A heroin-, but not a cocaine expecting, self-administration state preferentially alters brain endogenous peptides
1999 (English)In: European Journal of Pharmacology, ISSN 0014-2999, E-ISSN 1879-0712, Vol. 365, no 2-3, 175-182 p.Article in journal (Refereed) Published
The purpose of the current study was to assess neuropeptidergic alterations during a phase of the drug addiction cycle associated with drug craving as compared to a time period when the drug had been recently self-administered. Male Wistar rats were allowed to self-administer cocaine, heroin or saline for 6 h for 5 consecutive days. Immediately following the last self-administration session ('acute drug on board' state), and just before the next scheduled session ('drug expecting' state), the animals were decapitated and the levels of dynorphin A and B, [Met5]- and [Leu5]-enkephalin and substance P were measured in different brain areas. During the 'acute drug on board' state, peptide levels in animals that self-administered heroin or cocaine were not significantly changed. In contrast, during the 'drug expecting' state, heroin-treated animals had increased levels of dynorphin A, dynorphin B and [Met5]-enkephalin in the caudal striatum as compared to the cocaine- and saline-treated animals, and the level of [Leu5]-enkephalin was increased as compared to the cocaine-treated group. In the septum, an increase of [Met5]-enkephalin and substance P was observed in the animals expecting heroin as compared to the saline- and/or cocaine-treated animals. In the caudal striatum, substance P levels were elevated in the heroin- and cocaine-expecting animals. In conclusion, heroin, as compared to cocaine, appears to have a more pronounced effect on dynorphin, enkephalin and substance P levels in the caudal striatum and septum, especially during periods when self-administration of the drug is expected.
Place, publisher, year, edition, pages
1999. Vol. 365, no 2-3, 175-182 p.
craving, dynorphin, enkephalin, self-administration, substance P, withdrawal
Medical and Health Sciences Pharmaceutical Sciences
IdentifiersURN: urn:nbn:se:uu:diva-50737DOI: 10.1016/S0014-2999(98)00874-7ISI: 000078253900007PubMedID: 9988100OAI: oai:DiVA.org:uu-50737DiVA: diva2:78646