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.