Changes in c-fos expression in the rat heart during morphine withdrawal. Involvement of alpha2-adrenoceptors

Naunyn-Schmiedeberg's Archives of Pharmacology
A González-CuelloM Luisa Laorden

Abstract

We previously demonstrated an increase in Fos expression in the heart during morphine withdrawal. In the present study we examined the role of beta- and alpha-adrenoceptors in naloxone-precipitated increases in Fos expression in the heart. Dependence on morphine was induced by 7-day chronic subcutaneous implantation of six morphine pellets (75 mg). Morphine withdrawal was precipitated by administration of naloxone (5 mg/kg subcutaneously) on day 8. Using immunohistochemical staining of Fos, the present results indicate that morphine withdrawal induced marked Fos immunoreactivity (Fos-IR) within the cardiomyocyte nuclei. Moreover, Western blot analysis revealed a peak expression of c-fos in the right and left ventricles after naloxone-precipitated withdrawal in parallel with an increase in noradrenaline (NA) turnover. In the second study, the effects of the administration of adrenoceptor antagonists on withdrawal-induced Fos expression in the heart were studied. Pretreatment with the beta antagonist, propranolol (3 mg/kg intraperitoneally) or alpha1-adrenoceptor antagonist, prazosin (1 mg/kg intraperitoneally) did not block the marked Fos-IR or the hyperactivity of catecholaminergic neurons observed in the heart during withdrawa...Continue Reading

Citations

Oct 4, 2008·Cerebral Cortex·Li-Feng QiuZhi-Qi Xiong
Feb 14, 2006·Naunyn-Schmiedeberg's Archives of Pharmacology·Pilar AlmelaM Luisa Laorden
Jul 26, 2005·Peptides·Richard J Bodnar, Gad E Klein

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