Formalin-induced Licking Response Research Articles

Characterisation of the anti-inflammatory and antinociceptive activities of the Hyptis pectinata (L.) Poit essential oil

Hyptis pectinata Poit (Lamiaceae) is grown in the northeastern regions of Brazil and is popularly known as "sambacaitá" or "canudinho". It is extensively used in folk medicine to treat inflammatory conditions, bacterial infections, pain, and cancer. Hyptis pectinata essential oil (EO, 10, 30, and 100mg/kg, p.o.) and the reference drugs morphine (5mg/kg, p.o.) and acetylsalicylic acid (ASA, 200mg/kg, p.o.) were evaluated using models for analgesia (acetic acid-induced contortions and hot plate) or inflammation (formalin-induced licking response and the subcutaneous air-pouch model). To elucidate the EO's mechanism of action, animals were pre-treated with the opioid receptor antagonist naloxone (1mg/kg, i.p.), the cholinergic antagonist atropine (1mg/kg, i.p.), or l-nitro arginine methyl ester (l-NAME, 3mg/kg, i.p.) 30 min prior to the oral administration of the EO. The EO significantly inhibited the number of writhings and the time the animals spent licking their formalin-injected paws (second phase). The EO, at doses of 30 and 100mg/kg, increased baseline measurements and area under the curve measurements in the hot plate model, respectively. The administration of naloxone reversed the antinociceptive effect of the EO in the hot plate model. l-NAME significantly reversed the effects of the EO in the contortions and hot plate models. Atropine completely reversed the antinociceptive activity of the EO in all models. Additionally, the EO inhibited the inflammatory process induced by subcutaneous carrageenan injection by reducing cell migration, exudate volume, protein concentration, and inflammatory mediators (nitric oxide, prostaglandin E2, IL-6, and TNF-α) produced in the pouch. Our results indicate that the Hyptis pectinata essential oil exhibits antinociceptive effects, likely mediated by opioid and cholinergic receptors, and anti-inflammatory activity through the inhibition of nitric oxide and PGE2 production.

Analgesic, anti-inflammatory and anti-platelet activities of the methanolic extract of Acacia modesta leaves

The current study was aimed to evaluate Acacia modesta for analgesic, anti-inflammatory, and anti-platelet activities. The analgesic and anti-inflammatory effects were assessed in rodents using acetic acid and formalin-induced nociception, hot plate and carrageenan-induced rat paw oedema tests. The intraperitoneal (i.p.) administration of the methanolic extract (50 and 100 mg/kg) produced significant inhibition (P\0.01) of the acetic acid-induced writhing in mice and suppressed formalin-induced licking response of animals in both phases of the test. In the hot plate assay the plant extract (100 mg/kg) increased pain threshold of mice. Naloxone (5 mg/kg i.p.) partially reversed the analgesic effect of the extract in formalin and hot plate tests.A. modesta (100 and 200 mg/kg i.p.) exhibited sedative effect in barbiturate-induced hypnosis test similar to that produced by diazepam (10 mg/kg i.p.). The plant extract(50-200 mg/kg i.p.) produced marked anti-inflammatory effect in carrageenan-induced rat paw oedema assay comparable to diclofenac and produced a dose-dependent(0.5-2.5 mg/mL) inhibitory effect against arachidonic acid induced platelet aggregation. These data suggest that A. modesta possesses peripheral analgesic and antiinflammatory properties, with analgesic effects partially associated with the opioid system.

Characterization of the antinociceptive and anti-inflammatory activities of fractions obtained from Copaifera multijuga Hayne

