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Oral squamous cell carcinoma (OSCC) presents significant treatment challenges due to its poor survival and intense pain at the primary cancer site. Cancer pain is debilitating, contributes to diminished quality of life, and causes opioid tolerance. The stimulator of interferon genes (STING) agonism has been investigated as an anti-cancer strategy. We have developed STINGel, an extended-release formulation that prolongs the availability of STING agonists, which has demonstrated an enhanced anti-tumor effect in OSCC compared to STING agonist injection. This study investigates the impact of intra-tumoral STINGel on OSCC-induced pain using two separate OSCC models and nociceptive behavioral assays. Intra-tumoral STINGel significantly reduced mechanical allodynia in the orofacial cancer model and alleviated thermal and mechanical hyperalgesia in the hind paw model. To determine the cellular signaling cascade contributing to the antinociceptive effect, we performed an in-depth analysis of immune cell populations via single-cell RNA-seq. We demonstrated an increase in M1-like macrophages and N1-like neutrophils after STINGel treatment. The identified regulatory pathways controlled immune response activation, myeloid cell differentiation, and cytoplasmic translation. Functional pathway analysis demonstrated the suppression of translation at neuron synapses and the negative regulation of neuron projection development in M2-like macrophages after STINGel treatment. Importantly, STINGel treatment upregulated TGF-β pathway signaling between various cell populations and peripheral nervous system (PNS) macrophages and enhanced TGF-β signaling within the PNS itself. Overall, this study sheds light on the mechanisms underlying STINGel-mediated antinociception and anti-tumorigenic impact. [ABSTRACT FROM AUTHOR]

Clinically, neuropathic pain treatment remains a challenging issue because the major therapy, centred around pharmacological intervention, is not satisfactory enough to patient by reason of low effectiveness and more adverse reaction. Therefore, it is still necessary to find more effective and safe therapy to ameliorate neuropathic pain. The purpose of this study was to explore the antinociceptive effect of Echinacoside (ECH), an active compound of Cistanche deserticola Ma, on peripheral neuropathic pain induced by chronic constriction injury (CCI) in mice, and to demonstrate its potential mechanism in vivo and vitro. In the present study, results showed that intraperitoneal administration of ECH (50, 100, and 200 mg/kg) could alleviate mechanical allodynia, cold allodynia and thermal hyperalgesia via behavioural test. Moreover, the structure and function of injured sciatic nerve by CCI were taken a turn for the better to a certain extent after ECH treatment using histopathological and electrophysiological test. Furthermore, ECH repressed the expression of the P2X7R and FKN and reduced the expression and release of the IL-1β, IL-6 and TNF-α. Besides, ECH could decrease Ca2+ influx and Cats efflux and inhibit phosphorylation of p38MAPK. To sum up, the present study illustrated that ECH could alleviate peripheral neuropathic pain by inhibiting microglia overactivation and inflammation through P2X7R/FKN/CX3CR1 signalling pathway in spinal cord. This study would provide a new perspective and strategy for the pharmacological treatment on neuropathic pain.

The new synthetic anti-inflammatory agent, 4-(5'-dimethylamino)-naphthalenesulfonyl-2(3H)-benzoxazolone (W3D), has demonstrated definite biological activity both in vitro and in vivo. In this study, we investigated the antinociceptive effects of W3D on various animal pain models. Our results showed that W3D, at doses of 12.5 and 25 mg/kg, significantly reduced acetic acidinduced mice writhing by 65.9% and inhibited the pain response in the second phase of formalin-induced pain from 167.75 ± 6.76 s to 97.25 ±9.63 s. Moreover, W3D prolonged the latent period on the tail-immersion test, which was stronger than the positive drug, aspirin (50 mg/kg). However, W3D did not show analgesic activity on the hot plate test, indicating no central pain response. Furthermore, the antinociceptive effects of W3D were not antagonized by naloxone, EGTA, CaCl2, and reserpine. However, LArginine was able to reverse the antinociceptive effect, indicating that W3D's antinociceptive effect does not depend on opioid receptors, Ca2+ concentration, or monoamine content. Instead, it is closely associated with nitric oxide (NO) content. In addition, W3D was found to alleviate nocifensive behavior and improve brain histopathology by inhibiting NO, inducible nitric oxide synthase (iNOS), and calcitonin gene-related peptide in nitroglycerin-induced migraine mice, with more than 50% inhibition ratio at only 12.5 mg/kg orally. However, noradrenaline, dopamine, and 5-hydroxytryptamine levels were not significantly altered after treatment with W3D. In conclusion, the presented data suggest that W3D can be considered a new non-steroidal anti-inflammatory and antinociceptive agent for the treatment of peripheral pain and migraine mediated by NO and iNOS. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the antinociceptive effect of Asplenium nidus ethanolic extract (ANEE) using a Caenorhabditis elegans model. Methods: Sublethality assay was performed on ANEE to determine the experimental concentrations to be used for the antinociceptive assays. Antinociceptive effect of ANEE in C. elegans was investigated using mechanosensation assays in four treatment timepoints within 72 hours. Antinociceptive index (AI) was calculated for the cells treated with ANEE cells as well as morphine, paracetamol and control (!% DMSO). Results: The mechanosensation assays revealed that ANEE (104, 103, 102 µg/mL) had a significantly higher antinociceptive index (AI) (p<0.05) compared to the vehicle control (1% DMSO). The antinociceptive effects of ANEE, 2.5 µM morphine, and 0.01% mg/mL paracetamol in C. elegans were not significantly different (p>0.05). This effect of ANEE continued after four treatments within a 72-hour period. Conclusion: The findings revealed that A. nidus ethanolic extract (ANEE) possesses antinociceptive effect which validates folkloric use of A. nidus and suggest a potential for chronic therapeutic use. [ABSTRACT FROM AUTHOR]

Oral squamous cell carcinoma (OSCC) presents significant treatment challenges due to its poor survival and intense pain at the primary cancer site. Cancer pain is debilitating, contributes to diminished quality of life, and causes opioid tolerance. The stimulator of interferon genes (STING) agonism has been investigated as an anti-cancer strategy. We have developed STINGel, an extended-release formulation that prolongs the availability of STING agonists, which has demonstrated an enhanced anti-tumor effect in OSCC compared to STING agonist injection. This study investigates the impact of intra-tumoral STINGel on OSCC-induced pain using two separate OSCC models and nociceptive behavioral assays. Intra-tumoral STINGel significantly reduced mechanical allodynia in the orofacial cancer model and alleviated thermal and mechanical hyperalgesia in the hind paw model. To determine the cellular signaling cascade contributing to the antinociceptive effect, we performed an in-depth analysis of immune cell populations via single-cell RNA-seq. We demonstrated an increase in M1-like macrophages and N1-like neutrophils after STINGel treatment. The identified regulatory pathways controlled immune response activation, myeloid cell differentiation, and cytoplasmic translation. Functional pathway analysis demonstrated the suppression of translation at neuron synapses and the negative regulation of neuron projection development in M2-like macrophages after STINGel treatment. Importantly, STINGel treatment upregulated TGF-β pathway signaling between various cell populations and peripheral nervous system (PNS) macrophages and enhanced TGF-β signaling within the PNS itself. Overall, this study sheds light on the mechanisms underlying STINGel-mediated antinociception and anti-tumorigenic impact.

