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題 名 | Norepinephrine Transporter mRNA Expression After Coitus in the Rabbit Brainstem |
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作 者 | Bao,Jianzhong; Pau,Francis K. Y.; Spies,Harold G.; | 書刊名 | 中國生理學雜誌 |
卷 期 | 44:3 2001.09[民90.09] |
頁 次 | 頁103-110 |
分類號 | 397 |
關鍵詞 | Norepinephrine transporter; Tyrosine hydroxylase; GnRH; Coitus; Brainstem; |
語 文 | 英文(English) |
英文摘要 | In the female rabbit, coitus induces a massive release of hypothalamic gonadotropin-releasing hormone (GnRH) within 20 min The GnRH surge is preceded by an increase in hypothalamic norepinephrine (NE) release. Presumably, coitus stimulates NE, hence GnRH, release by increasing the activity of tyrosine hydroxylase (TH, the rate-limiting enzyme for NE synthesis) and/or decreasing the activity of norepinephrine transporter (NET, the key protein for NE re-uptake). Since NE cell bodies are located primarily in the brainstem, we hypothesize that coital signals are relayed to hypothalamic GnRH-secreting neurons via brainstem NE-containing perikarya. In support of this hypothesis, we found that both c-fos and TH mRNA expressions in brainstem noradrenergic areas, particularly in the A1 and A2 cell groups, increased within 30 min and returned to precoital levels within 60 min after coitus. Here we analyzed coitally induced changes in NET mRNA expression at 0, 15, 30 and 60 min postcoitus in the brainstem by in situ hybridization, using □S-labeled rabbit NET RNA probes. In comparison with nonmated females (i.e., at 0 min), the expression of NET mRNA significantly increased (P<0.05) within IS mm postcoitus in the Al, but not the A2 area. By 30 mm postcoitus, NET gene expression increased in the caudal portion of the Al and in the caudal and central portion of the AZ. By 60 nun postcoitus, NET mRNA expression in the caudal and rostral portion of the A1 and the caudal and central portion of the A2 was still higher than NET mRNA expression in nonmated rabbits (P<0.05). No change in NET mRNA expression was observed in the A6. The results suggest that coitus increases NET mRNA expression in Al and A2 noradrenergic areas within 15-30 min, and this enhanced NET mRNA expression was maintained for at least 60 min, particularly in the A2. These findings, in combination with our previous observation on increased TH gene expression within 30 min, but not 60 min, after coitus, further suggest that the coitus-induced NET transcriptional events within brainstem NE neurons may play an important role in the maintenance, and particularly in the termination, of hypothalamic NE release, hence regulating the size and duration of the coitus-induced GnRH surge. |
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