; 178:808-14. [PMID: 1714726 DOI: 10.1016/0006-291x(91)90963-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The effect on the vasocontractile response of pretreatment with NH4Cl at a concentration (10 mM) that made almost no change in the resting tension was investigated using aortic strips from rats. NH4Cl pretreatment for 10 min significantly potentiated strip contractions induced by KCl (less than or equal to 30 mM), BAY K 8644 (0.1 microM) and phenylephrine (0.01 microM). This potentiating action of NH4Cl was eliminated in presence of nifedipine (1 microM). KCl (14.7 mM)-stimulated 45Ca uptake in rat aorta was significantly potentiated by pretreatment with NH4Cl (10 mM) for 10 min, but this NH4Cl effect was also eliminated in the presence of nifedipine. These results suggest that NH4Cl potentiates contractions induced by KCl and agonists in rat aorta by facilitating calcium influx through the nifedipine-sensitive calcium channel.
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MESH Headings
- 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester/pharmacology
- Ammonium Chloride/pharmacology
- Animals
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/physiology
- Drug Synergism
- In Vitro Techniques
- Kinetics
- Male
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/physiology
- Nifedipine/pharmacology
- Phenylephrine/pharmacology
- Potassium Chloride/pharmacology
- Rats
- Rats, Inbred Strains
- Vasoconstriction/drug effects
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148
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Kakishita E, Sakiyama N, Wakabayashi I, Hatake K, Hishida S. Thrombin-induced vascular responses in rabbit aorta-modulation of endothelium. Thromb Res 1991. [DOI: 10.1016/0049-3848(91)90300-l] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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149
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Wakabayashi I, Hatake K, Sakamoto K. Mechanisms of ex vivo aortic hypocontractility in endotoxemic rat. Eur J Pharmacol 1991; 199:115-8. [PMID: 1893922 DOI: 10.1016/0014-2999(91)90645-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
To clarify the mechanism of the vascular hypocontractility in endotoxemia, the effect of endotoxin injection on phosphatidylinositol turnover and the contractile responses to NH4Cl and okadaic acid were investigated in aorta dissected from rats. The basal level of phosphatidylinositol hydrolysis and the phenylephrine- and 5-hydroxytryptamine-stimulated increase in hydrolysis were all markedly reduced in endotoxemic aortas as compared to in control aortas. Stimulation with KCl did not increase phosphatidylinositol hydrolysis in control or endotoxemic aortas. The NH4Cl-induced contractile response was significantly diminished in endotoxemic aorta, whereas the okadaic acid-induced contractile response was not altered. These results suggest that both transmembrane and intracellular signal transduction mechanisms are impaired in the endotoxemic artery whereas the contractile machinery remains intact.
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150
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Sakamoto K, Wakabayashi I, Yoshimoto S, Masui H, Katsuno S. Effects of physical exercise and cold stimulation on serum testosterone level in men. Nihon Eiseigaku Zasshi 1991; 46:635-8. [PMID: 1890772 DOI: 10.1265/jjh.46.635] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The concentrations of testosterone (TS) and other related hormones in serum were examined before and after physical exercise with a bicycle ergometer (90 Watts, 20 min.) and a cold water stimulation in 32 19-year-old males. While exercising, the serum TS level significantly increased by 20.8% (p less than 0.05), the luteinizing hormone (LH) level by 3.6% (p less than 0.05) and noradrenaline (NA) level by 140.0% (p less than 0.01). During cold water stimulation, TS decreased by 10.0%, LH increased by 22.1% and NA decreased by 23.8%. Based on changes in hormone levels within the individual during the loads. there was a significant positive correlation coefficient (r) between TS and LH, and between TS and NA, with r (TS-LH) = 0.399 (p less than 0.05) and r (TS-NA) = 0.481 (p less than 0.05) for physical exercise, while r (TS-LH) = 0.403 (p less than 0.05) and r (TS-NA) = 0.431 (p less than 0.05) for cold water stimulation, respectively. These results suggest that physical exercise increases TS level in serum by increasing LH and NA levels, but these tendencies were not found with cold water stimulation.
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