Tongkat ali (Eurycoma longifolia Jack) (ELJ) is a plant in the Simaroubaceae family. Its roots are used in traditional Thai medicine to treat inflammation, pain, and fever; however, the antiulcer abilities of its ethanolic extract have not been studied. This study examined the anti-inflammatory, antinociceptive, antipyretic, and gastroprotective effects of ethanolic ELJ extract in animal models and found that ELJ effectively reduced EPP-induced ear edema in a dose-dependent manner and that a high dose of ELJ inhibited carrageenan-induced hind paw edema formation. In cotton-pellet-induced granuloma formation, a high dose of ELJ suppressed the increases in wet granuloma weight but not dry or transudative weight. In the formalin-induced nociception study, ELJ had a significant dose-dependent inhibitory impact. Additionally, the study found that yeast-induced hyperthermia could be significantly reduced by antipyretic action at the highest dose of ELJ. In all the gastric ulcer models induced by chemical substances or physical activity, ELJ extracts at 150, 300, and 600 mg/kg also effectively prevented gastric ulcer formation. In the pyloric ligation model, however, the effects of ELJ extract on gastric volume, gastric pH, and total acidity were statistically insignificant. These findings support the current widespread use of Eurycoma longifolia Jack in traditional medicine, suggest the plant's medicinal potential for development of phytomedicines with anti-inflammatory, antinociceptive, and antipyretic properties, and support its use in the treatment of gastric ulcers due to its gastroprotective properties. [ABSTRACT FROM AUTHOR]

Salvia semiatrata Zucc. (Lamiaceae) is endemic to Oaxaca, Mexico, and is known for its analgesic properties. Terpenoids and phenolic compounds with antinociceptive potential have been characterised from this species. The aim of this research was to determine the variation in terpenoids and flavonoids in ethyl acetate extracts of S. semiatrata collected from ten different localities, as well as to evaluate the antinociceptive effect between plants with higher and lower contents of these secondary metabolites. Quantification of S. semiatrata compounds was performed via HPLC-DAD, whereas in vivo evaluation of the antinociceptive effect was performed via formalin test. The results showed that the most abundant groups of metabolites are oleanolic acid (89.60–59.20 µg/mg), quercetin (34.81–16.28 µg/mg), catechin (11.30–9.30 µg/mg), and 7-keto-neoclerodan-3,13-dien-18,19:15,16-diolide (7-keto) (8.01–4.76 µg/mg). Principal component and canonical correspondence analysis showed that the most contrasting localities in terms of compound content and climatic variables are Miahuatlán and Santiago Huauclilla. The differences in metabolite content between the two locations did not affect the antinociceptive effects evaluated at a dose of 300 mg/kg, p.o. In conclusion, the results indicate that S. semiatrata is effective in relieving pain, regardless of the site of collection, reinforcing its traditional use as analgesic. [ABSTRACT FROM AUTHOR]

Abstract Caesalpinia eriostachys Benth. (CE) is native to the Mexico and multiple effects have been observed from several plants belonging to the same family. CE was subjected to extraction with 95% ethanol, and the components were isolated through column chromatography. The structure of the compound was elucidated based on nuclear magnetic resonance (NMR) spectral data, electron ionization–mass (EI‐MS) spectroscopy, and liquid chromatography–mass (LC‐MS) spectroscopy. In vivo antinociceptive studies were conducted using writhing, 5% formalin, tail‐flick, hot‐plate, and von Frey filament tests. The ethanolic extract showed a significant effect in the acetic acid‐induced pain model and nociceptive behavior in the formalin model (second phase). In hot‐plate test and tail‐flick test, the results showed no difference compared to the control group. The results suggest that the ethanolic extract may act peripherally to reduce pain. In the streptozotocin (STZ)‐induced pain model, the ethanolic extract showed significant effect in the von Frey test model. The n‐Hex (Hexane) and MC (Methylene chloride) fractions and isolated compounds, ellagic acid and agathisflavone, showed increased effect. Based on these results, we confirmed that the CE ethanolic extract and their compounds, ellagic acid and agathisflavone, have antinociceptive effect on diabetes mellitus‐induced pain. Furthermore, the results of this study might be valuable for identifying compounds with antinociceptive activity from natural products.

Neuropathic pain is refractory to opioid analgesics. Since there are functional linkages between μ-opioid receptors (MOR) and cannabinoid receptors (CBR), the present study was designed to investigate the interactions between MOR and CB1R based on antinociceptive effects for neuropathic pain mediated through G protein-coupled inwardly-rectifying potassium channels (GIRKs). The antinociceptive effects against pseudonociceptive response or neuropathic pain of MOR and CBR agonists were assessed in mice with or without partial sciatic nerve ligation. To investigate the functional interaction between MOR and CB1R, electrophysiological recording through GIRK was performed using the two-electrode voltage-clamp method in oocytes along with Western blotting in the spinal cord of mice. Co-administration of the MOR agonist DAMGO and the CB1R agonist CP55,940 augmented inwardly rectifying K+ currents in Xenopus oocytes co-expressing MOR, CB1R and GIRK1/2. Further, combination of morphine and the CBR agonist WIN-55,212-2 produced prominent antinociceptive effects in an i.t. GIRK1 inhibitor-reversible manner. Furthermore, CB1R was upregulated under neuropathic pain in the spinal cord, and such upregulation and antinociceptive effects were not altered by repeated treatment with morphine plus WIN-55,212-2. Our findings suggest that co-administration of MOR and CBR agonists could enhance their antinociceptive effects through GIRK1 in the spinal cord of mice.

4-Arylhydrazinylidene-5-(polyfluoroalkyl)pyrazol-3-ones (4-AHPs) were found to be obtained by the regiospecific cyclization of 2-arylhydrazinylidene-3-(polyfluoroalkyl)-3-oxoesters with hydrazines, by the azo coupling of 4-nonsubstituted pyrazol-5-oles with aryldiazonium chlorides or by the firstly discovered acid-promoted self-condensation of 2-arylhydrazinylidene-3-oxoesters. All the 4-AHPs had an acceptable ADME profile. Varying the substituents in 4-AHPs promoted the switching or combining of their biological activity. The polyfluoroalkyl residue in 4-AHPs led to the appearance of an anticarboxylesterase action in the micromolar range. An NH-fragment and/or methyl group instead of the polyfluoroalkyl one in the 4-AHPs promoted antioxidant properties in the ABTS, FRAP and ORAC tests, as well as anti-cancer activity against HeLa that was at the Doxorubicin level coupled with lower cytotoxicity against normal human fibroblasts. Some Ph-N-substituted 4-AHPs could inhibit the growth of N. gonorrhoeae bacteria at MIC 0.9 μg/mL. The possibility of using 4-AHPs for cell visualization was shown. Most of the 4-AHPs exhibited a pronounced analgesic effect in a hot plate test in vivo at and above the diclofenac and metamizole levels except for the ones with two chlorine atoms in the aryl group. The methylsulfonyl residue was proved to raise the anti-inflammatory effect also. A mechanism of the antinociceptive action of the 4-AHPs through blocking the TRPV1 receptor was proposed and confirmed using in vitro experiment and molecular docking. [ABSTRACT FROM AUTHOR]

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Research background. Extracts from grape pomace, including the wine, show many biological effects such as antioxidant and anti-inflammatory activities. Unfortunately, winemakers discard the bagasse, so the waste is not exploited, although it contains bioactive compounds with antioxidant and anti-inflammatory properties. The work aims to analyze the hydroethanolic extract of peels from Vitis labrusca agro-industrial waste and to evaluate its antinociceptive and anti-inflammatory properties. This study is relevant for reusing a residue and adding value to the grape economic chain. Experimental approach. A representative sample of pomace was obtained and the peels were used to produce the extract. The phenolic compounds were determined by mass spectrometry in multiple reaction monitoring mode and Folin-Ciocalteu colorimetric method, using gallic acid as standard. The biological analyses were carried out using mice orally treated with crude extract at doses of 30, 100 and 300 mg/kg. We evaluated mechanical hyperalgesia by the von Frey method, thermal heat hyperalgesia using a hot plate at 55 °C, paw edema using a pachymeter, and neutrophil recruitment by measurement of myeloperoxidase activity. The nephrotoxicity and hepatotoxicity were evaluated by biochemical analyses using blood samples that were collected after the Vitis labrusca administration. Results and conclusions. In all wet winemaking residues peel mass fraction was 75%, and in dry residues 59%. We identified nine anthocyanins (3-O-glucosides: peonidin, delphinidin, petunidin and malvidin; 3-p-coumaroyl-glucosides: cyanidin, peonidin, petunidin and malvidin, and malvidin-3,5-diglucoside), five flavonoids (apigenin-7-glucoside, luteolin-7-glucoside, quercetin-3-galactoside, isorhamnetin-3-glucoside and myricetin-3-rutinoside), and mass fraction of phenolic compounds, expressed as gallic acid equivalents, was 26.62 mg/g. In vivo assays showed that Vitis labrusca extract at mass fractions 100 and 300 mg/kg reduced carrageenan-induced mechanical and thermal hyperalgesia, 50% of the paw edema, and neutrophil recruitment. In addition, there were no indications of nephrotoxicity and hepatotoxicity. Our extract obtained from winemaking residue has analgesic and anti-inflammatory properties, related at least in part to the presence of phenolic compounds, and it is not toxic to renal and hepatic tissues. Novelty and scientific contribution. This bio-product can be used as an alternative to synthetic anti-inflammatory agents with the same pharmacological potential and fewer side effects. We demonstrated that Vitis labrusca winemaking waste can be used for the production of antinociceptive and anti-inflammatory products (nutraceutical, pharmaceutical and cosmetics) without toxicity, contributing to the environmental economy.

