Central mechanism of triptorelin therapeutic effects on female precocious puberty in rats

AIM To observe the central mechanism of the GnRH analog-triptorelin on the precocious puberty female rats induced by danazol,through the pharmacologic detection of the hypothalamic expression of Kisspeptin and its receptor G protein-coupled receptor 54(GPR54)were detected.METHODS Thirty-six female SD rats at 3 days of age fed in company with their mothers were randomly divided into normal group (N),model group(M),and model with triptorelin treatment group(M + T).The animals in M and M + T at the postnatal 5th day were given a single dose(300μg)danazol by subcutaneous injection.At the postnatal 15th days,the rats in M+T were treated by subcutaneous injection of triptorelin(50 g·100 g~(-1)body weight) once per three weeks,totally for two times.From the postnatal 25th day,the days of the vaginal opening were recorded and the exfoliative vaginal epithelial cells were examined every day until the establishment of first estrus cycle.The organ coefficients of uterus and ovary in each group were observed.The expression of Kisspeptin/GPR54 mRNA was also detected by means of RT-PCR.RESULTS The days of vaginal opening and establishment of first estrus cycle were advanced,and the organ coefficients of uterus and ovary increased in M than those of N.The days of vaginal opening and the establishment of first estrus cycle were postponed,and the organ coefficients decreased in M+T comparing with those of M,but showing no significant difference with N (P0.05).The expressions of Kisspeptin and GPR54 mRNA in M((0.427±s 0.008)and(0.482±0.021)) were higher than those in N((0.266±0.029)and(0.31±0.03))and M + T((0.332±0.019)and (0.33±0.03))(P0.01),but no obvious difference was found between M + T and N(P0.05). CONCLUSION Triptorelin might inhibit abnormal early startup of hypothalamus-pituitary-gonad axis of precocious puberty rats induced by danazo,to synthesis and release the expression of hypothalamic Kisspeptin/ GPR54 mRNA,and thus probably be one of the mechanisms.