Tocotrienol improves the quality of impaired mouse embryos induced by corticosterone

Tocotrienol (TCT), a component of vitamin E is a powerful antioxidant proven to inhibit oxidative damage caused by various prooxidant agents. Corticosterone (CORT) on the other hand, is a known prooxidant that has been shown to impair the quality of embryos and retard the development of preimplantation embryos. This study aims to determine the effect of TCT supplementation on the quality and in vitro development of embryos in CORT-treated mouse. Five to six weeks old female mice were subjected to a daily administration of either intraperitoneal (ip) injection of corn oil, or 10 mg kg⁻¹ body weight (BW) of CORT. They were also given oral gavage of either corn oil or TCT-rich fraction palm oil for 7 consecutive days. Group 1 (negative control) received ip injection and oral administration of corn oil, Group 2 (positive control) received ip injection of CORT and oral administration of corn oil whereas Groups 3, 4 and 5 received CORT and TCT at doses of 60, 90 and 120 mg kg⁻¹ BW, respectively. Female mice were superovulated with PMSG and hCG then cohabited overnight with the fertile male mice. On Day 7, animals were sacrificed, fallopian tubes were excised and embryos were flushed out. The quality of embryos was categorized into normal and abnormal embryos and the in vitro development of normal embryos was compared between all five groups. Results showed that the number of abnormal embryos in Group 2 (CORT) and Group 3 were significantly higher compared to Group 1. Conversely, in Groups 4 and 5, the number of abnormal embryos was reduced to control. On the other hand, the number of embryos that reached hatched blastocyst stage was significantly lower in Group 2 (CORT) as compared to control. However, the embryos in Groups 3, 4 and 5 were successively developed into hatched stage. Tocotrienol is therefore, found to be beneficial in reducing the deleterious effect of CORT on the quality and development of embryos in vitro.