WITHDRAWAL FROM IV COCAINE BINGES IN RATS - ULTRASONIC DISTRESS CALLSAND STARTLE

Human cocaine abusers report that they experience intense anxiety duri ng withdrawal from chronic use or ''binging''. Because the symptoms of cocaine withdrawal are not easily observed, it has been difficult to develop an adequate animal model for cocaine withdrawal that detects a nxiety-like behavior. The objective of the present study was to examin e the effects of continuous access to IV self-administered cocaine on ultrasonic vocalizations (USVs) induced by startling tactile stimuli a s a possible animal model for cocaine withdrawal. Five days after impl antation of a jugular catheter, rats were placed into self-administrat ion chambers with access to cocaine (0.25 mg/infusion). Once the anima l had a stable response rate over 3 days, on a fixed schedule of reinf orcement (FR5), they were given unlimited access to cocaine (0.25 mg/i nfusion) for 48 or 12 h. Subsequently, animals were exposed to 18 air puffs (20 or 10 psi) at 6, 24, 72 h, 7 and 14 days after the ''binge'' . Rats that self-administered cocaine for 48 h and were subsequently s tartled with 20 psi stimuli increased the number of automatically reco rded ultrasonic distress calls and showed an enhanced startle response at 6 h after the last cocaine infusion when compared to handled contr ols. Animals that self-administered cocaine for 48 h and were subseque ntly startled with 10 psi stimuli showed increased USVs and an enhance d startle reflex at both 6 and 24 h after the unlimited access. Animal s that self-administered cocaine for 12 h also showed an increase in u ltrasonic distress calls and enhanced startle responses to 10 psi tact ile stimuli when compared to handled controls. USVs during cocaine wit hdrawal may be interpreted to reflect affective distress during the fi rst 24 h after the last cocaine infusion of 12 or 48 of continuous acc ess to drug.