The androgen receptor has been purified in the ‘70s and cloned in the ‘80s. It is a member of the steroid receptor superfamily and mediated the most important effects of androgen in androgen dependent or sensitive tissues. Several physiological function of the brain are differentially controlled in the two sexes and androgens play specific role in the processes of sexual differentiation and it is involved in the maintenance of male sex behaviour in adulthood. When mutated, the androgen receptor may impact on many of these androgen-regulated activities because of a loss of androgenic function in target cells. However, in the case of a peculiar type of mutation, the elongation of the polyglutamine tract normally present in its N-terminus, the androgen receptor becomes neurotoxic and induces cells death of a number of motoneurons in the spinal cord, which express very high level of this protein. Here, we will briefly discuss the most important actions of androgen receptor-mediated androgen activity in the brain and the mechanisms by which the mutant androgen receptor may lead to neurodegeneration in Spinal and Bulbar Muscular Atrophy (SBMA).
THE PHYSIOPATHOLOGICAL ROLES OF ANDROGENS IN MOTONEURONS