Abstract: OBJECTIVE: To investigate the effect of ethephon and its mechanisms on precocious puberty of prepubertal SD female rats. METHODS: Postnatal day-15 SD female rats were randomly divided into 4 groups according to their body weights. Rats in the control group were given distilled water and the low,medium and high doses groups were given the ethephon at 134,269 and 538 mg/kg,respectively. Water and ethephon were given orally,once a day for 5 days. The first batch of animals was used to observe the time for vaginal opening. After the second batch of animals were killed,blood,hypothalamus and pituitary tissues were taken,and serum FSH and LH levels were detected by enzyme-linked immunosorbent assay (ELASA). Real-time quantitative PCR (qPCR) was performed to examine the mRNA expression levels of the hypothalamic-pituitary-gonadal axis (HPGA)-related genes KISS-1,GPR54,GnRH,and GnRHR. RESULTS: Compared with the control group,vaginal opening time of the ethephon middle dose group was advanced (P < 0.05) and that for the high dose group was significantly prolonged (P < 0.05). In addition,qPCR analyses show that expression of HPGA axis-related genes in the ethephon middle dose group was increased,and the high-dose group was decreased,and the difference was statistically significant (P < 0.05). There was no significant difference in serum LH and FSH levels (P > 0.05). CONCLUSION: Ethephon exposure was effective in promoting precocious puberty in prepubertal SD rats at the medium dose,and its mechanism may be related to the expression of genes related to the HPGA axis.

Key words: ethephon, prepubertal female, precocious puberty, HPGA axis