A–B. Mean (± SEM) percent difference from saline control in free corticosterone for EC, SC, and IC rats (N = 5–6/group) at 15, 60, and 180 min following 0.5 mg/kg of amphetamine (Panel A) or 2.0 mg/kg of amphetamine (Panel B). *indicates a significant difference compared to EC rats; and # indicates a significant difference compared to SC rats; p < 0.05. Mean (±SEM) free corticosterone levels (ng/ml) at the 3 time intervals following saline for IC rats were 2.8±1.3, 2.1±0.8 and 3.5±0.6; for SC rats were 6.2±1.9, 2.6±0.6 and 2.6±0.8; and for EC rats were 9.1±1.5, 4.2±1.4 and 2.2±0.7.