Cannabinoid Withdrawal Syndrome Is Reduced in Pre-Proenkephalin Knock-Out Mice

This work was supported by European Commission Grant BIOMED-2/98–2227 and Fondo de Investigaciones Sanitaria Grant 99/0624 (R.M.), Dr. Esteve S.A. Laboratories, and La Fondation des Treilles, and by a grant from the Land Nordrhein-Westfalen (Innovationsprogramm Forschung) (A.Z.). We thank Eileen Briley and Miles Herkenham for their help with the receptor-binding studies.

Correspondence should be addressed to Andreas Zimmer, Department of Molecular Neurobiology, Clinic of Psychiatry, University of Bonn, Sigmund Freud Strasse 25, 53105 Bonn, Germany, E-mail:neuro{at}uni-bonn.de, or to Raphael Maldonado, Facultat de Ciéncies de la Salut i de la Vida, Universidat Pompeu Fabra, C/Dr Aiguader 80, 08003 Barcelona, Spain, E-mail: rafael.maldonado{at}cexs.upf.es.