Formalin Test In Mice Research Articles

Ferulic acid via attenuation of oxidative stress and neuro-immune response utilizes antinociceptive effect in mouse model of formalin test

IntroductionPlenty evidences suggests that neuroinflammation and oxidative stress augmented the neural sensitivity specifying that neuro-immune response is involved in the pathophysiology of pain. Ferulic acid (FA), a natural antioxidant found in various fruits, has various pharmacological properties. The purpose of the current study was to assess the antinociceptive effect of FA in a mouse model of formalin test with focus on its anti-neuroinflammatory and antioxidative stress effects. MethodsThe injection of FA (40 mg/kg), piroxicam (2 mg/kg), and saline (0.9% NaCl) (1 ml/kg) was done intraperitoneally and after one hour, formalin injected into the plantar surface of the hind paw of mice. Then pain behavior was documented during 60 min. Then mice were euthanized and prefrontal cortex (PFC) samples were taken. Malondialdehyde (MDA) level, antioxidant capacity and expression of inflammatory genes, counting tumor necrosis factor (TNF-) and interleukine 1 (IL-1) evaluated in the PFC. Resultsexhibited that FA declined the pain behavior following injection of formalin. Besides, FA significantly diminished the MDA level and increased the antioxidant capacity in the PFC. We revealed that FA diminished the expression of TNF-α and IL-1β genes in the PFC. ConclusionWe conclude that FA exerted antinociceptive effects in the formalin test in mice, at least partially, by reducing oxidative stress and neuroimmune response in the PFC.

N-palmitoylethanolamide synergizes the antinociception of morphine and gabapentin in the formalin test in mice.

The antinociceptive pharmacological interaction between N-palmitoylethanolamide (PEA) and morphine (MOR), as well as gabapentin (GBP), was investigated to obtain synergistic antinociception at doses where side effects were minimal. In addition, the possible antinociceptive mechanism of PEA + MOR or PEA + GBP combinations was explored. Individual dose-response curves (DRCs) of PEA, MOR and GBP were evaluated in female mice in which intraplantar nociception was induced with 2% formalin. Isobolographic method was used to detect the pharmacological interaction in the combination of PEA + MOR or PEA + GBP. The ED50 was calculated from the DRC; the order of potency was MOR > PEA > GBP. The isobolographic analysis was obtained at a 1:1 ratio to determine the pharmacological interaction. The experimental values of flinching (PEA + MOR, Zexp = 2.72 ± 0.2 μg/paw and PEA + GBP Zexp = 2.77 ± 0.19 μg/paw) were significantly lower than those calculated theoretically (PEA + MOR Zadd = 7.78 ± 1.07 and PEA + GBP Zadd = 24.05 ± 1.91 μg/paw), resulting in synergistic antinociception. Pretreatment with GW6471 and naloxone demonstrated that peroxisome proliferator-activated receptor alpha (PPARα) and opioid receptors are involved in both interactions. These results suggest that MOR and GBP synergistically enhance PEA-induced antinociception through PPARα and opioid receptor mechanisms. Furthermore, the results suggest that combinations containing PEA with MOR or GBP could be of interest in aiding the treatment of inflammatory pain.

Mechanism of Mongolian drug Naru-3 in initiation of neuroinflammation of neuropathic pain from MMP9/IL-1β signaling pathway

