Improvement of experimental allergic encephalomyelitis (EAE) by thymoquinone; an oxidative stress inhibitor

Experimental Allergic Encephalomyelitis (EAE) is an autoimmune demyelinating disease of the central nervous system that is widely accepted as an animal model for the human multiple sclerosis. Oxidative stress appears to play a role in the onset and progression of EAE. We reasoned that decreasing oxidative stress might ameliorate symptoms and signs of EAE. Thymoquinone is reported to inhibit oxidative stress. One way of decreasing oxidative stress is to induce glutathione (GSH). We tested the impact of Thymoquinone (1 mg/kg, injected at tail vein) in our EAE model. We induced (EAE) in female Lewis rats using myelin basic protein emulsified with complete Freund's adjuvant. 24 animals were placed into three groups: A) Rats with EAE B) EAE rats with concomitant five day injection of Thymoquinone days 1-5, C) EAE rats with five doses of Thymoquinone injected at day 12-17. Twenty-eight days later, animals were sacrificed; spinal cord tissues collected for glutathione (GSH).

63% of animals in group "A" developed hind limb weakness and/or paralysis while 37% developed mild tail weakness, perivascular inflammation and low spinal cord GSH level. 25% of animals in group "B" exhibited mild tail and hind limb weakness and 75% animals had no symptoms, no perivascular inflammation and high spinal cord GSH level. 63% of animals of group "C" showed improving symptoms following Thymoquinone injections, no perivascular inflammation and higher GSH level while 37% of animals showed no symptoms prior and post Thymoquinone injections. Clinical symptoms correlated well with perivascular inflammation and GSH level. Animals received Thymoquinone at day 12-17 had higher GSH level, no perivascular inflammation and no symptoms compared with other groups.

Thymoquinone inhibited oxidative stress which leads into improvement in our EAE animals. Thymoquinone may have a role in treatment of Multiple Sclerosis.