Effects of thyroidectomy and thyroxine replacement on the release of luteinizing hormone and gonadotropin-releasing hormone in vitro

Shyi Wu Wang, Hsiao Fung Pu, Shou Teh Chiang, Low Tone Ho, Paulus S. Wang*

*此作品的通信作者

研究成果: 期刊稿件文章同行評審

4 引文 斯高帕斯(Scopus)

摘要

The effects of thyroidectomy and thyroxine (T4) replacement on the release of luteinizing hormone (LH) and gonadotropin-releasing hormone (GnRH) in ovariectomized (Ovx) rats were studied. Immediately after ovariectomy, rats were thyroidectomized (Tx) or sham-Tx. The Ovx-Tx rats were injected subcutaneously with either saline or T4 (2 pg/100 g body weight) daily for 30 days before sacrifice. Sham-Tx rats were treated with saline only. Twenty hours after the last injection, the blood sample was obtained by decapitation. The excised anterior pituitary gland (AP) was bisected and incubated in vitro with or without 0.1, 0.5, 2.5, and 50 ng GnRH at 37 ° for 4 h. The mediobasal hypothalamus (MBH) was bisected and incubated with or without the AP of Ovx donor rat in vitro. Concentrations of LH and GnRH in the medium and that of LH in the serum were measured by radioimmunoassay. LH in the serum ofTx rats was higher than that in the serum of sham-Tx and Tx-T4 rats. Thyroidectomy resulted in an increase of LH release by Ovx rat AP, stimulated with or without 0.1 and 50 ng GnRH, as well as in an increase of immunoreactive GnRH release from MBH of Ovx rats in vitro. After a 4-hour incubation with donor APs, the LH in the medium containing MBH obtained from Tx rats was significantly higher than that obtained from sham-Tx and Tx-T4 rats. LH concentrations, in both sera and media, as well as GnRH concentration in the media of euthyroid and T4-replaced Tx groups were nonsignificantly different. These results suggest that T4 is inhibitory to the basal and GnRH-stimuIatcd LH release as well as to the release of GnRH in the absence of ovarian hormones.

原文英語
頁(從 - 到)215-222
頁數8
期刊Hormone Research in Paediatrics
25
發行號4
DOIs
出版狀態已出版 - 1987
對外發佈

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