CB1- and CB2-cannabinoid receptor-independent lipolysis induced by WIN 55,212-2 in male rat adipocytes

• Published in: Naunyn-Schmiedeberg's archives of pharmacology 2003-11, Vol.368 (5), p.352-359
• Main Authors: Nieri, Paola, Greco, Rosamiria, Adinolfi, Barbara, Breschi, Maria Cristina, Martinotti, Enrica, Nannetti, Carla, Podestà, Adriano
• Format: Article
• Language: English
• Subjects: Adipocytes - drug effects; Adipocytes - metabolism; Amidohydrolases - biosynthesis; Animals; Benzoxazines; Epididymis - cytology; Epididymis - metabolism; Gene Expression; Glycerol - metabolism; In Vitro Techniques; Lipolysis; Male; Morpholines - chemistry; Morpholines - pharmacology; Naphthalenes - chemistry; Naphthalenes - pharmacology; Rats; Rats, Wistar; Receptor, Cannabinoid, CB1 - agonists; Receptor, Cannabinoid, CB1 - antagonists & inhibitors; Receptor, Cannabinoid, CB1 - biosynthesis; Receptor, Cannabinoid, CB2 - agonists; Receptor, Cannabinoid, CB2 - antagonists & inhibitors; Receptor, Cannabinoid, CB2 - biosynthesis; Reverse Transcriptase Polymerase Chain Reaction; Stereoisomerism
• ISSN: 0028-1298
• DOI: 10.1007/s00210-003-0831-3

The expression of genes encoding the cannabinoid CB(1) and CB(2) receptors and fatty acid amide hydrolase (FAAH) and the lipolytic activity of cannabinoid agonists were investigated in rat adipose tissue.RT-PCR studies indicated that the genes encoding CB(1) and CB(2) receptors and FAAH are not expressed in epididymal adipocytes. In functional studies, the non-selective cannabinoid receptor agonist WIN 55,212-2 concentration-dependently (0.01-30 micro M) induced glycerol release above baseline ( E(max) 96.1+/-6.2% of isoprenaline-induced lipolytic response). The selective CB(2) agonist JWH-015 (0.01-30 micro M) had no lipolytic activity while the endocannabinoid 2-arachidonoylglycerol and the stable anandamide derivative, R(+)-methanandamide had, only a weak lipolytic effect at the highest concentrations employed (10 and 30 micro M). The concentration/response relationship for WIN 55,212-2-mediated lipolytic activity, mimicked by the S(-)-enantiomer WIN 55,212-3, was shifted significantly to the right by the CB(1) antagonist AM 251 only at 10 micro M, but was not modified by the beta-adrenoceptor antagonist propranolol (1 micro M). The protein kinase inhibitor H-89, but not the two adenylyl cyclase inhibitors (+/-) N(6)- R-phenylisopropyladenosine (R-PIA, 1 micro M, a selective A(1) adenosine receptor agonist) or SQ 22,536 (50 micro M) significantly reduced the glycerol efflux induced by WIN 55,212-2. Our data suggest that the cannabinoid drug WIN 55,212-2 may exert lipolytic activity in male rat adipocytes via an intracellular mechanism, not activated by CB(1) or CB(2) receptor stimulation, significantly reversed by H-89 but not clearly linked to stimulation of adenylyl cyclase.