Immunofluorescent spectral analysis reveals the intrathecal cannabinoid agonist, AM1241, produces spinal anti-inflammatory cytokine responses in neuropathic rats exhibiting relief from allodynia

During pathological pain, the actions of the endocannabinoid system, including the cannabinoid 2 receptor (CB2R), leads to effective anti-allodynia and modifies a variety of spinal microglial and astrocyte responses. Here, following spinal administration of the CB2R compound, AM1241, we examined immunoreactive alterations in markers for activated p38 mitogen-activated protein kinase, interleukin-1β (IL-1β), the anti-inflammatory cytokine, interleukin-10 (IL-10) as well as degradative endocannabinoid enzymes, and markers for altered glial responses in neuropathic rats. In these studies, the dorsal horn of the spinal cord and dorsal root ganglia were examined. AM1241 produced profound anti-allodynia with corresponding immunoreactive levels of p38 mitogen-activated kinase, IL-1β, IL-10, the endocannabinoid enzyme monoacylglycerol lipase, and astrocyte activation markers that were similar to nonneuropathic controls. In contrast, spinal AM1241 did not suppress the increased microglial responses observed in neuropathic rats. The differences in fluorescent markers were determined within discrete anatomical regions by applying spectral analysis methods, which virtually eliminated nonspecific signal during the quantification of specific immunofluorescent intensity. These data reveal expression profiles that support the actions of intrathecal AM1241 control pathological pain through anti-inflammatory mechanisms by modulating critical glial factors, and additionally decrease expression levels of endocannabinoid degradative enzymes

Novel Electrophilic and Photoaffinity Covalent Probes for Mapping the Cannabinoid 1 Receptor Allosteric Site(s)

ACKNOWLEDGMENTS The work was supported by National Institutes of Health grants DA027113 and EY024717 to G.A.T. and DA09158 to A.M. A portion of this work was submitted in 2011 by A. Kulkarni in partial fulfillment of M.S. degree requirements from Northeastern University, Boston, MA.Peer reviewedPublisher PD

Improved cyclobutyl nabilone analogs as potent CB1 receptor agonists

In earlier work, we explored the SAR for the C3 side chain pharmacophore in the hexahydrocannabinol template represented by the drug nabilone, which resulted in the development of AM2389. In an effort for further optimization, we have merged features of nabilone and AM2389 and explored the C3 side chain with varying chain lengths and terminal substitutions. Of the compounds described here, a nabilone analog, AM8936, with the C6′-cyano-substituted side chain, was identified as the most successful analog capable of serving as a potential candidate for further development and a valuable tool for further in vivo studies. AM8936 behaved as a balanced and potent CB1 agonist in functional assays and was a potent and efficacious CB1 agonist in vivo. Our SAR studies are highlighted with the docking of AM8936 on the crystal structure of the hCB1 receptor. © 202

Activation of CB(2) cannabinoid receptors by AM1241 inhibits experimental neuropathic pain: Pain inhibition by receptors not present in the CNS

We designed AM1241, a selective CB(2) cannabinoid receptor agonist, and used it to test the hypothesis that CB(2) receptor activation would reverse the sensory hypersensitivity observed in neuropathic pain states. AM1241 exhibits high affinity and selectivity for CB(2) receptors. It also exhibits high potency in vivo. AM1241 dose-dependently reversed tactile and thermal hypersensitivity produced by ligation of the L5 and L6 spinal nerves in rats. These effects were selectively antagonized by a CB(2) but not by a CB(1) receptor antagonist, suggesting that they were produced by actions of AM1241 at CB(2) receptors. AM1241 was also active in blocking spinal nerve ligation-induced tactile and thermal hypersensitivity in mice lacking CB(1) receptors (CB(1)(-/-) mice), confirming that AM1241 reverses sensory hypersensitivity independent of actions at CB(1) receptors. These findings demonstrate a mechanism leading to the inhibition of pain, one that targets receptors localized exclusively outside the CNS. Further, they suggest the potential use of CB(2) receptor-selective agonists for treatment of human neuropathic pain, a condition currently without consistently effective therapies. CB(2) receptor-selective agonist medications are predicted to be without the CNS side effects that limit the effectiveness of currently available medications