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357 CONTRIBUTION OF PERIPHERAL AND CENTRAL OPIOID RECEPTORS TO ANTINOCICEPTION IN RAT MUSCLE PAIN MODELS
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Poster Sessions / European Journal of Pain 13 (2009) S55–S285
tetrodotoxin-insensitive sodium channel Nav 1.8 may be involved in inflammatory (Joshi 2006) and neuropathic pain (Lai 2002). Our aim was to establish an appropriate mouse model of muscle pain and to analyze the involvement of Nav 1.8 channels in the development of muscle pain. Methods: Wildtype mice and NaV 1.8 knockout (ko) mice received a single intramuscular (i.m.) injection of either tumor necrosis factoralpha (TNFa), Complete Freund’s Adjuvant (CFA) or sodium chloride (NaCl). Motor deficiencies were monitored with rotarod. Spontaneous pain behavior was observed using Attal-Score (Attal 1990). With a remodeled Randall-Selitto test, pressure pain was measured at the hindlimb muscles. All behavioral tests were performed between 3 hours (h) and 14 days after injection. Results: The pressure pain test showed that TNF and CFA, but not NaCl, caused pressure hyperalgesia in the wildtype mice 6 h, 9 h and 24 h after i.m. injection. Whereas in the Nav 1.8 ko mice less pressure hyperalgesia could be observed (p < 0.05). No motor deficiencies or spontaneous pain behavior in both mice groups could be detected. Conclusion: TNF as well as CFA i.m. injections can be used as a mouse model of muscle pain. Nav 1.8 ko mice did not evolve muscle pain after TNF respectively CFA i.m. injection. Our results suggest that Nav 1.8 channels are probably involved in the pathophysiology of muscle pain. 355 ANALGESIC AND ANTI-INFLAMMATORY EFFECTS OF RIGID BENZOFURANE 3,4-DIHYDROXY CHALCON (DHC) IN MICE M.R. Heidari1 *, A. Foroumadi2 , A. Asadipour, H. Noroozi. Department of Toxicology and Pharmacology, Pharmaceutics, Neuroscience and Physiology Research Centers, Kerman, Iran; 2 Medicinal chemistry, Tehran, Iran 1
According to bibliography on the structure activity relationship it seems that the rigid Benzofuran dihydroxy chalcon (DHC) may be more effective on pain and inflammation. In this study the Rigid benzofuran DHC were synthesized and the analgesic and anti-inflammatory effect of different doses 12.5, 25 and 50 mg/kg of it, was evaluated by formalin Hot plate and caregeenan tests, in group of 7 mice. The result showed that, 3,4-DHC with dose of 25 mg/kg induced Significant antinociception and antiinflammation compared with control group. In additon the effect of DHC was higher in the chronic phase of formalin test, therefore it seems that DHC has better anti- inflammatory effect rather than analgesic effect. The dose of 25 mg/kg of DHC induces significant analgesia in hot plate test and antiu-inflammatory effect in carageenan test too. The doses of 25 and 50 mg/kg, induced lethargy in mice. The result showed that with modification of structure of the DHC, this derivative has potential for more studies as a lead compound. 356 VALIDATION OF INFLAMMATORY PAIN MODELS IN THE NON-HUMAN PRIMATE (NHP) D. Hygate *, A. Wilson, C.S. Chew, R. Manguiat, A. Juman, D. Hutcheson. Maccine Pte Ltd, The Alpha, Singapore Science Park II, Singapore Background and Aims: There is a need for more translatable and predictive NHP models to develop human pain treatment. Our aim is to develop robust models of inflammatory pain from existing rodent models into NHP’s whilst focusing on the 3R’s. Methods: Two classical inflammatory pain rodent models were chosen for development in NHP’s; capsaicin-induced thermal hyperalgesia and carrageenan-induced mechanical allodynia. Both models involved chaired monkeys trained to respond to either tail-dip testing at various waterbath temperatures (capsaicin) or mechanical allodynia testing utilizing von Frey filaments
(carrageenan). Baseline tail-dip or von Frey testing was performed pre and post-administration (capsaicin into tip of tail; carrageenan into plantar surface of foot). Cohorts of the best responders are to be used for subsequent validation with a TRPV-1 antagonist and celecoxib. Results: Injection of capsaicin induces thermal hyperalgesia at 35 and 40ºC with maximal possible effect (MPE) of 40 and 60% respectively. Carrageenan-induced mechanical allodynia elicited foot-withdrawal thresholds of 300 g pre-carrageenan to 13 g postcarrageenan; with inflammation of between 10 and 40% observed. Inflammation to some batches of carrageenan required longer recovery periods before re-testing, therefore, we have sourced new carrageenan resulting in much improved recovery. Conclusions: Achieved inflammatory pain responses in NHP’s with minimal animal use and distress and no self-harm. We are currently testing sensitivity to both a TRPV-1 antagonist and celecoxib. 