Realization Pathways of Prolactin Modulating Effect on the cAMP-Dependent Mechanism of Meiosis Regulation in Bovine Oocytes

摘要

Cyclic AMP is one of the key regulators of mammalian meiosis. In the present work, realization pathways of the previously revealed modulating effect of prolactin (PRL) on the cAMP-dependent mechanism of meiosis regulation in bovine oocytes were studied. A comparative investigation of individual and combined effects of PRL (50 ng/ml) and an activator of adenylate cyclase forskolin (FK, 20 fxM) on the meiotic reinitiation and completion of nuclear maturation in cumulus-surrounded and cumulus-free oocytes was performed. It has been shown that the pattern of the effects of PRL on the meiotic resumption in oocytes devoid of cumulus cells depends on the presence of FK in the culture medium. Furthermore, the realization of this effect is not associated with the activation of cytoplasmic isoforms of protein kinase C. It has also been found that PRL inhibits the retarding action of FK on the completion -of oocyte nuclear maturation both in the presence and absence of cumulus cells. These findings suggest that PRL may modulate the functioning of the cAMP-depen-dent mechanism of meiosis regulation by the direct action on bovine oocytes, with realization of this action being independent of the metabolic coupling of oocytes with cumulus cells.