Implantation and pregnancy outcome of Sprague-Dawley rats fed with low and high salt diet

Objective: To investigate the influence of low salt diet and high salt diet on implantation and pregnancy in rats. Design: This is an experimental animal study. Materials and methods: Female rats were acclimatized and divided into three groups consisting of control/normal salt diet (0.3% salt), low salt diet (0.14% salt) and high salt diet (8% salt). Rats were fed for six weeks and the cycles of the rats were observed in the 6th week for the introduction of male rats to female rats on the evening of proestrus for mating. Implantation studies were carried out on days 6 and 8 of pregnancy while fetal parameters were ascertained on day 19 of pregnancy and at term. Levels of progesterone, estradiol, prostaglandin E2, nitric oxide (NO) and cyclic guanosine monophosphate (cGMP), were measured on days 6, 8 and 19 of pregnancy. Results: The results showed decreased implantation sites on days 6 and 8 in high salt fed rats, decreased birth weight in low salt fed rats and increased placental to birth weight ratio in the high salt fed rats when compared with control. A significant decrease in PGE2 level was found on day 8 of pregnancy in the high salt fed rats, while progesterone:estradiol ratio was decreased on days 6 and 8 of pregnancy in both low salt and high salt fed rats. Also, NO and cGMP levels were decreased on day 19 of pregnancy in the low salt fed rats when compared with control (p < 0.05). Conclusion: The results showed that a shift in salt homeostasis either to a high or a low salt level causes hormonal imbalance and impaired reproductive outcome during pregnancy.