Ethnopharmacological relevance Copaifera multijuga Hayne (Leguminosae) is a tree that produces an oleoresin, which is extensively commercialized in Brazil as capsules or crude oil for the treatment of several disorders. Ethnopharmacological studies show a diversity of indications such as anti-inflammatory and epidermal wound cicatrization. Aim of the study In the present work three fractions obtained from Copaifera multijuga oleoresin (hexane (HF), chloroform (CF), and methanol (MF) from a KOH impregnated silica gel column chromatography, representing the three main classes of compounds in the Copaifera genus (hydrocarbon sesquiterpenes, oxygenated sesquiterpenes and acidic diterpenes), were evaluated using antinociceptive and anti-inflammatory models. Materials and methods HF, CF, and MF (doses ranging between 1 and 150 mg/kg, depending on the model used), Copaifera multijuga oleoresin (CMO, 100 mg/kg, p.o.) and the reference drug morphine (5 mg/kg, p.o.) were evaluated using models for analgesia (acetic acid-induced contortions and tail flick) or inflammation (rat paw oedema and increase in vascular permeability). To elucidate the mechanism of action from the fractions, animals were pre-treated with naloxone (opioid receptor antagonist, 5 mg/kg, i.p.). Results Fractions significantly inhibited (in a concentration-dependant way) the number of contortions induced by acetic acid and the second phase of formalin-induced licking response. Similar results were observed in the tail flick model. The central antinociceptive effect for HF and CF at the doses of 50 and 100 mg/kg was higher than the one observed for morphine (1 mg/kg). Administration of naloxone inhibited the antinociceptive effect of fractions indicating that HF, CF, and MF may be acting on opioid receptors. All three fractions also inhibited rat paw oedema and the increase in vascular permeability induced by several phlogistic agents (carrageenan, histamine, and serotonin). Conclusions Our results indicate that fractions obtained from Copaifera multijuga Hayne demonstrate an antinociceptive effect probably mediated by opioid receptors, and anti-inflammatory activity through inhibition of histaminergic and serotoninergic pathways.

Effects of honokiol and magnolol on acute and inflammatory pain models in mice

The antinociceptive actions of honokiol and magnolol, two major bioactive constituents of the bark of Magnolia officinalis, were evaluated using tail-flick, hot-plate and formalin tests in mice. The effects of honokiol and magnolol on the formalin-induced c-Fos expression in the spinal cord dorsal horn as well as motor coordination and cognitive function were examined. Data showed that honokiol and magnolol did not produce analgesia in tail-flick, hot-plate paw-shaking and neurogenic phase of the overt nociception induced by intraplantar injection of formalin. However, honokiol and magnolol reduced the inflammatory phase of formalin-induced licking response. Consistently, honokiol and magnolol significantly decreased formalin-induced c-Fos protein expression in superficial (I–II) laminae of the L4–L5 lumbar dorsal horn. However, honokiol and magnolol did not elicit motor incoordination and memory dysfunction at doses higher than the analgesic dose. These results demonstrate that honokiol and magnolol effectively alleviate the formalin-induced inflammatory pain without motor and cognitive side effects, suggesting their therapeutic potential in the treatment of inflammatory pain.

Lacosamide displays potent antinociceptive effects in animal models for inflammatory pain

Lacosamide is a functionalized amino acid which was initially synthesized as an antiepileptic drug. In addition to its broad anti-seizure activity, lacosamide was shown to display efficacy in animal models for neuropathic pain and is currently in phase III clinical development for the treatment of epilepsy and neuropathic pain. In order to further profile its antinociceptive properties, the effects of lacosamide on inflammatory pain in the formalin test, the carrageenan model and the adjuvant-induced arthritis model were investigated. For the formalin test, mice received an intraplantar injection of formalin and the subsequent licking response was measured over 45 min. Lacosamide was administered 30 min before formalin. For the carrageenan model, mechanical and thermal hyperalgesia were assessed 3 h following an intraplantar injection of carrageenan. Lacosamide was administered to rats 30 min before pain threshold measurements. For the adjuvant-induced arthritis test rats received intraplantar injections of Freund’s complete adjuvant into the right hindpaw which lead to the development of arthritic symptoms in all animals tested for antinociception. On day 11 after arthritis induction, mechanical hyperalgesia was assessed by the modified Randall Selitto paw pressure test following acute treatment with lacosamide. Lacosamide dose-dependently attenuated mechanical hyperalgesia following carrageenan injection and in rats suffering from Freund’s complete adjuvant-induced arthritis. Moreover, thermal hyperalgesia induced by carrageenan as well as the formalin-induced licking response were dose-dependently attenuated by lacosamide. These results suggest lacosamide may be active against various forms of acute and chronic inflammatory pain in humans.

