Estrogen receptor beta (ERβ) mRNA and protein in serotonin neurons of macaques

This study used double in situ hybridization (ISH) to examine the colocalization of estrogen receptor beta (ER beta) mRNA in serotonin neurons of rhesus macaques (Macaca mulatta). In addition, immunocytochemistry (ICC) was used to examine the expression and regulation of ER beta protein in raphe neurons of the macaque midbrain. For double ISH. monkey specific riboprobes for ER beta incorporating radiolabeled-UTP and a riboprobe for the human serotonin reuptake transporter (SERT) incorporating digoxigenin were applied to midbrain sections from spayed rhesus macaques. ER beta mRNA hybridization signal was expressed in most cells containing SERT mRNA in the dorsal and median raphe and pens. There were also non-SERT neurons expressing ERP mRNA. In addition, ER beta protein was detected with an affinity purified polyclonal antibody generated against a synthetic peptide corresponding to the D domain of human ER beta conjugated to bovine serum albumin (provided by Dr. Philippa Saunders, MRC, Edinburgh). Midbrain sections containing the dorsal raphe from spayed rhesus macaques with and without hormone replacement therapy were processed for ER beta immunostaining. ER beta protein was detected at a similar intensity and in a similar number of cells in the dorsal raphe neurons in all treatment groups. Thus, the expression of ER beta protein in the dorsal raphe was consistent with the expression of ER beta mRNA. In conclusion, ER beta mRNA is expressed by serotonin neurons and it is translated to protein. ER beta protein, like ER beta mRNA, is detected at similar levels in the presence or absence of ovarian hormones. (C) 2001 Elsevier Science B.V. All rights reserved.