Gender differences in the myocardial response to dietary CLA isomers during diabetes

Abstract

This study was undertaken to examine if conjugated linoleic acid (CLA) isomers c9,t11 and t10,c12, provide protection against cardiac dysfunction in diabetic male and female rats. Diabetes was induced by an intravenous injection of streptozotocin (65 mg/kg body weight) in male and female rats. Four wks after the induction of diabetes, the animals were treated daily for 4 wks with or without 0.5% of each CLA isomer by oral gavage. Eight wks diabetes was associated with elevated levels of plasma total cholesterol, HDL-cholesterol, triglycerides and glucose as well as depressed rate of cardiac relaxation (-dP/dt) in both male and female animals. However, unlike females, male diabetic rats showed an increase in heart weight: body weight ratio and decreased rates of cardiac contraction (+dP/dt) and fractional shortening (FS). Both CLA isomers improved the lipid profile in male diabetic rats, whereas only CLA c9,t11 isomer improved the lipid profile in females. CLA intervention did not affect blood glucose levels in male or female diabetic animals. While CLA c9,t11 isomer improved ± dP/dt in the male rats, a deterioration of +dP/dt and -dP/dt in the female diabetic rats was observed. Although FS was normalized by both CLA isomers in males, CLA t10,c12 isomer depressed FS in the female diabetic rats. CLA treatment normalized GLUT 4 gene expression levels, but markedly increased insulin receptor gene expression in the heart of male diabetic rats. These data suggest that, unlike females, improved myocardial function in male diabetic rats in response to CLA may be related to a favorable shift in myocardial energetics.