Regulation of the corpus luteum of early pregnancy in the marmoset monkey: local interactions of luteotrophic and luteolytic hormones in vivo and their effects on the secretion of progesterone.

Abstract

The interaction between luteotrophic and luteolytic agents in controlling progesterone production by the marmoset corpus luteum in the late luteal phase/early pregnancy was investigated at the local level in vivo using a perfusion cannula system. Perfusion of the prostaglandin F2 alpha (PGF2 alpha) analogue, cloprostenol (0.5 microgram/ml), resulted in an immediate fall in progesterone production. This response was not sustained in two out of five corpora lutea but pregnancy was terminated in all animals exposed to PGF2 alpha. Perfusion of human chorionic gonadotrophin (hCG) (4 micrograms/ml) alone significantly stimulated progesterone secretion but there was no response to hCG when the corpus luteum had previously been perfused with PGF2 alpha. Perfusion with hCG together with PGF2 alpha prevented a fall in progesterone secretion. The results suggest that the luteolytic action of PGF2 alpha in the marmoset may be to prevent luteotrophic support of the corpus luteum. Melatonin (860 pmol/l), perfused either with PGF2 alpha or after PGF2 alpha, stimulated progesterone production. The ability of melatonin to influence progesterone production by the primate corpus luteum may therefore be by both a direct luteotrophic action and the prevention of luteolysis. Application of the perfusion system in order to investigate the ability of deglycosylated hCG to antagonize the action of hCG at the corpus luteum showed the necessity of testing pure preparations of hormones.