Different expression of α and β mitochondrial estrogen receptors in the aging rat brain: Interaction with respiratory complex V

Recent evidence suggests that hormonal effects on mitochondria could be mediated by mitochondrial estrogen receptors (mtERs). These receptors are new candidates for the beneficial estrogenic effects on mitochondria in different physiological conditions. The aim of this investigation was to study mtER expression during brain aging. We analyzed mtER alpha and mtER beta expression in cortical, hippocampal and hypothalamic mitochondria of young adult (3 months) and aged (18 months) female Wistar rats by Western blot. In addition, we explored the interaction of mtER beta with respiratory complex V by using coimmunoprecipitation assays. The results show that mtER alpha and mtER beta are present in young and aged brain mitochondria. We also demonstrate that mtERs are expressed as variants and have a brain region specific distribution. The predominant mtER variants detected were of 61 and 55 KDa for mtER alpha and of 63 and 52 KDa for mtER beta. However, we did not observe differences in the mtER alpha or beta content between the two age groups studied. Additionally, we show that mtER beta interacts with complex V. The overall results demonstrate that there is a differential expression of mtER alpha and mtER beta variants in different brain areas, indicating that they may participate in different functions in the brain during aging. (C) 2010 Elsevier Inc. All rights reserved.