Correction PHARMACOLOGY Correction for “Anti-inflammatory lipoxin A4 is an endogenous allosteric enhancer of CB1 cannabinoid receptor,” by Fabricio A. Pamplona, Juliano Ferreira, Octávio Menezes de Lima, Jr., Filipe Silveira Duarte, Allisson Freire Bento, Stefânia Forner, Jardel G. Villarinho, Luigi Bellochio, Carsten T. Wotjak, Raissa Lerner, Krisztina Monory, Beat Lutz, Claudio Canetti, Isabelle Matias, João Batista Calixto, Giovanni Marsicano, Marilia Z. P. Guimarães, and Reinaldo N. Takahashi, which appeared in issue 51, December 18, 2012, of Proc Natl Acad Sci USA (109:21134–21139; first published November 12, 2012; 10.1073/ pnas.1202906109). The authors note that the author name Luigi Bellochio should instead appear as Luigi Bellocchio. The corrected author line appears below. The online version has been corrected. Fabricio A. Pamplona, Juliano Ferreira, Octávio Menezes de Lima, Jr., Filipe Silveira Duarte, Allisson Freire Bento, Stefânia Forner, Jardel G. Villarinho, Luigi Bellocchio, Carsten T. Wotjak, Raissa Lerner, Krisztina Monory, Beat Lutz, Claudio Canetti, Isabelle Matias, João Batista Calixto, Giovanni Marsicano, Marilia Z. P. Guimarães, and Reinaldo N. Takahashi www.pnas.org/cgi/doi/10.1073/pnas.1221727110 CORRECTION www.pnas.org PNAS | January 22, 2013 | vol. 110 | no. 4 | 1561 Downloaded by guest on September 26, 2021 Anti-inflammatory lipoxin A4 is an endogenous allosteric enhancer of CB1 cannabinoid receptor Fabricio A. Pamplonaa,b,1, Juliano Ferreirac, Octávio Menezes de Lima, Jr.a, Filipe Silveira Duartea, Allisson Freire Bentoa, Stefânia Fornera, Jardel G. Villarinhoc, Luigi Bellocchiod,e, Carsten T. Wotjakf, Raissa Lernerg, Krisztina Monoryg, Beat Lutzg, Claudio Canettih, Isabelle Matiasd,e, João Batista Calixtoa, Giovanni Marsicanod,e,2, Marilia Z. P. Guimarãesi,2, and Reinaldo N. Takahashia,1,2 aLaboratory of Psychopharmacology, Department of Pharmacology, Universidade Federal de Santa Catarina, 88049-900, Florianópolis, Brazil; bD’Or Institute for Research and Education, 22281-100, Rio de Janeiro, Brazil; cDepartment of Chemistry, Universidade Federal de Santa Maria, 97105-900, Santa Maria, Brazil; dInstitut National de la Santé et de la Recherche Médicale U862, NeuroCentre Magendie, Endocannabinoids and Neuroadaptation, 33077 Bordeaux, France; eU862 NeuroCentre Magendie, Group Endocannabinoids and Neuroadaptation, 33077 Bordeaux, France; fLaboratory of Neuroplasticity, Max Planck Institute of Psychiatry, D-80804 Munich, Germany; gInstitute of Physiological Chemistry, University Medical Center of the Johannes Gutenberg- University, D-55099 Mainz, Germany; hInstituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, 21941-902, Rio de Janeiro, Brazil; and iInstituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, 21941-599, Rio de Janeiro, Brazil Edited by Leslie Lars Iversen, University of Oxford, Oxford, United Kingdom, and approved October 16, 2012 (received for review February 27, 2012) Allosteric modulation of G-protein–coupled receptors represents a Two synthetic compounds, Org27596 and Org29647, enhance the key goal of current pharmacology. In particular, endogenous alloste- affinity and reduce the efficacy of CB1 agonists, suggesting the ric modulators might represent important targets of interventions existence of an allosteric binding site at CB1 receptor (9). However, aimed at maximizing therapeutic efficacy and reducing side effects the existence of endogenous allosteric cannabinoid modulators fl of drugs. Here we show that the anti-in ammatory lipid lipoxin A4 has not yet been proved. is an endogenous allosteric enhancer of the CB1 cannabinoid receptor. Synthetic and metabolic pathways of eicosanoids impact endo- Lipoxin A4 was detected in brain tissues, did not compete for the cannabinoid levels, suggesting functional relationships among 3 orthosteric binding site of the CB1 receptor (vs. H-SR141716A), and endocannabinoids, prostaglandins (10), and lipoxins (11). Lipoxin did not alter endocannabinoid metabolism (as opposed to URB597 A4 (LXA4), the most studied endogenous lipoxin (12), is largely and MAFP), but it enhanced affinity of anandamide at the CB1 re- involved in immune system regulation and is linked to resolution ceptor, thereby potentiating the effects of this endocannabinoid of inflammation (13). The metabotropic ALX receptor (also both in vitro and in vivo. In addition, lipoxin A4 displayed a CB1 called FPRL-1) is responsible for the immunological effects of receptor-dependent protective effect against β-amyloid (1–40)- LXA4 and is expressed in peripheral organs, but has negligible induced spatial memory impairment in mice. The discovery of lip- occurrence in the central nervous system (CNS) (14). Neverthe- oxins as a class