This study aimed to assess the antinociceptive activity of extracts and fractions of Paeonia daurica subsp. macrophylla in BALB/c mice. Various doses of hydro-alcoholic extract (HE), hexane fraction (F-hexane), methanol (F-MeOH), and chloroform (F-CHCl3), as well as aqueous extracts (AE), were evaluated by a well-known model, a formalin-induced pain test in mice. All extracts, piroxicam 0.1 mg/kg, and negative control groups were administered 30 minutes before formalin injection. Flinching, licking, and biting reflexes were measured as painful factors compared with controls at intervals of 0 to 5 minutes, 0 to 15, and 0 to 60 minutes after formalin injection. The acute oral toxicity test of total ethanolic and aqueous extracts showed no signs of toxic effect up to a dose of 5000 mg/kg. In the formalin test at a time interval of 0 to 5 minutes, there was no significant difference between the results of the study groups. In the range of 0 to 15 minutes, the effect of AE (1 g/kg), HE (2, 3 g/kg), and F-hexane (1 g/kg) was significantly higher than the positive control group (p

To evaluate the antinociceptive effect and the possible mechanism of action of two polar extracts of Mansoa alliacea, a medicinal plant used in Perú, Brazil, and Mexico to treat rheumatic pain, we used the formalin and hot-plate tests in mice. We found that ethanolic (MA-EtOH) and aqueous (MA-AQ) extracts of M. alliacea induced antinociceptive effects in both nociceptive tests. The antinociceptive efficacy of the highest dosage (300 mg/kg) of both extracts were also compared by using intraperitoneal and oral administration in the formalin test. Results showed that intraperitoneal injection of the two extracts produced better antinociceptive effects than that obtained by their oral administration. The mechanism of action involved in their antinociceptive activity was determined in the formalin test. Results showed that the presence of A784168 (TRPV1 antagonist) did not alter the antinociceptive effect induced by any of the M. alliacea extracts, whereas naltrexone (opioid antagonist) partially prevented the antinociceptive effect only of MA-EtOH in both phases of the formalin test. Furthermore, the effects of the extracts were diminished by L-NAME (inhibitor of nitric oxide synthase), but not by ODQ (inhibitor of the soluble guanylyl cyclase) or glibenclamide (blocker of K+ATP channels) in the neurogenic phase. However, the effect of MA-AQ was diminished by all the inhibitors in the inflammatory phase. These results support the use of M. alliacea as a potential natural product with efficacy for pain relief depending on the form of preparation and the route of administration by involving opioid receptors and the production of nitric oxide.

Salvia semiatrata Zucc. (Lamiaceae) is endemic to Oaxaca, Mexico, and is known for its analgesic properties. Terpenoids and phenolic compounds with antinociceptive potential have been characterised from this species. The aim of this research was to determine the variation in terpenoids and flavonoids in ethyl acetate extracts of S. semiatrata collected from ten different localities, as well as to evaluate the antinociceptive effect between plants with higher and lower contents of these secondary metabolites. Quantification of S. semiatrata compounds was performed via HPLC-DAD, whereas in vivo evaluation of the antinociceptive effect was performed via formalin test. The results showed that the most abundant groups of metabolites are oleanolic acid (89.60–59.20 µg/mg), quercetin (34.81–16.28 µg/mg), catechin (11.30–9.30 µg/mg), and 7-keto-neoclerodan-3,13-dien-18,19:15,16-diolide (7-keto) (8.01–4.76 µg/mg). Principal component and canonical correspondence analysis showed that the most contrasting localities in terms of compound content and climatic variables are Miahuatlán and Santiago Huauclilla. The differences in metabolite content between the two locations did not affect the antinociceptive effects evaluated at a dose of 300 mg/kg, p.o. In conclusion, the results indicate that S. semiatrata is effective in relieving pain, regardless of the site of collection, reinforcing its traditional use as analgesic.

Tongkat ali (Eurycoma longifolia Jack) (ELJ) is a plant in the Simaroubaceae family. Its roots are used in traditional Thai medicine to treat inflammation, pain, and fever; however, the antiulcer abilities of its ethanolic extract have not been studied. This study examined the anti-inflammatory, antinociceptive, antipyretic, and gastroprotective effects of ethanolic ELJ extract in animal models and found that ELJ effectively reduced EPP-induced ear edema in a dose-dependent manner and that a high dose of ELJ inhibited carrageenan-induced hind paw edema formation. In cotton-pellet-induced granuloma formation, a high dose of ELJ suppressed the increases in wet granuloma weight but not dry or transudative weight. In the formalin-induced nociception study, ELJ had a significant dose-dependent inhibitory impact. Additionally, the study found that yeast-induced hyperthermia could be significantly reduced by antipyretic action at the highest dose of ELJ. In all the gastric ulcer models induced by chemical substances or physical activity, ELJ extracts at 150, 300, and 600 mg/kg also effectively prevented gastric ulcer formation. In the pyloric ligation model, however, the effects of ELJ extract on gastric volume, gastric pH, and total acidity were statistically insignificant. These findings support the current widespread use of Eurycoma longifolia Jack in traditional medicine, suggest the plant’s medicinal potential for development of phytomedicines with anti-inflammatory, antinociceptive, and antipyretic properties, and support its use in the treatment of gastric ulcers due to its gastroprotective properties.

Caesalpinia eriostachys Benth. (CE) is native to the Mexico and multiple effects have been observed from several plants belonging to the same family. CE was subjected to extraction with 95% ethanol, and the components were isolated through column chromatography. The structure of the compound was elucidated based on nuclear magnetic resonance (NMR) spectral data, electron ionization–mass (EI‐MS) spectroscopy, and liquid chromatography–mass (LC‐MS) spectroscopy. In vivo antinociceptive studies were conducted using writhing, 5% formalin, tail‐flick, hot‐plate, and von Frey filament tests. The ethanolic extract showed a significant effect in the acetic acid‐induced pain model and nociceptive behavior in the formalin model (second phase). In hot‐plate test and tail‐flick test, the results showed no difference compared to the control group. The results suggest that the ethanolic extract may act peripherally to reduce pain. In the streptozotocin (STZ)‐induced pain model, the ethanolic extract showed significant effect in the von Frey test model. The n‐Hex (Hexane) and MC (Methylene chloride) fractions and isolated compounds, ellagic acid and agathisflavone, showed increased effect. Based on these results, we confirmed that the CE ethanolic extract and their compounds, ellagic acid and agathisflavone, have antinociceptive effect on diabetes mellitus‐induced pain. Furthermore, the results of this study might be valuable for identifying compounds with antinociceptive activity from natural products. [ABSTRACT FROM AUTHOR]

