FERTILIZATION AND EARLY DEVELOPMENT OF RAT OOCYTES INDUCED TO MATURE BY FORSKOLIN

Forskolin has been shown to successfully induce maturation of rat oocy tes as assessed by morphological markers. The present study was design ed in an attempt to elucidate whether oocytes, induced to mature by fo rskolin (10(-4) M, group A) in a follicle-enclosed oocyte culture, are fertilizable and can further develop into two-cell embryos. Oocytes e xposed in vitro to either luteinizing hormone (LH, 5 mug/ml, group B) or a GnRH agonist analogue (10(-7) M, group C) as well as oocytes that underwent maturation in vivo (group D), served as positive controls. We found that similar rates of fertilization were obtained in the expe rimental and all of the above mentioned control groups (A = 78.9 +/- 4 .2%, B = 77.9 +/- 3.1%, C = 77.5 +/- 5.5% and D = 84.7 +/- 2.7%). Clea vage rate of fertilized eggs from group A was significantly higher tha n that of eggs from groups B & C, and similar to that of eggs from gro up D (A = 63.1 +/- 6.7%, B = 37.8 +/- 4.9%, C = 50.0 +/- 4.1 %, D = 67 .8 +/- 4.1%). Using functional parameters we hereby demonstrate that f orskolin and LH are at least equally potent in producing fertilizable eggs that have a high potential of development into two cell embryos. These results further support the idea that cAMP is a mediator of LH a ction in inducing oocyte maturation.