Effects of estradiol on naphthalene-induced telomerase activity and apoptosis of LEC in ovariectomized female rats / 眼科新进展

ABSTRACT

Objective To explore the effects of estradiol on the telomerase activity and apoptosis of lens epithelial cells and its mechanisms.Methods Fifty adult female Sprague-Dawley rats were randomly divided into five groups (n =10)ovariectomized group,estradiol group 1,estradiol group 2,estradiol group 3 and sham group.All rats were prepared for ovariectomized models except that of the sham group.After 2 weeks of the operation,rats in the 5 groups were given naphthalene solution through a stomach tube,and meanwhile,estradiol group 1,estradiol group 2,estradiol group 3 received estradiol valerate with the dose of 0.21 mg · kg-1 · d-1,0.42 mg · kg-1 · d-1 and 0.84 mg · kg-1 · d-1,accordingly,while rats in the ovariectomized group and sham group were given 9 g · L-1 Nacl by stomach perfusion with a dose of 0.42 mg · kg-1 ·d-1.Then,the opacity of the lens in each group was examined by a slit lamp microscope every week.After 12 weeks of naphthalene solution administration,all rats were sacririced and the serum estradiol concentration was determined by radioimmunoassay.Next,the lenses were taken out,and TERT mRNA expression of lens epithelial cells (LEC) was measured by RT-qPCR,and finally,the apoptotic rate was detected by TUNEL method.Results The opacity of lens in the ovariectomized group was different from that in the estradiol group 1,estradiol group 2,estradiol group 3 and sham group,with statistical significances (all P ＜ 0.05),and the opacity of lens in the estradiol group 1,2,3 and sham group were mild and occurred later.The serum estradiol concentration in the ovariectomized group (8.19 ± 1.45)ng · L-1 was significantly lower than that of estradiol groupl,2,3 and sham group,and there were significant differences (all P ＜ 0.05).Thc relative expression of TERT mRNA in LEC in the ovariectomized group (0.371 2-±0.056 4) was significantly lower than that in estradiol group 1,2,3,but the apoptotic rate of LEC (0.602 1 ±0.010 8) was obviously higher than that of estradiol group 1,2,3 in a dose-dependent manner,and there were significant differences (all P ＜ 0.05).Pearson correlation analysis showed the relative expression of LEC TERT mRNA in rats was negatively correlated with the apoptosis rate(r =-0.859,P ＜ 0.05).Conclusion Estradiol can up-regulate TERT mRNA expression and enhance telomerase activity of LEC in naphthalene-induced ovariectomized female rats in a dose-dependent manner.Estradiol can inhibit the LEC apoptosis in naphthalene-induced ovariectomized female rats,and the mechanism may be related to the increase of telomerase activity in the LEC.