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(224) PROTEIN KINASES INFLUENCE BOVINE OOCYTE MATURATION DURING SHORT-TERM TREATMENT WITH RECOMBINANT HUMAN FOLLICLE-STIMULATING HORMONE. Sirard, Marc-André1, Ali, Atef1, 1 Laval University, Quebec, QC, Canada ABSTRACT- In this study, the possible role of protein kinase A (PKA) and protein kinase C (PKC) in mediating the positive action of recombinant human FSH on cytoplasmic maturation of bovine oocytes has been examined. The activators and inhibitors of PKA (forskolin, Sp-cAMPS, Rp-cAMPS) or PKC (phorbol-12-myristate 13-acetate (PMA), sphingosine) were used to investigate the in vitro effect of PKA or PKC on the developmental competence of bovine oocyte during a short (6 hours) incubation with recombinant human follicle stimulating hormone (r-hFSH). The results showed that when cumulus-oocyte complexes (COCs) were cultured with r-hFSH for the first 6h, a highly significant (p<0.0001) improvement is seen in blastocyst development rate as a proportion of oocyte in culture compared to those matured with r-hFSH for the first 2 h or 24 h. Although a transient exposure (6h) to the highest dose (100mM) of forskolin, an activator of adenylate cyclase, significantly (p<0.05) improved the developmental capacity of oocyte, the presence of the PKA inhibitors (Rp-cAMP) did not inhibited the beneficial effect of r-hFSH in terms of the blastocyst yield after in vitro fertilization. However, stimulation of PKC by PMA (0.1-0.5mM) during short-term treatment, significantly (p<0.0001) enhances the developmental capacity of oocyte in a dose-depended manner, while sphingosine (a specific inhibitor of PKC) significantly (p<0.05) inhibited the potential effect of r-hFSH as reflected by the blastocysts yield after in vitro fertilization. Our results indicate that although both the PKA, and the PKC pathways can modulate the developmental capacity of bovine oocytes in vitro, the activation of PKC during short-term treatment can mimic the effect of rhFSH on the cytoplasmic maturation in bovine oocytes in vitro. KEY WORDS: follicle stimulating hormone., protein kinase C, oocyte competence, oocyte development |
