Effects of levonorgestrel-releasing intra-uterine system on the expression of vascular endothelial growth factor and adrenomedullin in the endometrium in adenomyosis.
The levonorgestrel-releasing intra-uterine system (LNg-IUS) has been used to control menorrhagia, but irregular bleeding during the first 3 months of use was the most notable side effect. Endometrial angiogenesis is believed to be regulated by angiogenic factors. The study aim was to evaluate the effects of LNg-IUS on vascular endothelial growth factor (VEGF) and adrenomedullin (AM) expression in the endometrium. VEGF and AM expression were analysed using the avidin-biotin immunoperoxidase method on endometrial curettage specimens from menorrhagic women associated with adenomyosis before and 3 months after LNg-IUS insertion. VEGF expression was abundant both in the endometrial glands and stroma before LNg-IUS insertion, but became scanty 3 months after insertion. No immunostaining for AM was noted in the endometrial glands and stroma before LNg-IUS insertion, whereas AM immunostaining became prominent in the endometrial glands and stroma 3 months after LNg-IUS use. This is the first study to demonstrate that LNg-IUS insertion results in decreased expression of VEGF and increased expression of AM in the endometrial glands and stroma after 3 months of use. The results obtained suggest that the increase in AM expression in the endometrium may be responsible for the frequent occurrence of irregular bleeding during the initial 3 months of LNg-IUS use.