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A limited role for ghrelin in heroin self-administration and food deprivation-induced reinstatement of heroin seeking in rats

Authors

  • Tia Maric,

    1. Department of Psychology, Center for Studies in Behavioral Neurobiology, Group de Recherche en neurobiologie comportementale, Concordia University, Montreal, QC, Canada
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  • Firas Sedki,

    1. Department of Psychology, Center for Studies in Behavioral Neurobiology, Group de Recherche en neurobiologie comportementale, Concordia University, Montreal, QC, Canada
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  • Benedicte Ronfard,

    1. Department of Psychology, Center for Studies in Behavioral Neurobiology, Group de Recherche en neurobiologie comportementale, Concordia University, Montreal, QC, Canada
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  • Danielle Chafetz,

    1. Department of Psychology, Center for Studies in Behavioral Neurobiology, Group de Recherche en neurobiologie comportementale, Concordia University, Montreal, QC, Canada
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  • Uri Shalev

    Corresponding author
    1. Department of Psychology, Center for Studies in Behavioral Neurobiology, Group de Recherche en neurobiologie comportementale, Concordia University, Montreal, QC, Canada
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Uri Shalev, Dept. of Psychology/CSBN, Concordia University, 7141 Sherbrooke St. W, Montreal H4B 1R6, Quebec, Canada. E-mail: uri.shalev@concordia.ca

ABSTRACT

Food deprivation (FD) or restriction augments the locomotor activating and reinforcing effects of drugs of abuse. It has been proposed that these effects might be mediated by FD-induced increase in plasma levels of ghrelin, a 28-amino acid orexigenic peptide demonstrated to functionally interact with the mesolimbic dopaminergic system. However, a role for ghrelin has been demonstrated only with psychostimulant drugs and alcohol associated behaviors. We therefore examined the role of ghrelin in ongoing heroin self-administration and FD-induced reinstatement of extinguished heroin seeking. As expected, infusions of ghrelin [0.0, 1.5 and 3.0 µg/rat, intracerebroventricular (i.c.v.)] produced increases in breakpoints on a progressive ratio schedule of heroin reinforcement. In contrast, central administration of a ghrelin receptor antagonist, [D-Lys-3]-GHRP-6 (0.0, or 20.0 µg/rat, i.c.v.) had no effect on ongoing heroin self-administration under a fixed-ratio 1 schedule, or on FD-induced reinstatement of heroin seeking. These results suggest that signals mediated through ghrelin receptors play a limited role in FD-induced augmentation of heroin reinforcement and reinstatement of extinguished heroin seeking.

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