Neuropathic pain(NP) has similar phenotypes but different sequential neuroinflammatory mechanisms in the pathological process. It is of great significance to inhibit the initiation of neuroinflammation, which has become a new direction of NP treatment and drug development in recent years. Mongolian drug Naru-3 is clinically effective in the treatment of trigeminal neuralgia, sciatica, and other NPs in a short time, but its pharmacodynamic characteristics and mechanism of analgesia are still unclear. In this study, a spinal nerve ligation(SNL) model simulating clinical peripheral nerve injury was established and the efficacy and mechanism of Naru-3 in the treatment of NPs was discussed by means of behavioral detection, side effect evaluation, network analysis, and experimental verification. Pharmacodynamic results showed that Naru-3 increased the basic pain sensitivity threshold(mechanical hyperalgesia and thermal radiation hyperalgesia) in the initiation of SNL in animals and relieved spontaneous pain, however, there was no significant effect on the basic pain sensitivity threshold and motor coordination function of normal animals under physiological and pathological conditions. Meanwhile, the results of primary screening of target tissues showed that Naru-3 inhibited the second phase of injury-induced nociceptive response of formalin test in mice and reduced the expression of inflammatory factors in the spinal cord. Network analysis discovered that Naru-3 had synergy in the treatment of NP, and its mechanism was associated with core targets such as matrix metalloproteinase-9(MMP9) and interleukin-1β(IL-1β). The experiment further took the dorsal root ganglion(DRG) and the stage of patho-logical spinal cord as the research objects, focusing on the core targets of inducing microglial neuroinflammation. By means of Western blot, immunofluorescence, agonists, antagonists, behavior, etc., the mechanism of Naru-3 in exerting NP analgesia may be related to the negative regulation of the MMP9/IL-1β signaling pathway-mediated microglia p38/IL-1β inflammatory loop in the activation phase. The relevant research enriches the biological connotation of Naru-3 in the treatment of NP and provides references for clinical rational drug use.

The Additive Antinociceptive Effect of Resveratrol and Ketorolac in the Formalin Test in Mice.

Pain represents one of the leading causes of suffering and disability worldwide. Currently available drugs cannot treat all types of pain and may have adverse effects. Hence, the use of pharmacological combinations is an alternative treatment strategy. Therefore, this study aimed to evaluate the combination of resveratrol and ketorolac through isobolographic analysis. CD1 mice were used to study the antinociceptive effect of this combination using the formalin test and the study was divided into two phases. In the first phase, four individual doses of each drug were evaluated, totaling eight testing groups. From these data, the median effective doses (ED50) of each drug were calculated. In the second phase, four testing groups were used to evaluate the combination of sub-doses of both drugs and obtain the experimental ED50. To evaluate gastric damage, five groups were employed, including indomethacin, vehicle, resveratrol, ketorolac, and combined resveratrol and ketorolac groups. Stomach samples from the mice were taken after 5 h of treatment, and the area of the ulcers was determined. Resveratrol plus ketorolac elicited a reduction in nociceptive behavior during both phases of the formalin test, and isobologram analysis revealed that the theoretical and experimental ED50 values of resveratrol and ketorolac did not differ significantly, implying an additive interaction between the drugs. Additionally, the drug combination did not generate gastric ulcers, thus enhancing the desired effects without increasing the adverse effects. Consequently, these findings substantiate the efficacy of the resveratrol and ketorolac combination in the formalin test, thereby highlighting its potential as a viable alternative for alleviating pain.

Potent anticonvulsant compounds with anti-hyperalgesic activity in mouse formalin test of hyperalgesia

Potent anticonvulsant compounds with anti-hyperalgesic activity in mouse formalin test of hyperalgesia

Segmental Upregulation of ASIC1 Channels in the Formalin Acute Pain Mouse Model.

Hindpaw injection of formalin in rodents is used to assess acute persistent pain. The response to formalin is biphasic. The initial response (first minutes) is thought to be linked to inflammatory, peripheral mechanisms, while the latter (around 30 min after the injection), is linked to central mechanisms. This model is useful to analyze the effect of drugs at one or both phases, and the involvement of ion channels in the response. Acid-sensing ion channels (ASICs) regulate synaptic activities and play important roles in pain conditions. Recently, psalmotoxin-1 (Pctx-1), a toxin that inhibits ASIC1a-constituted channels, and antisense ASIC1a-RNA, intrathecal administered in mice were shown to affect both phases of the test. The mouse formalin test was performed on C57/BL6 7- to 9-week-old mice. Behavioral tests were conducted and tissue was extracted to detect proteins (ASIC1 and pERK) and ASIC1-mRNA and mir485-5p levels. The injection of formalin was accompanied by an increase in ASIC1 levels. This was detected at the contralateral anterior cingulate cortex (ACC) compared to the ipsilateral side, and both sides of the ACC of vehicle-injected animals. At the spinal cord and dorsal root ganglia, ASIC1 levels followed a gradient stronger at lumbar (L) 3 and decreased towards L5. Gender differences were detected at the ACC; with female mice showing higher ASIC1a levels at the ACC. No significant changes in ASIC1-mRNA levels were detected. Evidence suggests ASIC1 upregulation depends on regulatory microRNAs. This work highlights the important role of ASIC1 in pain and the potential role of pharmacological therapies aimed at this channel.

