am-36 and Inflammation

This study determined the antihyperalgesic effect of CNSB002, a sodium channel blocker with antioxidant properties given alone and in combinations with morphine in rat models of inflammatory and neuropathic pain.. Dose response curves for nonsedating doses of morphine and CNSB002 given intraperitoneally alone and together in combinations were constructed for antihyperalgesic effect using paw withdrawal from noxious heat in two rat pain models: carrageenan-induced paw inflammation and streptozotocin (STZ)-induced diabetic neuropathy.. The maximum nonsedating doses were: morphine, 3.2 mg/kg; CNSB002 10.0 mg/kg; 5.0 mg/kg CNSB002 with morphine 3.2 mg/kg in combination. The doses calculated to cause 50% reversal of hyperalgesia (ED50) were 7.54 (1.81) and 4.83 (1.54) in the carrageenan model and 44.18 (1.37) and 9.14 (1.24) in the STZ-induced neuropathy model for CNSB002 and morphine, respectively (mg/kg; mean, SEM). These values were greater than the maximum nonsedating doses. The ED50 values for morphine when given in combination with CNSB002 (5 mg/kg) were less than the maximum nonsedating dose: 0.56 (1.55) in the carrageenan model and 1.37 (1.23) in the neuropathy model (mg/kg; mean, SEM). The antinociception after morphine (3.2 mg/kg) was increased by co-administration with CNSB002 from 28.0 and 31.7% to 114.6 and 56.9% reversal of hyperalgesia in the inflammatory and neuropathic models, respectively (P < 0.01; one-way analysis of variance-significantly greater than either drug given alone).. The maximum antihyperalgesic effect achievable with nonsedating doses of morphine may be increased significantly when the drug is used in combination with CNSB002.

Topics: Amines; Analgesics, Opioid; Animals; Carrageenan; Cyclohexanecarboxylic Acids; Diabetes Mellitus, Experimental; Diabetic Nephropathies; Dose-Response Relationship, Drug; Drug Synergism; GABA Modulators; Gabapentin; gamma-Aminobutyric Acid; Inflammation; Male; Morphine; Motor Activity; Pain; Pain Measurement; Peripheral Nervous System Diseases; Piperazines; Rats; Rats, Wistar; Sodium Channel Blockers

Following transient focal stroke, rapid accumulation and activation of neutrophils in the ischaemic region is deleterious due to release of reactive oxygen species and myeloperoxidase (MPO). The purpose of this study was to examine whether AM-36, both a Na+ channel blocker and an antioxidant, afforded neuroprotection by modulating neutrophil accumulation into brain, following endothelin-1 (ET-1) induced middle cerebral artery occlusion (MCAo) in conscious rats.. AM-36 was administered at 3 and 24 h after ET-1-induced MCAo. Functional recovery was determined using grid-walking and cylinder tests. Image analysis of brain sections was used to determine infarct volume. The effect of AM-36 on neutrophil infiltration and their interaction with macrophages was examined in rats at 48 h following MCAo by both an MPO assay and double-label immunofluorescence. Blood brain barrier (BBB) breakdown was measured by the area stained by intravenous Evans Blue.. AM-36 reduced functional deficits in both tests such that no difference existed from pre-ischaemic values at 48 h. Neutrophil infiltration, assessed by MPO activity, and infarct volume were significantly reduced following AM-36 administration by 54 and 60% respectively. Similarly, immunofluorescence revealed that AM-36 reduced neutrophil infiltration by approximately 50% in selected brain regions, when compared to controls, and also modulated macrophage phagocytosis of neutrophils. Breakdown of the BBB was significantly reduced by 60% following AM-36 treatment.. These findings suggest that AM-36 can directly modulate the neutrophil inflammatory response and reduce BBB breakdown following MCAo.

Topics: Animals; Blood-Brain Barrier; Brain Ischemia; Endothelin-1; Fluorescent Antibody Technique; Inflammation; Male; Microscopy, Confocal; Neutrophils; Peroxidase; Piperazines; Rats; Rats, Long-Evans