1991 Fiscal Year Final Research Report Summary
Participation of Endogenous Opioid Peptide in Sudden Death
| Project/Area Number |
02670264
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Legal medicine
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| Research Institution | Showa University |
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Principal Investigator |
TSUNODA Kenji Showa University School of Medicine, Associate Professor, 医学部, 助教授 (40095906)
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| Co-Investigator(Kenkyū-buntansha) |
DOGE Koichi Showa University School of Medicine, Assistant Professor, 医学部, 助手 (60188844)
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| Project Period (FY) |
1990 – 1991
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| Keywords | Sudden Death / beta-Endorphin / Hypothalamic-Pituitary System / Respiratory Failure / Cardiac Failure / Agonal Period / Sex Difference / Sympathoinhibitory Effect |
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| Research Abstract |
Using male and female Wistar rats, pituitary response to cardiac and respiratory failure type (CFT and RFT) sudden death caused by the intravenous administration of KCl and SCC, respectively, was examined by analyzing variation in pituitary immunoreactive beta-endorphin (IR-beta-EP) levels determined by radioimmunoassay after death and in circulating IR-beta-EP levels during periods of agony. In the pituitary gland of both sexes which differed significantly in ratio of the organ weight to body weight for CFT and RFT (CFT>RFT), IR-beta-EP was significantly less in RFT than in CFT (P 0.05). No variation in plasma IR-beta-EP was noted during short periods of agony in CFT, but it markedly increased during long periods of agony in RFT. The highest elevation at 2 or 4 minutes after SCC administration was about 3 times the preadministration value for IR-beta-EP in males (P 0.01). But elevation in females was lower than in males. Rise in plasma IR-beta-EP during agony of RFT is regarded to be
… More
of pituitaryorigin due to dexamethasone treatment. The pituitary was thus concluded to respond more to the fatal agony in RFT than in CFT.
An attempt was made to determine sex differences in the effects of beta-endorphin ( beta-EP) on respiratory and cardiovascular systems using the same strain rats. By the intracerebroventicular administration of beta-EP (0.18 mg/kg) to normal male and female rats, respiratory rate (RR), heart rate (HR) and mean arterial blood pressure (MABP) were depressed significantly (P 0.01 or 0.001) and CO_2 in expired gas increased significantly (P 0.01). These suppressive effects of the peptide were transiently blocked by the intravenous injection of naloxone (0.2 mg/kg). No differences in the effects of beta-EP between estrous and diestrous female rats could be detected. The effects of the peptide were significantly stronger in RR, HR and MABP for females than for males (0.001 P 0.05). Testectomized rats showed suppressive effects of the peptide to the same extent as intact females, but the effects in overiectomized rats did not differ from those for intact females. In testectomized and ovariectomized rats treated with testosterone, the former showed the same results as intact males, but not the latter. The suppressive effects of beta-EP on the respiratory and cardiovascular systems are thus remarkably relieved by androgen in male rats. Less
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