Analysis of Estrogen Receptor Expression in Tissues

This chapter focuses on the analysis of estrogen receptor expression in tissues. The functions of estrogen are not confined to the female reproductive system, but it also has important functions in non reproductive tissues of both males and females. The two estrogen receptors—ERα and ERβ—have distinct and sometimes opposing actions in multiple tissues. To define the role of each receptor in estrogen-sensitive tissues, it is essential to have reliable methods to detect the expression of the two genes. Methods have been developed for the detection of ERα and its functions. The most common of these are immunohistochemistry and Western blotting with specific antibodies; the measurement of estrogen accumulation and retention in tissues; the measurement of the binding of estradiol in the 8S fraction after sedimentation in sucrose gradients of low salt tissue-extracts; and the assessment of changes in mRNA levels of classic estrogen responsive genes. There are several reasons why the presence of the second estrogen receptor has made it difficult to interpret results obtained with the use of these methods. Available estrogen receptor antibodies when tested with recombinant ERα or ERβ standards exhibit the appropriate specificity; however, this recognition does not indicate them to be high affinity antibodies.