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Abstract Recent findings have demonstrated new therapeutic functions of cardiotonic steroids, a process that is termed drug repositioning. Despite the confirmed anti-inflammatory effects of cardiotonic steroids, their clinical use has been discouraged due to toxicity related to inhibition of the Na+/K+ ATPase. A novel synthetic compound derived from digoxin, 21‑benzylidene digoxin (21‑BD), does not inhibit this enzyme. Herein, we evaluated the anti-inflammatory and antinociceptive effects and acute toxicity of 21‑BD. Murine (Swiss mice) models of paw oedema induced by carrageenan, acetic acid-induced abdominal writhing, and formalin and acute toxicity tests were used. Oral administration of 21‑BD (0.3 mg/kg) showed a significant and prolonged inhibition of paw oedema. Histological analysis demonstrated a reduction in inflammatory cells and expression of inducible nitric oxide synthase (iNOS) in footpads 6 h after administration of carrageenan. 21‑BD (0.3 mg/kg) also reduced the levels of tumour necrosis factor (TNF)-α 2 and 4 h after carrageenan. 21‑BD demonstrated antinociceptive activity, inhibiting abdominal writhes at all tested doses. However, in the formalin test, 21‑BD did not present antinociceptive activity. In the acute toxicity test, 21‑BD did not cause symptoms of toxicity or mortality. The present study demonstrated, for the first time, that 21‑BD is safe and exhibits a marked anti-inflammatory activity in acute local inflammation. This effect might be a consequence of its ability to inhibit the release of the PMN leucocyte-derived mediators, including TNF-α, and iNOS expression as well as its inhibitory effect on oedema and PMN leucocyte infiltration. Graphical abstract Unlabelled Image Highlights • 21‑BD exhibits marked anti-inflammatory activity in acute local inflammation. • 21‑BD inhibited paw oedema, leucocyte migration, iNOS expression and TNF-α levels. • 21‑BD does not exhibit pronounced antinociceptive activity. • In an acute toxicity test 21‑BD did not cause symptoms of toxicity or mortality. [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.

The results of controlled investigations suggest that botulinumtoxin type A (BTA) leads to decrease headache intensity and prevent migraine attacks. The antinociceptive mechanisms of BTA action remain unclear. Modern and previous hypothesis of antinociceptive action BTA in chronic migraine (CM) are discussed in details. Recent experimental and clinical evidence strongly suggest that BTA has aspecific antinociceptive effect realized through inhibition of proinflammatory neurotransmitters release not only from the sensory terminals but from muscle nociceptors. The mechanism of the action of BTA in CM has more than one target and is considered to involve different pathophysiological levels CM: neurogenic inflammation, peripheral and central sensitization. The administration of BTA on the PREEMPT principle (paradigm) ensures optimal neurotoxin distribution in the anatomic areas in accordance with their sensory innervation by cervical segments and sensory fibers in the trigeminal system, the terminal branches which are the major target of BTA in the treatment of CM.

Ethnopharmacological relevance Schinopsis brasiliensis is a native plant from Brazil, popularly used in folk medicine to relieve pain and treat inflammation. This study evaluated the antinociceptive and anti-inflammatory activities and antioxidant properties of the hydroethanol extract (HEE) and ethyl acetate fraction (EAF) obtained from S. brasiliensis bark. Materials and methods The HEE and EAF of S. brasiliensis bark (10, 30 and 100 mg/kg, p.o.) were evaluated using models of analgaesia (formalin-induced licking and hot-plate models) or inflammation (licking response by formalin-induced and carrageenan-induced cell migration into the subcutaneous air pouch). The antioxidant activities of HEE and EAF (50, 100 and 200 µg/ml) were evaluated using the lipoperoxidation method induced in egg yolk by 2′-azobis(2-amidinopropane) dihydrochloride (AAPH) and FeSO 4 . Results HEE and EAF presented a central antinociceptive effect (at 100 mg/kg dose), increasing the baseline and area under the curve in the hot plate model. EAF (100 mg/kg) significantly reduced (p< 0.005) the pain response in the first (45%) and second (35%) phases of the formalin-induced licking model, while HEE (100 mg/kg) reduced (38%) only the pain response in the second phase. Regarding anti-inflammatory activity, EAF (100 mg/kg) also inhibited the inflammatory process induced by subcutaneous carrageenan injection in the SAP model, reducing the amount of the cytokine TNF-α produced. Conclusion HEE and EAF from S. brasiliensis bark show pharmacological interest because they were able to inhibit the peripheral and central transmission of pain. Our data also suggest that the anti-inflammatory activity caused by EAF exposure occurs through the inhibition of the pro-inflammatory cytokine TNF-α, also reducing the spreading of the inflammatory processes by neutralizing reactive oxygen species, which are by-products in the biosynthesis of pain mediators. [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