The Ethanol Extract of Syringa oblata Heartwood, a Mongolian Folk Medicine Containing Major Lignans, Exerts Analgesic and Sedative Effects on Mice.

The heartwood of Syringa oblata Lindl. (SO) is one of Mongolian folk medicines to treat insomnia and pain, while its pharmacological evaluation and underlying mechanism remain unclear. In this study, the sedative effect of ethanol extract of SO (ESO) was evaluated with the locomotor activity test and the threshold dose of pentobarbital sodium-induced sleep test in mice, and the hot plate test, acetic acid-induced writhing test, and formalin test in mice were used to evaluate its analgesic effect. The underlying mechanism of ESO analgesia was explored by RT-PCR and western blot analysis, which is associated with the regulation of the NF-κB signaling pathway. Besides, the main constituents of ESO were characterized by LC/MS data analysis and comparison with isolated pure compounds. The current findings brought evidence for clinical application and further pharmacological and phytochemical studies on SO.

Separation and evaluation of potential antioxidant, analgesic, and anti-inflammatory activities of limonene-rich essential oils from Citrus sinensis (L.)

Abstract The peel of Citrus sinensis (L.) Osbeck is a source of essential oils, particularly limonene, which is this plant’s characteristic molecule. The main goal of this study was to test the potential analgesic and anti-inflammatory properties of limonene-rich essential oils derived from the peel of C. sinensis L. (orange) in vivo, as well as their antioxidant activity in vitro. Carrageenan-induced paw edema in Wistar rats and the formalin test in Swiss albino mice were used to examine anti-inflammatory activity. The analgesic activity was assessed using hot plate and acetic acid writhing tests, while the antioxidant activity was assessed using the 1,1-diphenyl-2-picrylhydrazyl and ferric reducing antioxidant power methods. The essential oil (EO) safety was determined using an acute toxicity experiment on mice. The phytochemical analysis confirmed the existence of limonene as the primary molecule (88.94%), and in vivo experiments revealed that the EO had a significant pain and inflammation-relieving effect, especially at the dose of 50 mg/kg, when compared to the used control drugs. The acute toxicity evaluation reported this EO’s safety. This study contributes to the pharmacological valorization of the peel of C. sinensis L., confirming that, in addition to its numerous cosmetic and industrial uses, it may be effective in the treatment of inflammatory and pain-related illnesses.

2-Arylpropionic Acid Pyrazolamides as Cannabinoid CB2 Receptor Inverse Agonists Endowed with Anti-Inflammatory Properties.

Among the most recent proposals regarding the mechanism of action of dipyrone, the modulation of cannabinoid receptors CB1 and CB2 appears to be a promising hypothesis. In this context, the present work describes a series of five novel pyrazolamides (7-11) designed as molecular hybrids of dipyrone metabolites and NSAIDs, such as ibuprofen and flurbiprofen. Target compounds were obtained in good overall yields (50-80%) by classical amide coupling between 4-aminoantipyrine and arylacetic or arylpropionic acids, followed in some cases by N-methylation of the amide group. The compounds presented good physicochemical properties in addition to stability to chemical (pH 2 and 7.4) and enzymatic (plasma esterases) hydrolysis and showed medium to high gastrointestinal and BBB permeabilities in the PAMPA assay. When subjected to functional testing on CB1- or CB2-transfected cells, compounds demonstrated an inverse agonist profile on CB2 receptors and the further characterization of compound LASSBio-2265 (11) revealed moderate binding affinity to CB2 receptor (Ki = 16 µM) with an EC50 = 0.36 µM (Emax = 63%). LASSBio-2265 (11) (at 1, 3, and 10 mg/kg p.o.) was investigated in the formalin test in mice and a remarkable analgesic activity in the late inflammatory phase was observed, suggesting it could be promising for the treatment of pain syndromes associated with chronic inflammatory diseases.

