The preventive effect to tocotrienol on delayed preimplantation embryonic development in aging mice / Nur Aida Dalilah Mohamed Almi

Oxidative stress induced by the aging process was known to cause impairment in female reproductive and antioxidant defense system. Tocotrienol (TCT), through its antioxidant properties has been suggested to play a role in reducing oxidative stress and promoting fertility. The present study evaluates the protective effect of TCT on the ovarian function which was assessed from the response for ovulation process, the quality and developmental competence of embryos produced, and the activity of catalase (CAT), a component of antioxidant defense system. Twelve weeks old female mice were subjected to daily oral gavages of either corn oil (vehicle) or TCT at different doses of 60, 120 and 240 mg kg _1 body weight (BW) for 8 weeks duration. Age control groups consisted of young mice (7 weeks old) and aging mice (20 weeks old). Animals were then, superovulated and cohabited with a fertile male at a ratio of 1:1. After 48 hours, animals were euthanized, the fallopian tubes were excised and embryos were flushed out. The embryos recovered were then be counted and graded based on its morphology. Only normal embryos were cultured to observe the developmental competence from 2 cells to expanded blastocyst stage. Counting the total number of embryos recovered quantified the ovarian response for ovulation process whereby grading the embryo morphology determined the embryo quality. We found out that the age related decline of embryo count, quality and in vitro development from 2 cells to 4 cells stage was improved with TCT treatment at the dose of 120 and 240 mg kg'1 BW. The embryos recovered from 240 mg kg"1 BW TCT treatment group also denoted to have a higher progression rate at 4 cells to morula stage when compared with all groups. There is no significant difference in CAT level in plasma and ovarian tissue samples in all TCT treatment groups as compared to aging control. Therefore, TCT is found to have a beneficial effect on the ovulation response, embryonic quality and in vitro development from 2 cells to morula stage in aging mice.