WITHDRAWAL FROM A SELF-ADMINISTERED OR NONCONTINGENT COCAINE BINGE - DIFFERENCES IN ULTRASONIC DISTRESS VOCALIZATIONS IN RATS

After termination of a self-administered cocaine ''binge,'' rats emit ultrasonic vocalizations (USVs) and these calls may represent affectiv e distress. The present study investigated whether the rates of USVs a s indices of withdrawal from a period of continuous access, depends on cocaine being self-administered versus given non-contingently. Five d ays after implantation of jugular catheter, triads of rats that were m atched for housing, food-training and surgery were placed into experim ental chambers. The active rats were allowed to acquire self-administr ation of cocaine (0.5 mg) while the two yoked animals passively receiv ed either cocaine (0.5 mg) or saline according to the active animal's pattern of administration. Once the active animal responded at a stabl e rate over 3 days, with every third lever press being reinforced by c ocaine (FR3), it Tvas allowed free access to cocaine (0.5 mg) for 16 h , Subsequently, all animals were exposed to 18 air puffs (10 psi) at 0 , or 1, 3, 5, 7 and 14 days after the ''binge''. Immediately following the binge, there was no significant difference ill the rate of startl e-induced USVs between the active cocaine group and the yoked saline g roup. However, the yoked or non-contigent cocaine rats emitted signifi cantly higher rates of USVs immediately after the last cocaine infusio n. At the time of the peak increase ill USVs, the active and yoked coc aine groups were significantly different. For Lip to 5 days after unli mited cocaine access, the active and passive sive-cocaine groups showe d an increase in USVs response when compared to the yoked saline group . The emerging increase in USVs and their gradual decline observed aft er termination of a cocaine ''binge'' can be interpreted as an abstine nce phenomenon. The non-contingent cocaine appears to be highly aversi ve, as indicated by the immediate significant increase in the rate of USVs after termination of a cocaine ''binge''.