Research background. Extracts from grape pomace, including the wine, show many biological effects such as antioxidant and anti-inflammatory activities. Unfortunately, winemakers discard the bagasse, so the waste is not exploited, although it contains bioactive compounds with antioxidant and anti-inflammatory properties. The work aims to analyze the hydroethanolic extract of peels from Vitis labrusca agro-industrial waste and to evaluate its antinociceptive and anti-inflammatory properties. This study is relevant for reusing a residue and adding value to the grape economic chain. Experimental approach. A representative sample of pomace was obtained and the peels were used to produce the extract. The phenolic compounds were determined by mass spectrometry in multiple reaction monitoring mode and Folin-Ciocalteu colorimetric method, using gallic acid as standard. The biological analyses were carried out using mice orally treated with crude extract at doses of 30, 100 and 300 mg/kg. We evaluated mechanical hyperalgesia by the von Frey method, thermal heat hyperalgesia using a hot plate at 55 °C, paw edema using a Vernier caliper, and neutrophil recruitment by measurement of myeloperoxidase activity. The nephrotoxicity and hepatotoxicity were evaluated by biochemical analyses using blood samples that were collected after the Vitis labrusca administration. Results and conclusions. In all wet winemaking residues peel mass fraction was 75 %, and in dry residues 59 %. We identified nine anthocyanins (3-O-glucosides: peonidin, delphinidin, petunidin and malvidin; 3-p-coumaroyl-glucosides: cyanidin, peonidin, petunidin and malvidin, and malvidin-3,5-diglucoside), five flavonoids (apigenin-7-glucoside, luteolin-7-glucoside, quercetin-3-galactoside, isorhamnetin-3-glucoside and myricetin-3-rutinoside), and mass fraction of phenolic compounds, expressed as gallic acid equivalents, was 26.62 mg/g. In vivo assays showed that Vitis labrusca extract at mass fractions 100 and 300 mg/kg reduced carrageenan-induced mechanical and thermal hyperalgesia, 50 % of the paw edema, and neutrophil recruitment. In addition, there were no indications of nephrotoxicity and hepatotoxicity. Our extract obtained from winemaking residue has analgesic and anti-inflammatory properties, related at least in part to the presence of phenolic compounds, and it is not toxic to renal and hepatic tissues. Novelty and scientific contribution. This bio-product can be used as an alternative to synthetic anti-inflammatory agents with the same pharmacological potential and fewer side effects. We demonstrated that Vitis labrusca winemaking waste can be used for the production of antinociceptive and anti-inflammatory products (nutraceutical, pharmaceutical and cosmetics) without toxicity, contributing to the environmental economy. [ABSTRACT FROM AUTHOR]

Context: The search of new substances with analgesic properties has grown in the last years. Brazil and Cuba have a big biodiversity allowing the study of several plants with potential pharmacological activities. Aims: To evaluate the chemical composition and potential antinociceptive effect of the ethanolic extract from Clusia minor L. leaves (Clusiaceae) in mice. Methods: Phytochemical characterization was performed by Gas Chromatography/Mass Spectrometry. Antinociceptive effect was evaluated using acetic acid, formalin, hot plate, and capsaicin models. Mechanical hypernociception was induced by intraplantar carrageenan, tumor necrosis factor α (TNFα) and prostagladin E2 (PGE2) and responses were measured after 3 h of injection. Results: Mass Spectrometry analysis allowed the identification of 16 compounds. Fatty acid derivatives, steroids, triterpenoids, and vitamin E were the main findings. The most abundant sterol was β-sitosterol (14.04%); followed by the triterpenes α-amyrin (11.94%), and β-amyrin (7.82%). Vitamin E represented the 8.44% of the total identified compounds. The evaluation of the acetic acid-induced nociception model showed that the extract was effective in reducing pain in a dose-dependent manner. This resulted in a maximal inhibition of 53 ± 4%. The extract was also effective in other pain models. Additionally, the extract presented a considerable inhibition of paw mechanical hypernociception. Conclusions: The data suggest that the antinociceptive effect of Clusia minor occurs by interaction of various mechanisms; which probably take places via central and peripheral pathway. Therefore, modulating the inflammatory and neurogenic pain.

Our previous research has shown that galanin plays an antinociceptive effect via binding to galanin receptors (GalRs) in nucleus accumbens (NAc). This study focused on the involvement of GalR2 in galanin-induced antinociceptive effect in NAc of neuropathic pain rats. The chronic constriction injury of sciatic nerve (CCI) was used to mimic neuropathic pain model. The hind paw withdrawal latency (HWL) to thermal stimulation and hind paw withdrawal threshold (HWT) to mechanical stimulation were measured as the indicators of pain threshold. The results showed that 14 and 28 days after CCI, the expression of GalR2 was up-regulated in bilateral NAc of rats, and intra-NAc injection of GalR2 antagonist M871 reversed galanin-induced increases in HWL and HWT of CCI rats. Furthermore, intra-NAc injection of GalR2 agonist M1145 induced increases in HWL and HWT at day 14 and day 28 after CCI, which could also be reversed by M871. Finally, we found that M1145-induced antinociceptive effect in NAc of CCI rats was stronger than that in intact rats. These results imply that the GalR2 is activated in the NAc from day 14 to day 28 after CCI and GalR2 is involved in the galanin-induced antinociceptive effect in NAc of CCI rats. [ABSTRACT FROM AUTHOR]

Objectives: Safe and effective drugs are still lacking for many pain therapies. In recent years, growing interest has been devoted thus on herbal drugs as an option to identify new pain killers. Based on this, extensive researches are carried out on Verbascum L. genus due to its therapeutic potency on pain and inflammation therapy. In this study, among Verbascum species, the antinociceptive effect of Verbascum exuberans Hub.-Mor., and its contributions to nitrergic, serotonergic, or opioidergic pathways as well as its antiinflammatory acitivity were investigated. Materials and Methods: Tail clip, tail flick, and hot plate tests were used to determine the central (spinal and supraspinal) antinociceptive effect, while an acetic acid-induced writhing test was used to measure the peripheral antinociceptive effect of the extract (250 and 500 mg/kg). The extract (250 mg/kg) was then combined with nω-nitro-L-arginine methyl ester, cyproheptadine, and naloxone to evaluate its involvement in nitrergic, serotonergic, or opioidergic pathways, respectively. Carrageenan-induced hind paw edema model was used to determine the antiinflammatory effect of the extract (250 mg/kg). Results: The extract shows central spinal but not central supraspinal antinociceptive effect, and presents peripheral antinociceptive effect. The antinociceptive actions of the extract is largely regulated via targeting the nitrergic pathway, while the opioidergic pathway is partly involved. Further, the extract shows antiinflammatory effect due to the significant inhibitions on the time dependent edema progression and the cytokine (tumor necrosis factor-alfa and interleukin-1beta) productions. [ABSTRACT FROM AUTHOR]

Chronic neuropathic pain poses a significant health problem, for which effective therapy is lacking. The current work aimed to investigate the potential antinociceptive efficacy of isorhynchophylline, an oxindole alkaloid, against neuropathic pain and elucidate mechanisms. Male C57BL/6J mice were subjected to chronic constriction injury (CCI) by loose ligation of their sciatic nerves. Following CCI surgery, the neuropathic mice developed pain-like behaviors, as shown by thermal hyperalgesia in the Hargreaves test and tactile allodynia in the von Frey test. Repetitive treatment of CCI mice with isorhynchophylline (p.o., twice per day for two weeks) ameliorated behavioral hyperalgesia and allodynia in a dose-dependent fashion (5, 15, and 45 mg/kg). The isorhynchophylline-triggered antinociception seems serotonergically dependent, since its antinociceptive actions on neuropathic hyperalgesia and allodynia were totally abolished by chemical depletion of spinal serotonin by PCPA, whereas potentiated by 5-HTP (a precursor of 5-HT). Consistently, isorhynchophylline-treated neuropathic mice showed escalated levels of spinal monoamines especially 5-HT, with depressed monoamine oxidase activity. Moreover, the isorhynchophylline-evoked antinociception was preferentially counteracted by co-administration of 5-HT1A receptor antagonist WAY-100635. In vitro, isorhynchophylline (0.1-10 nM) increased the Emax (stimulation of [35S] GTPγS binding) of 8-OH-DPAT, a 5-HT1A agonist. Of notable benefit, isorhynchophylline was able to correct co-morbidly behavioral symptoms of depression and anxiety evoked by neuropathic pain. Collectively, these findings confirm, for the first time, the disease-modifying efficacy of isorhynchophylline on neuropathic hypersensitivity, and this effect is dependent on spinal serotonergic system and 5-HT1A receptors.

