NICOTINE-INDUCED EXPRESSION OF NURR1 IN THE VENTRAL TEGMENTAL AREA OF THE RAT

PASTOR VERONICA; ANDRES MARIA ESTELA; BERNABEU RAMON OSCAR

Universidad Católica de Chile, Santiago de Chile, Chile

Workshop; INTERNATIONAL WORKSHOP Motivated behavior, stress and addiction: from molecules to behavior; 2009

The transcription factor Nurr1, a member of the NGFI-B family of nuclear orphan receptors, is highly expressed in rodent midbrain dopamine neurons and is essential for their phenotypic development. There are several lines of evidence indicating that nicotine produces behavioral effects via actions on the mesoaccumbens dopamine system, but little is known about the role of Nurr1 in the ability of nicotine to impact behavior. In this study, we investigated the relationship between nicotine-induced reward and the expression of Nurr1 in ventral tegmental area (VTA). Another aim of this study was to evaluate the levels of Nurr1 in rats with different locomotor responses to acute nicotine administration. Adolescent male Sprague-Dawley rats were studied in a conditioning place preference (CPP) paradigm with nicotine (0.4 mg/kg s.c.). In addition, we measured locomotor activity of another group of rats after a single injection of the same dose of the drug. Expression of Nurr1 protein was evaluated by using immunohistochemistry. During nicotine reward, an increase of Nurr1 expression occurs in VTA. Furthermore, we observed that nicotine induced an increase on Nurr1 expression in the VTA of locomotor responders to a single injection of the drug, but not in non-responders animals. These findings suggest that Nurr1 may be involved in mechanisms underlying nicotine reward. Additionally, these results indicate that an increased expression of Nurr1 in VTA accompany nicotine-induced locomotor activity.