Uterus and endometrium: Endometrial vascular smooth muscle oestrogen and progesterone receptor distribution in women with and without menorrhagia

Abstract

This study tested the hypothesis that alterations in the expression of oestrogen and progesterone receptors (ER and PR) in endometrial vascular smooth muscle cells (VSMC) may play a role in the increased blood loss that occurs during menorrhagia. Subject groups were: controls (n = 40), those with menorrhagia (menstrual blood loss > 80 ml, n = 39) and patients post-endometrial ablation (n = 16). The aims of our study were to describe the changing distribution of VSMC ER and PR during the menstrual cycle and to look for differences between the three groups. Immunohistochemical double-staining results for VSMC and either ER or PR were highly varied, with 0-85% of endometrial arterioles in a biopsy section having alpha smooth muscle actin/ER positive cells, and 0-70% demonstrating PR. There were no significant differences between controls, menorrhagia or post-ablation specimens (analysis of variance for ER P = 0.72; for PR P = 0.17). There were also no significant differences between the different stages of the menstrual cycle when all three groups were combined (analysis of variance for ER P = 0.11; for PR P = 0.13). The high variability found in this study may mask biologically relevant differences in endometrial vascular ER and PR distribution between different groups.