Context. In diabetes, abnormalities of granulosa cells (GCs) and steroidogenesis are associated with hyperglycaemia-induced oxidative stress. Betaine has beneficial effect in experimental model of diabetes by reducing oxidative stress, inflammation, and apoptosis. Aims. In this study we investigate the effects of betaine to prevent oxidative stress in GCs induced by high glucose and improve steroidogenesis. Methods. Primary GCs, isolated from ovarian follicles of C57BL/6 mice were cultured in 5 mM (control) and 30 mM (hyperglycaemia) of glucose and in presence of 5 mM of betaine for 24 h. Then antioxidant enzymes, malondialdehyde, oestradiol and progesterone were measured. In addition, the expression of Nrf2 and NF-κB, antioxidant enzymes (Sod1, Gpx and Cat) were analysed by qRT-PCR assay. Key results. We observed significant (P < 0.001) up-regulation of NF-κB and down-regulation of Nrf2 due to high concentration of glucose. Also significant (P < 0.001) down-regulation of related antioxidant genes (Cat, Sod1 and GPx) and activity reduction of these enzymes as well as significant (P < 0.001) elevation of malondialdehyde was observed. In addition, betaine treatment compensated the drastic effect of high glucose induced oxidative stress via down-regulating the expression of NF-κB and up-regulating the expression of Nrf2, Cat, Sod1 and GPx. It was also shown that betaine in the presence of FSH significantly (P < 0.001) restored the oestradiol and progesterone level. Conclusion. Betaine compensated the antioxidant stress in mouse GCs under hyperglycaemic condition via regulation of Nrf2/NF-κB at transcription level. Implications. As betaine is a natural product and no side effect has been reported to today, we suggest more research needs to be carried out especially on patients whom suffer from diabetes to find the probability of using betaine as a therapeutic agent.