This study offers a novel oral pregabalin (PG)-loaded drug delivery system based on chitosan and hypromellose phthalate-based polymeric nanocomposite in order to treat neuropathic pain (PG-PN). PG-PN has a particle size of 432 ± 20 nm, a polydispersity index of 0.238 ± 0.001, a zeta potential of +19.0 ± 0.9 mV, a pH of 5.7 ± 0.06, and a spherical shape. Thermal and infrared spectroscopy confirmed nanocomposite generation. PG-PN pharmacokinetics was studied after a single oral dose in male Wistar rats. PG-PN showed greater distribution and clearance than free PG. The antinociceptive effect of PG-PN in neuropathic pain rats was tested by using the chronic constriction injury model. The parameter investigated was the mechanical nociceptive threshold measured by the von Frey filaments test; PG-PN showed a longer antinociceptive effect than free PG. The rota-rod and barbiturate sleep induction procedures were used to determine adverse effects; the criteria included motor deficit and sedative effects. PG-PN and free PG had plenty of motors. PG-PN exhibited a less sedative effect than free PG. By prolonging the antinociceptive effect and decreasing the unfavorable effects, polymeric nanocomposites with pregabalin have shown promise in treating neuropathic pain.

Chronic neuropathic pain poses a significant health problem, for which effective therapy is lacking. The current work aimed to investigate the potential antinociceptive efficacy of isorhynchophylline, an oxindole alkaloid, against neuropathic pain and elucidate mechanisms. Male C57BL/6J mice were subjected to chronic constriction injury (CCI) by loose ligation of their sciatic nerves. Following CCI surgery, the neuropathic mice developed pain-like behaviors, as shown by thermal hyperalgesia in the Hargreaves test and tactile allodynia in the von Frey test. Repetitive treatment of CCI mice with isorhynchophylline (p.o., twice per day for two weeks) ameliorated behavioral hyperalgesia and allodynia in a dose-dependent fashion (5, 15, and 45 mg/kg). The isorhynchophylline-triggered antinociception seems serotonergically dependent, since its antinociceptive actions on neuropathic hyperalgesia and allodynia were totally abolished by chemical depletion of spinal serotonin by PCPA, whereas potentiated by 5-HTP (a precursor of 5-HT). Consistently, isorhynchophylline-treated neuropathic mice showed escalated levels of spinal monoamines especially 5-HT, with depressed monoamine oxidase activity. Moreover, the isorhynchophylline-evoked antinociception was preferentially counteracted by co-administration of 5-HT1A receptor antagonist WAY-100635. In vitro , isorhynchophylline (0.1-10 nM) increased the Emax (stimulation of [35S] GTPγS binding) of 8-OH-DPAT, a 5-HT1A agonist. Of notable benefit, isorhynchophylline was able to correct co-morbidly behavioral symptoms of depression and anxiety evoked by neuropathic pain. Collectively, these findings confirm, for the first time, the disease-modifying efficacy of isorhynchophylline on neuropathic hypersensitivity, and this effect is dependent on spinal serotonergic system and 5-HT1A receptors. [ABSTRACT FROM AUTHOR]

Abstract Background Bone cancer pain (BCP) severely compromises the quality of life, while current treatments are still unsatisfactory. Here, we tested the antinociceptive effects of triptolide (T10), a substance with considerable anti-tumor efficacies on BCP, and investigated the underlying mechanisms targeting the spinal dorsal horn (SDH). Methods Intratibial inoculation of Walker 256 mammary gland carcinoma cells was used to establish a BCP model in rats. T10 was intrathecally injected, and mechanical allodynia was tested by measuring the paw withdrawal thresholds (PWTs). In mechanism study, the activation of microglia, astrocytes, and the mitogen-activated protein kinase (MAPK) pathways in the SDH were evaluated by immunofluorescence staining or Western blot analysis of Iba-1, GFAP, p-ERK, p-p38, and p-JNK. The expression and cellular localization of histone deacetylases (HDACs) 1 and 2 were also detected to investigate molecular mechanism. Results Intrathecal injection of T10 inhibited the bone cancer-induced mechanical allodynia with an ED50 of 5.874 μg/kg. This effect was still observed 6 days after drug withdrawal. Bone cancer caused significantly increased expression of HDAC1 in spinal microglia and neurons, with HDAC2 markedly increased in spinal astrocytes, which were accompanied by the upregulation of MAPK pathways and the activation of microglia and astrocytes in the SDH. T10 reversed the increase of HDACs, especially those in glial cells, and inhibited the glial activation. Conclusions Our results suggest that the upregulation of HDACs contributes to the pathological activation of spinal glial cells and the chronic pain caused by bone cancer, while T10 help to relieve BCP possibly via inhibiting the upregulation of HDACs in the glial cells in the SDH and then blocking the neuroinflammation induced by glial activation.

Clinically, neuropathic pain treatment remains a challenging issue because the major therapy, centred around pharmacological intervention, is not satisfactory enough to patient by reason of low effectiveness and more adverse reaction. Therefore, it is still necessary to find more effective and safe therapy to ameliorate neuropathic pain. The purpose of this study was to explore the antinociceptive effect of Echinacoside (ECH), an active compound of Cistanche deserticola Ma, on peripheral neuropathic pain induced by chronic constriction injury (CCI) in mice, and to demonstrate its potential mechanism in vivo and vitro. In the present study, results showed that intraperitoneal administration of ECH (50, 100, and 200 mg/kg) could alleviate mechanical allodynia, cold allodynia and thermal hyperalgesia via behavioural test. Moreover, the structure and function of injured sciatic nerve by CCI were taken a turn for the better to a certain extent after ECH treatment using histopathological and electrophysiological test. Furthermore, ECH repressed the expression of the P2X7R and FKN and reduced the expression and release of the IL-1β, IL-6 and TNF-α. Besides, ECH could decrease Ca2+ influx and Cats efflux and inhibit phosphorylation of p38MAPK. To sum up, the present study illustrated that ECH could alleviate peripheral neuropathic pain by inhibiting microglia overactivation and inflammation through P2X7R/FKN/CX3CR1 signalling pathway in spinal cord. This study would provide a new perspective and strategy for the pharmacological treatment on neuropathic pain. [Display omitted] • Echinacoside ameliorated CCI-induced neuropathic pain in mice. • Echinacoside alleviated peripheral neuropathic pain through inhibiting P2X7R/FKN/CX3CR1 pathway in spinal cord. • Echinacoside may have potential as therapeutic agent for neuropathic pain. [ABSTRACT FROM AUTHOR]

The kappa opioid receptor (KOR) represents an attractive target for the development of drugs as potential antidepressants, anxiolytics and analgesics. A robust computational approach may guarantee a reduction in costs in the initial stages of drug discovery, novelty and accurate results. In this work, a virtual screening workflow of a library consisting of ~6 million molecules was set up, with the aim to find potential lead compounds that could manifest activity on the KOR. This in silico study provides a significant contribution in the identification of compounds capable of interacting with a specific molecular target. The main computational techniques adopted in this experimental work include: (i) virtual screening; (ii) drug design and leads optimization; (iii) molecular dynamics. The best hits are tripeptides prepared via solution phase peptide synthesis. These were tested in vivo, revealing a good antinociceptive effect after subcutaneous administration. However, further work is due to delineate their full pharmacological profile, in order to verify the features predicted by the in silico outcomes.

