Folic acid and melatonin ameliorate carbon tetrachloride-induced hepatic injury, oxidative stress and inflammation in rats

Abstract

This study investigated the protective effects of melatonin and folic acid against carbon tetrachloride (CCl4)-induced hepatic injury in rats. Oxidative stress, liver function, liver histopathology and serum lipid levels were evaluated. The levels of protein kinase B (Akt1), interferon gamma (IFN-γ), programmed cell death-receptor (Fas) and Tumor necrosis factor-alpha (TNF-α) mRNA expression were analyzed. CCl4 significantly elevated the levels of lipid peroxidation (MDA), cholesterol, LDL, triglycerides, bilirubin and urea. In addition, CCl4 was found to significantly suppress the activity of both catalase and glutathione (GSH) and decrease the levels of serum total protein and HDL-cholesterol. All of these parameters were restored to their normal levels by treatment with melatonin, folic acid or their combination. An improvement of the general hepatic architecture was observed in rats that were treated with the combination of melatonin and folic acid along with CCl4. Furthermore, the CCl4-induced upregulation of TNF-α and Fas mRNA expression was significantly restored by the three treatments. Melatonin, folic acid or their combination also restored the baseline levels of IFN-γ and Akt1 mRNA expression. The combination of melatonin and folic acid exhibited ability to reduce the markers of liver injury induced by CCl4 and restore the oxidative stability, the level of inflammatory cytokines, the lipid profile and the cell survival Akt1 signals.

Effects of folic acid on dyslipidemia and serum homocysteine in a rat model of cholestasis and hepatic fibrosis

“…As a result, fewer fatty acids for the production of cholesterol, triglyceride, and LDL are transported to the liver, resulting in reduced synthesis of the lipids. These results are consistent with findings from experimental models treated simultaneously with carbon tetrachloride and folic acid [26]. A reduction in serum cholesterol levels can result in a decrease in intra-hepatic circulation of bile acids and prevent production of excessive bile [37].…”

“…It has been found that leukocytes, potentially by producing pro-fibrotic mediators such as TGF-β1, affects HSCs and enhances ECM synthesis in various liver diseases [24]. Folic acid plays an important role as a potent antioxidant by scavenging free radicals and reducing oxidative stress, [25] to reduce the hepatic tissue damage in rats treated with carbon tetrachloride, [26] receiving a high-fat diet, [17] under chronic treatment with ethanol, [27] and receiving methotrexate [12]. Studies have shown that antioxidant supplements can significantly inhibit hepatic necrosis [28].…”

“…By eliminating free radicals and increasing acetaldehyde oxidation, folic acid prevents the inactivation of GSH [30]. Folic acid may act as a coenzyme for enzymes involved in the trans-sulfuration pathway and increases GSH synthesis and GSH levels [26] The lower GSH to GSSG ratio in BDL rats indicates oxidative stress [4,17]. Folic acid significantly improves this ratio by reducing the amount of oxidized glutathione and maintains the antioxidant defense in the liver [17].…”

Melatonin limits the expression of profibrogenic genes and ameliorates the progression of hepatic fibrosis in mice

“…Formation of fibrotic septa and increase in enzyme levels were impaired in animals treated with melatonin (5 and 10 mg/kg body weight), which is in line with previous reports on the effect of the pineal hormone in mice or rats with CCl 4 -induced fibrosis. [16][17][18][19][20][21][22] The critical step in the generation of liver fibrosis is the activation of HSCs resulting in a-SMA and collagen deposition. 28 The increased a-SMA expression in the livers of CCl 4 -treated mice was significantly diminished by melatonin administration, as indicated by immunohistochemical staining.…”

“…15 Using this toxinmediated model, it has been found that melatonin administration, at doses ranging from 2.5 to 20 mg/kg body weight, prevents liver histopathologic changes, reduces hepatic hydroxyproline content, inhibits oxidative stress and apoptosis, increases antioxidant enzyme levels, or reduces proinflammatory cytokine production, when administered intraperitoneally to rats or mice. [16][17][18][19][20][21][22] However, in these in vivo studies, effects of melatonin on the activation of HSCs and changes in the expression of fibrogenic factors or molecules involved in ECM degradation have not been tested. Moreover, because melatonin was always given before or in parallel to CCl 4 administration, only a preventive effect before the onset of liver toxicity was demonstrated.…”