Oestrogen receptor β is expressed in adult human skeletal muscle both at the mRNA and protein level

Aim: There are two known oestrogen receptors (ER), oestrogen receptor α (ERα) and the recently cloned oestrogen receptor β (ERβ). ERα mRNA has been detected in mouse, rat, bovine and human skeletal muscle. ERβ mRNA has been detected in bovine skeletal muscle. To our knowledge, no study has investigated the expression of oestrogen receptor β in human skeletal muscle. Therefore, the primary aim of the present investigation was to study ERβ mRNA and protein expression in human skeletal muscle. In addition the ERα expression was also studied. Methods: Muscle biopsies were taken from vastus lateralis in six healthy adults (three women and three men). mRNA expression was detected with real‐time PCR (TaqMan) and protein localization by immunohistochemistry. Results: A clear expression of ERα and ERβ mRNA was seen in skeletal muscle in all subjects. The ERα mRNA expression was 180 fold higher compared with that of ERβ mRNA. Immunohistochemistry demonstrated positive staining for ERβ, but not for ERα, with localization to the nuclei of skeletal muscle fibres. On average, 70% of all nuclei were ERβ‐positive. Conclusion: The present study shows for the first time ERβ mRNA and protein expression in human skeletal muscle tissue in both males and females.