1987 Fiscal Year Final Research Report Summary
Physiological and clinical significance of opioids and related peptides
| Project/Area Number |
60440053
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
内分泌・代謝学
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| Research Institution | Kyoto University |
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Principal Investigator |
IMURA Hiroo kyoto University Faculty of Medicine, Professor, 医学部, 教授 (10025570)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAO Kazuwa Kyoto University Radioisotope Research Center, Research Associate, 放射性同位元素センター, 助手 (00172263)
SEINO Yutaka Kyoto University Faculty of Medicine, Associate Professor, 医学部, 助教授 (40030986)
NAKAI Yoshikatsu Kyoto University Faculty of Medicine, Assist Professor, 医学部, 講師 (10115892)
KATA Yuzuru Shimane Medical University, Professor, 教授 (90030965)
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| Project Period (FY) |
1985 – 1987
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| Keywords | Opioid Peptides / Leumorphin / Pituitary Hormones / Blood Pressure / Vasopressin / Drinking / ANP |
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| Research Abstract |
Opioid peptides are widely distributed in the CNS and in peripheral tissues but their physiological significance is not yet understood. In this study, we first demonstrated that the processing of opioid precursors (POMC, proenkephalin A and proenkephalin B) differs in different tissues, thus giving rise to different end-products which have have different receptor subtype affinities. The existence of leumorphin (LM), a putative opioid peptide predicted from the nucleotide sequence of cDNA, was demonstrated in human and porcine brain by HPLC and specific radioimmunoassay. LH has a variety of actions. It was shown to stimulate prolactin and GH secretion. Its activity to stimulate prolactin secretion was very potent and considered to be partly due to the direct effect on the pituitary. GH secretory action of opioid petides seems to be mediated by GRF, since immunoneutralization with anti-GRF antisera blunted GH secretion induced by opioids. The central administrationof LH lowered plasma vasopressin (AVP) levels induced by angiotensin II (AII) and water deprivation. LH also inhibited drinking induced by these stimuli and blunted blood pressure increase induced by AII. Thus, LH may play a role in the central cardivascular control and may interest with another peptide, atrial natriuretic peptide (ANP). The central administration of ANP also inhibited drinking, AVP release and blood pressure rise induced by AII. These results suggest that there are renin-angiotensin system and ANP system in the brain, which are antagonistic each other in the central cardiovascular control. Opioid system is also antagonistic to the renin-angiotensin system.
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