Background. The increase of NSAIDs safety is current direction of modern pharmacology, because of so-called "class-specific" adverse reactions, which are common to this class, and the leading place among them is occupied by gastro-intestinal toxicity. In previous studies we have proved the ability of vinboron to neutralize ulcerogenic effect of ibuprofen (Hladkykh F.V. and al., 2014). The presence of the proven analgesic activity in the domestic antispasmodics (Stepaniuk H.I. and al., 2007) serves as the basis for research of vinboron action on analgesic aspect of ibuprofen pharmacotherapeutic effec. Aim is to conduct research in silico of the relation «molecular structure – anelgetic activity» of vinboron and to prove experimentally in vivo the practicability of vinboron using with the aim to increase the analgesic activity of ibuprofen on the model of adjuvant arthritis in rats. Materials and methods. The study of the relation «molecular structure – activity anelgetic» of vinboron was conducted in silico by PASS- analysis of biological activity spectrum. The analysis was set online with direct insertion of structural formula of vinboron in browser using Marvin JS web-resource «PASS Online» (http://www.way2drug.com/passonline). Analgesic activity in vivo was studied on the model of acute thermal pain, which was simulated in the conventional behavioral test of nociception «Hot plate». The lag of pain reaction was determined at the beginning («0» day), on 7, 14, 21 and 28 days of experiment. Results and discussion. According to the PASS-forecast the mechanisms of vinboron analgesic activity is caused by agonism towards the vanilloid (TRPV1) receptors (Pa=0,490; Pi=0,008), agonism to the μ (mu) – receptor (Pa=0,323; Pi=0,036), inhibition of GABA (Pa=0,329; Pi=0,089) and others. Experimental studies have shown that the combined administration of ibuprofen and vinboron analgesic activity was higher than the results by ibuprofen monotherapy at a dose of 73 mg/kg up by 15.3%, and at a dose of 218 mg/kg up by 20.4%. Besides, it is worthwhile to note that analgesic activity during the integrated administration of ibuprofen at a dose of 218 mg/kg and vinboron (+39.8%) was higher than the total analgesic activity of ibuprofen monotherapy at the same dose (+19.4%) and monotherapy of vinboron (+10.9%), that points at potentiation of analgesic effect of both drugs during their integrated administration. Conclusions. According to the PASS-analysis, the leading mechanism in analgesic component implementation of vinboron is its agonism to TRPV1. The results of our in vivo studies point at the ability of vinboron to intensify the antinociceptive activity of ibuprofen.

Sigma-1 receptor (σ1R) antagonism increases the effects of morphine on acute nociceptive pain. S1RA (E-52862) is a selective σ1R antagonist widely used to study the role of σ1Rs. S1RA alone exerted antinociceptive effect in the formalin test in rats and increased noradrenaline levels in the spinal cord, thus accounting for its antinociceptive effect. Conversely, while systemic S1RA failed to elicit antinociceptive effect by itself in the tail-flick test in mice, it did potentiate the antinociceptive effect of opioids in this acute pain model. The present study aimed to investigate the site of action and the involvement of spinal noradrenaline on the potentiation of opioid antinociception by S1RA on acute thermal nociception using the tail-flick test in rats. Local administration was performed after intrathecal catheterization or intracerebroventricular and rostroventral medullar (RVM) cannulae implantation. Noradrenaline levels in the spinal cord were evaluated using the concentric microdialysis technique in awake, freely-moving rats. Systemic or supraspinal administration of S1RA alone, while having no effect on antinociception, enhanced the effect of morphine in rats. However, spinal S1RA administration did not potentiate the antinociceptive effect of morphine. Additionally, the peripherally restricted opioid agonist loperamide was devoid of antinociceptive effect but produced antinociception when combined with S1RA. Neurochemical studies revealed that noradrenaline levels in the dorsal horn of the spinal cord were not increased at doses exerting potentiation of the antinociceptive effect of the opioid. In conclusion, the site of action of σ1R for opioid modulation on acute thermal nociception is located at the peripheral and supraspinal levels, and the opioid-potentiating effect is independent of the spinal noradrenaline increase produced by S1RA.

Neuropathic pain is described as the “most terrible of all tortures that a nerve wound may inflict.” The aim of the present study was to demonstrate the antinociceptive effect of Symplocos chinensis f. pilosa Ohwi water extract (SCW) and synthesized derivatives of the isolated compound. The antinociceptive effect was tested using the acetic acid-induced writhing and 5% formalin tests. Antinociceptive effects on neuropathic pain were evaluated using the von Frey test with chronic constriction injury (CCI) and surgical nerve injury (SNI) models and tail-flick test with a vincristine-induced pain model. An Ames test was also conducted. 5-hydroxymethylfurfural (5-HMF) was isolated and derivatives were synthesized with various acid groups. Among the plant water extracts, SCW showed significantly effective activity. Additionally, SCW presented antinociceptive effects in the neuropathic pain models. The SCW water fraction resulted in fewer writhes than the other fractions, and isolated 5-HMF was identified as an effective compound. Because 5-HMF revealed a positive response in the Ames test, derivatives were synthesized. Among the synthesized derivations, 5-succinoxymethylfurfural (5-SMF) showed the best effect in the neuropathic pain model. Our data suggest that SCW and the synthesized compound, 5-SMF, possess effective antinociceptive activity against neuropathic pain.

Purpose: To investigate the anti-nociceptive effect of gabapentin in acute and chronic pain models. Methods: Four mouse models of pain were used in this study. These comprised thermal tests (hot plate and tail immersion tests), and chemical tests (formalin and acetic acid-induced writhing tests). A total of seventy-two (72) albino mice weighing 25 - 40 g (mean weight = 32.5 ± 5.1 g) were used. In each test, the mice were randomly assigned to three sets of 6 mice each: control group, celecoxib group and drug treatment group. Each test was performed at intervals of 30, 60 and 90 min. Results: During the acute phase, there was no significant decrease in foot raising (FR) or licking and biting (L & B) episodes among the groups (p > 0.05). However, these episodes were significantly (p < 0.05) decreased in the second delayed phase, in the celecoxib and drug-treated groups, when compared with normal control group. Gabapentin significantly (p < 0.05) decreased pain response throughout the course of the thermal tests. The number of writhes within 30 min were significantly reduced in celecoxib and gabapentin-treated animals, compared with negative control group (p < 0.05). Gabapentin produced approximately 60 % protection of writhing, similar to that produced by celecoxib, the standard non-steroidal anti-inflammatory drug (NSAID) used (61 %). Conclusion: The results demonstrate that the gabapentin is effective against chronic inflammatory pain in mice and therefore can be potentially developed as an effective anti-inflammatory agent for humans. [ABSTRACT FROM AUTHOR]

Sigma-1 receptor (σ1R) antagonism increases the effects of morphine on acute nociceptive pain. S1RA (E-52862) is a selective σ1R antagonist widely used to study the role of σ1Rs. S1RA alone exerted antinociceptive effect in the formalin test in rats and increased noradrenaline levels in the spinal cord, thus accounting for its antinociceptive effect. Conversely, while systemic S1RA failed to elicit antinociceptive effect by itself in the tail-flick test in mice, it did potentiate the antinociceptive effect of opioids in this acute pain model. The present study aimed to investigate the site of action and the involvement of spinal noradrenaline on the potentiation of opioid antinociception by S1RA on acute thermal nociception using the tail-flick test in rats. Local administration was performed after intrathecal catheterization or intracerebroventricular and rostroventral medullar (RVM) cannulae implantation. Noradrenaline levels in the spinal cord were evaluated using the concentric microdialysis technique in awake, freely-moving rats. Systemic or supraspinal administration of S1RA alone, while having no effect on antinociception, enhanced the effect of morphine in rats. However, spinal S1RA administration did not potentiate the antinociceptive effect of morphine. Additionally, the peripherally restricted opioid agonist loperamide was devoid of antinociceptive effect but produced antinociception when combined with S1RA. Neurochemical studies revealed that noradrenaline levels in the dorsal horn of the spinal cord were not increased at doses exerting potentiation of the antinociceptive effect of the opioid. In conclusion, the site of action of σ1R for opioid modulation on acute thermal nociception is located at the peripheral and supraspinal levels, and the opioid-potentiating effect is independent of the spinal noradrenaline increase produced by S1RA. [ABSTRACT FROM AUTHOR]

Background: Pain is an unpleasant sensory and emotional experience. Pain is a protective mechanism. Pain occurs whenever any tissues are being damaged, and it causes the individual to react and to remove the pain stimulus. Aim and Objectives: To evaluate the antinociceptive effect of ondansetron in comparison with the standard diclofenac. Material and Methods: The antinociceptive effect was tested by using the acetic acid induced writhing model in Swiss Albino mice. Animals were divided into 4 groups of 6 animals each. Animals were received distilled water (control), diclofenac (standard), ondansetron 0.5mg/kg (test I) and ondansetron 1mg/kg (test II). After 30 minutes of drug administration, 0.1 ml of 1% acetic acid was injected. Mice were placed individually into glass beakers and five minutes were allowed to elapse. They were then observed for a period of ten minutes and the numbers of writhes were recorded in each animal. The results were expressed as mean ± SEM. One way ANOVA with post-test was used for statistical calculation. Results: The numbers of writhes were 1.33±0.494 for diclofenac; 6.33±1.872 and 9.33±1.706 for ondansetron 0.5 and 1mg/kg respectively. Conclusion: Ondansetron demonstrated statistical significant antinociceptive activity at both doses (0.5mg/kg and 1mg/kg) and statistically similar effect as diclofenac

