| Objective:To observe the effect of estradiol valerate on naphthalene-induced telomerase activity and apoptosis of LECs in ovariectomized female rats,to approach the action and mechanism of estradiol valerate on the telomerase activity and apoptosis of LECs,and to explore new methods for drug control of cataract.Methods:Sixty-five SPF female Sprague-Dawley rats aged 3 months were selected for experimental rats,the average weight was（200±30）g,and the lens and other ocular tissue diseases were excluded before the experiment.Rats were adaptive fed for 7 days and fasted overnight.Rats were divided into five groups randomly:ovariectomized group,estradiol group 1,estradiol group 2,estradiol group 3 and sham group,（Treated,n=13）.After intraperitoneal injection,the rats in ovariectomized group,estradiol group 1,estradiol group 2 and estradiol group 3 were ovariectomized bilaterally,and sham group performed the same incision but only bilateral peritoneal incision and fat resection.After 2weeks of operation,all rats in each group were received naphthalene solution（10%）through a stomach tube with a dose of 0.5g·kg-1 body weight every other day.The rats in estradiol group 1、the estradiol group 2 and the estradiol group 3 were received estradiol valproate through a stomach tube with a dose of 0.21 mg/kg、0.42 mg/kg、0.84 mg/kg every day.While other two groups were received 0.9%Nacl through a stomach tube with a dose of 0.42mg/kg every day.The rats were observed daily and recorded,and the weight of rats was measured every week,and the opacity of the lens in each group was observed by the slit-lamp microscope and recorded in detail every week.After12 weeks of naphthalene solution administration,all rats were killed and serum estradiol valerate levels were determined with radioimmunoassay.The rats lens were taken out,and TERT-m RNA expression of LECs were measured by RT-q PCR,and the apoptosis rate of LECs was detected by TUNEL.The changes of the lens fibers were observed under scanning electron microscope.Results:1、The opacity of the lens in each group at the 12 weeks of the gavage:The opacity of lens in ovariectomized group was higher than that in estradiol group1,estradiol group 2,estradiol group 3 and sham group,there were significant differences（Z=-3.528、-3.609、-3.702、-3.528;P=0.000、0.000、0.000、0.000）,and opacity of lens were slight and occurred later in estradiol and sham groups.There was no statistically significant difference between opacity of lens in sham group and that in estradiol group 1,estradiol group 2 and estradiol group 3（Z=0.000、-0.404、-0.791;P=1.000、0.686、0.429）;There was no statistically significant difference between opacity of lens in estradiol group 1 and that in estradiol group 2 and estradiol group 3（Z=-0.404、-0.791;P=0.686、0.429）;There was no statistically significant difference between opacity of lens in estradiol group 2 and that in estradiol group 3（Z=-0.389;P=0.697）.2、The level of serum estradiol valerate:the concentrations of serum estradiol valerate in ovariectomized group,estradiol group 1,estradiol group 2,estradiol group 3 and sham group were:8.19±1.38 pg/ml、46.44±4.82 pg/ml、82.14±9.52 pg/ml、176.08±21.71 pg/ml and 69.74±9.99 pg/ml.The concentrations of serum estradiol valerate in ovariectomized group was significantly lower than that in estradiol group 1,estradiol group 2,estradiol group 3 and sham group,and after different concentrations of estradiol valerate,The concentrations of serum estradiol valerate in estradiol group 1,estradiol group 2 and estradiol group 3 were successively increased,and the difference was statistically significant（all P<0.05）.3、The expression level of TERT-m RNA in LECs:the expression of TERT-m RNA of LECs in ovariectomized group,estradiol group 1,estradiol group 2,estradiol group 3 and sham group was:0.3712±0.0564、0.9106±0.1741、1.3560±0.3844、1.9114±0.3364、1.0280±0.0487.The expression of TERT-m RNA of LECs in ovariectomized group was lower than that in estradiol group 1,estradiol group 2,estradiol group 3 and sham group,furthermore,the expression of TERT-m RNA of LECs in estradiol group 1,estradiol group 2 and estradiol group 3 was positive related with the concentration of estradiol valerate,the difference was statistically significant（all P<0.05）.4、The apoptosis rate of LECs:the apoptosis rate of LECs in ovariectomized group,estradiol group 1,estradiol group 2,estradiol group 3and sham group was:0.6021±0.0108、0.3871±0.0097、0.3094±0.0089、0.2063±0.0101、0.3156±0.0118.The apoptosis rate of LECs in ovariectomized group was significantly higher than that in estradiol group 1,estradiol group 2,estradiol group 3 and sham group,furthermore,the apoptosis rate of LECs in estradiol group 1,estradiol group 2,estradiol group 3 was negative related with the concentration of estradiol valerate,the difference was statistically significant（all P<0.05）.5、Pearson correlation analysis:the expression of TERT-m RNA of LECs in rats was negatively correlated with the apoptosis rate（r=一0.859,P<0.05）.6、Morphological changes of lens fibers in each group:in sham group,the fibers were arranged in disorder,with a slightly roughened surface and a small loss of some of the fibers in the superficial cortex of the lens,and finger-like protrusions were basically arranged along the long axis of the lens.In ovariectomized group,the fibers arrangement were disordered,with obvious edema and broken of the fibers in the superficial cortex of the lens,and the number of finger-like protrusions decreased.In estradiol group 1,estradiol group 2 and estradiol group 3,the fibers were arranged regularly,with a small loss of fiber in the superficial cortex of the lens,and the finger-like protrusions were more regular.Conclusion:1、Estradiol valerate can up-regulate the expression of TERT-m RNA and increase telomerase activity of LECs in naphthalene-induced ovariectomized female rats,and there is a positive correlation with its concentration.2、Estradiol valerate could inhibit the apoptosis of LECs in naphthalene-induced ovariectomized female rats,and the mechanism might be related to the increase of telomerase activity in LECs. |
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