ABSTRACT
Background Recently researches indicated that estrogen plays important role in maintaining the normal metabolism of lens. Objective This study was to investigate the changes of estrogen receptor( ER ) α and β expressions in lens upon estrogen level in castrated female rat. Methods Sixty clean adult female Wistar rats were randomized into castrated group,sham operation group,ovariectomy group,ovariectomy with low-dose estradiol eyedropping group,ovariectomy with high-dose estradiol eyedropping group,ovariectomy with low-dose estradiol injecting group and ovariectomy with high-dose estradiol injecting group,and 10 rats for each.The castrated animal models were established by ovariectomy for 5 months.Then 50％,100％ oestradiol benzoate eyedrops were used 4 times per day respectively and 0.2 or 0.4 mg/kg oestradiol benzoate were intramuscularly injected at two-day interval for 6 weeks in corresponding experimental group.Serum estradiol concentration was detected in the rats of various groups at 5 months after ovariectomy and 6 weeks after administration of estradiol benzoate.The animals were sacrificed using the excessive anesthesia method and the lenses were obtained for the assay of ERα and ERβ expressions.The use of the animals complied with the Statement of ARVO. Results No obvious opacification of lenses and the changes of structure and morphology in lens were seen in the rats of various groups under the slit lamp microscope and light microscope during the observing duration after ovariectomy.The significant differences were found in serum estradiol concentrations among the 6 groups ( F=15490.527,P=0.000) or between before and after usage of estradiol benzoate( F=943.236,P =0.001 ).Six weeks after usage of estradiol benzoate,the expressions of ERα and ERβ in the lenses were lower in the castrated group,ovariectomy with high-dose estradiol eyedropping group and ovariectomy with low-dose estradiol injecting group compared with the the sham operative group (P＜0.05),but those in the ovariectomy with low-dose estradiol eyedropping group and ovariectomy with high-dose estradiol injecting group were elevated in comparison with above groups( P＜0.05 ),and expressions of ERα and ERβ in the lenses were similar to the sham operative group ( ERα:28.04±6.80 vs.31.30±7.11 ;ERβ:27.75±7.13 vs.25.38±5.59).Mean A values of ERα and ERβ in the lenses were lower in the castrated group,ovariectomy with high-dose estradiol eyedropping group and ovariectomy with low-dose estradiol injecting group compared with the sham operative group (P＜0.05),but those in the ovariectomy with low-dose estradiol eyedropping group and ovariectomy with high-dose estradiol injecting group were elevated in comparison with above groups ( P＜0.05 ),and mean 4 values of ERα and ERβ in the lenses were similar to the sham operative group (ERα:0.1833 ±0.0087 vs.0.1859 ±0.0067; ERβ:0.1689±0.0059 vs.0.1686±0.0095). Conclusions The expressions of ERα and ERβ in the LECs are associated with the level of serum estradiol.The effects of estrogen on lens were different by different medication way.Low-dose estradiol eyedropping was a more feasible approach to the prevention of cataract.
ABSTRACT
Background Epidemiological investigation in human has been conclusive. In postmenopausal women,the incidence of cataract is higher than men at the same age. In addition,hormone replacement therapy may protect against the development of cataract. However,this role of androgen is not clear. Objective This study was to explore the effects of estrogen and androgen on anti-oxidative ability of lens after ovariectomy. Methods Fifty-six three-month-old clean female Wistar rats were randomly divided into normal control group,sham operation group, castration group,estrogen eyedrops group;estrogen injection group;androgen eyedrops group;androgen injection group and 8 rats for each. Ovariectomy was performed in the rats of castration group and gonadal hormone application group, and estradiol benzoate solution or testosterone propionate solution were utilized topically or systemly in 5 months after ovariectomy for 6 weeks respectively. Only abdominal cut was curried out in sham operation group. The lenses of rats were examined weekly under the slit lamp. The serum estrogen and androgen levels of rats were detected before,after operation and 6 weeks following the administration of gonadal hormone. The contents of superoxide dismutase( SOD) , glutathione( GSH) ,malondialdehyde( MDA) and water-soluble protein ( WSP) in rat lens homogenate were detected at the end of the experiment. Utilization of animals complied with the Regulation for the Administration of Affair Concerning Experimental Animals by State Science and Technology Commission. Results No opacity of lenses was found during the experiment duration in various groups. The serum estradiol levels of rats in sham group were insignificantly different from normal groups in various time points( P>0. 05). The evident decline of serum estradiol was detected in the rats of castration group and gonadal hormone application groups compared with sham group in 5 months after operation( all P<0. 01). However,at the sixth weeks after the system use of estradiol or testosterone,the serum estradiol levels were significantly higher than the castration group and topical application groups of gonadal hormone(P<0. 01). The contents of SOD,GSH and WSP in lenses were considerably increased,but the MDA level in lenses was decreased after system use of estrogen ( P<0. 01). The activity of SOD and GSH were lower after system use of testosterone in comparison with castration rats ( P < 0. 05 ). Conclusion Estrogen can protect lens against oxidation damage. However, androgen, to a certain extent, may contribute to the development of oxidative damage in OVX female rats.