OBJECTIVE  To investigate the effect of Zhibai Dihuang Decoction on the MKRN3 and Kiss-1/GPR54/GnRH axis in female rats with precocious puberty.

METHODS Forty 15 day old female SD rats were randomly divided into two groups: A blank group of 10 rats and a model preparation group of 30 rats. The model preparation group was continuously gavaged with bisphenol A solution for 10 d. After successful model identification, the model was randomly divided into three groups: The model group, traditional Chinese medicine intervention group was given a modified formula of Modified Zhibai Dihuang Decoction at a dose of 9.24 g·kg⁻¹·d⁻¹, and the Western medicine intervention group was given triptorelin at a dose of 100 µg·kg⁻¹·d⁻¹. Afterwards, the control group and model group were orally administered with an equal volume of physiological saline for 6 consecutive weeks; recorded the opening time of the female mouse's vagina; ELISA was used to detect the levels of MKRN3, Kiss-1, GPR54, GnRH, LH, FSH, and E2 in peripheral blood of rats; observed the morphological changes of the ovaries and uterus using HE staining; qPCR and Western blotting were used to examine the mRNA and protein expression of ovarian Kiss-1, GPR54, GnRH, and MKRN3.

RESULTS Compared with the blank group, the model group female mice had an earlier opening time of the vagina(P<0.01); various levels of follicles could be seen in the ovarian cortex, with the majority being primitive follicles; the uterine volume increases, with a large number of glands visible; the protein expression levels of Kiss-1, GPR54, and GnRH in ovarian and uterine tissues were upregulated(P<0.05), while the protein expression levels of MKRN3 in uterine and ovarian tissues were downregulated(P<0.05); the serum levels of Kiss-1, GnRH, LH and E2 in the model group were significantly higher than those in the blank group(P<0.05), while those in the traditional Chinese medicine intervention group were significantly lower(P<0.05); the expression of Kiss-1 mRNA, GPR54 mRNA, and GnRH mRNA was significantly upregulated(P<0.05), while the MKRN3 mRNA and protein expression were significantly up-regulated(P<0.05). Compared with the model group, the traditional Chinese medicine intervention group had a slightly later opening time of the vagina(P<0.01); follicles at all levels could be seen in ovarian cortex, with a small number of mature follicles; the uterus was small in size and rare in glands; the mRNA and protein expression levels of Kiss-1, GPR54 and GnRH in ovarian and uterine tissues were down regulated(P<0.05), while the mRNA and protein expression levels of MKRN3 were up-regulated(P<0.05); serum GnRH, LH and E2 levels were significantly down regulated(P<0.01).

CONCLUSION The modified formula of Modified Zhibai Dihuang Decoction can regulate the serum hormone levels, inhibit the expression of GnRH, LH, FSH, and E2 factors in the ovaries and uterus of sexual precocity model female mice, improve the development of the uterus and follicles, and delay the occurrence of precocious puberty.