Acamprosate suppresses the expression of morphine-induced sensitization in rats but does not affect heroin self-administration or relapse induced by heroin or stress |
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Authors: | R Spanagel Inge Sillaber Walter Zieglgänsberger William A Corrigall Jane Stewart Yavin Shaham |
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Affiliation: | (1) Max Planck Institute of Psychiatry, Kraepelinstrasse 2-10, D-8084 Munich, Germany, DE;(2) Addiction Research Foundation and University of Toronto, Toronto, Canada e-mail: spanagel@mpipsykl.mpg.de, Fax: +49-89-306 22569, CA;(3) Center for Studies in Behavioral Neurobiology, Concordia University, Montreal, Canada, CA |
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Abstract: | Acamprosate (calcium-acetyl homotaurinate) is a new compound used in the treatment of alcohol abuse. Because of the putative
link between alcoholism and the endogenous opioid systems in both humans and laboratory animals, we tested in rats the effects
of acamprosate on behavioral and neurochemical effects of opioid drugs related to their abuse potential. These included sensitization
to the behavioral effects of morphine, morphine-induced dopamine (DA) release in the nucleus accumbens (NAS), intravenous
(IV) heroin self-administration and relapse to heroin seeking in drug-free rats. In experiment 1, rats were injected daily
with either morphine (10 mg/kg, SC) or saline for 14 days. Three days later in a test for the expression of sensitization,
an injection of morphine (10 mg/kg) resulted in increased locomotor activity and enhanced DA release in the NAS in rats previously
exposed to morphine. Acamprosate (two injections of 200 mg/kg; 12 h apart; IP) suppressed the expression of the sensitized
responses, but did not alter the effects of morphine in drug-naive control rats. In experiment 2, it was found that acamprosate
(two injections of 50–200 mg/ kg; IP) had no consistent effects on IV heroin self-administration (50–100 μg/kg per infusion)
and, in experiment 3, that acamprosate (100–200 mg/ kg, IP) did not alter reinstatement of drug seeking induced by priming
injections of heroin (0.25 mg/kg, SC) or a footshock stressor (15 min; 0.5 mA) after a 5- to 8-day period of extinction. Thus,
although acamprosate attenuated the expression of sensitized locomotor activity and DA release in the NAS, it did not have
any consistent effect on either the intake of heroin during the maintenance phase or the relapse to heroin seeking in a drug-free
state. Thus, to the extent that the self-administration and the reinstatement procedures provide valid preclinical models
for drug use and relapse in humans, our data suggest that acamprosate may not be effective in altering drug-taking behavior
in heroin users.
Received: 4 November 1997/Final version: 25 January 1998 |
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Keywords: | Acamprosate Dopamine Heroin self-administration Nucleus accumbens Reinstatement Relapse Sensitization Stress |
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