Vitamin D3 receptor is expressed in the endometrium of cycling mice throughout the estrous cycle

Objective To investigate the expression and localization of vitamin D 3 receptor (VDR) in reproductive organs of cycling mice. Design Experimental animal study. Setting Academic research center. Animal(s) Mature (8 to 12 weeks old) cycling female Balb/c mice. Intervention(s) Reproductive tissue, including endometrium, ovary, and fallopian tubes, were collected at each phase of estrous cycle to examine VDR expression. Main Outcome Measure(s) Expression of VDR messenger (mRNA) was determined by semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR). The presence and localization of VDR was assessed by immunohistochemistry, and the intensity of VDR expression was quantified with U.S. National Institutes of Health image-analysis software. Result(s) The VDR mRNA was expressed in the endometrium throughout the estrous cycle. The relative expression of VDR mRNA at the estrus phase was more prominent compared with the other phases. Immunohistochemical analysis revealed that dendritic cells, macrophages, and luminal and glandular epithelial cells of the endometrium, granulosa, and cumulus oophorus cells of the ovary and fallopian epithelial cells strongly express VDR, particularly during the estrus phase. Conclusion(s) Our findings have demonstrated, for the first time, that VDR is present and differentially expressed in murine reproductive organs throughout the estrous cycle. Further studies are required to evaluate the functional immunologic role of VDR.