Withdrawal from a self-administered or non-contingent cocaine binge: differences in ultrasonic distress vocalizations in rats |
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Authors: | Nicole H Mutschler Klaus A Miczek |
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Institution: | (1) Department of Psychology, Tufts University, Medford, MA 02155, USA, US;(2) Department of Psychiatry, Tufts University, Boston, MA 02111, USA, US;(3) Department of Pharmacology, Tufts University, Boston, MA 02111, USA, US;(4) Tufts University, Research Building, 490 Boston Ave, Medford, MA 02155, USA e-mail: kmiczek@ tufts.edu, US |
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Abstract: | After termination of a self-administered cocaine “binge,” rats emit ultrasonic vocalizations (USVs) and these calls may represent
affective distress. The present study investigated whether the rates of USVs as indices of withdrawal from a period of continuous
access, depends on cocaine being self-administered versus given non-contingently. Five days after implantation of a jugular catheter, triads of rats that were
matched for housing, food-training and surgery were placed into experimental chambers. The active rats were allowed to acquire
self-administration of cocaine (0.5 mg) while the two yoked animals passively received either cocaine (0.5 mg) or saline according
to the active animal’s pattern of administration. Once the active animal responded at a stable rate over 3 days, with every
third lever press being reinforced by cocaine (FR3), it was 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 in the rate of startle-induced USVs between the active cocaine group and the
yoked saline group. However, the yoked or non-contigent cocaine rats emitted significantly higher rates of USVs immediately
after the last cocaine infusion. At the time of the peak increase in USVs, the active and yoked cocaine groups were significantly
different. For up to 5 days after unlimited cocaine access, the active and passive-cocaine groups showed an increase in USVs
response when compared to the yoked saline group. The emerging increase in USVs and their gradual decline observed after termination
of a cocaine “binge” can be interpreted as an abstinence phenomenon. The non-contingent cocaine appears to be highly aversive,
as indicated by the immediate significant increase in the rate of USVs after termination of a cocaine “binge”.
Received: 29 August 1997/Final version: 17 October 1997 |
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Keywords: | Cocaine Ultrasound Vocalization Withdrawal Non-contingent Self-administration Reinforcement Anxiety Stimulant Binge Intravenous Triads |
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