Glycosaminoglycans Prevent Induction of Fragmentation of Porcine Oocytes Stimulated by Dibutyryl Cyclic Adenosine 3', 5'-Monophosphate in Culture

Abstract

The in vitro effects of derivatives of cyclic adenosine 3', 5'-monophosphate (cAMP) and glycosaminoglycans (GAGs) on the spontaneous induction of fragmentation of cultured porcine oocytes were examined. Oocytes cultured for 72h or longer undergo spontaneous fragmentation, and the percent of fragmented oocytes increased thereafter. The fragmented oocytes consisted of several "blastomeres" showing uneven distribution of DNA among the "blastomeres". Cytoplasmic bodies were also identified on the surface of fragmented oocytes and in the space among fragmented "blastomeres". Dibutyryl cyclic adenosine 3', 5'-monophosphate (dbcAMP) at concentrations exceeding 50μM markedly increased the induction of fragmentation. 8-bromoadenosine 3', 5'-cyclic monophosphate, butyrate, cAMP and GAGs isolated from porcine follicular fluid (pFF) did not stimulate the induction of fragmentation. pFF-GAGs added to the suspending medium at concentrations of 10 μg/ml or greater prevented the occurrence of dbcAMP-stimulated fragmentation of isolated porcine oocytes in a dose-dependent manner. Preparations of hyaluronic acid and chondroitin sulfate from a commercial source prevented the occurrence of fragmentation stimulated by dbcAMP. The present findings suggest that cAMP may involve the induction of fragmentation of porcine oocytes and GAGs prevent the activation of cAMP-dependent fragmentation.