Effect of letrozole on expressions of VEGF and MVD in endometriotic rats

Objective To study the different expression patterns of vascular endothelial growth factor(VEGF)and micro-vessel density(MVD)in tissues of endometriosis in rat models after letrozole therapy,and to explore the underlying mechanism of letrozole treatment for endometriosis(EM).Methods Rat models were established by autologous transplantation of uterine tissues to an ectopic site beside the uterines.Then the successful rat models were randomly divided into the NS control group and the Letrozole(p.o.)treated groups.To compare the difference of ectopic lesion volumes after the treatment,an immunohistochemical method was used to detect VEGF and MVD expressions in tissues of endometriosis in the rat models.Results The volume of endometriotic tissues in the letrozole groups decreased compared with the control group(P0.05).The inhibitory effect of the drug significantly increased with the duration of treatment.Expressions of VEGF and MVD in tissues of endometriosis decreased after using letrozole.Compared with the control group,the differences were significant(P0.05).Conclusions The volume of the ectopic focus in rat models was obviously changed after letrozole treatment,and a significant effect appeared in a short time.Letrozole can treat EM through down-regulating expressions of VEGF and MVD in ectopic tissues.