1992 Fiscal Year Final Research Report Summary
Study on the pathophysiological role of melatonin in the ovulatory mechanism.
| Project/Area Number |
03670790
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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 |
Obstetrics and gynecology
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| Research Institution | KOCHI MEDICAL SCHOOL |
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Principal Investigator |
OKATANI Yuji Kochi Medical School, Department of Obstetrics and Gynecology, Instructor, 医学部, 講師 (70145142)
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| Project Period (FY) |
1991 – 1992
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| Keywords | Melatonin / Prolactin / Pineal body / Pituitary gland / Hyperprolactinemia |
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| Research Abstract |
The present study was undertaken in order to evaluate the role of nocturnal melatonin secretion in the control of the nocturnal prolactin release occuring in women with normoprolactinemia, nocturnal hyperprolactinemia(NHP) and mild hyperprolactinemia(MHP).
Nocturnal melatonin and prolactin secretion changes in association with various awake/sleep and dark/light conditions suggest that melatonin can regulate nocturnal prolactin secretion independent of sleep-related factors. Abnormal prolactin release in patients with NHP, who have high prolactin levels only at nighttime, is not due to higher sensitivity to melatonin, but due to amplification of nocturnal melatonin secretion. The marked nocturnal prolactin release was also found in patients with MHP.However, nocturnal melatonin secretion in patients with MHP was not different from that for women with normoprolactinemia. The nature of response to exogeneons melatonin administration suggests MHP may be unusual sensitivity to melatonin.
Furthermore, this study was undertaken to clarify the mechanism of the stimulatory effect of melatonin on the prolactin release by determing dopamine and serotonin neuronal activity in the median eminence of the rat. Melatonin administration resulted in significant decreases in DOPAC contents and DOPAC/Dopamine ratio in the median eminence obtained at one hour following melatonin administration, at which seurm prolactin showed a maxmal value. However no significant changes in 5-HT,5-HIAA and 5-HIAA/5-HT ration in the median eminence was found. These results suggest that the stimulatory effect of melatonin on prolactin secretion may be mediated by dopaminergic but not serotoninergic system. In vivo human study also suggests that the stimulatory effect of melatonin on prolactin secretion may not be mediated by the opioid system.
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