ACTA ENDOCRINOLOGICA (BUC)

Leptin is much more than a simple sensor of body fat levels. Its biological activities, include angiogenesis, osteogenesis and modulation of the immune and reproductive systems. There are no reports on fluctuations of the level in normal human functional glandular epithelium during the menstrual cycle. Objective. We aimed to determine the expression level of the leptin receptor by immunohistochemistry and to correlate this with estrogen and progesterone receptor levels in normal endometrial tissue throughout the menstrual cycle. Study design. Thirty-seven paraffin wax blocks of biopsy specimens of histologically normal endometrium were evaluated and classified according to the stage of the menstrual cycle during the 2004–2006 period. Results. The OB-R level underwent fluctuations during the menstrual cycle in the different tissue compartments; these were most marked in the functional glandular epithelium and during the proliferative stage. OB-R levels were correlated positively with the expression levels of estrogen and negatively with those for progesterone receptors, suggesting that these steroids modulate the expression of OB-R in vivo. Conclusion. This finding underscores the importance of considering the menstrual cycle stage for studies seeking possible impacts of the OB-R on reproductive pathology, because its expression level varies with the hormonal environment.