Systemic administration of dorsomorphin relieves inflammatory nociception in the mouse formalin test.

Inflammatory pain is the most important clinical symptom of inflammatory diseases. Despite intensive research into inflammatory pain mechanisms, the majority of analgesics available are based on mechanistic classes of compounds that have been known for many years, as a result, inflammatory pain control remains a challenge for drug design in the context of clinically unmet needs in terms of safety and efficacy. A growing literature supports that pro-inflammatory cytokine signaling plays a crucial role in the development of inflammatory pain. Modulation of the pro-inflammatory cytokine may hold the key to improved pain management. Previous studies have reported that dorsomorphin played key roles in inflammation. But the role of dorsomorphin in the formalin-induced inflammatory nociception in mice has never been reported. Here, we report a new function of dorsomorphin which can inhibit formalin-induced inflammatory nociception in mice. The antinociceptive effect of dorsomorphin mainly depended on inhibiting the p38 MAPK/c-fos signaling and regulating inflammatory mediators.

Bio-guided study of the antinociceptive, anti-inflammatory, and free-radical scavenging capacity of the leaves of Rhus virens Lindh. ex A. Gray and its possible mechanism of antinociception

Ethnopharmacological relevanceRhus 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. Aim of the studyThe aim of this study was to determine the antinociceptive, anti-inflammatory and antioxidant effect of R. virens through a bio-guided chemical separation. Materials and methodsThe 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. ResultsRhus 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. ConclusionsIn 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.

Melatonin synergizes with the antinociceptive effect of N-palmitoylethanolamide and paracetamol.

Melatonin has been shown to have an antinociceptive effect and its administration could enhance the antinociceptive effect of other drugs. This study assessed the antinociceptive effects of melatonin in combination with paracetamol and N-palmitoylethanolamide (PEA) using the formalin test in mice. Melatonin, paracetamol, and PEA were administered intraplantarly (paw) alone or combined to mice. A concentration-response curve was generated to determine the concentration needed to reach 30% of the maximal antinociceptive effect (EC30). Melatonin, paracetamol and PEA induced a concentration-dependent antinociceptive effect in both phases of the formalin test, being PEA more potent (EC30 = 7.4±0.2 mg/paw) than melatonin (EC30 = 20.5±3.1 mg/paw) or paracetamol (EC30 = 41.8±2.6 mg/paw). Combinations of melatonin with paracetamol or PEA also induced a concentration-dependent antinociceptive effect in the formalin test. Isobolographic analysis showed that melatonin interacts synergistically with either paracetamol or PEA to reduce formalin-induced inflammatory pain. However, the experimental values of EC30 were significantly smaller than those calculated theoretically.

Antinociceptive activity of Pereskia sacharosa Griseb. (Cactaceae) and localization of bioactive compounds in mice brain

