Dihydrotestosterone as a Protective Agent in Chronic Experimental Autoimmune Encephalomyelitis

Multiple sclerosis is a chronic inflammatory disease affecting the central nervous system. As reported by clinical observations, variation in hormonal levels might alter disease susceptibility and progression. Specifically, decreased levels of testosterone in males are reported to be permissive for disease onset. Accordingly, testosterone seems to exert protective effects in experimental autoimmune encephalomyelitis (EAE). In this context, it is important to highlight that testosterone is further metabolized into 17ß-estradiol or dihydrotestosterone (DHT). In this study, we aimed to explore the protective effects of DHT treatment in EAE Dark Agouti rats (i.e. an experimental model showing a protracted relapsing EAE). Data obtained 45 days after EAE induction showed that DHT exerts a beneficial effect on clinical scores, coupled with decreased gliosis (i.e. glial fibrillary acidic protein and major histocompatibility complex of class II staining) and inflammation (i.e. translocator protein 18 kDa, interleukin-1ß, Toll-like receptor 4 and nuclear factor-κB expression) in the spinal cord. Moreover, parameters linked to oxidative stress and tissue damage, like thiobarbituric acid-reactive substance levels and Bcl-2-associated X protein expression, and to mitochondrial activity (i.e. content of mitochondrial DNA and proteins), were improved after DHT administration. This neuroactive steroid may be further metabolized into 3a- or 3ß-diol. However, assessment of the levels of these metabolites after DHT treatment seems to suggest that the protective effects observed here are due to DHT itself. Altogether, the present results indicate that DHT was effective in reducing the severity of chronic EAE and, consequently, may represent an interesting perspective for multiple sclerosis treatment.