Effect of nourishing “Yin”-removing “Fire” Chinese herbal mixture on hypothalamic kisspeptin expression in female precocious rats

Abstract

The present study aims to investigate the effect of nourishing "Yin"-removing "Fire" herbal mixture, a Chinese herb-based formulation, on hypothalamic kisspeptin expression in danazol-induced female precocious model rats. The female Sprague-Dawley rats were divided into intact normal (N), central precocious puberty (CPP) model (M), vehicle without CPP (V), CPP model exposed to herbal mixture (HM) and CPP model exposed to saline (S) groups. At postnatal day 5, a single subcutaneous injection of 300 microg of danazol was administered to induce CPP model rats. From P15, rats in the HM group were continuously gavaged with the 1 ml/50 g body weight mixture, until two consecutive regular estrous cycles were established. The hypothalamic Kiss-1 expression was detected by RT-PCR and immunohistochemistry. The day of vaginal opening and establishment of two regular estrous cycles were delayed in the HM group compared with M and S groups (P<0.05, respectively). The level of hypothalamic Kiss-1 mRNA and the number of kisspeptin-immunoreactive (kisspeptin-ir) cells in the arcuate nucleus (ARC), preoptic area (POA) and periventricular nucleus (PeN), were decreased significantly in the HM group compared with the M and S groups (P<0.01, respectively) on the day of onset-puberty. These results indicate that the kisspeptin signaling pathway might be involved in the effect of herbal mixture treatment on CPP.