Role of Melatonin in Regulating Rat Skeletal Muscle Tissue Inflammation and Damage Following Carbon Tetrachloride Intoxication

Abstract

Carbon tetrachloride (CCl₄) is a toxic compound that causes severe oxidative stress and inflammation in skeletal muscles, resulting in structural damage, mitochondrial dysfunction, and impaired contractile function. While CD45 and melatonin (MLT) are implicated in immune modulation and antioxidative defense, their precise roles in mitigating CCl₄-induced muscle damage remain incompletely understood, warranting further investigation. This study used 24 Wistar rats divided into four groups to evaluate the effects of MLT on CCl₄-induced muscle inflammation. The first group was used as a control group, the second received only MLT (50 mg/kg), and the third group received CCl₄, while the fourth group received MLT (50 mg/kg) and CCl₄. Muscle tissues, obtained 24 h after the commencement of the experiment, were analyzed using biochemical assays for inflammatory markers, histological staining, and immunohistochemistry to assess structural and cellular changes. CCl₄ exposure significantly increased NF-κB activity, nitric oxide levels, iNOS expression, and CD45-positive immune cell infiltration in skeletal muscles, indicating heightened inflammation and oxidative stress. Pretreatment with MLT markedly reduced these inflammatory markers, restoring damaged tissue and diminishing immune cell infiltration. Histological analyses confirmed reduced inflammatory cell presence and tissue damage in MLT-treated animals, highlighting its protective effects. Melatonin demonstrates significant protective effects against CCl₄-induced skeletal muscle damage by reducing inflammation, oxidative stress, and immune cell infiltration, highlighting its potential as a therapeutic agent.

Keywords: CCl4; CD45; inflammation; nitric oxide; skeletal muscles.

Figure 1

NF-kB content in animals belonging to different groups. The data are presented as mean ± SD (n = 6). The comparison was performed using one-way ANOVA followed by Tukey’s post hoc test. *** p < 0.05 vs. control.

Figure 2

Effect of MLT on CCl₄ muscle tissue (A) nitric oxide (μmol/mg of proteins) and (B) iNOS (ng/mg of proteins) concentrations. The data are presented as mean ± SD (n = 6). The comparison was carried out using one-way ANOVA followed by Tuckey’s post hoc test, * p < 0.001, ** p < 0.01, *** p < 0.05 vs. control, ^## p < 0.01 vs. CCl₄-treated animals.

Figure 3

Effect of MLT on CCl₄ muscle tissue MPO activity. The data are presented as mean ± SD (n = 6). The comparison was carried out using one-way ANOVA followed by Tuckey’s post hoc test, * p < 0.001 vs. control, ^# p < 0.001 vs. CCl₄-treated animals.

Figure 4

Skeletal muscle tissue of rats belonging to control (A), MLT (B), CCl₄ (C,E), and MLT + CCl₄ (D,F) group stained for CD45 expression in inflammatory cells—circled (×400 and ×630 for E,F).