Study On Effects Of Gonadal Axis And Growth Axis Of Chinese Herbal Medicine For Nourishing Yin And Purging Fire In Nma-Induced CPP Model Of Female Rats

Objective: To elucidate the effect and effective mechanism of Chinese herbal medicine (CHM) for nourishing Yin and purging Fire on thehypothalamus-pituitary-gonadal axis and hypothalamus-pituitary-growth axis in the NMA induced CPP model of female rats.Methods: 60 26-day-old SD female rats were randomly assigned to the normal control group (n=10), the model group (n=10), the leuprorelin group (n=10),the high-dose of CHM group (n=10) ,the middle-dose of CHM group (n=10),and the low-dose of CHM group(n=10).All Rats, except that in the normal group, were subcutaneously administered 40mg/kg of NMA in saline twice a day. In the meantime,the leuprorelin group,high-dose,middle-dose and low-dose of CHM groups received gavage of 100μg/kg leuprorelin,30ml/kg,15ml/kg and 7.5ml/kg CHM once a day respectively. The normal group were received with normal saline until vaginal opening (VO) occurred.Vaginal smear was taken daily.The model groups were decapitated at the first day of its proestrous.Normal group and three CHM groups and the leuprorelin group were killed at the same day on decapitation of the model group. The parameters of puberty were analyzed, which including the expression level of GnRH mRNA of hypothalamus and GH mRNA of pituitary by real time RT-PCR, the concentration of serum IGF-I, the ovary index, the uterus index, the corpora luteum in the ovary and the bone mineral density in tibia (determined by PQCT).Results: There are regular estrous cycles in the model group.The parameters of puberty and growth in model group were much higher than those in the normal group. The parameters of puberty and growth in high-dose and middle-dose of CHM groups were no differences from the normal group and the leuprorelin group, which were much lower than those in the model group. The parameters of puberty and growth in low-dose of CHM group were no differences from the model group, which were much lower than those in the normal group.Conclusions: The precocious puberty induced by NMA in female rats was true precocious puberty .CHM for nourishing Yin and purging Fire may inhibit the function of hypothalamus-pituitary-gonadal axis and arrest the occurrence of the true precocious puberty, which may be the primary mechanism of CHM in effectively treating true precocious puberty. CHM for nourishing Yin and purging Fire may inhibit the function hypothalamus-pituitary-growth axis, which may be one of the mechanisms of GHM reducing epiphyseal maturity.