1. ¹Laboratory of the Biology of Addictive Diseases, The Rockefeller University, New York, NY, USA
2. ²Department of Psychology, University of Guelph, Guelph, ON, Canada

Correspondence: Dr Y Zhou, Laboratory of the Biology of Addictive Diseases, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA. Tel: +1 212 327 8248; Fax: +1 212 327 8574; E-mail: yan.zhou@rockefeller.edu

³These authors contributed equally to this work.

Received 20 November 2006; Revised 6 March 2007; Accepted 9 March 2007; Published online 18 April 2007.

Abstract

A previous study has shown that the stress responsive neurohormone arginine vasopressin (AVP) is activated in the amygdala during early withdrawal from cocaine. The present studies were undertaken to determine whether (1) AVP mRNA levels in the amygdala or hypothalamus, as well as hypothalamic–pituitary–adrenal (HPA) activity, would be altered during chronic intermittent escalating heroin administration (10 days; 7.5–60 mg/kg/day) or during early (12 h) and late (10 days) spontaneous withdrawal; (2) foot shock stress would alter AVP mRNA levels in the amygdala or hypothalamus in rats withdrawn from heroin self-administration (7 days, 3 h/day, 0.05 mg/kg/infusion); and (3) the selective V1b receptor antagonist SSR149415 (1 and 30 mg/kg, intraperitoneal) would alter heroin seeking during tests of reinstatement induced by foot shock stress and by heroin primes (0.25 mg/kg), as well as HPA hormonal responses to foot shock. We found that AVP mRNA levels were increased during early spontaneous withdrawal in the amygdala only. This amygdalar AVP mRNA increase was no longer observed at the later stage of heroin withdrawal. Foot shock stress increased AVP mRNA levels in the amygdala of rats withdrawn from heroin self-administration, but not in heroin naïve rats. Behaviorally, SSR149415 dose-dependently attenuated foot shock-induced reinstatement and blocked heroin-induced reinstatement. Finally, SSR149415 blunted the HPA activation by foot shock. Together, these data in rats suggest that stress responsive AVP/V1b receptor systems (including the amygdala) may be critical components of the neural circuitry underlying the aversive emotional consequences of drug withdrawal, as well as the effect of negative emotional states on drug-seeking behavior.