Nicotine affected meiosis during oocyte maturation is associated with poor subsequent embryonic development. The aim of this study was to analyze the effects of nicotine exposure during in vitro maturation (IVM) on the outcomes of in vitro fertilization (IVF) and the expression of gene related development of oocytes and embryos. Immature (germinal vesicle, GV) oocytes were randomly cultured in IVM media containing nicotine at concentrations of 0.0 (control) 2.5, 5.0, and 10.0 mM. After culturing for 24 h, oocytes were assessed for their maturation rate, subjected to IVF and mRNA extraction for gene expression analysis using quantitative real time PCR (qRT-PCR). The maturation rates of oocytes exposed to nicotine at 5.0 (62%) and 10.0 mM (54%) was significantly (P<0.05) lower than oocytes exposed to nicotine at 2.5 mM (87%) and the control (95%). Following IVF, oocytes exposed to nicotine at 0, 2.5, 5 and 10 mM resulted in similar cleavage rates (96, 91, 91 and 89%, respectively). However, blastocyst rates developed from oocytes treated with nicotine were lower than the control (11, 14, 12 and 24%, respectively). The expressions of GDF9 and ZAR1 in oocytes treated with nicotine at 5 mM were upregulated significantly (P<0.05) than the control. The expression of BCL2 and DMNT in oocytes treated with nicotine at 2.5 and 5.0 mM was upregulated significantly (P<0.05) than the control. The expression of BAX in all nicotine treated groups was comparatively higher than the control but not statistically different (P>0.05). The present study indicated that nicotine negatively affected oocyte and blastocyst development in a dose dependent manner and altered the expression levels of genes associated with the development of oocytes and embryos.
Teerapong, Seree; Faisaikarm, Tassanee; Nimsanor, Natakarn; Changsangfa, Chinarat; Promthep, Kornkanok; and Saikhun, Kulnasan
"Effect of nicotine on gene expression and developmental competence of bovine oocytes,"
The Thai Journal of Veterinary Medicine: Vol. 49:
1, Article 6.
Available at: https://digital.car.chula.ac.th/tjvm/vol49/iss1/6