ABSTRACT
<p><b>OBJECTIVE</b>To investigate the expression of aquaporin 1 (AQP1) in endometrium of patients with menorrhagia.</p><p><b>METHODS</b>RT-PCR and immunohistochemistry were carried out in twenty women with normal menstrual cycle to confirm the expression of AQP1 in endometrium and locate it. Then 51 women with menorrhagia and 40 women with normal menstrual cycle were included in the study. RT-PCR and immunohistochemistry were used to examine the expression of AQP1.</p><p><b>RESULT</b>AQP1 mRNA was expressed in the human endometrium throughout menstruation cycle, which was mainly located in the endothelia of the capillaries and small blood vessels. Quantification of the immunostaining revealed higher density during secretary phase than that in proliferative phase (P<0.01). The staining intensity and density of AQP1-positive microvessel decreased significantly in simple hyperplasia group (P<0.01) and then gradually increased in complex hyperplasia and atypical hyperplasia groups (P<0.001).</p><p><b>CONCLUSION</b>Decreased expression of AQP1 may lead to disturbed endometrial vascular remodeling and may be involved in the occurrence of menorrhagia.</p>