Repeated Water Avoidance Stress in Rats

Repeated water avoidance (WA) stress to adult rats was conducted as described previously.^{12 (link)} The rats were placed on the glass platform in the middle of a test Plexiglas tank that was filled with water (25°C) to 1 cm below the height of the platform. The animals were maintained on the block for 1 hour daily for 10 consecutive days. This repeated WA procedure represents a potent psychological stressor.^{13 (link)} The sham control rats were placed similarly for 1 hour daily for 10 days in the container without water. In a separate study, a group of 8 rats were subcutaneously injected with WIN (2 mg/kg) consecutively for 10 days after rats were subjected to WA stress. A group of 9 WA stress rats were injected IP with capsazepine (5 mg/kg) one hour before the VMR assessment. WIN 55,212-2 and capsazepine were dissolved in 10% DMSO/5% Tween 80/85% saline and the doses were selected based on published reports.^{14 (link), 15 (link)}