Modulation of the endogenous opioid system after morphine self-administration and during its extinction: A study in Lewis and Fischer 344 rats
| Autor: | Sonsoles Martı́n, Nuria Del Olmo, Alejandro Higuera-Matas, Emilio Ambrosio, Pilar Sánchez-Cardoso, Miguel Miguéns, Carmen García-Lecumberri |
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| Rok vydání: | 2007 |
| Předmět: |
Male
Narcotics medicine.medical_specialty Time Factors Self Administration Tritium Extinction Psychological Cellular and Molecular Neuroscience Basal (phylogenetics) Internal medicine medicine Animals Protein Precursors Receptor In Situ Hybridization Endogenous opioid Pharmacology Analysis of Variance Behavior Animal Morphine Chemistry CPVL Brain Enkephalins Enkephalin Ala(2)-MePhe(4)-Gly(5) Rats Inbred F344 Rats Proenkephalin Endocrinology Opioid Rats Inbred Lew Anesthesia Receptors Opioid Autoradiography Self-administration medicine.drug |
| Zdroj: | Neuropharmacology. 52:931-948 |
| ISSN: | 0028-3908 |
| DOI: | 10.1016/j.neuropharm.2006.10.011 |
| Popis: | Lewis (LEW) and Fischer 344 (F344) rats show differential morphine self-administration rates. In this study, after animals of both strains self-administered morphine (1 mg/kg) or extinguished this behaviour for 3, 7 or 15 days, we measured the binding to, and functional state of μ opioid receptors (MORs) as well as proenkephalin (PENK) mRNA content in several brain regions. The results showed that in most brain areas: 1) LEW rats had less binding to MORs in basal conditions than F344 rats; 2) after morphine self-administration, either one of the strains or both (depending on the brain area) showed increased levels of binding to MORs as compared to basal groups; and 3) these binding levels in morphine self-administration animals came down in each extinction group. Moreover, F344 rats exhibited, in general, an increased functionality of MORs after morphine self-administration, as compared to basal groups, which also went down during extinction. Finally, the basal content of PENK mRNA was lower in LEW rats than in F344 rats and it decreased more after self-administration; during extinction, the levels of PENK mRNA got normalized in this strain. This differential modulation of the endogenous opioid system might be related to the different rates of morphine self-administration behavior exhibited by both inbred rat strains. |
| Databáze: | OpenAIRE |
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