Protective role of l-carnitine supplementation against exhaustive exercise induced oxidative stress in rats

The objective of this study was to investigate temperature dependent effects of oral l-carnitine supplementation on exhaustive exercise induced oxidative damage in rats. 42 male Spraque Dawley rats were randomly divided into seven experimental groups. These groups were formed as three non-carnitine exercise groups, three carnitine-exercise groups and a sedentary group. l-carnitine was given intraperitoneally to the carnitine-exercise groups 1 h before the exercise in 100 mg/kg. Blood was collected to measure paraoxonase-1 (PON1) activity, plasma malondialdehyde (MDA), low-density lipoprotein (LDL) and cholesterol concentrations. These biomarkers were measured in venous blood samples collected before and after the rats swam in pools at different water temperatures (18 °C, 28 °C and 38 °C). In the non-carnitine group, exercise caused a significant decrease in PON1 activity and a significant elevation in MDA concentration at 28 °C compared to the sedentary group. No significant alterations were evidenced in LDL and cholesterol concentrations upon exercise. The decrease in PON1 activity became higher with increasing temperature whereas the elevation in MDA levels increased at 18 °C. In the l-carnitine supplementation group, recovery in PON1 activity was observed significant at 28 °C and very significant at 38 °C. MDA concentration was almost the same with that of the non-carnitine group at 18 and 38 °C, but it significantly decreased at 28 °C. Considering the recovery in PON1 and MDA levels at 28 °C, which is the temperature of the sedentary group; our results suggest that l-carnitine supplementation has a protective role on exhaustive exercise-induced oxidative stress. Findings of this study also demonstrate influences of thermal stress on these parameters during exhaustive exercise.