BackgroundPereskia sacharosa Griseb is mainly distributed in the Bolivian Amazon. It is widely used to treat infections and pain in traditional medicine, such as headache, muscle pain, stomachache, and inflammation. PurposeThis study aimed to evaluate the antinociceptive activity of the leaf ethanolic extract and fractions of P. sacharosa that was obtained through micropropagation, possible mechanisms of action, and to identify the main bioactive compound by high liquid chromatography-mass spectrometry, as well as its localization in the brain of mice by means of histological analysis and epifluorescence. MethodsThe fractions (C1F9 and C2F13) were isolated from the ethanolic extract of P. sacharosa leaves using open column chromatography. The antinociceptive activity of the ethanolic extract (10–100 mg kg−1, intra peritoneal, i.p.) and fractions C1F9 and C2F13 (30 mg kg−1, i.p.) were evaluated in a nociceptive pain model (formalin test) in mice. In addition, a possible mechanism of action was investigated by exploring some inhibitory receptors using naltrexone (NTX, a non-selective opioid receptor antagonist), flumazenil (FMZ, a benzodiazepine site antagonist in the Gamma-aminobutyric acid A [GABAA] receptor), or WAY100635 (a 5-hydroxytryptamine 1A [5-HT1A] serotonin 1A receptor antagonist). ResultsRegarding the mechanism of action, only antinociceptive activity of treatments in the neurogenic phase of the formalin test was inhibited in the presence of the three explored antagonists. Furthermore, the presence of phenolic compounds was confirmed at the central nervous system (CNS) using their epifluorescence in coronal brain sections and histological analysis. Finally, acid hydrolysis of the ethanolic extract was performed, and it was shown that kaempferol is a product of acid hydrolysis confirmed with a posterior high liquid chromatography-mass spectrometry analysis. ConclusionThe leaves of P. sacharosa contain bioactive metabolites with antinociceptive activity, whereby epifluorescence was an optimum property to detect them at CNS. To the best of our knowledge, this is the first report that provides preclinical evidence of the medicinal use of this species in folk medicine for pain relief.

Antinociceptive effect of Mansoa alliacea polar extracts involves opioid receptors and nitric oxide in experimental nociception in mice.

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 (300mg/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.

Vortioxetine as an analgesic in preclinical inflammatory pain models: Mechanism of action.

Vortioxetine is a novel atypical antidepressant with multimodal activity that has recently demonstrated efficacy against neuropathic pain. There is no published data about its analgesic properties in models characterized by peripheral inflammation and consequent pain pathway sensitization, nor data on its mechanism of antinociceptive action. This study aimed to investigate vortioxetine's antinociceptive/antihyperalgesic effects in trigeminal, visceral, and somatic inflammatory pain models, and provide evidence on its mechanism of action in the modulation of trigeminal nociception. Vortioxetine's effects on the nociceptive behavior in orofacial formalin test (OFT) and acetic acid-writhing test in mice and on mechanical hyperalgesia in carrageenan-induced paw inflammation in rats were examined following peroral single administration. The involvement of serotonergic/adrenergic/cholinergic/cannabinoid/adenosine receptors was evaluated in OFT by intraperitoneally treating mice with an appropriate antagonist immediately after vortioxetine application. We used antagonists of 5-HT1B/1D serotonergic (GR 127935), α1 -adrenergic (prazosin), α2 -adrenergic (yohimbine), β1 -adrenergic (metoprolol), muscarinic (atropine), α7 nicotinic (methyllycaconitine), CB1 /CB2 cannabinoid (AM251 and AM630), and adenosine A1 (DPCPX) receptors. Vortioxetine dose-dependently reduced pain behavior in OFT and acetic acid writhing test, as well as inflammatory hyperalgesia in paw pressure test. All examined antagonists except prazosin dose-dependently inhibited vortioxetine's antinociceptive effects. In conclusion, vortioxetine exerted analgesic efficacy in trigeminal, visceral, and somatic inflammatory pain. The effect is at least in part mediated by 5-HT1B/1D serotonergic, α2 /β1 -adrenergic, muscarinic and nicotinic cholinergic, CB1 /CB2 cannabinoid, and adenosine A1 receptors. These findings contribute to better understanding of the analgesic effect of vortioxetine and suggest its potential usefulness for inflammatory pain treatment.

Evaluating the Antinociceptive Efficacy of Cannabidiol Alone or in Combination with Morphine Using the Formalin Test in Male and Female Mice.

