Decreased maternal levels of insulin-like growth factor-1 and transforming growth factor beta-1, during pregnancy in rats fed with low salt diet

Abstract

Low birth weight has been reported in offspring of low salt fed rats.This study investigated the levels of maternal growth factors in rats fed with low salt and high salt diet and the outcome of their offspring. Seventy-two female rats were acclimatized and divided into three groups of control (0.3% salt), low salt diet (0.14% salt) and high salt diet (8% salt). Rats were fed for six weeks. Male rats were introduced to female rats in the 6^th week for mating on proestrous evening. The levels of transforming growth factor β-1 (TGFβ-1) and Insulin like growth factor -1 (IGF-1) were measured at days 6, 8 and 19 of pregnancy.Birth weight, placenta weight and fetal weight (day 19) were decreased in low salt fed rats while placenta weight and fetal weight (Day 19) were increased in high salt fed rats. IGF-1 levels were decreased on days 8 and 19 of pregnancy in low salt fed rats while TGFβ-1 levels were also decreased on days 6, 8 and 19 of pregnancy in the low salt fed rats when compared with control.Growth of low salt offspring’s matched that of controls on day 6 of lactation while the growth of the control and low salt fed rats only reached same values as those of the offspring’s of high salt fed rats on day 15 of lactation. In conclusion,reduced fetal development and low birth weight in low salt fed rats is associated with reduced levels of IGF-1 and TGFβ-1 during pregnancy.

Keywords: Salt; growth factors; transforming growth factor beta-1;insulin like growth factor-1; lactation; catch-up growth