of endogenous allosteric modulators of CB1 receptors less, LXA4 is released in brain tissues during ischemia (15), sug- may foster the therapeutic exploitation of the endocannabinoid sys- gesting the presence of non-ALX receptor targets in the brain. tem, in particular for the treatment of neurodegenerative disorders. Brain effects of LXA4 include modulation of slow wave sleep (16), neuronal signaling (via PKCγ) (17, 18), and plasticity (19) allosteric modulation | psychopharmacology | GPCR | inflammation | through unknown mechanisms. Interestingly, these effects are neuroprotection similar to those of the endocannabinoid AEA (20, 21). We previously showed that intracerebroventricular (i.c.v.) injections he endocannabinoid system, comprising metabotropic can- of the aspirin-triggered LXA4 (15-Epi-LXA4) induce cannabinoid- Tnabinoid receptors (CB1 and CB2), endogenous lipid ligands like catalepsy in mice, which was prevented by the CB1 antagonist (endocannabinoids), and enzymes responsible for their synthesis SR141716A and not by an ALX antagonist. Altogether, these and degradation, is a key regulator of neuronal function, being findings suggest that LXA could have CB receptor-dependent proposed as a therapeutic target for several diseases (1). Acti- 4 1 effects in the brain (22). Here we report that LXA4 not only vation of CB1 receptors reduces cAMP levels, inhibits voltage- 2+ + binds to CB1 receptors to exert cannabimimetic effects in the dependent Ca channels, and activates inward-rectifying K brain, but does so by allosterically enhancing AEA signaling. channels, resulting in reduced neuronal excitability and pre- This may have important implications for the therapeutic ex- synaptic inhibition of neurotransmitter release (1, 2). The effi- ploitation of the endocannabinoid system. cacy of endogenous CB1 agonists varies according to the nature of the molecule (3). The endocannabinoid anandamide (AEA) is Results considered a partial agonist, whereas 2-arachidonoylglycerol LXA4 Displays Cannabimimetic Effects in the Brain. The cannabinoid (2-AG) is a full agonist inducing maximal responses (4, 5). At “tetrad” represents a prototypic signature of cannabinoid effects least three other endocannabinoids are known (noladin ether, (23). Brain injection of LXA (1 pmol/5 μL, i.c.v.) induced the virodhamine, and N-arachidonoyl dopamine) (1, 2). Each endo- 4 cannabinoid has different affinities, efficacies, and sometimes distinct effects at the CB1 receptor, which could also be cell type- Author contributions: F.A.P., J.F., O.M.d.L., B.L., I.M., J.B.C., G.M., M.Z.P.G., and R.N.T. dependent (1, 2). Cannabinoids have many effects on laboratory designed research; F.A.P., J.F., F.S.D., A.F.B., S.F., J.G.V., L.B., R.L., K.M., I.M., and M.Z.P.G. animals, but the prominent ones are known as the cannabinoid performed research; C.T.W., B.L., and C.C. contributed new reagents/analytic tools; F.A.P. and tetrad: analgesia, catalepsy, hypolocomotion, and hypothermia. J.F. analyzed data; and F.A.P., G.M., and M.Z.P.G. wrote the paper. fl The selectivity of CB1 agonists may be explained by multiple The authors declare no con ict of interest. binding sites in the CB1 receptor (6), in agreement with the cur- This article is a PNAS Direct Submission. rent view of metabotropic receptors as dynamic macromolecules, See Commentary on page 20781. rather than mere on/off switches of a transduction system (7). 1To whom correspondence may be addressed. E-mail: [email protected] or Allosteric modulators bind to additional site(s) on the receptor [email protected]. influencing the affinity and/or efficacy of endogenous molecules 2G.M., M.Z.P.G., and R.N.T. contributed equally to this work. binding to the orthosteric or primary site (the orthosteric site is This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10. defined as the binding site for known endogenous ligand) (8). 1073/pnas.1202906109/-/DCSupplemental. 21134–21139 | PNAS | December 18, 2012 | vol. 109 | no. 51 www.pnas.org/cgi/doi/10.1073/pnas.1202906109 B (Fig. 3A), but not the one of 2-AG (Fig. S3A)orsignificantly of A SEE COMMENTARY CP55940 (Fig. S4). LXA4 might potentiate the effect of AEA by inhibiting endocannabinoid degradation. However, LXA4 did not alter the activity of the main AEA-degrading enzyme fatty acid amide hydrolase (FAAH; Fig. 3B), nor of the main 2-AG– degrading enzyme monoacylglycerol lipase (Fig. S3B). Consis- tently, i.c.v. administration of LXA4 did not alter brain levels of AEA (Fig. 3C) or of 2-AG (Fig. S3C). The interaction between LXA4 and AEA was further confirmed in HEK cells transfected with mouse CB1 receptors. LXA4 increased the potency of AEA in decreasing forskolin (FSK)-induced cAMP levels by ∼386 times (EC50 AEA 1,547 nM