Aim: 

We studied the role of 17b-estradiol replacement during aging on insulin sensitivity and the possible relationship between key components of insulin signalling and estrogen receptor expression in adipose tissue.

Methods: 

Virgin female Wistar rats were separated in two groups: ovariectomized rats treated with vehicle and ovariectomized rats treated with estradiol, using subcutaneous implants with placebo or 17b-estradiol, respectively. Each group was subdivided according to the date in which they were sacrificed: 0, 6, 12, 18 and 24 months. The day of sacrifice, rats were anesthetized and clamp experiment was performed. 17ß-estradiol was determined by RIA. Adipose tissue was recovered and processed in order to obtain crude extracts. IRS-1 was inmunoprecipitated and p85 alpha interaction was detected by Western-Blot. Plasma membrane fractions were obtained and ER alpha and Glut4 amount were determined by Western Blot analysis. Analysis of Variance and Student-Newman-Keuls were employed. A p <= 0.05 considered significant. Animal procedures accord with current and National Guidelines.

Results and Conclusions: 

Our results showed that estradiol treatment during aging leads to lower body weight gain which could be related to a higher amount of estrogen receptor alpha located at plasma membrane in adipose tissue. Moreover, insulin sensitivity is improved by estradiol treatment through a specific up-regulation of insulin signalling pathway in adipose tissue, such as the amount of Glut4 located at plasma membrane. Taking together, it could be possible a specific relationship between non-nuclear estrogen receptor alpha and insulin signalling in order to orchestrate the physiological adaptations to aging.