THE EFFECT OF MICROTUBULE-DISRUPTING DRUGS ON MORPHOLOGY, PROGESTERONE AND PRORENIN SECRETION OF BOVINE CULTURED OVARIAN THECA CELLS

The effect of three microtubule-disrupting drugs (vinblastine, colchic ine and nocodazole) on basal and LH-stimulated secretion of progestero ne and prorenin by bovine theca cells was studied. Microtubules were v isualized immunocytochemically using a monoclonal antibody against the cr-subunit of tubulin and a secondary antibody conjugated with rhodam ine. Progesterone and prorenin secretion were detected by adequate rad ioimmunoassays. Theca cells treated with LH alone or with a combinatio n of LH, colchicine and vinblastine, showed round shape and disorganiz ation of microtubules which were more obvious than after treatment wit h the two disrupting drugs alone. Nocodazole or LH treatment alone res ulted in the formation of numerous cell processes, conspicously differ ent in shape from those in the controls. All three drugs increased bas al progesterone secretion independently on the dose, but were without effect on basal prorenin secretion. LH-stimulated progesterone secreti on was significantly suppressed by each of the three drugs while LH-st imulated prorenin secretion was decreased only by high doses of vinbla stine and nocodazole. Colchicine in all three doses used did not exert any significant effect. The results obtained suggest that microtubule s are involved in progesterone but not in prorenin secretion.