Identification of heme oxygenase in human endometrium

The aim of the present study was to investigate the presence of heme oxygen ase (HO)-1 and HO-2 in human endometrium at various stages of the menstrual cycle using RT-PCR, Western blotting, and immunohistochemistry. RT-PCR det ected mRNA for HO-1 and HO-2 in human endometrium at all stages of the mens trual cycle. Western blotting also revealed the expression of the two disti nct HO proteins throughout the menstrual cycle. HO-1 was constitutively exp ressed, whereas HO-2 expression was apparently greater in the secretory pha se than in the menstrual and proliferative phases. Immunohistochemistry sho wed that distribution of the two HO isoforms had distinct topographic patte rns: HO-1 was observed in endometrial epithelial cells and macrophages, whe reas HO-2 was found in endothelial cells and smooth muscle cells of blood v essels in the endometrium. The detection of MRNA and protein for HO-1 and H O-2 in normal human endometrium suggests that the carbon monoxide/HO system may play a role in the local control of endometrial. function.