Protective Effect of Magnesium Deficiency on Experimental Allergic Encephalomyelitis in the Rat. ∗

Summary

Acutely magnesium deficient rats exhibit hyperemia of the skin, leukocy-tosis, eosinophilia, degranulation of mast cells and histaminuria. These changes are preventable with antihistaminic therapy. The histological lesions of more prolonged magnesium deficiency bear a resemblance to those of delayed hypersensitivity. Because of the suggestion of a hyperimmune state in magnesium deficiency, an attempt to produce experimental allergic encephalomyelitis (EAE) in magnesium deficient rats was made. The results show that, rather than enhancing the development of EAE, magnesium deficiency exerts a protective effect. Histological evidence of EAE occurred in 70% of control rats fed normal diets and in only 18% of rats started on a magnesium deficient diet at various intervals before and after injection of the encephalitogenic mixture. Furthermore, the degree of EAE in magnesium deficient rats was inversely proportional to the severity of the myopathy characteristic of magnesium deficiency. The reason for the resistance of the magnesium deficient animal to EAE remains obscure.