The effect of neonatal immune challenge on reproduction by altering intraovarian kisspeptin/GPR54 system in the rat

Immune challenge in early life has been observed to influence the long-term reproductive dysfunction. On PNDs 3 and 5, female offsprings were administered with LPS (50 μg/kg, i.p.) or saline. Vaginal opening was recorded, and oestrous cyclicity was monitored immediately post puberty and again at 56-70 days. At 10 weeks of age, the ovaries were removed for immunostaining and RNA analysis. Neonatal exposure to LPS resulted in a significant delay puberty onset as well as destroyed expression of ovulation related genes. At PND 42 and 70, a significant increase in Kiss1 mRNA and Kisspeptin expression was detected at proestrus and oestrus in neo-LPS treated rats compared with the counterparts. Therefore, neonatal LPS exposure had a long-term effect on reproductive function and the up-regulated expression of ovarian Kiss1 and kisspeptin during the ovulatory transition stage may contribute to ovulatory dysfunction induced by peripheral LPS administration in early life.