Cytogenetic effects of caffeine during in vivo mouse oocyte maturation.

Numerous investigators have studied the reproductive and genetic toxicity of caffeine. Caffeine has also been reported to retard meiotic progression and induce aneuploidy in hamster oocytes in vitro. However, the ability of caffeine to induce aneuploidy in mammalian oocytes in vivo has not been reported. The objective of this study was to test the hypothesis that chemical-induced perturbations during in vivo oocyte meiotic maturation (OM) predispose oocytes to chromosome missegregation. Caffeine inhibits cAMP phosphodiesterase, which is needed for dephosphorylating p34(cdc2) kinase and initiating OM. Following superovulation, a dose of 150 mg/kg caffeine was administered to Institute of Cancer Research (ICR) female mice at various times prior to metaphase I (MI). Ovulated oocytes were collected from the oviducts and processed for cytogenetic analysis. Statistical analyses of the frequencies of hyperploid, MI, diploid, premature centromere separation and single chromatids revealed nonsignificant (P > 0.05) differences between the controls and each of the caffeine groups. Structural chromosome aberrations were not found. Under our experimental conditions, we rejected the hypothesis and concluded that caffeine neither retarded the rate of OM nor increased the incidence of aneuploidy in mouse oocytes. The factors responsible for the different in vivo and in vitro responses require investigation.