Nigella sativa as an anti-inflammatory and promising remyelinating agent in the cortex and hippocampus of experimental autoimmune encephalomyelitis-induced rats

Experimental autoimmune encephalomyelitis (EAE) is a well-established animal model of multiple sclerosis. This study aimed to investigate the protective and therapeutic effects of Nigella sativa (N. sativa) seeds (2.8 g/kg body weight) in EAE-induced rats. EAE-induced animals were divided into: (1) EAE-induced animals (‘‘EAE’’ group). (2) ‘‘N. sativa + EAE’’ group received a daily oral administration of N. sativa 2 weeks prior to EAE induction until the end of the experiment. (3) ‘‘EAE+ N. sativa’’ group received a daily oral administration of N. sativa after the appearance of the first clinical signs until the end of the experiment. All animals were sacrificed at the 28th day post EAE-induction. Disease pathogenesis was monitored using a daily clinical scoring, body weight, open field test, histopathological and ultrastructural examination and determination of some oxidative stress parameters in the cortex and hippocampus. N. sativa ameliorated the clinical signs and suppressed inflammation observed in EAE-induced rats. In addition, N. sativa enhanced remyelination in the hippocampus. However, protection of rats with N. sativa administered 2 weeks prior to EAE induction and its continuation until the end of the experiment resulted in a significant increase in the cortical lipid peroxide level with reference to control and ‘‘EAE’’ rats. In conclusion, N. sativa seeds could be used as a protective agent or an adjunct treatment for EAE even when the treatment started after the appearance of the first clinical signs. However, the dose and duration of N. sativa must be taken into consideration to avoid its probable pro-oxidant effect.