Exaggerated responses to chronic nociceptive stimuli and enhancement of N-methyl- d-aspartate receptor-mediated synaptic transmission in mutant mice lacking d-amino-acid oxidase

Formalin-induced nociceptive behaviors and N-methyl- d-aspartate (NMDA) subtype glutamate receptor-mediated excitatory synaptic transmission were analyzed in mutant mice lacking d-amino-acid oxidase, which catalyzes the oxidative deamination of d-amino acids. The second phase of the formalin-induced licking response, a part of which is known to be mediated by NMDA receptors in the spinal cord, was significantly augmented in mutant mice. NMDA receptor-mediated excitatory postsynaptic currents recorded from spinal cord dorsal horn neurons by tight-seal whole-cell methods were significantly potentiated in mutant mice. The present observations provide another line of evidence that d-serine functions as an endogenous coagonist at the glycine site of NMDA receptors, and raise the possibility that d-amino-acid oxidase exerts a neuromodulatory function by controlling the concentration of d-serine in the central nervous system.

Studies on the anti-inflammatory and analgesic activity of Curatella americana L.

Curatella americana L. (Dilleneaceae) popularly known as ‘cajueiro-bravo’ and ‘sambaı́ba’ is used in Brazilian folk medicine for the treatment of inflammation and ulcer. The anti-inflammatory and analgesic tests were conducted with the hydroalcoholic extract (HAE) of the bark of the plant. The HAE inhibited mouse ear oedema induced by o-tetradecanoyl phorbol acetate (TPA) and by capsaicin. While the ID 50 values obtained for the HAE against these two irritants were 40.8±1.7 and 30±1.2 mg/kg i.p. (mean±S.E.M., n=6), respectively, the corresponding value for carrageenan induced paw oedema (3 h) was 21.8±2.1 mg/kg, i.p., n=6. In the established adjuvant-induced arthritis model, the HAE significantly inhibited the oedema in daily doses of 50 mg/kg, i.p. ( n=10). The HAE also inhibited acetic acid-induced writhing (ID 50 23.2±0.8 mg/kg, i.p., n=6) and the formalin-induced late phase paw licking response (ID 50 11.9±1.2 mg/kg, i.p., n=10) in the mice. However, the HAE was inactive in the formalin-induced initial paw licking response in mice or heat induced tail flick response in rats. The HAE has shown both anti-inflammatory and peripheral analgesic activities when administrated in the mouse by the intraperitoneal route in doses which are at least 12 times lower than its LD 50 dose of 647 mg/kg, i.p.

The neurokinin-1 receptor antagonist, sendide, exhibits antinociceptive activity in the formalin test

Sendide is a selective and extremely potent antagonist of neurokinin-1 (NK 1) receptors in the mouse spinal cord. The antinociceptive activities of sendide, an antagonist of NK 1 receptors, and its analogue, [ d-Trp 7]sendide have been examined after intrathecal (i.t.) administrations in the mouse paw formalin test. Intrathecal administration of sendide (in pmol) reduced both the early and late phases of the formalin-induced licking response. [ d-Trp 7]sendide also produced a significant antinociceptive response with less potent activity than sendide. Even highest doses (4000 pmol sendide and 8000 pmol [ d-Trp 7]sendide) examined, there was no motor paralysis of the hindlimbs. Intrathecal morphine inhibited both the early and late phases of the formalin-induced licking response in a dose-dependent manner. The results indicate that the antinociceptive effects of sendide and [ d-Trp 7]sendide may be mediated at NK 1 receptors in the formalin-induced nociception.

Differential antinociceptive effects of morphine and methylmorphine in the formalin test

The antinociceptive activities of morphine, and its quaternary analogue methylmorphine, have been compared after intraperitoneal and intracerebroventricular administrations in the mouse paw formalin test. Systemic morphine inhibited both the early and late phases of the formalin-induced licking response and this activity was naloxone sensitive. In contrast, systemic methylmorphine inhibited only the late phase, and this activity was blocked by pre-treatment with methylnaloxone. Central administration of either morphine or methylmorphine inhibited the early phase of the licking response partially and the late phase completely. Systemic naloxone inhibited the central action of both opioids, whilst systemic methylnaloxone did not affect the central action of methylmorphine. The results indicate that the early phase of the response to formalin in the mouse may be inhibited by stimulation of central opioid receptors whilst inhibition of the late phase may involve both peripheral and central opioid receptors.