Pituitary and hypothalamic action of progestagens in castrated female rats
Bieglmayer, C.; Spona, J.; Schroeder, R.
Endocrinologia Experimentalis 14(1): 17-25
1980
ISSN/ISBN: 0013-7200 PMID: 6772424 Document Number: 163098
Different doses of progesterone, D-norgestrel and .DELTA.15-D-norgestrel were injected s.c. for 7 days to female rats were estimated by radioimmunoassay. LH-RH serum levels were determined in progestagen-treated control groups by an anterior pituitary cell culture bioassay. Dose-dependent inhibitory effects of steroids on LH-RH-stimulated gonadotropin release were observed and a dissociation of rLH and rFSH serum levels was found. The modulatory influence of progestagens used in this study on LH-RH-provoked gonadotropin release correlated with their biological efficiency evaluated in the Clauberg test. Progesterone, D-norgestrel and .DELTA.15-D-norgestrel treatment had no significant effects on basal rLH levels, but LH-RH-provoked rLH levels were higher than in the control animals. Progesterone and D-norgestrel suppressed basal as well as LH-RH-stimulated rFSH levels, whereas .DELTA.15-D-norgestrel showed a complex influence on rFSH secretion. A progestagen-stimulated rise of LH-RH serum levels was found and indicated an additional effect of these hormones at the hypothalamic level. Progestagens apparently act at various levels of the hypothalamus-pituitary axis.