Opposing Control of Cannabinoid Receptor Stimulation on Amyloid--Induced Reactive Gliosis: In Vitro and in Vivo Evidence Giuseppe Esposito, Teresa Iuvone, Claudia Savani, Caterina Scuderi, Daniele De Filippis, Michele Papa, Vincenzo Di Marzo, and Luca Steardo Department of Human Physiology and Pharmacology, University of Rome “La Sapienza”, Rome, Italy (G.E., C.Sa., C.Sc. L.S.); Department of Experimental Pharmacology, University of Naples Federico II, Naples, Italy (T.I., D.D.F.); Department of Public Medicine, Second University of Naples, Naples, Italy (M.P.); and Endocannabinoid Research Group, Institute of Biomolecular Chemistry, Consiglio Nazionale delle Ricerche, Pozzuoli (Naples), Italy (V.D.M.) Received February 15, 2007; accepted May 31, 2007 ABSTRACT Beside cytotoxic mechanisms impacting on neurons, amyloid  (A)-induced astroglial activation is operative in Alzheimer’s disease brain, suggesting that persistent inflammatory re- sponse may have a role in the illness and that positive results may be achieved by curbing the astroglial reaction. Because the role of the endocannabinoid system could represent a promising field of research, the present study conducted in vitro and in vivo experiments to assess this system. C6 rat astroglioma cells were challenged with 1 g/ml A 1-42 in the presence or absence of selective agonists and antagonists of cannabinoid (CB)1 and CB2 receptors. Furthermore, rats were inoculated into the frontal cortex with 30 ng of A 1-42 and were i.p. administered with 5 mg/kg of the same substances. Immunohistochemical and biochemical findings revealed that selective agonism at CB1 and antagonism at CB2 receptors was able to blunt A-induced reactive astrogliosis with subse- quent overexpression of glial fibrillary acidic protein and S100B protein. Moreover, A provoked down-regulation of CB1 re- ceptors together with a reduction of anandamide concentra- tion, whereas CB2 receptors were up-regulated and 2-arachi- donoyl glycerol concentration was increased. Finally, to our knowledge, the current study is the first showing that interac- tions at cannabinoid receptors result in a dual regulation of A-induced reactive astrogliosis. The data support the as- sumption that compounds able to selectively block CB2 recep- tors may have therapeutic potential in controlling A-related pathology, due to their beneficial effects devoid of psycho- tropic consequences. Alzheimer’s disease (AD), the most common cause of de- mentia in the elderly, is a significant health problem and its impact is escalating as the human population ages. The characteristic and invariant lesions in brains of afflicted in- dividuals include extracellular accumulation of A fibrils in senile plaques (SP), and intraneuronal fibrillary tangles (Katzman and Saitoh, 1991). These are associated with syn- aptic dysfunction and neuronal death, especially in limbic and association cortical areas, which have roles in memory and cognitive functioning (Small et al., 2001). At present, the exact cause accounting for the sporadic cases of AD remains elusive. In the recent past, research has focused on single metabolic disorders or single gene muta- tions because of the similarities between familial and spo- radic AD. However, even if they are phenotypically similar, they seem etiologically different. Inflammation represents a consistent feature of the AD brain, and mounting evidence suggests that a neuroinflam- matory response may be implicated in disease development (Craft et al., 2006). Insoluble deposits of A protein are This work was supported by Cofin Ministero dell’Universita ` e della Ricerca Scientifica e Tecnologica 2004 (to L.S.). G.E. and T.I. equally contributed to this work. Article, publication date, and citation information can be found at http://jpet.aspetjournals.org. doi:10.1124/jpet.107.121566. ABBREVIATIONS: AD, Alzheimer’s disease; SP, senile plaque(s); 2-AG, 2-arachidonoyl glycerol; CB, cannabinoid receptor type; ECS, endocan- nabinoid system; A, amyloid-; ACEA, arachidonyl-2'-chloroethylamide; JWH-015, (2-methyl-1-propyl-1H-indol-3-yl)-1-naphthalenylmeth- anone; SR141716A, N-(piperidin-1-yl)-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3 carboxamide hydrochloride; SR144528, N-((1S)-endo-1,3,3-trimethyl bicyclo heptan-2-yl]-5-(4-chloro-3-methylphenyl)-1-(4-methylbenzyl)-pyrazole-3-carboxamide); RT-PCR, reverse transcription-polymerase chain reaction; OD, optical density; PBS, phosphate-buffered saline; GFAP, glial fibrillary acidic protein; AEA, anand- amide; PEA, palmitoylethanolamide; ctrl, control; WIN 55,212, (R)-(+)-[2,3-dihydro-5-methyl-3-(4-morpholinylmethyl)pyrrolo[1,2,3-de)-1,4-benzo- xazin-6-yl]-1-naphthalenylmethanone. 0022-3565/07/3223-1144–1152$20.00 THE JOURNAL OF PHARMACOLOGY AND EXPERIMENTAL THERAPEUTICS Vol. 322, No. 3 Copyright © 2007 by The American Society for Pharmacology and Experimental Therapeutics 121566/3240823 JPET 322:1144–1152, 2007 Printed in U.S.A. 1144 at Fac di FarmaciaUniv Studi di Napoli on February 18, 2013 jpet.aspetjournals.org Downloaded from