The effect of intake of lamb meat on energy metabolism of Sprague-Dawley rats: possible role of carnitine

Abstract

The purpose of the present study was to determine whether carnitine was responsible for the increased energy metabolism observed in Sprague-Dawley rats following inclusion of lamb meat in their diet. This was tested by feeding one of the following three diets: a control diet (control) based on a standard formulation (AIN-93G), a carnitine-supplemented control diet (CD) and a lamb meat diet (LD). All diets were isocaloric (15.46 kJ/g DM) and contained 18.3% protein, 7.1% fat and 58.3% carbohydrate. The carnitine concentrations in the control diet, CD and LD were 29, 984 and 953 mg/kg, respectively. The expression of carnitine palmitoyltransferase-I(CPT-I)α and CTP-Iβ genes, Na,K-ATPase activities and the contents of fat, ATP and creatine phosphate (Cr.P) in liver and skeletal muscle tissues were measured on Days 7 and 14. Bodyweights, bodyweight gains and oxygen consumption rates (OCR) of rats were also measured. The rats fed the LD had higher OCR, ATP and Cr.P concentrations, expressions of CPT-I gene, Na,K-ATPase activities, and lower fat contents, bodyweights and bodyweight gains (P < 0.05) than did the control-group rats. However, rats fed the CD were not significantly different from those fed the control diet, except for the higher CPT-Iα expression, ATP concentrations and lower fat contents in liver (P < 0.05). We conclude that carnitine intake from lamb was not the main factor accounting for the significant effects of lamb consumption on energy metabolism. However, it is likely that carnitine intake by consumption of lamb meat in the LD partly contributed to lowering fat contents in liver, compared with the CD and the control diet groups.