Lesions of the nucleus accumbens in rats reduce opiate reward but do not alter context-specific opiate tolerance.
Bilateral electrolytic lesions of the nucleus accumbens in rats eliminated the capacity of 10 mg/kg morphine to produce a conditioned place preference (Experiment 1). However, these lesions did not alter the capacity to establish context-specific tolerance to the analgesic effects of 5 mg/kg of morphine (Experiment 2). This latter finding indicates that rats with nucleus accumbens lesions are not impaired in associating the effects of morphine with a particular location. Thus, the failure of morphine to produce a conditioned place preference in these lesioned rats probably cannot be attributed to an inability to associate the effects of morphine with a particular chamber, i.e., the initially nonpreferred chamber. Rather, morphine may fail to establish a conditioned place preference in these rats because nucleus accumbens lesions disrupt a pathway that is critical in mediating the rewarding effects of opiates.
Kelsey
J E
JE
Department of Psychology, Bates College, Lewiston, Maine 04240.
Carlezon
W A
WA
Falls
W A
WA
D000818:Animals; D001143:Arousal / Q000187:drug effects*; D001245:Association Learning / Q000187:drug effects*; D001931:Brain Mapping; D007858:Learning / Q000187:drug effects*; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009434:Neural Pathways / Q000187:drug effects; D009714:Nucleus Accumbens / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000187:drug effects*; D012686:Septal Nuclei / Q000187:drug effects*; D012931:Social Environment; D013681:Tegmentum Mesencephali / Q000187:drug effects*
D011957:Receptors, Opioid; D009020:Morphine