453 Neuroendocrinology Letters ISSN 0172–780X Copyright © 2001 Neuroendocrinology Letters ORIGINAL ARTICLE Cellular Localization of a Renin-like Enzyme in Leeches Michel Salzet & Martine Verger-Bocquet Laboratoire de Neuroimmunologie des Annélides, ESA CNRS 8017, SN3, IFR 17 INSERM, Université des Sciences et Technologies de Lille. 59650 Villeneuve d’Ascq, France. Correspondence to: Professor Michel Salzet, Ph.D., Directeur, Lab. Neuroimmunologie des Annélides Membre de l’Institut Universitaire de France ESA CNRS 8017, SN3; IFR17 INSERM Cité Scientifique, 59650 Villeneuve d’ascq, France; TEL: +33 3 2043 7277; FAX : 33 3 2004 1130 E-MAIL: michel.salzet@univ-lille1.fr Submitted: November 29, 2001 Accepted: December 5, 2001 Key words: Renin; nephridia; leech; immunocytochemistry Neuroendocrinology Letters 2001; 22:453–459 pii: NEL220601A05 Copyright © Neuroendocrinology Letters 2001 Abstract OBJECTIVES : The purpose of this study was to localize in leeches the renin- like enzyme previously characterized as well as the leech angiotensin-con- verting like enzyme (ACE). METHODS : Immunocytochemical as well as whole mount experiments were performed with an antibody raised against a fragment of the leech renin-like enzyme (VLWAAEKTQLDTGSS) and with anti-leech ACE. RESULTS : Anti-leech renin stains the vascular pole of the glomerulus and the afferent arteriole of the rat kidney. Immunostaining of leech sections revealed labeling in neurons and glial cells of the central nervous system (CNS), immunocytes and the nephridial canal, canaliculi and the periph- ery of the ciliated funnel, as well as the epithelium lining nephridia. Co- localization between antibodies raised against this fragment and a fragment of leech angiotensin-converting enzyme was demonstrated in neurons and glial cells of the leech CNS, as in vertebrates MAIN FINDING : Leech renin is localized in leeches like in vertebrate in the excretory system and in the nervous system. CONCLUSIONS : Our findings suggest the presence of a renin-angiotensin system involved in osmoregulation in leeches.