REALIZATION PATHWAYS OF PROLACTIN MODULATING INFLUENCE ON THE cAMP-DEPENDENT MECHANISM OF MEIOSIS REGULATION IN
BOVINE OOCYTES
I. Yu. Lebedeva,1, 2, * G. N. Singina,1 L. K. Ernst,1 A. K. Golubev 2
1 All-Russian State Research Institute of Animal Breeding, Podolsk, and
2 Department of Animal Genetics, Breeding and Biotechnology, St. Petersburg State Agrarian University, St.Petersburg-Pushkin;
* e-mail: irledv@mail.ru
Cyclic AMP is one of the key regulators of mammalian meiosis. In the present work, realization pathways of the previously revealed modulating influence of
prolactin (PRL) on the cAMP-dependent mechanisms 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 μM) on the meiotic reinitiation and nuclear maturation completion in
cumulus-enclosed and cumulus-free oocytes was performed. It has been shown that the pattern of PRL influence on the meiotic resumption in oocytes devoid of
cumulus cells depends on the presence of FK in the culture medium. Furthermore, realization of this influence is not associated with the activation of cytoplasmic
isoforms of protein kinase C. It has been also found that PRL inhibits the retarding action of FK on the completion of oocyte nuclear maturation in both the presence
and absence of cumulus cells. The findings suggest that PRL may modulate the functioning of the cAMP-dependent mechanism of meiosis regulation by the direct
action on bovine oocytes, with realization of the action being independent of the metabolic coupling of oocytes with cumulus cells.
Key words: prolactin, cAMP, oocytes, cumulus cells, in vitro maturation, meiosis
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