Early handling influences on behavioral and physiological responses during active avoidance.

The effects of early handling on behavioral and physiological responses of the rat during active avoidance learning were investigated. Handled and nonhandled males and females were run in a 2-way shuttlebox task with an unconditioned stimulus of either .5 mA or .8 mA. Animals exposed to .8 mA showed a higher corticosterone response, a shorter response latency, and increased defecation. Early handling did not affect performance of the task, however handling did alter the patterns of the plasma corticosterone response over the course of avoidance training. Handled females showed less elevation of plasma corticosterone than nonhandled females, but all females showed a decrease in corticosterone over the course of avoidance learning. All males showed the drop in corticoids if run at .5 mA shock, but only handled males showed this change at .8 mA shock.