Expression of glucose transporter 4 mRNA in adipose tissue and skeletal muscle of ovariectomized rats treated with sex steroid hormones

The effects of 17 beta-estradiol (E) and/or progesterone (P) on; glucose tr ansporter 4 (GLUT4) expression in the adipose tissue and skeletal muscle of ovariectomized female rats were studied. The Sprague-Dawley rats received daily subcutaneous injections of various doses of E and/or P for 7 days (n= 5-6 per dose). The expression of GLUT4 mRNA was assessed by performing ribo nuclease protection assays. GLUT4 protein levels were assessed by Western b lotting assays. The adipose tissue levels of GLUT4 mRNA were reduced by the administration of 50 mu g E, which resulted in unphysiologically high seru m E concentrations. Although the GLUT4 mRNA levels did not change after the administration of 10 mu g E or 5 mg P, they were reduced significantly to approximately half the control group level by the administration of both ho rmones (p <0.01). The skeletal muscle GLUT4 mRNA levels were not changed si gnificantly by hormone treatment. These findings suggest that E and P may b e involved in the regulation of GLUT4 mRNA expression in adipose tissue.