Selective mu- and kappa-opioid receptor antagonists administered into the nucleus accumbens interfere with rapid tolerance to ethanol in rats.
Psychopharmacology (Berl)
; 206(1): 85-96, 2009 Sep.
Article
em En
| MEDLINE
| ID: mdl-19506836
BACKGROUND: Previous findings have shown that intra-accumbens injection of naltrexone, a non-selective opioid antagonist, blocks the acquisition of rapid tolerance to ethanol in rats. This study investigates the effects of intra-accumbens injection of the selective mu-, delta-, and kappa-opioid antagonists, respectively, naloxonazine, naltrindole, and nor-binaltorphimine, on rapid tolerance to ethanol. METHODS: Male Wistar rats with guide cannulae directed to the shell or the core portions of the nucleus accumbens received a microinjection of naloxonazine (2-4 microg), naltrindole (2-4 microg), nor-binaltorphimine (2.5-5 microg), or vehicle. After 5 min, each group was divided in two groups that received ethanol (2.7 g/kg i.p.) or saline. Rats were then tested for motor coordination on the tilting plane apparatus. Twenty four hours later, all rats received a challenge dose of ethanol (2.7 g/kg i.p.) and were tested on the tilt plane again. RESULTS: Repeated injections of ethanol caused a reduction in motor impairment suggesting the development of tolerance. However, rats injected with 4 microg naloxonazine into either core or shell portions of the nucleus accumbens did not exhibit tolerance when challenged with ethanol on day 2. Rats treated with 5 microg nor-binaltorphimine into accumbens core plus intraperitoneal saline on day 1 showed reduced motor impairment when challenged with ethanol on day 2, suggesting cross-tolerance to ethanol. CONCLUSIONS: Taken together, our results suggests that mu-opioid receptors in both shell and core portions of the nucleus accumbens, and possibly kappa-opioid in the core, participate in the modulation of rapid tolerance to ethanol.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Receptores Opioides kappa
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Receptores Opioides mu
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Etanol
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Antagonistas de Entorpecentes
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Núcleo Accumbens
Limite:
Animals
Idioma:
En
Revista:
Psychopharmacology (Berl)
Ano de publicação:
2009
Tipo de documento:
Article
País de afiliação:
Brasil
País de publicação:
Alemanha