Variation of mouse oocyte sensitivity to griseofulvin-induced aneuploidy and meiotic delay during the first meiotic division.
The effects of varying the time of chemical treatment on the induction of aneuploidy and meiotic delay in metaphase II (MII) oocytes were studied by administering 1,500 mg/kg griseofulvin (GF) at 0, 2, 4, 6, or 8 hr after an injection of human chorionic gonadotrophin (HCG). The results show that the oocytes have a different sensitivity to GF-induced aneuploidy and meiotic delay during the course of meiotic maturation. Although not restricted to a particular period of meiotic maturation, the frequency of aneuploidy was highest (P < 0.05) when GF was given at 2, 4, or 6 hr after HCG. The maximum frequency of hyperploidy (42.4%) occurred at the 4-hr treatment time. Also, GF treatment resulted in the induction of meiotic delay as demonstrated by ovulated metaphase I (MI) and polyploid MII oocytes. The meiotic delay data depict a period of relative resistance between two periods of sensitivity in that the percentages of ovulated MI oocytes were 53.3, 21.3, 3.5, 6.7, and 25.7 when GF was given at 0, 2, 4, 6, and 8 hr after HCG, respectively. Also, at these treatment times the percentages of polyploid oocytes were 0.6, 1.7, 7.7, 20.1, and 15.4, respectively. Therefore, the oocytes seem to be more sensitive to GF-induced meiotic delay during the periods preceding and following meiotic spindle assembly. In conclusion, the results demonstrate that the time of chemical treatment influences the frequency of aneuploidy and the degree of meiotic delay. Also, the results emphasize that to thoroughly characterize the aneugenic potential of a specific chemical several treatment times may be needed.
Marchetti
F
F
Department of Obstetrics and Gynecology, Louisiana State University Medical Center, Shreveport 71130.
Mailhes
J B
JB
D000782:Aneuploidy; D000818:Animals; D016009:Chi-Square Distribution; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D005260:Female; D006118:Griseofulvin / Q000633:toxicity*; D008540:Meiosis / Q000187:drug effects*; D008677:Metaphase / Q000187:drug effects; D051379:Mice; D008813:Mice, Inbred ICR; D009153:Mutagens / Q000633:toxicity*; D009865:Oocytes / Q000187:drug effects*; D008941:Spindle Apparatus / Q000187:drug effects; D013997:Time Factors
D006063:Chorionic Gonadotropin; D009153:Mutagens; D006118:Griseofulvin