The ruthenium nitric oxide donor, [Ru(HEDTA)NO], inhibits acute nociception in mice by modulating oxidative stress,cytokine production and activating the cGMP/PKG/ATP-sensitive potassium channel signaling pathway

Nitric oxide plays an important role in various biological processes including antinociception. The control of its local concentration is crucial for obtaining the desired effect and can be achieved with exogenous nitric oxide-carriers such as ruthenium complexes. Therefore, we evaluated the analgesic effect and mechanism of action of the ruthenium nitric oxide donor [Ru(HEDTA)NO] focusing on the role of cytokines, oxidative stress and activation of the cyclic guanosine monophosphate/protein kinase G/ATP-sensitive potassium channel signaling pathway. It was observed that [Ru(HEDTA)NO] inhibited in a dose-dependent (1–10 mg/kg) manner the acetic acid-induced writhing response. At the dose of 1 mg/kg, [Ru(HEDTA)NO] inhibited the phenyl-p-benzoquinone-induced writhing response, and formalin- and complete Freund’s adjuvant-induced licking and flinching responses. Systemic and local treatments with [Ru(HEDTA)NO] also inhibited the carrageenin-induced mechanical hyperalgesia and increase of myeloperoxidase activity in paw skin samples. Mechanistically, [Ru(HEDTA)NO] inhibited carrageenin-induced production of the hyperalgesic cytokines tumor necrosis factor-α and interleukin-1β, and decrease of reduced glutathione levels. Furthermore, the inhibitory effect of [Ru(HEDTA)NO] in the carrageenin-induced hyperalgesia and myeloperoxidase activity was prevented by the treatment with ODQ (soluble guanylyl cyclase inhibitor), KT5823 (protein kinase G inhibitor) and glybenclamide (ATP-sensitive potassium channel inhibitor), indicating that [Ru(HEDTA)NO] inhibits inflammatory hyperalgesia by activating the cyclic guanosine monophosphate/protein kinase G/ATP-sensitive potassium channel signaling pathway, respectively. These results demonstrate that [Ru(HEDTA)NO] exerts its analgesic effect in inflammation by inhibiting pro-nociceptive cytokine production, oxidative imbalance and activation of the nitric oxide/cyclic guanosine monophosphate/protein kinase G/ATP-sensitive potassium channel signaling pathway in mice.     

Quercetin reduces neutrophil recruitment induced by CXCL8, LTB4, and fMLP: inhibition of actin polymerization

Recent in vitro data have suggested that the flavonoid quercetin (1) does not affect the functioning of neutrophils. Therefore, we evaluated in vivo and in vitro whether or not 1 affects neutrophil function, focusing on recruitment. The in vivo treatment with 1 inhibited in a dose-dependent manner the recruitment of neutrophils to the peritoneal cavity of mice induced by known chemotatic factors such as CXCL1, CXCL5, LTB(4), and fMLP. Furthermore, 1 also inhibited in a concentration-dependent manner the chemoattraction of human neutrophils induced by CXCL8, LTB(4), and fMLP in a Boyden chamber. In vitro treatment with 1 did not affect human neutrophil surface expression of CXCR1, CXCR2, BLT1, or FLPR1, but rather reduced actin polymerization. These results suggest that 1 inhibits actin polymerization, hence, explaining the inhibition of neutrophil recruitment in vivo and in vitro and highlighting its possible usefulness to diminish excessive neutrophil migration during inflammation.     

Probucol attenuates overt pain-like behavior and carrageenan-induced inflammatory hyperalgesia and leukocyte recruitment by inhibiting NF-кB activation and cytokine production without antioxidant effects

Objective and design

This study aimed to evaluate the effect of probucol in inflammatory hyperalgesia and leukocyte recruitment in mice.

Treatment

Probucol at 0.3–3 mg/kg was administrated per oral 1 h before inflammatory stimulus.Author: Kindly check and confirm the affiliation 1 have been correctly processed or not and amend if necessary.Thank you. We have corrected affiliation 1. We added the information to the appropriate boxes. However the state and the postal code are in a different order when compared to the other affiliations.

