Effects of Nicotine and Tocotrienol-Rich Fraction Supplementation on Cytoskeletal Structures of Murine Pre-Implantation Embryos

BACKGROUND Cytoskeletal structures, in particular actin and tubulin, provide a fundamental framework in all cells, including embryos. The objective of this study was to evaluate the effects of nicotine, which is a source of oxidative stress, and subsequent supplementation with Tocotrienol-rich fraction (TRF) on actin and tubulin of 2- and 8-cell murine embryos. MATERIAL AND METHODS Thirty female Balb/C mice were divided into 4 groups: Group 1 received: subcutaneous (sc) injection of 0.9% NaCl; Group 2 received sc injection of 3.0 nicotine mg/kg bw/day; Group 3 received 3.0 sc injection of nicotine mg/kg bw/day +60 mg/kg bw/day TRF; and Group 4 received 60 sc injection of TRF mg/kg bw/day for 7 consecutive days. The animals were superovulated with 5 IU PMSG followed by 5 IU hCG 48 h later. Animals were cohabited with fertile males overnight and euthanized through cervical dislocation at 24 h post coitum. Embryos at the 2- and 8-cell stages were harvested, fixed, and stained to visualize actin and tubulin distributions by using CLSM. RESULTS Results showed that at 2-cell stage, actin intensities were significantly reduced in the nicotine group compared to that of the control group (p<0.001). In Group 3, the intensity of actin significantly increased compared to that of the nicotine group (p<0.001). At 8-cell stage, actin intensity of the nicotine group was significantly lower than that of the control group (p<0.001). The intensities of actin in Group 3 were increased compared to that of nicotine treatment alone (p<0.001). The same trend was seen in tubulin at 2- and 8-cell stages. Interestingly, both actin and tubulin structures in the TRF-treated groups were enhanced compared to the control. CONCLUSIONS This study suggests that TRF prevents the deleterious effects of nicotine on the cytoskeletal structures of 2- and 8-cell stages of pre-implantation mice embryos in vitro.