This study aimed to investigate whether treatments with vitamin E, L-carnitine and melatonin can protect against CCl₄ and diabetes-induced hepatic oxidative stress. Hepatic oxidative stress was performed in rats through 50% v/v carbon tetrachloride (CCl₄) (1 ml/kg/3days, i.p.), and through diabetes mellitus induced by streptozotocin (STZ) (40 mg/kg, i.p.). Vitamin E (100 mg/kg/day, i.p), L-carnitine (300 mg/kg/day, i.p.) and melatonin (10 mg/kg/day, i.p.) were injected for a period of 6 weeks. Thereafter, changes in serum glucose level, liver function tests, hepatic malondialdehyde (MDA) content, hepatic reduced glutathione (GSH) content, hepatic superoxide dismutase (SOD) activity, and serum total antioxidant capacity (TAC) level were evaluated. In CCl₄-induced liver fibrosis, the efficacy order was melatonin > L-carnitine > vitamin E, while in STZ-induced diabetes, the efficacy order was vitamin E ≥ melatonin > L-carnitine. In conclusion, these data indicate that low dose of melatonin is more effective than high doses of vitamin E and L-carnitine in reducing hepatic oxidative stress induced by CCl₄ and diabetes. Moreover, the potent effect of vitamin E in ameliorating diabetes can be linked not only to the antioxidant actions, but also to the superior effect in reducing diabetes-induced hyperglycaemia. Meanwhile, potency of L-carnitine was nearly the same in CCl₄ and diabetes-induced liver damage.

中文翻译：

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维生素 E、左旋肉碱和褪黑激素在改善四氯化碳和糖尿病诱导的肝氧化应激方面的比较。

本研究旨在调查维生素 E、左旋肉碱和褪黑激素治疗是否可以预防 CCl ₄和糖尿病引起的肝脏氧化应激。通过 50% v/v 四氯化碳 (CCl ₄ ) (1 ml/kg/3days, ip) 和链脲佐菌素 (STZ) (40 mg/kg, ip) 诱导的糖尿病对大鼠进行肝脏氧化应激。维生素 E (100 mg/kg/day, ip)、L-肉碱 (300 mg/kg/day, ip) 和褪黑激素 (10 mg/kg/day, ip) 注射了 6 周。此后，评估血清葡萄糖水平、肝功能检查、肝丙二醛 (MDA) 含量、肝还原型谷胱甘肽 (GSH) 含量、肝超氧化物歧化酶 (SOD) 活性和血清总抗氧化能力 (TAC) 水平的变化。覆铜板₄-诱导的肝纤维化，功效顺序为褪黑激素>左旋肉碱>维生素E，而在STZ诱导的糖尿病中，功效顺序为维生素E≥褪黑激素>左旋肉碱。总之，这些数据表明，在减少由 CCl ₄和糖尿病引起的肝脏氧化应激方面，低剂量的褪黑激素比高剂量的维生素 E 和左旋肉碱更有效。此外，维生素 E 在改善糖尿病方面的有效作用不仅与抗氧化作用有关，而且与降低糖尿病引起的高血糖症的优越效果有关。同时，L-肉碱的效力几乎是在四氯化碳同一₄和糖尿病诱导的肝损伤。