Changes in dietary fatty acids modify the decreased lipolytic beta(3)-adrenergic response to hyperinsulinemia in adipocytes from pregnant and nonpregnant rats

The effect of dietary olive oil and fish oil on the lipolytic dose-response of the beta(3)-adrenergic agonists, epinephrine, isoproterenol, BRL-37344, and CGP-12177, in adipocytes was studied in pregnant and virgin rats eithe r untreated or under hyperinsulinemic-euglycemic conditions. Rats were fed a semisynthetic diet containing 5% of either olive oil or fish oil and stud ied at day 20 of treatment and/or gestation. Plasma glucose was lower and p lasma insulin, triglycerides, and free fatty acids (FFAs) were higher in pr egnant versus virgin rats, and the insulin sensitivity index was lower in t he former. Lumbar adipose tissue phospholipid fatty acids showed a signific antly higher monounsaturated fatty acid and a lower(n - 3) fatty acid conte nt in rats fed the olive oil diet versus the fish oil diet. The lipolytic d ose-response curve of either adrenergic agent was always lower in adipocyte s from untreated pregnant rats versus virgin rats, and whereas the hyperins ulinemic-euglycemic clamp decreased these responses in adipocytes from virg in rats fed the olive oil diet only, adipocytes from pregnant rats always s howed a decreased dose-response lipolytic curve. Thus, the lipolytic respon siveness of beta(3)-adrenoceptor (beta(3)-AR) agonists by adipocytes is imp aired in cells from rats made hyperinsulinemic chronically by pregnancy or acutely by the hyperinsulinemic-euglycemic clamp. but such response to the acute condition disappears when the adipocyte phospholipid composition is m odified by changes in dietary fatty acids. Copyright (C) 2000 by W.B. Saund ers Company.