Abstract
BackgroundPoncirin is flavanone derivative (isolated from Poncirus trifoliata) with known pharmacological activities such as anti-tumor, anti-osteoporotic, anti-inflammatory and anti-colitic. The present study aimed to explore the anti-allodynic and anti-hyperalgesic potentials of poncirin in murine models of inflammatory pain.MethodsThe analgesic potential of poncirin was evaluated in formalin-, acetic acid-, carrageenan- and Complete Freund’s Adjuvant (CFA)-induced inflammatory pain models in mice. Anti-allodynic and anti-hyperalgesic activities were measured using Von Frey filaments, Randall Selitto, hotplate and cold acetone tests. The serum nitrite levels were determined using Griess reagent. The Quantitative Real-time PCR (qRT-PCR) was performed to assess the effect of poncirin on mRNA expression levels of inflammatory cytokines and anti-oxidant enzymes.ResultsIntraperitoneal administration of poncirin (30 mg/kg) markedly reduced the pain behavior in both acetic acid-induced visceral pain and formalin-induced tonic pain models used as preliminary screening tools. The poncirin (30 mg/kg) treatment considerably inhibited the mechanical hyperalgesia and allodynia as well as thermal hyperalgesia and cold allodynia. The qRT-PCR analysis showed noticeable inhibition of pro-inflammatory cytokines (mRNA expression levels of TNF-α, IL-1β and IL-6) (p < 0.05) in poncirin treated group. Similarly, poncirin treatment also enhanced the mRNA expressions levels of anti-oxidant enzymes such as transcription factor such as nuclear factor (erythroid-derived 2)-like 2 (Nrf2) (p < 0.05), heme oxygenase (HO-1) (p < 0.05) and superoxide dismutase (SOD2) (p < 0.05). Chronic treatment of poncirin for 6 days did not confer any significant hepatic and renal toxicity. Furthermore, poncirin treatment did not altered the motor coordination and muscle strength in CFA-induced chronic inflammatory pain model.ConclusionThe present study demonstrated that poncirin treatment significantly reduced pain behaviors in all experimental models of inflammatory pain, suggesting the promising analgesic potential of poncirin in inflammatory pain conditions.
Highlights
IntroductionPoncirin is flavanone derivative (isolated from Poncirus trifoliata) with known pharmacological activities such as anti-tumor, anti-osteoporotic, anti-inflammatory and anti-colitic
Poncirin is flavanone derivative with known pharmacological activities such as anti-tumor, anti-osteoporotic, anti-inflammatory and anti-colitic
In addition to directly activating nociceptive fibers, these cytokines potentiate the inflammatory responses and increase the release of proalgesic agents including nerve growth factor (NGF), extracellular protons, bradykinin, and prostaglandins, resulting in pain hypersensitivity [5]. These inflammatory mediators are linked with an increased transcription of various inflammatory genes through transcription factors including mitogen activated protein kinases (MAPKs), cAMP response element-binding protein (CREB) and Nuclear factor kappa B (NF-κB), which further aggravates the immune and pain responses by altering the neuronal threshold [5,6,7]
Summary
Poncirin is flavanone derivative (isolated from Poncirus trifoliata) with known pharmacological activities such as anti-tumor, anti-osteoporotic, anti-inflammatory and anti-colitic. In addition to directly activating nociceptive fibers, these cytokines potentiate the inflammatory responses and increase the release of proalgesic agents including nerve growth factor (NGF), extracellular protons, bradykinin, and prostaglandins, resulting in pain hypersensitivity [5]. These inflammatory mediators are linked with an increased transcription of various inflammatory genes through transcription factors including mitogen activated protein kinases (MAPKs), cAMP response element-binding protein (CREB) and Nuclear factor kappa B (NF-κB), which further aggravates the immune and pain responses by altering the neuronal threshold [5,6,7]
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