Introduction: Phytocannabinoids have emerged as a potential alternative treatment option for individuals experiencing persistent pain. However, evidence-based research regarding their clinical utility in both males and females remains incomplete. In addition, it is unknown whether combining readily available cannabinoids with opioids has a synergistic or subadditive effect on pain modulation. To begin to fill this knowledge gap, we investigated the antinociceptive effects of the phytocannabinoid, CBD, either alone or in combination with opioids in male and female C57BL/6J mice. Results: Using the formalin test, our results show that CBD (10 mg/kg, i.p.) treatment evoked antinociception in phase I, but not in phase II, of the formalin test in male mice. However, in female mice, CBD showed no significant antinociceptive effect. In addition, a direct sex comparison showed that CBD evoked a significant increase in nociceptive behaviors in female versus male mice during phase I of the formalin test. Furthermore, we show that CBD (10 mg/kg, i.p.) in combination with low-dose morphine (1 mg/kg, i.p.) was ineffective at eliciting a synergistic antinociceptive response in both male and female mice. Lastly, consistent with previous literature, we showed that females treated with a relatively higher dose of morphine (10 mg/kg, i.p.) displayed a significant increase in the variability of nociceptive behaviors compared to morphine-treated male mice. Conclusion: Overall, our results suggest that CBD treatment may have beneficial antinociceptive effects during the acute phase of persistent pain, but these effects are more beneficial to males than females. We provide further pre-clinical support that treatments geared toward reducing nociceptive behaviors differentially affect males and females.

Anti-inflammatory secondary metabolites from Scrophularia kotschyana.

The species belonging to Scrophularia genus grow mainly in Irano-Turanian and Mediterranean regions and have been used as folk remedy for inflammatory-related diseases since ancient times. The present study was aimed to evaluate the anti-inflammatory activity of the extracts of Scrophularia kotschyana as well as the isolated compounds. The aerial parts and the roots of the plant were separately extracted with methanol. Anti-inflammatory activities of both extracts were evaluated with formalin test in mice. As the methanolic extract of the aerial parts significantly (p < .05) inhibited inflammation, it was then submitted to successive solvent extractions with n-hexane, dichloromethane, ethyl acetate and n-butanol to yield subextracts. Anti-inflammatory activities of the subextracts were evaluated within the same test system. Among the subextracts tested, the n-butanol subextract produced a significant (p < .05) anti-inflammatory activity at all doses (5, 10, and 30mg/kg, ip.). Sequential chromatographic separation of the n-butanol subextract yielded 8-O-acetyl-4'-O-(E)-p-coumaroylharpagide, 8-O-acetyl-4'-O-(Z)-p-coumaroylharpagide, β-sitosterol 3-O-β-glucopyranoside, apigenin 7-O-β-glucopyranoside, apigenin 7-O-rutinoside, luteolin 7-O-β-glucopyranoside and luteolin 7-O-rutinoside. The anti-inflammatory activities of the isolates were evaluated at 5mg/kg dose. Luteolin 7-O-β-glucopyranoside and apigenin 7-O-rutinoside caused a significant (p < .05) inhibition of oedema formation.

Antinociceptive and Anti-Inflammatory Effects of Recombinant Crotamine in Mouse Models of Pain.

Crotamine, a toxin found in the venom of the South American rattlesnake Crotalus durissus terrificus, has been reported to have antinociceptive effects. We purified recombinant crotamine expressed in Escherichia coli and investigated its antinociceptive and anti-inflammatory effects using the hot-plate test, acetic-acid-induced writhing method, and formalin test in mice. Recombinant crotamine was administered intraperitoneally (0.04–1.2 mg kg−1) or intraplantarly (0.9–7.5 μg 10 μL−1) before the tests. The paw volume was measured with a plethysmometer. To evaluate the antagonistic and anti-inflammatory effects of naloxone, subcutaneous naloxone (4 mg kg−1) or intraplantar naloxone (5 μg 10 μL−1) was administered before recombinant crotamine. For tumor necrosis factor (TNF)-α assays, blood was drawn 3 h after formalin injection and measured using enzyme-linked immunosorbent assay. Intraperitoneal and intraplantar recombinant crotamine had antinociceptive and anti-inflammatory effects, neither of which were affected by pre-treatment with naloxone. The mean serum TNF-α levels were significantly lower in the intraperitoneal recombinant crotamine (0.4 and 1.2 mg kg−1) or intraplantar (2.5 and 7.5 μg 10 μL−1) recombinant crotamine groups than in the saline group and were not affected by naloxone pre-treatment. In conclusion, recombinant crotamine possesses significant antinociceptive and anti-inflammatory effects that do not appear to be related to the opioid receptor. The antinociceptive and anti-inflammatory effects of intraperitoneal or intraplantar recombinant crotamine are related to TNF-α.

