1 Characterization of the endocannabinoid system in human spermatozoa and involvement of TRPV1 vanilloid receptor in their fertilizing ability Abbreviated title: TRPV1 and human sperm fertilizing ability Francavilla F. 1* , Battista N. 2 , Barbonetti A. 1 , Vassallo M.R.C. 1 , Rapino C. 2 , Antonangelo C. 1 , Pasquariello N. 2 , Catanzaro G. 2 , Barboni B. 2 , and Maccarrone M. 2,3* 1 Department of Internal Medicine, University of L’Aquila, 67100 L’Aquila, Italy 2 Department of Biomedical Sciences, University of Teramo, 64100 Teramo, Italy 3 European Center for Brain Research (CERC)/IRCCS S. Lucia Foundation, 00143 Rome, Italy *Corresponding authors: Prof. Felice Francavilla, Department of Internal Medicine, University of L’Aquila Blocco 11, I-67100 Coppito, L'Aquila, Italy. Tel: +39 0862 368338, Fax: +39 0862 368342 E-mail: francavi@cc.univaq.it Prof. Mauro Maccarrone, Department of Biomedical Sciences, University of Teramo Piazza A. Moro 45, I-64100 Teramo, Italy. Tel: +39 0861 266875; Fax: +39-0861-266877 E-mail: mmaccarrone@unite.it Disclosure statement: The authors have nothing to disclose Key words: Acrosome reaction, anandamide, sperm/oocyte fusion Precis: Human spermatozoa exhibit a functional endocannabinoid system related to anandamide (AEA) and AEA-binding vanilloid receptor is involved in the sperm fertilizing ability. Grant support: This investigation was partly supported by Ministero dell’Istruzione, dell'Università e della Ricerca (PRIN 2006) to FF, BB and MM, and by Fondazione TERCAS (Research Programs 2004 and 2005) to MM. Endocrinology. First published ahead of print July 16, 2009 as doi:10.1210/en.2009-0057 Copyright (C) 2009 by The Endocrine Society