Role of Fatty Acid Composition in the Development of Metabolic Disorders in Sucrose-Induced Obese Rats

Abstract

Fatty acids have been shown to be involved in the development of insulin resistance associated with obesity. We used sucrose loading in rats to analyze changes in fatty acid composition in the progression of obesity and the related metabolic disorder. Although rats fed a sucrose diet for 4 weeks had body weights similar to those of control animals, their visceral fat pads were significantly larger, and serum triglyceride levels were higher; however, neither plasma glucose nor insulin levels were significantly higher. After 20 weeks of sucrose loading, body weight and visceral and subcutaneous fat pads had increased significantly compared with those in control rats. Moreover, plasma glucose, insulin, and triglyceride levels were significantly higher. An analysis of individual fatty acid components in the blood and peripheral tissues demonstrated phase- and tissue-dependent changes. After 20 weeks of sucrose loading, palmitoleic acid (16:1 n-7) and oleic acid (18:1 n-9), the major components of monounsaturated fatty acid, showed a ubiquitous increase in plasma and all tissues analyzed. In contrast, linoleic acid (18:2 n-6) and arachidonic acid (20:4 n-6), the major components of polyunsaturated fatty acid in the n-6 family, decreased in plasma and all tissues analyzed. After 4 weeks of sucrose loading, these changes in fatty acid composition were observed only in the liver and plasma and not in fat and muscle. This led us to conclude that elevation of plasma glucose and insulin develop at the late phase of sucrose-induced obesity, when changes in fatty acid composition appear in fat and muscle. Furthermore, changes in fatty acid composition in liver seen after 4 weeks of sucrose loading, when increases in neither plasma glucose nor insulin were detected, suggest that liver may be the initial site of fatty acid imbalance and that aberrations in hepatic fatty acid composition may lead to fatty acid imbalances in other tissues.

Western diet increases wheel running in mice selectively bred for high voluntary wheel running

“…Different types of fatty acids, however, are not identical in their effects on performance 45 or health. 4,46 There seem to be differences between polyunsaturated verses monounsaturated and saturated fats, and differences among types of polyunsaturated fats. 45,47 In our study, only 4% of the fat in the WD was polyunsaturated, with less that 0.5% coming from eicosapentaenoic acid and docosahexaenoic acid, whereas 64% was saturated fat, with 10.3, 29.4, 12.6% of total fatty acids coming from saturated fatty acid chains of 14, 16 and 18 carbons long, respectively.…”

“…3 Diet is a highly variable environmental factor (although behavior and physiology affect dietary choices), and elucidating the role that dietary macronutrients have in providing energy during locomotion and other physiological processes should shed light on the current human obesity epidemic. 4,5 Furthermore, comparative, ecological and evolutionary physiologists are attempting to reveal how dietary physiology may interact with, and even constrain, behavioral ecology and evolution. 2,6,7 In this study, we investigated genotype-by-environmental interactions and potential limitations that diet places on locomotor behavior through the use of an artificial selection experiment using laboratory house mice.…”

Role of Fat Body Lipogenesis in Protection against the Effects of Caloric Overload in Drosophila

“…Labeled glucose can be metabolized into acetyl-CoA (which can be either singly or doubly labeled with 13 C and incorporated into de novo synthesized non-esterified fatty acids (1). These labeled fatty acids can be esterified as TAG (2). B, larval weights at 24 h after transfer to tracer diets.…”

“…More recently, caloric excess has been shown to elicit many of the same negative consequences in model organisms as have long been observed in humans (1)(2)(3)(4)(5)(6)(7). Work from our laboratory and that of others has shown that feeding Drosophila a high sugar diet (HSD) 2 results in a model of type 2 diabetes (T2D) that includes hyperglycemia, obesity, insulin resistance, cardiac arrhythmias, and reduced lifespan (4,8,73).…”

“…High calorie diets are associated with non-alcoholic fatty liver disease, obesity, and insulin resistance in rodents and humans (2,(15)(16)(17)(18), but the role of lipid accumulation remains controversial. An emerging concept is that obesity is protective against T2D (19,20).…”