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

Abstract

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.

Improvement of spinal non-viral IL-10gene delivery by D-mannose as a transgene adjuvant to control chronic neuropathic pain

“…The bilateral decrease in IL-1β IR in the spinal cord upon D-mannose pretreatment supports prior work that significantly reduced bilateral IL-1β expression occurs concurrently with allodynia reversal [55,56]. Therefore, mannose pretreatment, rather than pDNA-IL-10 alone, is important in generating sufficient spinal IL-10 transgene expression to inhibit bilateral IL-1β expression and bilateral allodynia.…”

Mesoporous silica-supported lipid bilayers (protocells) for DNA cargo delivery to the spinal cord

“…The surgical procedure for chronic constriction injury (CCI) was performed identically as previously described [22–24]. Briefly, under isofluorane anesthesia (1.5–2.0% vol.…”

“…Briefly, images were obtained using an Axioscope microscope connected to a Nuance Camera 2.8 (FX) Multispectral Imaging System, (Cambridge Research and Instrumentation Inc., (CRI) Wolburn, MA) [24]. This camera contains a liquid crystal tunable filter (LCTF) capable of filtering light from 400–720 nm, and can capture a series of images of a particular tissue region at 10 nm wavelength increments.…”

Basic/Translational Development of Forthcoming Opioid- and Nonopioid-Targeted Pain Therapeutics

“…195 CB1 and CB2 selective agents intrathecally-delivered decreased facilitated states such formalin model, hyperpathia in neuropathy models and in tumor bone pain in rodents. 196–198 Cannabinoid role in pain processing is based on spinal and nociceptive neuron inhibition, although peripheral sites of action have also been identified. The use of spinal cord stimulation (SCS) in a rodent neuropathic pain model revealed long-lasting and incremental reduction of hyperalgesia mediated by endocannabinoids.…”