Figure 2: Male C57BL/6J mice wheel running distance, duration, and speed under normal physiological condition (Baseline), with low circulating steroid levels (Gonadectomy), and with artificially elevated steroid levels (Replacement). White bars=sham controls; Hatched bars=testosterone during replacement period; Black bars=17ß-estradiol during replacement period; *=significantly different from sham controls and baseline treatments.