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In response to lipopolysaccharide (LPS), tissue resident macrophages and recruited neutrophils produce inflammatory mediators through activation of Toll-like receptor 4 (TLR4)/nuclear factor kappa B (NF-κB) signaling pathway. These mediators include inflammatory cytokines and reactive oxygen species that, in turn, sensitize nociceptors and lead to inflammatory pain. Vinpocetine is a nootropic drug widely used to treat cognitive and neurovascular disorders, and more recently its anti-inflammatory properties through inhibition of NF-κB activation have been described. In the present study, we used the intraplantar and intraperitoneal LPS stimulus in mice to investigate the effects of vinpocetine pre-treatment (3, 10, or 30 mg/kg by gavage) in hyperalgesia, leukocyte recruitment, oxidative stress, and pro-inflammatory cytokine production (TNF-α, IL-1β, and IL-33). LPS-induced NF-κB activation and cytokine production were investigated using RAW 264.7 macrophage cell in vitro . Vinpocetine (30 mg/kg) significantly reduces hyperalgesia to mechanical and thermal stimuli, and myeloperoxidase (MPO) activity (a neutrophil marker) in the plantar paw skin, and also inhibits neutrophil and mononuclear cell recruitment, superoxide anion and nitric oxide production, oxidative stress, and cytokine production (TNF-α, IL-1β and IL-33) in the peritoneal cavity. At least in part, these effects seem to be mediated by direct effects of vinpocetine on macrophages, since it inhibited the production of the same cytokines (TNF-α, IL-1β and IL-33) and the NF-κB activation in LPS-stimulated RAW 264.7 macrophages. Our results suggest that vinpocetine represents an important therapeutic approach to treat inflammation and pain induced by a gram-negative bacterial component by targeting NF-κB activation and NF-κB-related cytokine production in macrophages. [ABSTRACT FROM AUTHOR]

Vinpocetine is a safe nootropic agent used for neurological and cerebrovascular diseases. The anti-inflammatory activity of vinpocetine has been shown in cell based assays and animal models, leading to suggestions as to its utility in analgesia. However, the mechanisms regarding its efficacy in inflammatory pain treatment are still not completely understood. Herein, the analgesic effect of vinpocetine and its anti-inflammatory and antioxidant mechanisms were addressed in murine inflammatory pain models. Firstly, we investigated the protective effects of vinpocetine in overt pain-like behavior induced by acetic acid, phenyl-p-benzoquinone (PBQ) and formalin. The intraplantar injection of carrageenan was then used to induce inflammatory hyperalgesia. Mechanical and thermal hyperalgesia were evaluated using the electronic von Frey and the hot plate tests, respectively, with neutrophil recruitment to the paw assessed by a myeloperoxidase activity assay. A number of factors were assessed, both peripherally and in the spinal cord, including: antioxidant capacity, reduced glutathione (GSH) levels, superoxide anion, tumor necrosis factor alpha (TNF-α) and interleukin 1 beta (IL-1β) levels, as well as nuclear factor kappa B (NF-κB) activation. Vinpocetine inhibited the overt pain-like behavior induced by acetic acid, PBQ and formalin (at both phases), as well as the carrageenan-induced mechanical and thermal hyperalgesia and associated neutrophil recruitment. Both peripherally and in the spinal cord, vinpocetine also inhibited: antioxidant capacity and GSH depletion; increased superoxide anion; IL-1β and TNF-α levels; and NF-κB activation. As such, vinpocetine significantly reduces inflammatory pain by targeting oxidative stress, cytokine production and NF-κB activation at both peripheral and spinal cord levels. [ABSTRACT FROM AUTHOR]

Cutaneous leishmaniasis (CL) is the most common form of the leishmaniasis in humans. Ulcerative painless skin lesions are predominant clinical features of CL. Wider data indicate pain accompanies human leishmaniasis, out with areas of painless ulcerative lesions per se . In rodents, Leishmania (L.) major infection induces nociceptive behaviors that correlate with peripheral cytokine levels. However, the role of the spinal cord in pain processing after Leishmania infection has not been investigated. Balb/c mice received intraplantar (i.pl.) injection of Leishmania (L). amazonensis and hyperalgesia, edema, parasitism, and spinal cord TNFα, TNFR1 and TNFR2 mRNA expression, and NFκB activation were evaluated. The effects of intrathecal (i.t.) injection of morphine, TNFα, TNFα inhibitors (etanercept and adalimumab) and NFκB inhibitor (PDTC) were investigated. The present study demonstrates that Leishmania (L.) amazonensis infection in balb/c mice induces chronic mechanical and thermal hyperalgesia in an opioid-sensitive manner. Spinal cord TNFα mRNA expression increased in a time-dependent manner, peaking between 30 and 40 days after infection. At the peak of TNFα mRNA expression (day 30), there was a concomitant increase in TNFR1 and TNFR2 mRNA expression. TNFα i.t. injection enhanced L. (L.) amazonensis -induced hyperalgesia. Corroborating a role for TNFα in L. (L.) amazonensis -induced hyperalgesia, i.t. treatment with the TNFα inhibitors, etanercept and adalimumab inhibited the hyperalgesia. L. (L.) amazonensis also induced spinal cord activation of NFκB, and PDTC (given i.t.), also inhibited L. (L.) amazonensis -induced hyperalgesia, and spinal cord TNFα, TNFR1 and TNFR2 mRNA expression. Moreover, L. (L.) amazonensis -induced spinal cord activation of NFκB was also inhibited by etanercept and adalimumab as well as PDTC i.t. treatment. These results demonstrate that endogenous spinal cord TNFα and NFκB activation contribute to L. (L.) amazonensis -induced hyperalgesia in mice. Thus, spinal cord TNFα and NFκB are potential therapeutic targets for Leishmania infection-induced pain. [ABSTRACT FROM AUTHOR]

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by articular lesions, recruitment of inflammatory cells and increased levels of pro-inflammatory cytokine. The intra-articular administration of zymosan is an experimental model that promotes inflammatory parameters resembling RA. Therefore, this model was used to investigate the efficacy of quercetin as a treatment of articular inflammation. Treatment with quercetin dose-dependently reduced zymosan-induced hyperalgesia, articular edema and the recruitment of neutrophils to the knee joint cavity. Histological analysis confirmed that quercetin inhibited zymosan-induced arthritis. The treatment with quercetin also inhibited zymosan-induced depletion of reduced glutathione (GSH) levels, TNFα and IL-1β production, and gp91 phox , prepro-endothelin-1 (preproET-1), and cyclooxygenase-2 mRNA expression. These molecular effects of quercetin were related to the inhibition of the nuclear factor kappa-B and induction of Nuclear factor erythroid 2- related factor (Nrf2)/home oxygenase (HO-1) pathway. Thus, quercetin exerted anti-inflammatory, analgesic and antioxidant effects in experimental arthritis, suggesting quercetin is a possible candidate for arthritis treatment. [ABSTRACT FROM AUTHOR]