The effects of prenatal undernutrition and postnatal high-fat diet on hypothalamic Kiss1 mRNA and serum leptin levels

Prenatal undernutrition and postnatal overnutrition increase the risk of some metabolic disorders in adulthood, and hypothalamic leptin resistance makes an important contribution to these effects. Leptin plays important roles in the maintenance of reproductive function, and its actions might be partially mediated by kisspeptin, which is a potent positive regulator of gonadotropin-releasing hormone. In this study, the effects of prenatal undernutrition and postnatal overnutrition on reproductive parameters and sexual maturation during the peripubertal period were evaluated. Rats subjected to prenatal undernutrition (IUGR) and fed a postnatal high-fat diet (HFD) (n = 7) exhibited 40% higher serum leptin levels and 30% lower hypothalamic Kiss1 (the gene encoding kisspeptin) mRNA levels than those subjected to prenatal undernutrition (IUGR) and fed a normal diet (n = 7). No such HFD-induced postnatal alterations were observed in the rats fed a normal diet during the prenatal period (control) (n = 7 per group). Although the consumption of the HFD did not affect the serum luteinizing hormone levels or body weight of the IUGR or control rats, it did promote vaginal opening in both groups (evaluated in 14 rats per group). These findings indicate that hypothalamic leptin resistance might occur in IUGR-HFD rats, but these changes do not influence downstream effectors of the reproductive endocrinological system. They also suggest that the relationships between nutritional conditions, body weight, reproductive factors, and sexual maturation are complex.