High Fat Diet Rich in Saturated Fatty Acids, but Not Monounsaturated Fatty Acids, Impairs Glycogen Preservation after Adiponectin Treatment
High fat diet (HFD) is associated with the progression of obesity, type 2 diabetes and diminished insulin sensitivity, which is characterized by a lower glucose uptake and glycogen synthesis capacity in skeletal muscle. Adiponectin (Ad), on the other hand, is a cytokine secreted by adipose tissue that promotes glucose uptake and fatty acid oxidation in skeletal muscle. PURPOSE: To determine the effects of Ad on skeletal muscle glycogen, GLUT 4, mitochondrial and lipid content in animals fed with a HFD but with alterations in dietary fatty acids (mixed fat western diet and predominately monounsaturated fatty acid). METHODS: Male Sprague Dawley rats were fed a Western-style (21% fat) HFD for 9 weeks to induce obesity, then, for 6 weeks, continued the mixed fat Western diet (WD) (9.8% saturated fat; 7.7% mono; 3.5% poly; n=8) or a HFD high in monounsaturated fatty acids (MUFA) (21% fat; 17.76% mono; 1.8% poly; n=8). A control group followed a 15-week standard Chow diet (CD) (4.8% fat; 0.74% saturated fat; 2% mono; 1.77% poly; n=9). Right and left hind-leg extensor digitorum longus (EDL) muscles were incubated in an organ bath (containing Krebs-Henseleit buffer with 2000 mg/L glucose, without calcium chloride and sodium bicarbonate) with or without 0.1 mg/ml Ad for 30 minutes. Glycogen content in the EDL muscle was measured by using periodic acid-schiff staining, while GLUT 4 protein content was measured using rabbit polyclonal antibody against GLUT 4 (ab654), mitochondrial content was measured using a mouse polyclonal antibody against COX 4 protein (ab14744) and lipid content was measured using BODIPY 493/503, using immunohistochemistry techniques. Images were quantified with ImageJ software. RESULTS: The Ad incubation resulted in a decrease in muscle glycogen content in animas fed with WD (4.85 ± 0.13 to 4.29 ± 0.11 AU; p=0.05). This decrease in glycogen content in the WD group was significantly different compared to a better preservation of glycogen in both CD (p=0.04) and the MUFA diet groups (p=0.012) (CD: 0.11 ± 0.071 AU; WD: -0.25 ± 0.14 AU; MUFA: 0.18 ± 0.05 AU; one way ANOVA, p=0.01). Animals fed with CD tended to have a better preservation of lipid content compared to animals fed with WD (p=0.07) and a diet high in MUFA (p=0.09) (CD: 25.93 ± 11.2 AU; WD: -21.09 ± 14.81 AU; MUFA: 25.97 ± 16.17 AU; one way ANOVA, p=0.06). There were no significant changes in GLUT 4 and mitochondrial content regardless of diet and adiponectin incubation. CONCLUSIONS: Animals fed with a western style HFD rich in saturated fat show an impaired response to adiponectin induced increase/preservation of glycogen in skeletal muscle compared to a chow diet, as well as a HFD rich in MUFA. Diets high in saturated fatty acids may have an impaired response to adiponectin treatment.
Montenegro, Cynthia; De La Pena, Catalina; Meza, Cesar; Naughton, Shaan; Simcocks, Anna; O'Keefe, Lannie; Skelly, Deanne; Mathai, Michael; McAinch, Andrew; and Bajpeyi, Sudip
"High Fat Diet Rich in Saturated Fatty Acids, but Not Monounsaturated Fatty Acids, Impairs Glycogen Preservation after Adiponectin Treatment,"
International Journal of Exercise Science: Conference Proceedings: Vol. 2:
9, Article 18.
Available at: https://digitalcommons.wku.edu/ijesab/vol2/iss9/18