Methods

Overt pain-like behaviors were determined by the number of abdominal writhings induced by phenyl-p-benzoquinone and acetic acid. Mechanical and thermal hyperalgesia induced by carrageenan were determined using an electronic anesthesiometer and hot plate apparatus, respectively. Leukocyte recruitment was evaluated by direct count or by determination of myeloperoxidase and N-acetylglucosaminidase activities. Antioxidant ability was determined by measurement of GSH levels, ABTS and FRAP assays. Cytokine production and NF-кB activation were evaluated by ELISA. Data were analyzed by ANOVA followed by Tukey’s post-hoc. p?<?0.05 was considered significant.

Results

Probucol reduced overt pain-like behavior, and carrageenan-induced mechanical and thermal hyperalgesia. These effects were accompanied by reduced leukocyte influx in both paw skin and peritoneum exudate. Probucol did not alter carrageenan-induced tissue antioxidant capacity at anti-inflammatory/analgesic dose. On the other hand, probucol inhibited carrageenan-induced IL-1β, TNF-α and CXCL1 production as well as NF-кB activation.

Conclusion

Probucol presents analgesic and anti-inflammatory activities by employing mechanisms other than its antioxidant properties. These mechanisms involve targeting of pro-inflammatory cytokines and NF-кB activation.

     

IL-33 enhances macrophage release of IL-1β and promotes pain and inflammation in gouty arthritis

Inflammation Research - To investigate the role of IL-33 in gouty arthritis. 174 Balb/c (wild-type) and 54 ST2?/? mice were used in this study. In vitro experiments were conducted in...     

Pyrrolidine dithiocarbamate inhibits superoxide anion-induced pain and inflammation in the paw skin and spinal cord by targeting NF-κB and oxidative stress

We evaluated the effect of pyrrolidine dithiocarbamate (PDTC) in superoxide anion-induced inflammatory pain. Male Swiss mice were treated with PDTC and stimulated with an intraplantar or intraperitoneal injection of potassium superoxide, a superoxide anion donor. Subcutaneous PDTC treatment attenuated mechanical hyperalgesia, thermal hyperalgesia, paw oedema and leukocyte recruitment (neutrophils and macrophages). Intraplantar injection of superoxide anion activated NF-κB and increased cytokine production (IL-1β, TNF-α and IL-10) and oxidative stress (nitrite and lipid peroxidation levels) at the primary inflammatory foci and in the spinal cord (L4–L6). PDTC treatment inhibited superoxide anion-induced NF-κB activation, cytokine production and oxidative stress in the paw and spinal cord. Furthermore, intrathecal administration of PDTC successfully inhibited superoxide anion-induced mechanical hyperalgesia, thermal hyperalgesia and inflammatory response in peripheral foci (paw). These results suggest that peripheral stimulus with superoxide anion activates the local and spinal cord oxidative- and NF-κB-dependent inflammatory nociceptive mechanisms. PDTC targets these events, therefore, inhibiting superoxide anion-induced inflammatory pain in mice.     

Quercetin inhibits gout arthritis in mice: induction of an opioid-dependent regulation of inflammasome

We investigated the anti-inflammatory and analgesic effects of quercetin in monosodium urate crystals (MSU)-induced gout arthritis, and the sensitivity of quercetin effects to naloxone, an opioid receptor antagonist. Mice were treated with quercetin, and mechanical hyperalgesia was assessed at 1–24 h after MSU injection. In vivo, leukocyte recruitment, cytokine levels, oxidative stress, NFκB activation, and gp91^phox and inflammasome components (NLRP3, ASC, Pro-caspase-1, and Pro-IL-1β) mRNA expression by qPCR were determined in the knee joints at 24 h after MSU injection. Inflammasome activation was determined, in vitro, in lipopolysaccharide-primed macrophages challenged with MSU. Quercetin inhibited MSU-induced mechanical hyperalgesia, leukocyte recruitment, TNFα and IL-1β production, superoxide anion production, inflammasome activation, decrease of antioxidants levels, NFκB activation, and inflammasome components mRNA expression. Naloxone pre-treatment prevented all the inhibitory effects of quercetin over MSU-induced gout arthritis. These results demonstrate that quercetin exerts analgesic and anti-inflammatory effect in the MSU-induced arthritis in a naloxone-sensitive manner.