Different effects of cyclic nucleotide derivatives upon the rat oocyte-cumulus complex in vitro.

The influence of cyclic nucleotides on meiosis in isolated rat oocytes was studied. It is known that dbcAMP inhibits the spontaneous maturation of isolated rat oocytes. However, the effect of other cyclic nucleotide derivatives upon meiosis has been poorly investigated. The present study shows that 8-BrcAMP is comparatively ineffective in inhibiting oocyte meiosis but exerts a potent stimulatory effect on progesterone production in cumulus cells. Neither dbcGMP nor 8-BrcGMP were able to inhibit the spontaneous maturation of cumulus-enclosed oocytes. On the other hand, 8-BrcGMP dose-dependently inhibited the meiosis of denuded oocytes. This indicates that the cumulus cells may be of importance for a possible regulatory role of cGMP. These results show the differences in meiotic response to various cyclic nucleotide derivatives.