Mechanisms of action of dietary fatty acids in a syrian hamster model: the role of fatty acid ethanolamides on feeding intake, body composition and energy expenditure
Lin, Lyyn (Lin)
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Replacement of saturated fatty acids (SFA) with monounsaturated fatty acids (MUFA) or polyunsaturated fatty acids (PUFA) impacts risk of atherosclerosis and cardiovascular disease (CVD). However, although dietary fatty acids (DFA) have been established as an important factor related to CVD, their exact mechanisms of action have not been clearly established. One of the possible mechanisms is that DFA convert to fatty acid ethanolamides (FAEs), such as oleoylethanolamide (OEA), palmitoylethanolamide (PEA) and arachidonoylethanolamide (AEA), which are thought to associate with lipid signalling, fat oxidation and appetite control. Hence, the objectives of this thesis were to identify the impact of diets containing corn oil, canola oil, DHA + canola oil and fish oil on plasma and organ levels of FAEs as well as energy metabolism and lipid profiles in Syrian Golden hamsters. Forty-eight hamsters were provided diets containing 6% treatment oil for 30 d before sacrifice. Across all diets, in proximal small intestine and liver, animals fed canola oil showed higher (p<0.05) levels of OEA than corn oil and fish oil fed groups, but no difference compared to those fed DHA +canola oil. In plasma, fish oil fed animals showed higher (p<0.05) OEA and PEA levels and lower (p<0.05) AEA levels compared to all other groups. Feed intakes (g/d), oxygen consumption (ml/g) and body composition of total fat (%) and mass (g) did not differ across groups. However, energy expenditure associated with fat oxidation (%) was higher (p<0.01) in canola oil and DHA + canola oil fed hamsters compared to those consuming corn oil and fish oil. Also, body composition of fish oil fed animals showed a lower (p<0.01) total lean mass (g) compared to other three groups and a lower (p<0.01) total mass (g) compared to DHA + canola oil diets, but no difference compared to animals fed the canola oil diet. None of the treatments had any effect on triglyceride (TG) or C-reactive protein (CRP) levels. The fish oil group showed a higher (p<0.01) plasma total cholesterol (TC) levels than all other three groups. No differences existed between DHA + canola oil and fish oil groups in HDL or Non-HDL levels, but these levels were different (p<0.01) compared to corn oil group and canola oil groups. To conclude, different DFA affect whole body energetics and plasma lipid profiles. Also DFA produced marked shifts in plasma and organ levels of OEA, PEA and AEA. These dietary induced shifts in FAEs may translate into discernable changes in energy expenditure and lipid levels which in turn influence CVD risk.