1989 Fiscal Year Final Research Report Summary
Analysis of physiological and pathological effects of melatonin
| Project/Area Number |
62480140
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Experimental pathology
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| Research Institution | The University of Tokyo |
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Principal Investigator |
MACHINAMI Rikuo University of Tokyo, school of medicine, Professor, 医学部(医), 教授 (30010052)
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| Co-Investigator(Kenkyū-buntansha) |
OKA Teruaki University of Tokyo, school of medicine, Assistant Professor, 医学部(医), 助手 (60177029)
MORI Wataru University of Tokyo, Honorary Professor, 名誉教授 (40013825)
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| Project Period (FY) |
1987 – 1989
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| Keywords | Melatonin / Anti-glucocorticoid effect / Anti-hypercholesterolemic effect |
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| Research Abstract |
To extend our previous experiment anti-glucocorticoid erects of melatonin which was performed under a very special condition using young rats, we have carried out another experiment of long administration of melatonin to adult female rats which was conditioned by overdose glucocorticoid. The results demonstrated significant protection, by melatonin, from the injurious effect of glucocorticoid, dexamethasone: decrease pf body weight gain, atrophy of the thymus and adrenals and elevation of the level of total cholesterol in blood. In order to confirm and extend this observation, we examined whether melatoninhas a general antihyperlipemic effect. It was demonstrated that melatonin could ameliorate, partially but definitely, the increase in total cholesterol levels in the plasma of these genetically hypercholesterolemic rats. Similar effects on triglyceride and phospholopid levels have been seen, although the differences were not statistically significant. Moreover, melatonin greatly reduced the fatty development in the liver. Next, we wished to determine whether melatonin really was an antagonist of glucocorticoids or whether this effect was simply antihyperlipemic. From this point, we planned study on the effect of melatonin administration on rats with hypercholesterolemia produced by feeding them with a special diet. Melatonin administration had no significant effect on plasma lipids and lipoproteins in rats on normal diet but blunted the effects of a high-cholesterol diet on the these parameters. Melatonin also diminished the fatty infiltration in the liver of animals on the high-cholesterol diet. The high-cholesterol diet produced major increases in VLDL and LDL cholesterol and protein content, and decreases in HDL cholesterol and protein. Melatonin decreased the extent of this plasma lipoprotein increase, although it did not completely prevent the phenomenon.
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