Effect of fish oil on glucose metabolism in the interleukin-1α-treated rat

Abstract

Fish oil has been demonstrated to ameliorate many of the responses to infection. This study was conduced to determine whether fish oil feeding could modify the alterations of glucose metabolism induced by interleukin-1α (IL-1α) infusion in the rat. Male Sprague-Dawley rats were pair-fed for 5 weeks on two experimental diets in which the source of fat was either fish oil or soybean oil and provided 20% of calories; the diets were isonitrogenous and isocaloric. After 5 weeks of feeding, rats from both diet regiments were further divided into two subgroups to receive a 3-hour infusion of either 0.1% albumin in saline or 0.1% albumin in saline containing IL-1α. A total of 20 μg/kg IL-1α was administered, and half the dose of IL-1α was given as a bolus and the remaining portion (10 μg/kg) was continuously infused into the jugular vein. During the last 2 hours of IL-1α infusion, a primed constant infusion of d-(6- 3H)glucose and d-(U- 14C)glucose was combined to determine the effects of IL-1α and diet on glucose kinetics. Plasma levels of glucose and insulin, energy expenditure, and respiratory quotient were also measured. IL-1α significantly increased concentrations of plasma insulin and the percentage of glucose carbon recycling, confirming previous findings. Concentrations of glucose and insulin with IL-1α treatment were significantly higher in soybean oil- fed animals compared with fish oil-fed animals. In contrast, the contribution of glucose oxidation to total energy expenditure was significantly higher in fish oil-fed groups, and even more so in fish oil-fed, IL-1α-treated animals. These results indicated that fish oil prefeeding may improve the effective insulin action on glucoregulatory response and increase glucose oxidation during infection and inflammation.