Multiple sclerosis (MS) is a progressive inflammatory demyelinating disease in the central nervous system (CNS). Melatonin is an effective treatment in MS patients and experimental autoimmune encephalomyelitis (EAE), a mouse model of MS. Melatonin secretion peaks at 2 AM, concomitant with the time at which the muscles are resting and the body is exerting its antioxidant activity. The current study was designed to investigate combination treatment of baclofen, a muscle relaxant drug, and melatonin in EAE mice. Results showed that melatonin (Mel) alone or in combination with baclofen (Bac + Mel) reduced clinical scores and demyelination by significantly increasing myelin oligodendrocyte glycoprotein (MOG) levels, a marker for mature oligodendrocytes, compared to EAE mice. Moreover, Mel or Bac + Mel therapy caused a significant increase in IL-4 serum levels, an anti-inflammatory cytokine, whereas IFN-γ serum levels, a pro-inflammatory cytokine, were significantly reduced. On the other hand, Mel or Bac + Mel caused a significant reduction in malondialdehyde (MDA) levels, a marker of oxidative stress, in comparison to EAE mice. In contrast, the activity of antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD) was significantly increased in Mel and Bac + Mel groups. In summary, combination therapy improved clinical scores and tend to enhance the efficiency of melatonin treatment by further promoting remyelination, decreasing inflammation, and stimulating the activity of antioxidant enzymes, which suggests that prior spasticity treatment increases the efficacy of melatonin therapy in EAE mouse model of MS. Further experimental and clinical studies are needed to ensure the beneficial role of this combination strategy.
Keywords: Baclofen; Melatonin; Multiple sclerosis; Muscle relaxant; Spasticity.