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]

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]

The molecular modification and synthesis of compounds is vital to discovering drugs with desirable pharmacological and toxicity profiles. In response to pyrazole compounds' antipyretic, analgesic, and anti-inflammatory effects, this study sought to evaluate the analgesic, anti-inflammatory, and vasorelaxant effects, as well as the mechanisms of action, of a new pyrazole derivative, 5-[1-(4-fluorophenyl)-1 H-pyrazol-4-yl]-2 H-tetrazole. During the acetic acid-induced abdominal writhing test, treatments with 5-[1-(4-fluorophenyl)-1 H-pyrazol-4-yl]-2 H-tetrazole reduced abdominal writhing, while during the formalin test, 5-[1-(4-fluorophenyl)-1 H-pyrazol-4-yl]-2 H-tetrazole reduced licking times in response to both neurogenic pain and inflammatory pain, all without demonstrating any antinociceptive effects, as revealed during the tail flick test. 5-[1-(4-fluorophenyl)-1 H-pyrazol-4-yl]-2 H-tetrazole also reduced carrageenan-induced paw edema and cell migration during the carrageenan-induced pleurisy test. As demonstrated by the model of the isolated organ, 5-[1-(4-fluorophenyl)-1 H-pyrazol-4-yl]-2 H-tetrazole exhibits a vasorelaxant effect attenuated by Nω-nitro- l-arginine methyl ester, 1H-[1,2,4]oxadiazolo[4,3-alpha]quinoxalin-1-one, tetraethylammonium or glibenclamide. 5-[1-(4-fluorophenyl)-1 H-pyrazol-4-yl]-2 H-tetrazole also blocked CaCl2-induced contraction in a dose-dependent manner. Suggesting a safe toxicity profile, 5-[1-(4-fluorophenyl)-1 H-pyrazol-4-yl]-2 H-tetrazole reduced the viability of 3T3 cells at higher concentrations and was orally tolerated, despite signs of toxicity in doses of 2000 mg/kg. Lastly, the compounds' analgesic activity might be attributed to the involvement of the NO/cGMP pathway and K+ channels observed in the vasorelaxant effect. [ABSTRACT FROM AUTHOR]

Aerial parts (leaves and stems) of Berberis ruscifolia Lam. are a usual preparation as an analgesic, anti-inflammatory, antimalarial, antibacterial, and digestive in folk medicine. However, there were no previous studies of its chemical composition and biological activity related to analgesic effects. The evaluation of the anti-nociception of the infusion (I), the decoction (D), and the ethanolic extract (EE) obtained from aerial parts of B. ruscifolia and its main chemical constituent in them, in mouse models. The chemical constituent of B. ruscifolia extracts was evaluated and quantified by LC-MS and HPLC methodology. The inhibition of nociception in mice was analyzed by formalin and acetic acid-induced contortions tests. Also, when the formalin test was performed to evaluate the antinociceptive activity, the inhibition of edema formation and the antipyretic effect of each extract were simultaneously evaluated in the same experiment. For the oral administration in the in vivo assays, doses ranging from 10 to 1000 mg/kg and 10–30 mg/kg were used for extract and the chemical compound, respectively. The presence of berberine (Berb) was identified in the three evaluated extracts where the EE showed the highest content of this compound getting a yield of 2%, while in the I and D, Berb is present at 0.2%. The three extracts promoted a reduction of the contortions induced by acetic acid, being observed in EE the highest activity with 63 ± 6% of significant inhibition of the nociceptive behavior at a dose of 300 mg/kg, while D significantly inhibited 32 ± 12% at the same dose and for I at a dose of 1000 mg/kg an inhibition of 44 ± 8% was observed. Likewise, in the formalin trial, I and EE reduced nociception at a dose of 1000 (31 ± 5%) and 300 (35 ± 3%) mg/kg, respectively in the neurogenic phase, while in the second phase of the experiment, all the extracts evaluated showed an antinociceptive effect, with significant inhibition of I of 54 ± 6% and D of 44 ± 5% at a dose of 1000 mg/kg and for EE showed a 63 ± 2% inhibition at a dose of 300 mg/kg being the one with the highest antinociceptive activity. These extracts showed no inhibition in temperature and formalin-injected paw edema formation when compared to the control. As for Berb, at a 30 mg/kg dose, it showed significant inhibition of 70 ± 5% in the acetic acid-induced contortion test. Altogether, the present results evidenced the analgesic properties of B. ruscifolia , scientific information presented for the first time, and also provided important knowledge not reported so far about the chemical composition of its extracts, by identifying the presence of Berb in them. Finally, we were able to conclude that the analgesic effect demonstrated by this medicinal plant is partly due to the presence of Berb. [Display omitted] • For the first time, the presence of Berberine alkaloid in Berberis ruscifolia extracts was demonstrated. • The extracts of the medicinal plant B. ruscifolia demonstrated an analgesic effect an in vivo assays. • EE showed the most analgesic effect that can be correlated with its higher berberine content. • The participation of berberine in the analgesic effect observed was demonstrated. [ABSTRACT FROM AUTHOR]

