[Expression of vascular endothelial growth factor and its receptors, flt-1 and kinase insert domain-containing receptor in normal human endometrium during menstrual cycle].

OBJECTIVE: To detect the expression of the vascular endothelial growth factor (VEGF) and its receptors, the fms-like tyrosine (flt-1), kinase insert domain-containing receptor (KDR) in normal human endometrium during menstrual cycle and investigate the functions of VEGF and its receptors for development and differentiation of human endometrium. METHODS: Immunohistochemistry and in situ hybridization techniques were used to measure the level of VEGF, flt-1 and KDR protein and mRNA in normal endometrium from 50 women. Few samples of endometrium respectively in the proliferative and secretory phase were homogenized for Western Blot analysis of VEGF subtypes. The blood vessel density was estimated by counting staining with a endothelial marker VIII factor. RESULTS: The VEGF and its receptors mainly expressed in endometrial endothelial cells and gland epithelium. The level of VEGF, protein and mRNA, as well as flt-1 in mid-secretory and menstrual phase were highest (P < 0.05). The expression in early proliferative phase was lowest. KDR was with more intense expression from mid-proliferative phase to westrual phase. The acreage of the blood vessel wall and cavity was larger in the secretory than that in proliferative phase (P 0.05). Western Blot analysis showed stained VEGF bands in 34,000 (VEGF(121)), 46,000 (VEGF(165)), 54,000 (VEGF(189)), 68,000 (VEGF(206)), predominantly in 34,000 and 46,000. CONCLUSIONS: VEGF, flt-1 and KDR, including both protein and mRNA, showed a pronounced menstrual cycle-dependent expression in cycling endometrium. VEGF and its receptors expressing higher in secretory phase and menstruation probably be involved in embryonic implantation and endometrial shedding.