1. ¹School of Psychology, University of Sydney, Sydney, Australia
2. ²Department of Pharmacology, Bosch Institute, University of Sydney, Sydney, Australia

Correspondence: Professor IS McGregor, School of Psychology, University of Sydney, Sydney, NSW 2006, Australia. E-mail: iain@psych.usyd.edu.au

Received 21 August 2007; Accepted 28 August 2007; Published online 24 September 2007.

Abstract

In contrast to drugs such as alcohol, amphetamine and cocaine, cannabis use in humans has proven difficult to model in laboratory animals. Recent breakthrough discoveries of intravenous THC self-administration in rhesus monkeys and self-administration of the synthetic cannabinoid agonist WIN 55,212-2 in rats have allowed new studies of the genetic, neural and environmental determinants of cannabis use. In the present issue of BJP, Fattore and colleagues further demonstrate genetic (strain) differences in WIN 55,212-2 self-administration in rats, with Long Evans (LE) and Lister Hooded (LH), but not Sprague–Dawley, rats self-administering this drug. They then show that female LE and LH rats self-administer more WIN 55,212-2 than male rats. Ovariectomy abolished this sex difference, suggesting a permissive role for oestrogen in cannabis reward. This accompanying Commentary reviews recent progress in animal models of cannabis use and highlights the role of genetic, developmental and endocrine factors in driving cannabis use and dependence.