It has been indicated that acute and chronic morphine administrations enhance nociceptin/orphanin FQ (N/ OFQ) levels in the brain, which might play role in the development of tolerance to the antinociceptive effect of morphine. Accordingly, N/ OFQ receptor ( NOP) antagonists have been shown to prevent the development of antinociceptive tolerance to morphine. Our aim is to observe whether cannabinoids, similarly to opioids, enhance N/ OFQ levels in pain-related brain regions and whether antagonism of NOP receptors attenuates the development of tolerance to the antinociceptive effect of cannabinoids. Hot plate and Tail flick tests are used to assess the antinociceptive response in Sprague-Dawley rats. N/ OFQ levels are measured in cortex, amygdala, hypothalamus, periaqueductal gray, nucleus raphe magnus and locus coeruleus of rat brains using Western blotting and immunohistochemistry. Within 9 days, animals became completely tolerant to the antinociceptive effect of the cannabinoid agonist WIN 55,212-2 (2, 4, 6 mg/kg, i.p.). Chronic administration of JTC-801, a NOP receptor antagonist, at a dose that exerted no effect on its own (1 mg/kg, i.p.), attenuated development of tolerance to the antinociceptive effect of WIN 55,212-2 (4 mg/kg, i.p.). Western blotting and immunohistochemistry results showed that N/ OFQ levels significantly increased in amygdala, periaqueductal gray, nucleus raphe magnus and locus coeruleus of rat brains when WIN 55,212-2 was combined with JTC-801. We hypothesize that, similar to opioids, chronic cannabinoid + NOP antagonist administration may enhance N/ OFQ levels and NOP receptor antagonism prevents development of tolerance to cannabinoid antinociception. [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.

Rhus genus is commonly known as sumac and widely used in the folk medicine. Rhus virens is a plant commonly used to treat diabetes or pain in the northern territory of Mexico. Even though R. virens is used in the folk medicine there is still a lack of evidence about the pharmacological effect of this species. The aim of this study was to determine the antinociceptive, anti-inflammatory and antioxidant effect of R. virens through a bio-guided chemical separation. The aqueous, methanolic, and hexane extract of R. virens were obtained and tested in the formalin test, TPA-induced ear edema, and DPPH, ABTS, and FRAP assay. Also, possible interaction of pain pathways was studied using naloxone, bicuculline, L-NAME, ODQ, and glibenclamide in the formalin test in mice. Rhus virens methanolic extract (30 mg/kg, p.o.) produced higher antinociceptive activity in both the early and late phases of the formalin test (35.0 and 52.9%, respectively). Also, pre-administration with naloxone, bicuculline, L-NAME, ODQ and glibenclamide prevented the antinociceptive effect of R. virens in the early phase of the formalin test. Meanwhile, only naloxone and bicuculline prevented the antinociceptive effect on the late phase of the formalin test. Chemical separation of methanolic extract allowed to isolate 1,2,3,4,6-penta- O -galloyl-glucopyranose (PGG), it was tested in the formalin test, producing an antinociceptive effect on the late phase of the formalin test. On the other hand, topical application of the derivatives of R. virens methanolic extract produced an anti-inflammatory effect in the TPA-induced ear edema, being PGG an anti-inflammatory molecule. Lastly, radical scavenging activity was higher in the extracts of higher polarity, comparable to the standard used Camellia sinensis. In conclusion, R. virens produce an antinociceptive, anti-inflammatory and free-radical scavenging activity. The antinociceptive effect could be related to the opioidergic, GABAergic, and NO-GMPc-K + ATP channels pathways. These effects could be partially produced by the presence of PGG. [Display omitted] [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. [ABSTRACT FROM AUTHOR]

