Effects of estrogen and androgen on expression of metalloproteinase-2 in lachrymal gland in ovariectomized rats / 中华实验眼科杂志

ABSTRACT

Background The pathogenesis of dry eye is complicated,hormone level is thought to be one of impact factors in the development of dry eye.The regulation of the synthesis process of metalloproteinases(MMPs) in tissue has been reported.However,the effects of hormone on expression of MMP-2 in lachrymal gland is not clear.Objective This study was to investigate the effects of estrogen and androgen on the expression of MMP-2 in lachrymal gland in ovariectomized rats,and explore the role of MMP-2 in dry eye.Methods Sixty-four 3-monthold clean female Wistar rats were randomized into control group(8 rats),sham operation group(8 rats)and experiment group(48 rats).Ovariectomy(OVX) was performed on the rats of experiment group,and only fat tissue of abdominal cavity was cut off in the rats of the sham operation group.After 5 months of OVX,the experimental rats were subdivided into model control group,vehicle group,estrogen and androgen systemic or topical utilization groups and 8 rats for each group.Six weeks after administration of the drugs,the lachrymal gland was obtained.The expression of MMP-2 mRNA in the lachrymal gland was detected by reverse transcription PCR(RT-PCR),β-actin mRNA was used as an internal control,and the expression of MMP-2 protein was detected by Western blot,GAPDH was used as protein loading control.The use and care of the rats complied with the ARVO Statement.Results The expression of MMP-2 mRNA was strongest in the systemic estrogen group and was weakest in the systemic androgen utilization group.A significant difference in the MMP-2 mRNA expression was found among the 8 groups(F=18.60,P＜0.01),and the MMP-2 mRNA was significantly higher in the model group than that of the normal control group(0.66±0.10vs.0.47±0.10)(q=3.01,P＜0.05).In addition,the MMP-2 mRNA was significantly higher in the systemic estrogen group compared with the model group (0.83 ±0.10 vs.0.66-0.10) (q =2.79,P＜0.05) ; while the expression of MMP-2 mRNA was significantly declined in the systemic androgen group in comparison with the model group(0.12±0.04 vs.0.66±0.10)(q=11.41,P＜0.01).The MMP-2 protein presented with a strongest expression in the systemic estrogen utilization group and a weakest expression in the systemic androgen utilization groups.The expression level of the MMP-2 protein in the lachrymal gland was significantly different among the 8 groups(F =7.28,P＜0.01).The MMP-2 in the model group was significantly higher than that of the normal group(0.55±0.13 vs.0.38±0.08) (q =2.39,P＜0.05),and that in the systemic estrogen group was increased in comparison with the model group(0.69±0.12 vs.0.55±0.13) (q =1.85,P＜0.05).However,the MMP-2 in the systemic androgen group was significantly lowed in comparison with the model group(0.27±0.07 vs.0.55±0.13) (q =4.32,P＜0.01).Conclusions Estrogen may up-regulate the expression of MMP-2 in lachrymal gland,but the effect of androgen is opposite.Hormone level may play an important role in the regulation of the function of lachrymal gland.