Nigella sativa (NS) has been used for centuries in various inflammatory conditions because of its anti-inflammatory and antioxidant activities. The study aimed to evaluate the anti-inflammatory, antinociceptive and antioxidant activity of Nigella sativa oil (NSO) in two models of acute (carrageenan-induced) and sub-acute inflammation (complete Freund’s adjuvant induced) in rats. Materials and Methods: NSO was administered orally 1, 2 and 4 mL/kg in the acute phase. For subacute phase, NSO was administered 4 mL/kg, 7 days before or after inflammation induction, or in association with diclofenac 5 mg/kg. Results: The gas chromatography coupled with mass spectroscopy (GC-MS) analysis showed that NSO is an important source of bioactive compounds, especially p-cymene and thymoquinone. In the acute phase, 1.5 h after administration, NSO (2 and 4 mL/kg) determined an anti-inflammatory effect comparable with that of diclofenac. In the sub-acute administration, NSO had no anti-inflammatory effect. The analgesic effect of NSO was observed only in the sub-acute inflammation in the analgesy-meter test. NSO as treatment proved its antioxidant effect through the reduction of malondialdehyde (MDA) and oxidized glutathione (GSSG), and increases in hydrogen donor capacity (DH) compared to the control group, but the effect was not as intense as that of diclofenac. Conclusion: The present study has proven inconstant anti-inflammatory, analgesic and antioxidative properties of NSO.

Aristolochia trilobata, popularly known as “mil-homens,” is widely used for treatment of stomach aches, colic, asthma, pulmonary diseases, diabetes, and skin affection. We evaluated the antinociceptive and anti-inflammatory activities of the essential oil (EO) and the main constituent, 6-methyl-5-hepten-2-yl acetate (sulcatyl acetate, SA). EO and SA (1, 10, and 100 mg/kg, p.o.) were evaluated using chemical (formalin-induced licking) and thermal (hot-plate) models of nociception or inflammation (carrageenan-induced cell migration into the subcutaneous air pouch, SAP). The mechanism of antinociceptive activity was evaluated using opioid, cholinergic receptor antagonists (naloxone and atropine), or nitric oxide synthase inhibitor (L-NAME). EO and SA presented a central antinociceptive effect (the hot-plate model). In formalin-induced licking response, higher doses of EO and SA also reduced 1st and 2nd phases. None of the antagonists and enzyme inhibitor reversed antinociceptive effects. EO and SA reduced the leukocyte migration into the SAP, and the cytokines tumor necrosis factor and interleukin-1 (TNF-α and IL-1β, respectively) produced in the exudate. Our results are indicative that EO and SA present peripheral and central antinociceptive and anti-inflammatory effects.

Machaerium hirtum (Vell.) Stellfeld (Fabaceae) known in Brazil as “jacaranda de espinho” or “espinheira santa nativa” is a medicinal plant commonly used in folk medicine to treat ulcers, cough and diarrhea. This study aimed to investigate the anti-inflammatory and antinociceptive effects of hydroalcoholic extracts from M. hirtum twig (HEMh) using in vivo experimental models of nociception through the involvement of transient receptor potential channels, acid-sensing ion channel (ASIC), nitrergic, opioidergic, glutamatergic, and supraspinal pathways. Our results revealed an antinociceptive effect of HEMh mediated by the opioidergic, l-arginine-nitric oxide and glutamate systems, as well as by interactions with TRPA1/ASIC channels. The anti-inflammatory effect of HEMh evaluated with a xylene-induced ear edema and by the involvement of arachidonic acid and prostaglandin E2 (PGE2) showed involvement of the COX pathway, based on observed decreases in PGE2 levels. A phytochemical investigation of the HEMh led to the isolation of α-amyrin, β-amyrin, allantoin, apigenin-7-methoxy-6-C-β-d-glucopyranoside, and apigenin-6-C-β-d-glucopyranosyl-8-C-β-d-xylopyranoside. In conclusion, the acute oral administration of HEMh inhibits the nociceptive behavioral response in animals through the nitrergic, opioid, glutamatergic pathways, and by inhibition of the TRPA1 and ASIC channels, without causing locomotor dysfunction. In addition, its anti-inflammatory effect is associated with the COX pathway and decreased PGE2 levels.

N-type calcium channels (Neuronal-type Calcium channel, Cav2.2) is a member of high voltage activated calcium channels. There are two native small peptides for N-type calcium channels (NTCC) directly which are derived from cone snail, ω-conotoxin-GVIA isolated from Conus geographus and ω-conotoxin-MVIIA (SNX-111, Ziconotide, PrialtTM), from Conus magus which both directly block the α1-ion conducting pore. NTCCs, have been shown to play a key role in nociceptive transmission due to their strategic location, presynaptically in afferent C & Aᵹ fiber terminals and postsynaptically in descending neuron. NTCCs, which are highly expressed at the pre-synaptic terminals of nociceptive neurons in dorsal horn of the spinal cord regulate release of the key pro-nociceptive neurotransmitters such as glutamate, substance P, neurokinin A, and CGRP. There have been many preclinical studies demonstrating the effect of different NTCC blockers in various acute, inflammatory and neuropathic animal pain models. In 2004 ziconotide has been approved in US and Europe to be used in clinical practice. Furthermore, many clinical trials have been performed in more than 1000 patients studying the efficacy and safety of ziconotide. IT administrated of ziconotide showed significant decrease in pain scores in patients with malignant and nonmalignant pain which are practically in neuropathic pain characteristic and resistant to IT opioids.

Recent studies have demonstrated the antinociceptive, anti-inflammatory, and gastric protective effects of trimetazidine (TDZ) on various models in rats. The present study proposes to demonstrate the antinociceptive action in mice, evaluated in conditions of inflammatory pain, together with the determination of the type of pharmacodynamic interaction between trimetazidine and ketoprofen (KETO). In this study we used as experimental model of nociception the abdominal constrictive response (writhing test), induced with Zymosan A in mice, and for the study of the interaction we used as quantitative evaluation method the method of binary combinations in fixed proportions. The experimental results allowed the demonstration of the ED 50 for ketoprofen (DE50 = 0.606 ± 0.108 mg/kg) and the demonstration of the synergism for the associated substances. (Zadd = 1.818 ± 0.326 mg/kg, Zmix = 0. 458 ± 0.101 mg/kg, γ = 0.251, Tc = 4.928, Tt = 3.84, P< 0.05). The results demonstrate that for the same level of activity (50%), smaller doses of each substance can be used, compared to the doses of the substances administered alone, which might contribute to a reduction in the number or severity of adverse effects. on the other side, the demonstration of the synergism might contribute to the clarification of the action mechanisms. The experiments presented below were made in agreement with the rules and regulations concerning the work with lab animals.

