Regulation of estrogen receptor α by estradiol in pregnant and estradiol treated rats

Estrogens play an important role in tissue metabolism through specific regulation of several intracellular pathways. We studied ER alpha regulation in muscle and adipose tissue from pregnant and estradiol treated rats. In both groups, we identified three different ER alpha. inmunoreactive proteins (80, 67 and 46 kDa) using total protein extracts. Because it has been showed that estrogens are able to promote rapid effects in several cellular models, we looked for three ER alpha-related proteins at plasma membrane. In skeletal muscle of both groups, we positively identified the three ERa-related isoforms in plasma membrane, but in adipose tissue from pregnant we were not able to identify ER alpha 67, and in estradiol treated animals ER alpha 80 was absent. Taking together, our results showed a tissue-specific regulation of whole-cell ER alpha-related proteins and ERa located at plasma membrane, which should be involved in non-genomic actions of 17 beta-estradiol. The role of the three ER alpha inmunoreactive proteins is unknown, however, seems probably related to rapid activation of signalling pathways. (c) 2006 Elsevier Inc. All rights reserved.