Objective: It has been reported that liver oxidative stress increases in streptozotocin induced experimental diabetes. The aim of this study is to investigate the effects of L-carnitine possessing antioxidant activity on liver protein oxidation seen in diabetes.

Materials and Methods: In the study, twenty adult male rats of Wistar strain were randomly divided into three groups as follows: control (n=5), diabetes (n=8) and L-carnitine+diabetes groups (n=7). Diabetes and L-carnitine+diabetes groups were intraperitoneally injected with a single dose of 50 mg/kg streptozotocin prepared in the citrate buffer (pH 4.5). Control group was injected with only citrate buffer. 72 hours after the streptozotocin injection, intraperitoneal L-carnitine injection (500 mg/kg/day) was given L-carnitine+diabetes groups, physiological saline were given to other groups for 15 days.

Results: The levels of liver tissue non-protein thiol of the diabetes and L-carnitine+diabetes groups were found to be lower than those in the control group (p<0.001 for both). Liver protein thiol levels of the diabetes and L-carnitine+diabetes groups were higher than those in the control group (p<0.05 for both). Liver protein carbonyl level of the diabetes group was determined higher than those in the control group and L-carnitine+diabetes group (p<0.05 for both). There was a significant positive correlation between liver tissue total and protein thiol levels in control, diabetes, L-carnitine+diabetes groups (p<0.01, p<0.001, p<0.01 respectively) as well as between liver protein thiol and non-protein thiol levels (p<0.05) in L-carnitine+diabetes group.

Conclusion: L-carnitine partially prevents liver protein oxidation seen in diabetes mellitus.