Gene Expression Of Kiss-1 In Hypothalamus Of Central Precocious Female Rats

Objective To investigate the gene expression of Kiss-1 in the hypothalamus of central precocious female rats at various stages of development.Methods Forty 5-day-old normal female Sprague-Dawley rats were randomly assigned into four groups of 10 rats: Control group 1, Control group 2, Model group 1 and Model group 2. The rats from the two model groups were injected with 300 ug of danazol at 5 days of age to induce central precocious puberty. The two control groups were injected with normal saline instead .Rats were used to observe the day of vaginal opening and the day setup regular estrous cycle on day 25. For the determination of Kiss-1 mRNA expression in the hypothalamus, the rats of the Model group 1 were sacrificed during the first diestrus (early puberty) and meanwhile the rats of the Control group 1 were sacrificed when they were at prepuberty; the Control group 2 rats were sacrificed at the first diestrus (early puberty); the rats of the Model group 2 were sacrificed during the second diestrus (middle puberty). The expression of Kiss-1 mRNA and GnRH mRNA in the hypothalamus in the four groups was detected using semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). The weights of body, uterus and ovary were measured and the serum LH concentrations were measures by chemiluminescentassay (CLIA).Results 1. The day of vaginal and first diestrus in Model group 1 and Model group 2 significantly advance , respectively, compared with that of Control group 1 (p<0.05). It showed the onset of puberty advances; The serum LH concentrations in Model group 1 and Model group 2(D1) were significantly differences, respectively, compared with that of Control group 1 (p<0.05).There were no statistical differences between Model groups and Control groups; That illustrated the model coincident with the demand of the experiment. 2. The serum LH concentrations and the weights of uterus and ovary in Model group 2 showed significantly higher than Model group 1 (p<0.05). There were no statistical differences between Control group 2 and Model group 1.3. Kiss-1 mRNA expression in the hypothalamus in Model group 1 and Model group 2 increased by 1.4-fold and 2.8-fold, respectively, compared with that of Control group 1 (p<0.05). Model group 2 showed significantly higher Kiss-1 mRNA levels than Model group 1 (p<0.05). There were no statistical differences in the Kiss-1 mRNA expression between Control group 2 and Model group 1.Conclusion Gene expression of Kiss-1 is associated with the developmental period of central precocious puberty, suggesting that Kiss-1 might play a role in the pathogenesis of this disorder.