Effects of Opioid Peptides on Changes in Lipid Metabolism in Rats Subjected to Swimming Stress

Blood levels of nonesterified fatty acids, total cholesterol, triglycerides, and LDL increased in rats subjected to forced swimming stress. Administration of opioid peptides dynorphin A(1-13), DSLET, or DAGO reduced stress-induced disturbances in lipid metabolism. Dynorphin A(1-13) and DAGO produced the most pronounced effects and prevented an increase in concentrations of nonesterified fatty acids, triglycerides, total cholesterol, and LDL as soon as 39 h after treatment. Only DSLET increased HDL content in the plasma of stressed rats. The observed effects can be explained by the stress-limiting effects of opioids, e.g. attenuation of the effect of catecholamines on the adipose tissue and inhibition of the generation LPO products suppressing activity of the cholesterol metabolizing enzyme.