Arrabidaea brachypoda (DC) Bureau is a medicinal plant found in Brazil. Known as "cipó-una", it is popularly used as a natural therapeutic agent against pain and inflammation. This study evaluated the chemical composition and antinociceptive activity of the dichloromethane fraction from the roots of A. brachypoda (DEAB) and its mechanism of action. The chemical composition was characterized by high-performance liquid chromatography, and this fraction is composed only of dimeric flavonoids. The antinociceptive effect was evaluated in formalin and hot plate tests after oral administration (10-100 mg/kg) in male Swiss mice. We also investigated the involvement of TRPV1 (transient receptor potential vanilloid 1), TRPA1 (transient receptor potential ankyrin 1), TRPM8 (transient receptor potential melastatin 8), and ASIC (acid-sensing ion channel), as well as the opioidergic, glutamatergic, and supraspinal pathways. Moreover, the nociceptive response was reduced (30 mg/kg) in the early and late phase of the formalin test. DEAB activity appears to involve the opioid system, TRPM8, and ASIC receptors, clearly showing that the DEAB alleviates acute pain in mice and suggesting the involvement of the TRPM8 and ASIC receptors and the opioid system in acute pain relief. [ABSTRACT FROM AUTHOR]

Purpose: The current study was designed to investigate the antinociceptive effects of several biuret derivatives with N, N`-diphenyl, N-phenyl-N`-alkylphenyl, N,N`-bis alkylphenyl, 2-methylquinoline-4-yl, benzo[d]thiazol-2-ylthio and (1-phenyl-1H-tetrazol-5-yl)thio substituents on the formalin-evoked pain in mice. Methods: Antinociceptive activity of the nine biurets derivatives were assessed at different doses in mice using formalin test and the results were compared with those of indomethacin(20 mg/kg) and vehicle of the compounds. Area under the pain score curve against time (AUEC) up to 60 minutes was used as the measure of pain behavior. Results: A rather good analgesic effect was seen for most of the tested biuret derivatives. Significant reduction in median AUEC0-5 minutes was observed at the doses of 50 and 25 mg/kg for biurets with either benzyl and 2-methylquinoline-4-yl (C8) or phenylethyl and benzo[d]thiazol-2-ylthio(C9) moieties, respectively(p-value

Objective: The aim of this study was to evaluate the antinociceptive activity of the methanol extract of Tabebuia hypoleuca stems (THME).Materials and Methods: The animals were divided into 5 groups of 8 mice for each test (negative controls, positive controls, and 3 groups treated with THME at doses of 150, 300, and 500 mg/kg, p.o.). The antinociceptive effect of THME was evaluated using the writhing, formalin, tail flick, and hot plate models in mice.Results: In the writhing test, THME (150, 300, and 500 mg/kg) produced significantly (p < 0.001) fewer writhes induced by acetic acid than in the control group. In the formalin test, the licking time for THME at doses of 300 and 500 mg/kg was significantly shorter (p < 0.001) compared to the control group in the first phase of the formalin test, whereas in the second phase only the dose of 500 mg/kg showed an antinociceptive effect. In addition, THME at doses of 300 and 500 mg/kg significantly increased the latency time in the tail flick test (p < 0.05 and p < 0.001, respectively) and in the hot plate test (p < 0.01 and p < 0.001, respectively) compared to the control group.Conclusions: These results show that THME had antinociceptive activity using several models of nociception, and they suggest that the effect is mediated by the participation of both peripheral and central antinociceptive mechanisms. [ABSTRACT FROM AUTHOR]

Acetaminophen is one of the most popular and widely used analgesics for the treatment of pain and fever but few studies have evaluated its effects on neuropathic pain. This study examined the effect of acetaminophen on thermal hyperalgesia, mechanical and cold allodynia in a rat model of neuropathic pain. Male Sprague-Dawley rats were prepared by tightly ligating the left L5 and L6 spinal nerves to produce a model of neuropathic pain. Sixty neuropathic rats were assigned randomly into six groups. Normal saline and acetaminophen (25, 50, 100, 200 and 300 mg/kg) were administered intraperitoneally to these individual groups. Thermal hyperalgesia, mechanical and cold allodynia were examined at preadministration and at 15, 30, 60, 90, 120, 180, 240 and 360 min after administering the drug. Mechanical allodynia was quantified by measuring the paw withdrawal threshold to stimuli with von Frey filaments. Cold allodynia was quantified by measuring the frequency of foot lift after applying 100% acetone. Thermal hyperalgesia was quantified by measuring the thermal withdrawal threshold. The rotarod performance was measured to detect any drug-induced adverse effects, such as drowsiness. The hepatic and renal adverse effect was also assessed by measuring the serum levels of aspartate aminotransferase, alanine aminotransferase, blood urea nitrogen and creatinine. The paw withdrawal thresholds to mechanical stimuli and the thermal withdrawal threshold were increased significantly and withdrawal frequencies to cold stimuli were reduced by acetaminophen administration in a dose-dependent manner. Acetaminophen reduces thermal hyperalgesia, mechanical and cold allodynia in a rat model of neuropathic pain, and might be useful for managing neuropathic pain.

The ethanol extract from Vernonia polyanthes leaves (EEVP) was investigated for antinociceptive and anti-inflammatory effects at the doses (p.o.) of 100, 200 and 400 mg/kg in animal models. The extract reduced the number of abdominal contortions by 16.75% and 31.44% at a dose of 200 and 400 mg/kg, respectively. The results obtained showed that EEVP exerted a significant antinociceptive effect in the two phases of formalin. The EEVP increased the reaction time on a hot plate at the doses of 100, 200 and 400 mg/kg after 90 min of treatment. The paw edema was reduced by EEVP at the doses of 100, 200 and 400 mg/kg after 4 h of application of carrageenan. Doses of 200 and 400 mg/kg, administered 4 h before the carrageenan injection, significantly reduced the exudate volume (29.25 and 45.74%, respectively) and leukocyte migration (18.19 and 27.95%, respectively). These results suggest that V. polyanthes can be an active source of substances with antinociceptive and anti-inflammatory activities.

The objective of the present study was to determine the antihyperalgesic effect of sertraline, measured indirectly by the changes of sciatic afferent nerve activity, and its effects on cardiorespiratory parameters, using the model of formalin-induced inflammatory nociception in anesthetized rats. Serum serotonin (5-HT) levels were measured in order to test their correlation with the analgesic effect. Male Wistar rats (250-300 g) were divided into 4 groups (N = 8/per group): sertraline-treated group (Sert + Saline (Sal) and Sert + Formalin (Form); 3 mg·kg-1·day-1, ip, for 7 days) and saline-treated group (Sal + Sal and Sal + Form). The rats were injected with 5% (50 µL) formalin or saline into the right hind paw. Sciatic nerve activity was recorded using a silver electrode connected to a NeuroLog apparatus, and cardiopulmonary parameters (mean arterial pressure, heart rate and respiratory frequency), assessed after arterial cannulation and tracheotomy, were monitored using a Data Acquisition System. Blood samples were collected from the animals and serum 5-HT levels were determined by ELISA. Formalin injection induced the following changes: sciatic afferent nerve activity (+50.8 ± 14.7%), mean arterial pressure (+1.4 ± 3 mmHg), heart rate (+13 ± 6.8 bpm), respiratory frequency (+4.6 ± 5 cpm) and serum 5-HT increased to 1162 ± 124.6 ng/mL. Treatment with sertraline significantly reduced all these parameters (respectively: +19.8 ± 6.9%, -3.3 ± 2 mmHg, -13.1 ± 10.8 bpm, -9.8 ± 5.7 cpm) and serum 5-HT level dropped to 634 ± 69 ng/mL (P < 0.05). These results suggest that sertraline plays an analgesic role in formalin-induced nociception probably through a serotonergic mechanism.

Arrabidaea brachypoda (DC) Bureau is a medicinal plant found in Brazil. Known as “cipó-una”, it is popularly used as a natural therapeutic agent against pain and inflammation. This study evaluated the chemical composition and antinociceptive activity of the dichloromethane fraction from the roots of A. brachypoda (DEAB) and its mechanism of action. The chemical composition was characterized by high-performance liquid chromatography, and this fraction is composed only of dimeric flavonoids. The antinociceptive effect was evaluated in formalin and hot plate tests after oral administration (10–100 mg/kg) in male Swiss mice. We also investigated the involvement of TRPV1 (transient receptor potential vanilloid 1), TRPA1 (transient receptor potential ankyrin 1), TRPM8 (transient receptor potential melastatin 8), and ASIC (acid-sensing ion channel), as well as the opioidergic, glutamatergic, and supraspinal pathways. Moreover, the nociceptive response was reduced (30 mg/kg) in the early and late phase of the formalin test. DEAB activity appears to involve the opioid system, TRPM8, and ASIC receptors, clearly showing that the DEAB alleviates acute pain in mice and suggesting the involvement of the TRPM8 and ASIC receptors and the opioid system in acute pain relief.