Ananas comosus (L) Merrill (pineapple) fruit peel extract demonstrates antimalarial, anti-nociceptive and anti-inflammatory activities in experimental models

Ethnopharmacology relevancePineapple (Ananas comosus) peel is a major waste in pineapple canning industry and it is reported to be used in ethnomedicine as a component of herbal remedies for malarial management. This study aimed to evaluate the antimalarial, antinociceptive and anti-inflammatory properties of Ananas comosus peel extract (PEAC). MethodsAnanas comosus peel was extracted with 80% methanol. PEAC (100, 200 and 400 mg/kg) was investigated for antimalarial effect using Peter's 4-day suppressive test (4-DST) model in mice. Antinociceptive activity of PEAC was investigated in hot plate, acetic acid-induced writhing and formalin tests in mice. The anti-inflammatory activity was evaluated using the lipopolysaccharides-induced sickness behavior in mice and carrageenan-induced air pouch in rats' models. ResultsPEAC could not significantly (p > 0.05) suppressed parasitemia level at 7-day post-infection in 4-DST. PEAC (400 mg/kg) mildly prolongs survival of infected mice up till day 21. PEAC demonstrated significant (p < 0.05) antinociceptive activity by increasing latency to jump on the hot plate, reduced number of writhings in acetic acid test and reduced paw licking time in 2nd phase of formalin test. PEAC significantly reduced anxiogenic and depressive-like symptoms of sickness behavior in LPS-injected mice. PEAC demonstrated significant anti-inflammatory activity in carrageenan-induced air pouch experiment by reducing exudates formation, inflammatory cell counts, and nitrite, tumor necrosis factor-alpha and interleukin-6 levels. ConclusionAnanas comosus peel extract demonstrated mild antimalarial activity but significant anti-nociceptive and anti-inflammatory properties probably mediated via inhibition of pro-inflammatory mediators.

PCC-0105002, a novel small molecule inhibitor of PSD95-nNOS protein-protein interactions, attenuates neuropathic pain and corrects motor disorder associated with neuropathic pain model

In view of postsynaptic density 95kDA (PSD95) tethers neuronal NO synthase (nNOS) to N-methyl-d-aspartate receptor (NMDAR), the PSD95-nNOS complex represents a therapeutic target of neuropathic pain. This study therefore sought to explore the ability of PCC-0105002, a novel PSD95-nNOS small molecule inhibitor, to alter pain sensitivity in rodent neuropathic pain models. Firstly, the IC50 of PCC-0105002 for PSD95 and NOS1 binding activity was determined using an Alpha Screen assay kit. Then, we examined the effects of PCC-0105002 in the mouse formalin test and in the rat spinal nerve ligation (SNL) model, and explored the ability of PCC-0105002 to mediate analgesia and to effect motor coordination in a rota-rod test. Moreover, the mechanisms whereby PCC-0105002 mediates analgesia was explored via western blotting, Golgi staining, and co-immunoprecipitation experiments in dorsal horn. The outcomes indicated that PCC-0105002 exhibited dose-dependent attenuation of phase II pain-associated behaviors in the formalin test. The result indicated that PCC-0105002 disrupted the PSD95-nNOS interaction with IC50 of 1.408 μM. In the SNL model, PCC-0105002 suppressed mechanical allodynia, thermal hyperalgesia, and abnormal dorsal horn wide dynamic range neuron discharge. PCC-0105002 mediated an analgesic effect comparable to that of MK-801, while it was better able to enhance motor coordination as compared with MK-801. Moreover, PCC-0105002 altered signaling downstream of NMDAR and thus functionally and structurally attenuating synaptic plasticity through respective regulation of the NR2B/GluR1/CaMKIIα and Rac1/RhoA pathways. These findings suggest that the novel PSD95-nNOS inhibitor PCC-0105002 is an effective agent for alleviating neuropathic pain, and that it produces fewer motor coordination-associated side effects than do NMDAR antagonists.