Estradiol in vivo induces changes in cardiomyocytes size in obese rats.

We studied the in vivo effects of estradiol on size and biochemical parameters of cardiomyocytes in pathophysiological conditions such as obesity and insulin resistance. Male Wistar rats were normally fed (controls, n = 7) or fed with high-fat diet (obese, n = 14). Half of the obese rats (obese + estradiol, n = 7) were treated with a single dose of estradiol (40 μg/kg, intraperitoneally) and 24 hours after treatment all the rats were killed. Estradiol in vivo in obese rats resulted in a significant increase in protein kinase B (Akt) activation (P < .05) and decrease in heart mass (P < .05), ratio of the heart mass/body mass (P < .05), transverse diameters of cardiomyocytes (P < .001), concentration of serum high-sensitivity C-reactive protein (P < .001), and total cholesterol (P < .01) compared with obese nontreated rats. Our results suggest that estradiol in obese/IR rats affects the size of cardiomyocytes and its actions lead in vivo to a reduction in obesity-induced cardiac hypertrophy, via Akt.