Morphine attenuates the expression of sensitization to ethanol, but opioid antagonists do not

Morphine attenuates the expression of sensitization to ethanol, but opioid antagonists do not

Autor Abrahao, Karina Possa Autor UNIFESP Google Scholar
Quadros, I. M. Google Scholar
Souza-Formigoni, M. L. O. Autor UNIFESP Google Scholar
Instituição Universidade Federal de São Paulo (UNIFESP)
Tufts Univ
Resumo Behavioral sensitization to ethanol is characterized by an increased locomotor activity after repeated exposure. A great variability exists among species and strains in the development of sensitization. There is a growing amount of evidence to indicate that the opioid system is involved in alcoholism; it is possible, therefore, that this system also modulates the sensitization to ethanol. in this study we evaluated the role of the opioid system in determining the variability of the sensitized response to ethanol. Mice received repeated administrations of ethanol (2.2 g/kg) or saline every other day for 10 days. According to their locomotor response on the last day of treatment, ethanol-treated animals were classified into two groups: sensitized or non-sensitized mice. After the treatment, mice were submitted to four challenges 48 h apart. in experiments 1 and 2, mice were challenged, respectively, with i.p. administration of opioid antagonists (naloxone or naltrexone) or an opioid agonist (morphine), followed immediately by 2.2 g/kg ethanol. in experiment 3, animals received morphine by i.c.v., followed by 2.2 g/kg of ethanol (i.p.). Pretreatment with opioid antagonists (naloxone or naltrexone) did not block the expression of ethanol sensitization; however pretreatment with morphine attenuated the increased locomotor activity after ethanol administration in sensitized mice. in experiment 4, after the ethanol or saline treatment, mice brains were processed and brain mu opioid binding was assessed by autoradiography using [3H]D-Ala2,N-mePhe4, Gly-ol5-enkephalin ([3H]DAMGO). No differences were seen between any of the groups of mice, so the agonist effect is not likely to be mediated by differences in binding to mu opioid receptors. (C) 2008 IBRO. Published by Elsevier B.V. All rights reserved.
Palavra-chave naloxone
naltrexone
morphine
locomotor activity
mice
autoradiography
Idioma Inglês
Financiador the Associacao Fundo Incentivo a Psicofarmalogia (AFIP)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Data de publicação 2008-10-28
Publicado em Neuroscience. Oxford: Pergamon-Elsevier B.V., v. 156, n. 4, p. 857-864, 2008.
ISSN 0306-4522 (Sherpa/Romeo, fator de impacto)
Publicador Elsevier B.V.
Extensão 857-864
Fonte http://dx.doi.org/10.1016/j.neuroscience.2008.08.012
Direito de acesso Acesso restrito
Tipo Artigo
Web of Science WOS:000260596000005
Endereço permanente http://repositorio.unifesp.br/handle/11600/30972

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