Microinjection of oxytocin into limbic-mesolimbic brain structures disrupts heroin self-administration behavior: a receptor-mediated event?
The systemic injection of oxytocin (OXT) decreases the self-administration of heroin in heroin-tolerant rats. Since OXT-ergic binding sites are present in limbic and mesolimbic brain regions, the effects of intracerebral microinjections of OXT were investigated. In heroin-tolerant rats, the microinjection of OXT (2 ng) into the anterodorsal part of the nucleus accumbens or into the ventral hippocampus disrupted the self-administration of heroin. The effect of intrahippocampal microinjections lasted longer than that of intraaccumbens injections. The administration of N alpha-acetyl-(2-0-methyltyrosine)-oxytocin (ACME-OXT), an inhibitor of oxytocin receptors, prevented the disruptive effect of intrahippocampal OXT injections on heroin self-administration. It is concluded that limbic-mesolimbic brain structures have an essential role in the expression of the disruptive action of OXT on heroin self-administration. It appears that OXT-ergic binding sites mediate the effects of OXT.
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000502:physiology*; D004361:Drug Tolerance; D003932:Heroin / Q000008:administration & dosage*; D006624:Hippocampus / Q000502:physiology; D008032:Limbic System / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008845:Microinjections; D009714:Nucleus Accumbens / Q000502:physiology; D010121:Oxytocin / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011945:Receptors, Angiotensin / Q000502:physiology*; D018045:Receptors, Oxytocin; D012646:Self Administration; D012653:Self Stimulation / Q000187:drug effects*
D011945:Receptors, Angiotensin; D018045:Receptors, Oxytocin; D010121:Oxytocin; D003932:Heroin