Abstract:

Objective To investigate the changes of expression of NELL2 and GnRH mRNA in hypothalamus of female SD rats at different sex development stages. Methods SD rats were assigned to juvenile group (20 days old), prepubertal group (30 days old), early pubertal group (35 days old) and adult stage group (45 days old), with ten rats in each group. Real-time PCR was employed to detect the expression of NELL2 and GnRH mRNA in hypothalamus of rats in each group, and comparison was made among groups. Results The relative expression of NELL2 mRNA in hypothalamus of rats in juvenile group, prepubertal group, early pubertal group and adult stage group was －1.01±0.09, －0.78±0.16, －1.09±0.10 and －1.14±0.12, respectively, and that of GnRH mRNA was －2.92±0.15, －2.44±0.10, －1.66±0.13 and －2.13±0.19, respectively. Statistic analysis revealed that the expression of NELL2 mRNA was the highest in prepubertal group, followed by juvenile group, early pubertal group and adult stage group, with significant differences among groups (P<0.05). The expression of GnRH mRNA was the highest in early pubertal group, followed by adult stage group, prepubertal group and juvenile group, with significant differences among groups (P<0.05). Conclusion There were significant differences in expression of NELL2 and GnRH mRNA in hypothalamus of female SD rats at different sex development stages. The higher expression of NELL2 mRNA comes earlier than that of GnRH mRNA. In prepubertal stage, NELL2 may participate in the puberty onset via up-regulating the expression of GnRH mRNA.

Key words: sex development, NELL2, GnRH, gene expression, rat, female