Expression and localization of estrogen receptors α and β mRNA in medullary bone of laying hens

The aim of this study was to observe the expression and localization of estrogen receptor (ER) α and ER β mRNA in the medullary bone of laying hens. First, medullary bone, liver, kidney, and shell gland of the oviduct tissues were dissected from laying hens. Then, the total cellular RNA was isolated from each tissue specimen, and the ER α and ER β mRNA expression was observed using semiquantitative RT-PCR. Second, the localization of ER α mRNA in the medullary bone was detected with in situ hybridization using digoxigenin-11-UTP-labeled cRNA probes. As a result, the expression of ER α mRNA was higher than that of ER β mRNA in the medullary bone, liver, and shell gland of the oviduct from laying hens. In the kidney, ER α mRNA expression was lower than that of ER β mRNA. The expression pattern of ER α and ER β mRNA of the medullary bone was similar to that of the shell gland of the oviduct. Moreover, ER α mRNA was intensively expressed in osteoblasts on the medullary bone surface and bone marrow stromal cells but was not expressed in osteoclasts. These results suggest that in medullary bone, estrogen action may be regulated not by ER β but by ER α.