Pharmacological characterization of a novel cannabinoid ligand, MDA19, for treatment of neuropathic pain.
BACKGROUND
Cannabinoid receptor 2 (CB2) agonists have recently gained attention as potential therapeutic targets in the management of neuropathic pain. In this study, we characterized the pharmacological profile of the novel compound N'-[(3Z)-1-(1-hexyl)-2-oxo-1,2-dihydro-3H-indol-3-ylidene]benzohydrazide (MDA19), a CB2 agonist.


METHODS
We used radioligand binding assays and multiple in vitro functional assays at human and rat CB(1) and CB(2) receptors. The effects of MDA19 in reversing neuropathic pain were assessed in various neuropathic pain models in rats and in CB2(+/+) and CB2(-/-) mice.


RESULTS
MDA19 displayed 4-fold-higher affinity at the human CB(2) than at the human CB1 receptor (K(i) = 43.3 +/- 10.3 vs 162.4 +/- 7.6 nM) and nearly 70-fold-higher affinity at the rat CB2 than at the rat CB1 receptor (K(i) = 16.3 +/- 2.1 vs 1130 +/- 574 nM). In guanosine triphosphate (GTP)gamma[(35)S] functional assays, MDA19 behaved as an agonist at the human CB1 and CB2 receptors and at the rat CB1 receptor but as an inverse agonist at the rat CB2 receptor. In 3',5'-cyclic adenosine monophosphate (cAMP) assays, MDA19 behaved as an agonist at the rat CB1 receptor and exhibited no functional activity at the rat CB(2) receptor. In extracellular signal-regulated kinases 1 and 2 activation assays, MDA19 behaved as an agonist at the rat CB2 receptor. MDA19 attenuated tactile allodynia produced by spinal nerve ligation or paclitaxel in a dose-related manner in rats and CB2(+/+) mice but not in CB2(-/-) mice, indicating that CB2 receptors mediated the effects of MDA19. MDA19 did not affect rat locomotor activity.


CONCLUSIONS
We found that MDA19 exhibited a distinctive in vitro functional profile at rat CB2 receptors and behaved as a CB1/CB2 agonist in vivo, characteristics of a protean agonist. MDA19 has potential for alleviating neuropathic pain without producing adverse effects in the central nervous system.
Department of Anesthesiology and Perioperative Medicine, The University of Texas M. D. Anderson Cancer Center, Houston, Texas, USA.
Jijun J
JJ
Xu
Philippe
P
Diaz
Fanny
F
Astruc-Diaz
Suzanne
S
Craig
Elizandro
E
Munoz
Mohamed
M
Naguib
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D001711:Biotransformation / Q000187:drug effects; D016466:CHO Cells; D002186:Cannabinoids / Q000494:pharmacology*; D006224:Cricetinae; D003412:Cricetulus; D000242:Cyclic AMP / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006801:Humans; D006834:Hydrazines / Q000494:pharmacology*; D007211:Indoles / Q000494:pharmacology*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D017239:Paclitaxel; D010146:Pain / Q000139:chemically induced / Q000188:drug therapy* / Q000209:etiology; D010147:Pain Measurement / Q000187:drug effects; D010523:Peripheral Nervous System Diseases / Q000139:chemically induced / Q000150:complications / Q000188:drug therapy*; D051381:Rats; D017207:Rats, Sprague-Dawley; D043884:Receptor, Cannabinoid, CB1 / Q000187:drug effects / Q000235:genetics; D043885:Receptor, Cannabinoid, CB2 / Q000819:agonists* / Q000235:genetics; D013127:Spinal Nerves / Q000293:injuries
D002186:Cannabinoids; D006834:Hydrazines; D007211:Indoles; C550670:N'-((3Z)-1-(1-hexyl)-2-oxo-1,2-dihydro-3H-indol-3-ylidene)benzohydrazide; D043884:Receptor, Cannabinoid, CB1; D043885:Receptor, Cannabinoid, CB2; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D000242:Cyclic AMP; D048049:Extracellular Signal-Regulated MAP Kinases; D017239:Paclitaxel