MULTIPLE WITHIN-DAY CONFLICT TESTING TO DEFINE THE TIME-COURSE OF ANXIOLYTIC DRUG EFFECTS

The present article describes a method for multiple within-day conflic t testing to conduct drug treatment time course studies more efficient ly. Groups of female Sprague-Dawley rats were trained for conflict tes ting in a standard one-session/day procedure [conditioned suppression of drinking (CSD)]. In this task, thirsty rats (24 h water-restricted) drink from a tube that is electrified only when a tone is on (approxi mately 20% of the 10-min session time). In Experiment 1 it was found t hat there was no significant variation in CSD conflict behavior when s ubjects were tested at 0600, 1200, or 1800 h using the traditional pro cedure of one test/day. In Experiment 2, subjects were assigned to tre atment groups such that there were three 5-min test sessions per day a nd the test-retest interval was either 2, 4, or 6 h (centered around 1 200 h). Test-retest intervals of 6 h (i.e., tests at 0600, 1200, and 1 800 h) resulted in comparable levels of punished responding across the repeated within-day tests, whereas test-retest intervals of 2 h and, to a lesser extent 4 h, resulted in unequal within-day conflict behavi or characterized by a greater number of shocks accepted and a greater volume of water consumed during the earliest test periods each day. In another group of rats, it was determined that conflict behavior sampl ed five times/day in 3-min sessions separated by a 3-h test-retest int erval (i.e., tests at 0600, 0900, 1200, 1500, and 1800 h) also resulte d in stable conflict behavior across the various within-day test perio ds. In Experiment 3, it was found that acute IP challenges with antico nflict treatments that exhibit either a long duration of action (pheno barbital: 40 mg/kg) or a significant delay to onset in addition to a l ong duration (MK-801: 0.20 mg/kg) yielded time course data comparable to those obtained using the traditional one test/day procedure. These findings indicate that the use of multiple within-day conflict testing can greatly increase the efficiency of these procedures, particularly when drug treatment timecourse information is desired.