1995 Fiscal Year Final Research Report Summary
Plasticity of neuro-endocrine cells induced by sex hormone.
| Project/Area Number |
06670081
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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 |
Environmental physiology (including Physical medicine and Nutritional physiology)
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| Research Institution | Kyoto Institute of Technology |
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Principal Investigator |
NAKASHIMA Toshihiro Kyoto Institute of Technology, Dept.Applied Biology, Associate Professor, 繊維学部, 助教授 (30128136)
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| Co-Investigator(Kenkyū-buntansha) |
MIYATA Seiji Kyoto Institute of Technology, Dept.Applied Biology, Assistant Professor, 繊維学部, 助手 (30243124)
KIYOHARA Toshikazu Kyoto Institute of Technology, Dept.Applied Biology, Professor, 繊維学部, 教授 (50071874)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Plasticity / Neurosecretory Cell / Estrogen / Oxytocin / Na^+ channel |
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| Research Abstract |
It has been known that oxytocin (OXT) neurons in the hypothalamus were by OXT in male animals. Recently, we have demonstrated that inhibitory responses of OXT neurons to OXT in virgin and pregnant rats reverse to excitatory responses in delivering and lactating animals and return to inhibitory responses after delivery. It may be a new type of neural plasticity. The present work was carried out to investigate the key factor for reverse the response in OXT neurons to OXT and the difference of membrane mechanisms of responses to OXT between male and female rats.
1.Supraoptic OXT neurons of ovariectomized virgin female rat were excited by OXT application. It means the inhibitory responses in virgin female rats may be derived from ovarian hormones.
2.In Ovariectimized virgin female rat treated with estrogen, activity of OXT neurons was inhibited by OXT.It indicates estrogen, one of ovarian hormone, is a candidate of reversal factor.
3.In virgin female rats pretreated with tamoxifen, anti-estrogen, OXT induced excitatory responses in OXT neurons. It is confirmed that estrogen is the key factor for reverse the response in the hypothalamic OXT neurons to OXT.
4.Both excitatory responses in male and ovariectomized virgin female rats and inhibitory responses in normal and estrogen treated virgin female rats to OXT were effectively blocked by same OXT receptor antagonist. It is possible that both excitatory and inhibitory responses to OXT are mediated same type of OXT receptor.
5.Excitatory response of OXT neurons in male rats results in opening of Na^+ channel but the channel did not participate in inhibitory response in virgin female
These results suggest that estrogen reversal of OXT response in OXT neurons is not due to modification at OXT receptor but due to redistribution of the functioning ionic channels.
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