Bioflavonoid exerts analgesic and anti-inflammatory effects via transient receptor potential 1 channel in a rat model.

BACKGROUND: Pain is an uncomfortable sensation in the body. Kaempferol is a flavonoid with antinociceptive effects. Transient receptor potential (TRP) channels have been characterized in the sensory system. OBJECTIVE: This study evaluated the central antinociceptive effect of Kaempferol and possible mechanisms of action of transient receptor potential cation channel subfamily V member 1 (TRPV1). METHODS: Capsaicin as a TRPV agonist (5 µg/µL, intracerebroventricular [ICV]) and capsazepine as its antagonist (10 µg/µL, icv) were used to test the analgesic effect of kaempferol (1.5 mg, ICV). Morphine (10 µg, ICV) was used as a positive control. The other groups were treated with a combination of kaempferol and capsaicin, kaempferol and capsazepine, and capsaicin and capsazepine. The cannula was implanted in the cerebroventricular area. The tail-flick, acetic acid, and formalin tests were used to assess analgesic activity. For evaluation of antiinflammatory effect, the formalin-induced rat paw edema was used. RESULTS: Kaempferol significantly decreased pain in the acute pain models, including the tail-flick and the first phase of the formalin test. In the late phase of the formalin test, as a valid model of nociception, capsazepine inhibited the antinociceptive effect of kaempferol. CONCLUSIONS: Kaempferol has an analgesic effect in the acute pain model and can affect inflammatory pain. Also, the TRPV1 channel plays a role in the antinociceptive activity of kaempferol.

ANTECEDENTES: A dor é uma sensação desconfortável no corpo. Kaempferol é um flavonoide com efeitos antinociceptivos. Canais receptores de potencial transitório têm sido caracterizados no sistema sensorial. OBJETIVO: Este estudo avaliou o efeito antinociceptivo central do kaempferol e os possíveis mecanismos de ação do TRPV1. MéTODOS: Capsaicina como agonista de TRPV (5 µg/µL, intracerebroventricular [ICV]) e capsazepina como seu antagonista (10 µg/µL, icv) foram usados para testar o efeito analgésico do kaempferol (1,5 mg, ICV). A morfina (10 µg, ICV) foi usada como controle positivo. Os outros grupos foram tratados com uma combinação de kaempferol e capsaicina, kaempferol e capsazepina e capsaicina e capsazepina. A cânula foi implantada na área cerebroventricular. Os testes de movimento de cauda, ácido acético e formalina foram usados para avaliar a atividade analgésica. Para avaliação do efeito anti-inflamatório, foi utilizado o edema de pata de rato induzido por formalina. RESULTADOS: Kaempferol diminuiu significativamente a dor nos modelos de dor aguda, incluindo o movimento da cauda e a primeira fase do teste de formalina. Na fase tardia do teste da formalina, como modelo válido de nocicepção, a capsazepina inibiu o efeito antinociceptivo do kaempferol. CONCLUSõES: Kaempferol tem efeito analgésico no modelo de dor aguda e pode afetar a dor inflamatória. Além disso, o canal TRPV1 desempenha um papel na atividade antinociceptiva do kaempferol.

Bioflavonoid exerts analgesic and antiinflammatory effects via transient receptor potential 1 channel in a rat model / Bioflavonoide exerce efeitos analgésicos e antiinflamatórios via canal receptor do potencial transitório 1 em um modelo de rato

Abstract Background Pain is an uncomfortable sensation in the body. Kaempferol is a flavonoid with antinociceptive effects. Transient receptor potential (TRP) channels have been characterized in the sensory system. Objective This study evaluated the central antinociceptive effect of Kaempferol and possible mechanisms of action of transient receptor potential cation channel subfamily V member 1 (TRPV1). Methods Capsaicin as a TRPV agonist (5 μg/μL, intracerebroventricular [ICV]) and capsazepine as its antagonist (10 μg/μL, icv) were used to test the analgesic effect of kaempferol (1.5 mg, ICV). Morphine (10 μg, ICV) was used as a positive control. The other groups were treated with a combination of kaempferol and capsaicin, kaempferol and capsazepine, and capsaicin and capsazepine. The cannula was implanted in the cerebroventricular area. The tail-flick, acetic acid, and formalin tests were used to assess analgesic activity.For evaluation of antiinflammatory effect, the formalin-induced rat pawedema was used. Results Kaempferol significantly decreased pain in the acute pain models, including the tail-flick and the first phase of the formalin test. In the late phase of the formalin test, as a valid model of nociception, capsazepine inhibited the antinociceptive effect of kaempferol. Conclusions Kaempferol has an analgesic effect in the acute pain model and can affect inflammatory pain. Also, the TRPV1 channel plays a role in the antinociceptive activity of kaempferol.

