Melatonin prevents methotrexate‐induced hepatorenal oxidative injury in rats

Abstract

: Regarding the mechanisms of methotrexate (MTX) hepatotoxicity and nephrotoxicity, several hypotheses have been put forward, among which oxidative stress (including depletion of glutathione) is likely. This investigation elucidates the role of free radicals in MTX‐induced toxicity and the protection by melatonin. Wistar albino rats were injected with MTX intraperitoneally. Following a single dose of MTX (20 mg/kg), either saline (MTX group) or melatonin (10 mg/kg, MTX + Mel group) was administered for 5 days. In other rats, physiologic saline (control group) or melatonin (10 mg/kg, Mel group) was injected for 5 days, following a single injection of saline. On the sixth day, rats were killed to obtain blood, liver, and kidney tissue samples. Malondialdehyde (MDA), an end product of lipid peroxidation, and glutathione (GSH), a key antioxidant, levels were evaluated in blood and tissue homogenates. Reactive oxygen metabolite‐induced inflammatory changes in kidney and liver tissues were evaluated by measuring myeloperoxidase (MPO) activity, an index of neutrophil infiltration. MTX administration resulted in increased MDA levels and MPO activity and decreased GSH levels in the blood, liver, and kidney whereas melatonin reversed these effects. When melatonin was administered alone, no significant changes in biochemical parameters were noted. In conclusion, the present study suggests that melatonin may be of therapeutic benefit when used with MTX.

Vitamin C attenuates methotrexate-induced oxidative stress in kidney and liver of rats

“…Although the mechanism of MTX-induced hepatorenal toxicity is not well understood, recent studies indicated the oxidative damage to be the causative factor (19). It had been shown that the cytosolic NADP-dependent dehydrogenases and NADPmalic enzymes were inhibited by MTX, suggesting that the drug could either decrease the availability of reduced NADPH in cells (12) or NADPH was used by GSH reductase to reduce an important cytosolic antioxidant, GSH. The significant reduction in GSH levels promoted by MTX could cause two results: first, in conjunction with reduced GSH levels, inactivation of reactive molecules; second, the tendency of covalent bonding with other macromolecules increases.…”

“…The involvement of oxidative stress in the cell death mechanism has been well documented in the literature. Using antioxidant molecules, which increase the synthesis of GSH against drug-induced hepatorenal injury, has become a common means to investigate the relationship between GSH and the toxic effects of MTX (12). For example, rats having increased MDA levels in blood, liver, and kidney tissues along with reduced blood GSH levels were restored to normal levels using melatonin treatment (12).…”

“…Using antioxidant molecules, which increase the synthesis of GSH against drug-induced hepatorenal injury, has become a common means to investigate the relationship between GSH and the toxic effects of MTX (12). For example, rats having increased MDA levels in blood, liver, and kidney tissues along with reduced blood GSH levels were restored to normal levels using melatonin treatment (12). Vit C has been shown to be an important antioxidant, to regenerate vitamin E (Vit E) through redox cycling and to raise intracellular GSH levels (20).…”

“…Group II: The MTX alone group received 20 mg of MTX/kg of body weight (i.p.) (Emthexate-S 5 mg 1 vial/Pharmachemie B.V./Holland) at a single dose (12). Group III: The Vit C alone group received 250 mg of Vit C/kg of body weight (1) for 3 days.…”

“…Another complication of MTX treatment is the nephrotoxicity that also seems to be related to reactive oxygen species (ROS). As the oxidative damage by ROS has been implicated in the pathogenesis of MTX toxicity (11,27), several antioxidant agents have been reported to specifically prevent hepatorenal damage following the MTX administration (12).…”