Effect of Meal-Feeding on Insulin Sensitivity and Incorporation of [U-14C] Glucose into Lipids in Rat Aorta

Abstract

In vitro aortic lipogenesis from o-(U-14C)glucose was sig nificantly greater in meal-fed rats than in ad libitum fed controls. In addi tion, aortic tissue from meal-fed rats showed a sensitivity to insulin which was absent in the same preparations from nibbling rats. Two preparations of aortic tissue were used in this study. Intima-media contained intima and approximately the inner two-third of the media. Adventitia contained the remainder of the media and the inner, fat-free adventitia. This latter preparation was more sensitive to the change from a nibbling to a meal- eating regime, although the effects were clearly evident in the intima- media, suggesting that both adventitial and medial cells were susceptible to the metabolic changes associated with the adaptation to meal-eating. Of the two major aortic lipid components synthesized from glucose in vitro, phospholipids and triglycA©rides,the former were essentially unaltered in meal fed rats. However, in comparison with nibbling rats, 14C-incorporation into aortic triglycA©rideswas increased two-fold in the intima-media and three-fold in the media-adventitia, and was almost doubled again in both preparations in the presence of insulin. The development of adaptive hyper- lipogenesis and insulin sensitivity in these preparations is discussed in terms of possible variations in insulin receptor number in target tissues of meal- fed rats. J. Nutr. 107: 1896-1901, 1977.