Resumo Antecedentes A dor é uma sensação desconfortável no corpo. Kaempferol é um flavonoide com efeitos antinociceptivos. Canais receptores de potencial transitório têm sido caracterizados no sistema sensorial. Objetivo Este estudo avaliou o efeito antinociceptivo central do kaempferol e os possíveis mecanismos de ação do TRPV1. Métodos Capsaicina como agonista de TRPV (5 μg/μL, intracerebroventricular [ICV]) e capsazepina como seu antagonista (10 μg/μL, icv) foram usados para testar o efeito analgésico do kaempferol (1,5 mg, ICV). A morfina (10 μg, ICV) foi usada como controle positivo. Os outros grupos foram tratados com uma combinação de kaempferol e capsaicina, kaempferol e capsazepina e capsaicina e capsazepina. A cânula foi implantada na área cerebroventricular. Os testes de movimento de cauda, ácido acético e formalina foram usados para avaliar a atividade analgésica. Para avaliação do efeito anti-inflamatório, foi utilizado o edema de pata de rato induzido por formalina. Resultados Kaempferol diminuiu significativamente a dor nos modelos de dor aguda, incluindo o movimento da cauda e a primeira fase do teste de formalina. Na fase tardia do teste da formalina, como modelo válido de nocicepção, a capsazepina inibiu o efeito antinociceptivo do kaempferol. Conclusões Kaempferol tem efeito analgésico no modelo de dor aguda e pode afetar a dor inflamatória. Além disso, o canal TRPV1 desempenha um papel na atividade antinociceptiva do kaempferol.

Effect of Hydroalcoholic Leaves Extract of Rhus Coriaria on Pain in Male Rats.

BACKGROUND: The drive toward the use of medicinal plants has been increasing in recent years. They have few side effects and a large variety of efficient components. OBJECTIVES: This study was designed to investigate the analgesic effects of hydroalcoholic Rhus coriaria leaf extract (HRCLE) in a rat model. MATERIALS AND METHODS: A total of 42 adult male rats were divided into seven groups: a control group (the animals did not receive any drug), three HRCLE groups, (receiving 80, 100, and 300 mg/kg, intraperitoneally [ip]), a morphine group (1 mg/kg, ip) an aspirin group (1 mg/kg, ip), and a group that received 300 mg/kg of HRCLE plus naloxone (1 mg/kg, ip). The analgesic effects of HRCLE were assessed via writhing, tail flick, and formalin tests, and the data obtained were compared with the control group using one-way analysis of variance and Tukey post hoc tests. RESULTS: HRCLE significantly inhibited the number of contractions induced by acetic acid in the writhing test at all doses, while anti-nociceptive activity was only shown at the 100 mg/kg dose (in the chronic phase) and at the 300 mg/kg dose (in the chronic-acute phase) in the formalin test. Interestingly, the greatest effect was observed at the 300 mg/kg HRCLE dose in the tail flick test. Simultaneous utilization of naloxone and HRCLE inhibited the anti-nociceptive effect of the extract in all tests. It is worth mentioning that aspirin and morphine revealed anti-nociceptive effects in all tests. CONCLUSIONS: Our findings suggest that the analgesic effect of HRCLE may be mediated via both peripheral and central mechanisms. The presence of flavonoids might be responsible for the anti-nociceptive activity of this plant.

Antinociceptive effects of Rhus coriaria L. extract in male rats.

It is well known that the tendency toward the medicinal plants is increasing in recent years. They have low side-effects and high varieties of efficient components. This study was designed to investigate the analgesic effect of hydro alcoholic leaf extract of Rhus coriaria (HRCLE) in a rat model. For this purpose, 42 adult male rats were divided into 7 groups: control, HRCLE (80, 100 and 300 mg/kg, i.p.), morphine (1 mg/kg, i.p.), aspirin (1 mg/kg, i.p.), and HRCLE 300 mg/kg plus naloxone (1 mg/kg, i.p.). The analgesic effects of HRCLE were assessed with writhing, tail flick and formalin tests. The data were compared with control by one-way ANOVA and Tukey post hoc test. All dose levels of HRCLE inhibited the number of contractions induced by acetic acid in the writhing test signfiicantly. None of the dose levels of HRCE have been showed antinociceptive activity in the formalin test except the dose of 100 mg/kg (at chronic phase) and the dose of 300 mg/kg (at chronic- acute phase). In the tail flick model, the highest effect was at the dose of 300 mg/kg of HRCLE (P < 0.01). Utilization of naloxone plus extract inhibited the antinociceptive effect of HRCLE. In this study, our findings suggest that analgesic effect for the HRCLE may be mediated via both peripheral and central mechanisms. The presence of flavonoids might be responsible for the antinociceptive activity of this plant.