Synergism between gonadotrophins and vinblastine relative to the frequencies of metaphase I, diploid and aneuploid mouse oocytes.

Abstract

Ovulated oocytes are used to obtain estimates of germ cell aneuploidy following in vivo treatment with various chemicals. Such studies commonly use exogenous gonadotrophins to increase the number of ovulated oocytes and to induce ovulation during specific time periods. However, the gonadotrophin dosages have not been evaluated relative to the possibility that synergistic and antagonistic interactions may exist between the hormones and the chemical being studied. We, therefore, studied the interactions of different hormone dosages (5 IU pregnant mare's serum (PMS) and 2.5 IU human chorionic gonadotrophin (HCG), 7.5 IU PMS and 5 IU HCG, and 10 IU PMS and 7.5 IU HCG) alone (controls) and in combination with 0.2 mg/kg of the aneugen vinblastine sulfate (VBS) relative to the number of oocytes ovulated, the frequencies of metaphase I (MI), diploid and aneuploid oocytes. The results indicated that the proportions of oocytes ovulated were not significantly (P > 0.05) different among the various control and VBS groups. VBS, however, resulted in significantly (P < 0.01) higher levels of MI oocytes than in controls. In the VBS-treated females, higher frequencies (P < 0.05) of MI oocytes were found in the 7.5 IU PMS and 5 IU HCG and 10 IU PMS and 7.5 IU HCG groups as compared to the 5 IU PMS and 2.5 IU HCG group. The frequencies of diploid oocytes did not differ significantly (P > 0.05) within the control of VBS groups; whereas, when comparisons were made between each control and VBS group, only the difference between the 5 IU PMS and 2.5 IU HCG groups was significant (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)