Objective: To investigate the effects of 17 beta-estradiol and progesterone on the expression of glucose transporter 4 (GLUT4) in the adipose tissue and skeletal-muscle tissue of ovariectomized rats.
Methods: Female Sprague-Dawley rats (n = 63) received a daily subcutaneous injection of 10 micrograms, 50 micrograms, or 250 micrograms of 17 beta-estradiol (Group E) or of 1 mg, 5 mg or 25 mg of progesterone (Group P) for 3 days, 7 days, or 10 days (n = 3, at each dose). The expression of GLUT4 mRNA was assessed by performing ribonuclease protection assays.
Results: The levels of GLUT4 mRNA in adipose tissue was significantly reduced by treatment with estradiol, 50 micrograms or 250 micrograms, relative to findings in control rats (p < 0.01). No such reductions were seen regarding the progesterone treatment. The level of GLUT4 mRNA in skeletal-muscle tissue did not change, regardless of treatment.
Conclusion: In ovariectomized rats, higher than physiologic dosages of 17 beta-estradiol can suppress the expression of GLUT4 mRNA in adipose tissue.