The combination of pomegranate seed oil and ketoprofen in nanoemulsions aiming to improve the antinociceptive effect was evaluated according to the writhing test and Complete Freud’s Adjuvant induced paw inflammation in mice. The formulations showed adequate characteristics and improved ketoprofen’s photostability against UVC radiation exposure. The dialysis bag technique showed that 100% of the drug was released from the nanoemulsions after 3 h and the oil amount had no influence on the releasing. Furthermore, time- and dose-response curves were obtained to determine the antinociceptive effect of the formulations. In the post-test, the nanoemulsion containing ketoprofen significantly reduced abdominal constrictions in time-response curve, showing effect up to 12 h while the free ketoprofen showed effect up to 3 h. In addition, the blank nanoemulsion presented a reduction of abdominal constriction up to 1 h of pre-treatment. Regarding the dose-response curve, the free ketoprofen presents effect at 0.5 mg/Kg dose and nanoemulsion at 1.0 mg/Kg dose. Time- and dose-response curves were performed to determine the antinociceptive effect in inflammatory pain. After the evaluation of mechanical allodynia testing at the Von Frey Hair, the free ketoprofen showed effect up to 6 h while nanoemulsions presented effect up to 10 h. Moreover, acute toxicity was performed with ALT and AST activity evaluations and urea levels. After 7 days of treatment, no toxic effects for nanoemulsions were found. In conclusion, ketoprofen-loaded pomegranate seed oil nanoemulsions presented adequate characteristics and a high antinociceptive activity in the animal models tested. [ABSTRACT FROM AUTHOR]

Structurally different water-insoluble (1 → 3),(1 → 6) β- d -glucans were isolated from aqueous and alkaline extracts of the mushroom-forming ascomycete Cookeina tricholoma , a wild edible mushroom found in Brazilian Amazon forest. The structures showed different substitution patterns, which may influence their extractability and consequently their conformation in solution, and different M W (4.3 × 10 5 Da, 3.7 × 10 5 Da and 8.2 × 10 5 Da, for ICW- Ct , IHW- Ct and IK2- Ct , respectively). The main-chains are composed of (1 → 3)-linked β- d -Glc p units O-6 substituted by side chains with different lengths of (1 → 6)-linked β- d -Glc p units (ICW- Ct and IHW- Ct ) or by a combination of (1 → 6)-linked β- d -Glc p units and single units of β- d -Glc p (IK2- Ct ). β- d -glucans with similar M W and showing only (1 → 6)-linked β- d -Glc p units as side chains (ICW- Ct and IHW- Ct ) showed significant inhibition of neurogenic pain, 69 ± 11 and 57 ± 11% at the dose of 10 mg kg −1 , respectively, in the model of nociception induced by intraplantar injection of formalin. [ABSTRACT FROM AUTHOR]

Peripheral painful neuropathy is one of the most common complications in diabetes and necessitates improved treatment. Fisetin, a naturally occurring flavonoid, has been reported to exert antidepressant-like effect in previous studies. As antidepressant drugs are employed clinically to treat neuropathic pain, this work aimed to investigate whether fisetin posses beneficial effect on diabetic neuropathic pain and explore the mechanism(s). We subjected mice to diabetes by a single intraperitoneal (i.p.) injection of streptozotocin (200 mg/kg), and von Frey test or Hargreaves test was used to assess mechanical allodynia or thermal hyperalgesia, respectively. Chronic treatment of diabetic mice with fisetin not only ameliorated the established symptoms of thermal hyperalgesia and mechanical allodynia, but also arrested the development of neuropathic pain when given at low doses. Although chronic fisetin administration did not impact on the symptom of hyperglycemia in diabetic mice, it reduced exacerbated oxidative stress in tissues of spinal cord, dorsal root ganglion (DRG) and sciatic verve. Furthermore, the analgesic actions of fisetin were abolished by repetitive co-treatment with the reactive oxygen species (ROS) donor tert -butyl hydroperoxide ( t -BOOH), but potentiated by the ROS scavenger phenyl- N - tert -butylnitrone (PBN). Finally, acute blockade of spinal GABA A receptors by bicuculline totally counteracted such fisetin analgesia. These findings indicate that chronic fisetin treatment can delay or correct neuropathic hyperalgesia and allodynia in mice with type 1 diabetes. Mechanistically, the present fisetin analgesia may be associated with its antioxidant activity, and spinal GABA A receptors are likely rendered as downstream targets. [ABSTRACT FROM AUTHOR]