Differential basal proenkephalin gene expression in dorsal striatum and nucleus accumbens, and vulnerability to morphine self-administration in Fischer 344 and Lewis rats
| Autor: | José Antonio Crespo, Carmen García-Lecumberri, Emilio Ambrosio, Javier Corchero, Jorge Manzanares, José A. Fuentes, Sonsoles Martı́n |
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| Rok vydání: | 1999 |
| Předmět: |
Male
Narcotics medicine.medical_specialty Gene Expression Self Administration Striatum Nucleus accumbens Nucleus Accumbens Basal (phylogenetics) Internal medicine Basal ganglia medicine Animals RNA Messenger Protein Precursors Molecular Biology Behavior Animal Morphine Chemistry General Neuroscience Enkephalins Corpus Striatum Rats Inbred F344 Rats Proenkephalin Endocrinology Opioid Rats Inbred Lew Neurology (clinical) Opiate Morphine Dependence Neuroscience Developmental Biology medicine.drug |
| Zdroj: | Brain Research. 821:350-355 |
| ISSN: | 0006-8993 |
| DOI: | 10.1016/s0006-8993(99)01122-1 |
| Popis: | We have previously shown that the acquisition rate of intravenous morphine self-administration under a fixed ratio one (FR1) schedule of reinforcement was greater in Lewis (LEW) than Fischer 344 (F344) rats. The purpose of the present experiment was to examine the relative motivational properties of morphine (1 mg/kg) or food under progressive ratio (PR) schedules of reinforcement in LEW and F344 rats. In addition, by using in situ hybridization histochemistry we have measured in both strains of rats the basal level of proenkephalin (PENK) gene expression in dorsal striatum and nucleus accumbens (NAcc). The results show that LEW rats responded to significantly higher breaking points (BPs) than F344 rats for intravenous morphine self-administration. In contrast, no differences were found in BPs for food pellets. Basal PENK mRNA levels were significantly higher in the dorsal striatum and nucleus accumbens of F344 than in LEW rats. Taken together, these results reveal a strain difference in the reinforcing efficacy of morphine and in the basal PENK gene expression in brain regions involved in the reinforcing actions of opiates. These data also suggest that the strain differences in opiate self-administration behavior found in this and other studies may be related, at least in part, to differences in basal opioid activity between LEW and F344 rats. |
| Databáze: | OpenAIRE |
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