EFFECT OF DL111-IT ON PROGESTERONE BIOSYNTHESIS AND VIABILITY OF RAT LUTEAL CELLS IN-VITRO

AIM: To study the influence of DL111-IT on progesterone biosynthesis o f cultured luteal cells (LC). METHODS: LC viability was assessed with trypan blue dye exclusion and progesterone concentration was measured with radioimmunoassay. RESULTS: DL111-IT decreased the viability of LC after 24-h incubation, its ED50 being 7.7 (95 % confidence limits: 7. 1 - 8.5) mg.L-1. DL111-IT inhibited basal secretion of progesterone in a concentration-dependent manner, and 3 mg.L-1 decreased progesterone concentration by 25 % vs control. DL111-IT 3 mg.L-1 also inhibited th e stimulatory effect of forskolin (cAMP activator) 10 mu mol.L-1 and p regnenolone [converted to progesterone by 3 beta-hydroxysteroid dehydr ogenase-isomerase complex (3 beta-HSD)] 10 mu mol.L-1 on progesterone production in cultured LC, and their inhibitory rates were 43 % and 15 5 %, respectively. At the same concentration, DL111-IT did not influen ce hCG-induced progesterone production. CONCLUSION: DL111-IT inhibited progesterone synthesis by suppressing the conversion of pregnenolone to progesterone (inactivating 3 beta-HSD) and suppressed the activity of cAMP. DL111-IT 6 - 24 mg.L-1 decreased the viability of LC.