Effects of pentoxlfylline and caffeine on spontaneous maturation of rat ocytes
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The effects of two phosphodiesterase inhibitors (caffeine and pentoxifylline) and a membrane permeable analog of cAMP (dibutyryl- cAMP) on spontaneous maturation of cumulusenclosed (CE) and denuded (Dd) oocytes were investigated in vitro. When the mechanically denuded oocytes were cultured in a hormone-free medium, a significant increase in the rate of oocyte maturation was recorded after 3 hrs of incubation (47.67 9.08%) which was further increased to 83.53 2.77% after 5 hrs of culture. The maximum rate of oocyte maturation was noticed after 20 hrs of culture (97.78 2.03%). On the other hand, the presence of cumulus cells encircling the oocytes significantly reduced the rate of maturation during initial period of incubations (3hrs, 9.09 4.95% : 5hrs, 32.11 8.14%). However, the inhibitory effect of cumulus cells on oocyte maturation was nullified following 20 hrs of incubation and the rate of maturation was similar to Dd oocyte group (Dd, 97.78 2.03% versus CE, 90.15 2.79%). Similarly, during initial period of incubation, various doses of db-cAMP completely inhibited oocyte maturation but the inhibitory effect was observed dose-dependent after 20 hrs of incubation. Pentoxifylline or caffeine significantly reduced the maturation of CE and Dd oocytes but the later was found to be more potent. Caffeine ( 0.4 mM) completely inhibited oocyte maturation in CE oocytes, at all the time points studied. Pentoxifylline mediated inhibition of CE oocyte maturation was dose-dependent following 20 hrs of incubation. In addition, 1 mM of both pentoxifylline and caffeine also reduced the rate of maturation significantly (P<0.001) in Dd oocyte at all the time points studied. Taken together these results indirectly suggest that the cumulus cells delay the initiaton of oocyte maturation probably by synthesis and transfer of cAMP to oocyte and that these phosphodiesterase inhibitors directly act at oocyte level to inhibit spontaneous maturation in vitro.
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author list (cited authors)
Chaube, S. K., Chaki, S. P., & Misro, M. M.
complete list of authors
Chaube, SK||Chaki, SP||Misro, MM