Neuritin mRNA levels in axotomized hamsters (open bars) and axotomized hamsters treated with testosterone (black bars) at 6 hours and 1, 2, 4, 6, and 7 days post-axotomy. Also shown are axotomized hamsters treated with both testosterone and flutamide for 2 days following axotomy (gray bar). Neuritin mRNA levels are displayed as the percent difference between the axotomized side and the control side within each animal. Testosterone caused a dramatic increase in neuritin mRNA levels 2 days post-axotomy; however, this increase was completely prevented by flutamide treatment. Bars heights represent means (± SEM).