Developmental changes in the expression of Kiss1 gene and estrogen receptor α gene in hypothalamus of female Sprague-Dawley rats

Abstract

Objective To investigate the function of Kiss1 gene and estrogen receptor α gene (ERα gene) in puberty of rats, by detecting the expressions of Kiss1 mRNA and ERα mRNA in the hypothalamus and the serum luteinizing hormone(LH) and estradiol(E2) level of female Sprague-Dawley(SD) rats at various stage of development with Real-time PCR and enzyme-linked immunosorbent assay(ELISA). Methods Thirty-five female SD rats of 3 days were weaned on postnatal(PND)22 and then the vaginal opening condition was observed daily.The rats were sacrificed at PND 15(juvenile group, n=19) and PND 35(pubertal group, n=16). The hypothalamus were segregated and the serum were extracted from heart blood.All of the samples were stored at-80 ℃ prepared.Then the mRNA were extracted from the hypothalamus and the cDNA obtained by reverse transcription were tested with real-time PCR.The relative mRNA expression level of Kiss1 gene and ERα gene were calculated. Results 1.Entire level: it was found that the pubertal group vaginal opening time was (32.1±1.0) days, while the juvenile group was not found with vaginal opening until sacrificed.2.Real-time PCR: the expressions of Kiss1 and ERα gene were significantly increased in pubertal group(Kiss1 gene: 5.39±2.52, ERα gene: 1.57±1.87) compared with juvenile group(Kiss1 gene: 1.06±1.09, ERα gene: 0.59±0.68), and the differences were statistically significant(all P<0.001).3.ELISA: the serum LH and E2 in pubertal group[LH(11.61±0.95) IU/L, E2(167.53±31.09) ng/L]were significantly higher than LH[(5.46±1.89) IU/L]and E2[(58.59±29.96) ng/L]in juvenile group, and the differences were statistically significant(all P<0.001). Conclusion Kiss1 gene and ERα gene are involved in the start of the sexual development of female SD rat. Key words: Kiss1 gene; Estrogen receptor α; Hypothalamus; Sexual development; Female Sprague-Dawley rat