Expression of estrogen receptor (ER) α and β in mouse cerebral cortex:: Effect of age, sex and gonadal steroids

Estrogen receptor (ER), which mediates the multiple effects of estrogen in brain, is regulated by several factors including its own ligand. In the present study, we have examined the effect of age, sex and gonadal steroids (estrogen and testosterone) on the level of ER alpha and ER beta in the cerebral cortex of AKR mice. Adult and old mice of both sexes were divided into four groups: intact, gonadectomized, 17 beta-estradiol treated and testosterone treated. Western blot analysis showed higher level of ERa and ER beta in the cerebral cortex of adult female than male mice. ER beta level decreased significantly with advancing age in both sexes, whereas 17 beta-estradiol supplementation decreased ER alpha level in old male and increased in old female, it also increased ER beta level in old male and adult female. On the other hand, testosterone treatment decreased ER alpha level significantly in old female and ER beta level in adult female but increased ER beta level in male mice of both ages. Thus, these findings showed that the expression of ER alpha and ER beta protein is differentially influenced by age, sex and gonadal steroids in the mouse cerebral cortex, suggesting differences in ER-mediated brain functions. (c) 2005 Elsevier Inc. All rights reserved.