Sex dimorphism in the onset of the white adipose tissue insulin sensitivity impairment associated with age.

The aim of this study was to investigate the time-course response of retroperitoneal white adipose tissue (WAT) insulin and adiponectin signaling pathway intermediates in relation to the systemic age-associated impairment of insulin sensitivity in male and female rats. The main markers of the insulin and adiponectin signaling pathways of the retroperitoneal WAT, as well as of the systemic insulin sensitivity profile of 3-, 9- and 18-month old Wistar rats of both sexes were determined. Our results indicate that age leads to a decrease in the insulin sensitivity in both sexes that agrees with the decline in the levels of the WAT insulin signaling pathway intermediates, the increase in the adiposity index and the rise in the serum insulin resistance markers. This is accompanied by a sex-dimorphism that involves a gradual insulin signaling pathway decrease in female rats and an earlier and acute decrease in males and suggests a better insulin responsiveness in female rats at any age group. Our results confirm the idea that in rats, the insulin signaling pathway of WAT is altered at earlier ages than that of skeletal muscle and also provides further evidence of the impairment of the WAT adiponectin signaling pathway.
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