Stimulation of the Secretion of Luteinizing Hormone by Ginsenoside-Rb1 in Male Rats

Shiow-Chwcn Tsai ； Yu-Chung Chiao ； Chien-Chen Lu ； Paulus S. Wang

《The Chinese Journal of Physiology》 46卷1期 (2003/03) Pp. 1-7

並列摘要

Ginsenoside-Rb1 is one of the pharmacologically active components of ginseng, the dry root of Panax ginseng C. A. Meyer (Araliaceae), a well-known traditional Chinese medicine. Ginseng enhanced mounting behaviour of male rats and increased sperm counts in rabbit testes. Some experimental results suggested no sex hormone-like function in ginseng but probably gonadotropin-like action. The present study was to explore the effect of ginsenoside-Rb1 on the secretion of luteinizing hormone (LU) both in vivo and in vitro. Male rats were orchidectomized (Orch) for 2 weeks or subjected to swim training for 1 week before catheterization via the right jugular vein. They were intravenously injected with ginsenoside-Rb1 (10μg/kg) or saline at 15 mm prior to a challenge of gonadotropin-releasing hormone (GnRU) or 10 min-swim. Blood samples were collected at several time intervals following intravenous injection of ginsenoside-Rb1. In the in vitro experiment, male rats were decapitated and their anterior pituitary gland (APs) were either bisceted or enzymatically dispersed. The hemi-APs were preincubated with Locke’s medium at 37℃ for 90 min and then incubated with Locke’s medium containing ginsenoside-Rbl (10(superscript -7)~ 10(superscript -4) M) for 30 min. The dispersed AP cells (1×10^5 cells per well) were primed with dihydrotestosterone (BUT, 10(superscript -4) M) for 3 days, and then challenged with ginsenoside-Rbl (10(superscript -6) and 10(superscript -4) M, n=8) for 3 h. The concentrations of LU or testosterone in samples were measured by radioimmunoassays. Administration of ginsenoside-Rb1 did not alter the levels of plasma LU in both intact and Orch rats but significantly increased plasma LU concentration at the termination of the 10 mm swimming exercise. Administration of ginsenoside-Rb1 resulted in a lower testosterone response to GnRU challenge or swimming exercise as compared with saline-treated rats. Ginsenoside-Rb1 dose- dependently increased the release of LU from both hemi-AP tissues and the BUT-primed dispersed AP cells in vitro. These results suggest that ginsenoside-Rb1 increases LU secretion by acting directly on rat AP cells.

並列關鍵字

ginsenoside-Rb1 ； LU ； swimming

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