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

This study used double in situ hybridization (ISH) to examine the colocaliz ation of estrogen receptor beta (ER beta) mRNA in serotonin neurons of rhes us macaques (Macaca mulatta). In addition, immunocytochemistry (ICC) was us ed to examine the expression and regulation of ER beta protein in raphe neu rons of the macaque midbrain. For double ISH. monkey specific riboprobes fo r ER beta incorporating radiolabeled-UTP and a riboprobe for the human sero tonin 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 m edian raphe and pens. There were also non-SERT neurons expressing ERP mRNA. In addition, ER beta protein was detected with an affinity purified polycl onal 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 dorsa l raphe from spayed rhesus macaques with and without hormone replacement th erapy were processed for ER beta immunostaining. ER beta protein was detect ed at a similar intensity and in a similar number of cells in the dorsal ra phe neurons in all treatment groups. Thus, the expression of ER beta protei n in the dorsal raphe was consistent with the expression of ER beta mRNA. I n conclusion, ER beta mRNA is expressed by serotonin neurons and it is tran slated to protein. ER beta protein, like ER beta mRNA, is detected at simil ar levels in the presence or absence of ovarian hormones. (C) 2001 Elsevier Science B.V. All rights reserved.