Vascular smooth muscle cen proliferation in arterioles of the human endometrium

Menorrhagia affects approximately 15% of all women, often without identifia ble cause. Endometrial spiral arterioles are believed to play a major role in controlling menstruation, and are a major site of menstrual loss. We pos tulate that, alterations in the growth and, development of spiral arteriole s, particularly the vascular smooth muscle cells (VSMC), may contribute to menorrhagia, We examined VSMC proliferation around endometrial arterioles i n central and menorrhagic tissues and the possible roles of transforming gr owth factor beta (TGF-beta) and endothelin in this process. Proliferating V SMC were located immunohistochemically, then evaluated using computer-aided image analysis. VSMC proliferation was low and constant during the early s tages of the menstrual cycle, increasing; at the mid to late secretory stag es (P < 0.002), Menorrhagic women had significantly reduced VSMC proliferat ion in their spiral arterioles at the mid and late secretory stages (P < 0. 02), VSMC around straight arterioles proliferated at similar rates across t he cycle, apart from a significant decrease in VSMC proliferation in menorr hagic women at the late secretary stage (P < 0.002). Endothelin concentrati ons decreased significantly in the epithelium of menorrhagic women (P = 0.0 5), while TGF-beta demonstrated no significant differences in the mid to la te secretory tissues studied. The results indicate a significant functional difference between the spiral arterioles of control and menorrhagic women that may play a role in menorrhagia, while leaving the roles of endothelin and TGF-beta undetermined.