Both Ca²⁺-Protein Kinase C Pathway and cAMP-Protein Kinase A Pathway are Involved in Progesterone Production in FSH- and LH-stimulated Cumulus Cells during In Vitro Maturation of Porcine Oocytes

Abstract

We investigated the role of cAMP-Protein kinase A pathway and Ca²⁺-Protein kinase C pathway which were activated by FSH and/or LH in the progesterone production by cumulus cells during in vitro maturation of porcine oocytes. The level of progesterone in the medium in which COCs had been cultured for 24 hr without FSH was 7.8 ± 1.5 ng/ml. The addition of FSH significantly increased the progesterone level in a dose-dependent fashion during 24-hr cultivation of COCs; a plateau was detected in 0.02 μg/ml, but no significant increase in the level of progesterone was observed in the medium in which COCs had been cultured for 24 hr with 1 or 10 μg/ml LH. When COCs were cultured with both 0.02 μg/ml FSH and 1.0 μg/ml LH for 24 hr, the maximal level of progesterone was detected. The effects of the addition of LH to FSH-supplemented medium on the response of cumulus cells were affected by the suppression of the Ca²⁺-Protein kinase C pathway. Forskolin-induced progesterone production was not affected by suppression of the Ca²⁺-Protein kinase C pathway but was reduced by Protein kinase A inhibitor. These results showed that Ca²⁺-Protein kinase C pathway in cumulus cells stimulated by FSH, enhanced LH-induced progesterone production via a cAMP-Protein kinase A dependent pathway.