Exposing asymptomatic myogenic Tg females to testosterone (T) for only 5 days induces a significant, more than 6-fold, decrease in muscle BDNF transcript levels (A) compared to either T-treated Wt controls or asymptomatic control-treated Tg females (Tg+Blank). Androgen’s effect on BDNF expression in muscle of Tg females correlates with a robust induction of motor dysfunction (B). Control treated Tg females show a small but significant deficit (< 2 fold) in muscle BDNF mRNA compared to Wt controls (Wt+Blank, dashed line, A) despite having normal motor function, suggesting that a small deficit in BDNF mRNA in asymptomatic Tg females may prime the system for rapid collapse once exposed to male levels of androgens. Error bars represent standard error of the mean. A) * indicates p<0.05 from Wt+Blank, † indicates p<0.05 from Tg+Blank. B) # p<0.05 Tg+Blank versus Tg+T.