357 CONTRIBUTION OF PERIPHERAL AND CENTRAL OPIOID RECEPTORS TO ANTINOCICEPTION IN RAT MUSCLE PAIN MODELS Ma.I. Martin *, A. Bagues, ¨ E.Ma. Sanchez. Rey Juan Carlos University, Alcorcon (Madrid), Spain Pain of muscle origin is the major presenting symptom of many clinically defined conditions. Several animal models of pain also have been developed to investigate acute and chronic pain mechanisms. The aim of our study is to compare the role of central and peripheral opioid receptors on two muscle acute pain models (rat masseter and gastrocnemius). Effects of intraperitoneal (i.p.) administration of morphine and loperamide, a peripherally acting opioid receptor agonist, were examined. In order to reveal the peripheral components, naloxone and its quaternary derivate, naloxone methiodide, an opioid receptor antagonist that poorly penetrates into the brain were used. Male rats (250–300 g) were used. In masseter model, hypertonic saline (HS) was injected into muscle to evoke a paw shaking behaviour that is considered as an index of nociception. In gastrocnemius model, HS was injected into muscle and the time that rat spent with lifted or retracted paw was counted. The modification of these behaviours, induced by intramuscular injection of HS, after pharmacological treatments, was studied. Morphine and loperamide (0.6–2.5 mg/kg) reduced HS-induced nociceptive behaviours on masseter model and these effects were antagonized by naloxone and naloxone methiodide (1 mg/kg). However, on gastrocnemius model, morphine (2.5–10 mg/kg), but not loperamide (5–10 mg/kg), was able to avoid the pain behaviour induce by HS, and this effect only was antagonized by naloxone. Our results suggest that peripheral opioid receptors can be implicated in masseter pain, induced by HS injection, whereas on gastrocnemius pain, central, and not peripheral opioid receptors, are involved. 358 SKIN PIGMENTATION SIGNIFICANTLY CONFOUNDS MAPPING GENES FOR RADIANT HEAT PAIN IN MICE M. Mashregi *, S. Biton, J. Hu, B. Sessle, Z. Seltzer. University of Toronto Centre for the Study of Pain, Toronto, Canada Background: A/J (‘A’; albino) and C57BL/6J (‘B’; black) mice contrast on radiant heat pain. Our objective is to compare heat pain in recombinant lines of crossed A and B mice (AXB-BXA), map chromosomal regions that harbour pain genes (‘quantitative trait loci’, QTLs) and identify these genes. However, AXB-BXA lines inherit albino, agouti and black skin/fur that could confound comparison of pain sensitivity, since darker skin may absorb more radiant heat. Aim: To test if skin pigmentation affects radiant heatinduced nociception, and test ways to correct any such confound. Methods: A 0–4 pain scale was used to construct stimulus/response curves correlating ear pigmentation [in A, B and 23 AXB-BXA lines (8 mice/gender)] to diode laser pulses (270 msec, 6 pulses/intensity,
Poster Sessions / European Journal of Pain 13 (2009) S55–S285
tetrodotoxin-insensitive sodium channel Nav 1.8 may be involved in inflammatory (Joshi 2006) and neuropathic pain (Lai 2002). Our aim was to establish an appropriate mouse model of muscle pain and to analyze the involvement of Nav 1.8 channels in the development of muscle pain. Methods: Wildtype mice and NaV 1.8 knockout (ko) mice received a single intramuscular (i.m.) injection of either tumor necrosis factoralpha (TNFa), Complete Freund’s Adjuvant (CFA) or sodium chloride (NaCl). Motor deficiencies were monitored with rotarod. Spontaneous pain behavior was observed using Attal-Score (Attal 1990). With a remodeled Randall-Selitto test, pressure pain was measured at the hindlimb muscles. All behavioral tests were performed between 3 hours (h) and 14 days after injection. Results: The pressure pain test showed that TNF and CFA, but not NaCl, caused pressure hyperalgesia in the wildtype mice 6 h, 9 h and 24 h after i.m. injection. Whereas in the Nav 1.8 ko mice less pressure hyperalgesia could be observed (p < 0.05). No motor deficiencies or spontaneous pain behavior in both mice groups could be detected. Conclusion: TNF as well as CFA i.m. injections can be used as a mouse model of muscle pain. Nav 1.8 ko mice did not evolve muscle pain after TNF respectively CFA i.m. injection. Our results suggest that Nav 1.8 channels are probably involved in the pathophysiology of muscle pain. 355 ANALGESIC AND ANTI-INFLAMMATORY EFFECTS OF RIGID BENZOFURANE 3,4-DIHYDROXY CHALCON (DHC) IN MICE M.R. Heidari1 *, A. Foroumadi2 , A. Asadipour, H. Noroozi. Department of Toxicology and Pharmacology, Pharmaceutics, Neuroscience and Physiology Research Centers, Kerman, Iran; 2 Medicinal chemistry, Tehran, Iran 1
According to bibliography on the structure activity relationship it seems that the rigid Benzofuran dihydroxy chalcon (DHC) may be more effective on pain and inflammation. In this study the Rigid benzofuran DHC were synthesized and the analgesic and anti-inflammatory effect of different doses 12.5, 25 and 50 mg/kg of it, was evaluated by formalin Hot plate and caregeenan tests, in group of 7 mice. The result showed that, 3,4-DHC with dose of 25 mg/kg induced Significant antinociception and antiinflammation compared with control group. In additon the effect of DHC was higher in the chronic phase of formalin test, therefore it seems that DHC has better anti- inflammatory effect rather than analgesic effect. The dose of 25 mg/kg of DHC induces significant analgesia in hot plate test and antiu-inflammatory effect in carageenan test too. The doses of 25 and 50 mg/kg, induced lethargy in mice. The result showed that with modification of structure of the DHC, this derivative has potential for more studies as a lead compound. 356 VALIDATION OF INFLAMMATORY PAIN MODELS IN THE NON-HUMAN PRIMATE (NHP) D. Hygate *, A. Wilson, C.S. Chew, R. Manguiat, A. Juman, D. Hutcheson. Maccine Pte Ltd, The Alpha, Singapore Science Park II, Singapore Background and Aims: There is a need for more translatable and predictive NHP models to develop human pain treatment. Our aim is to develop robust models of inflammatory pain from existing rodent models into NHP’s whilst focusing on the 3R’s. Methods: Two classical inflammatory pain rodent models were chosen for development in NHP’s; capsaicin-induced thermal hyperalgesia and carrageenan-induced mechanical allodynia. Both models involved chaired monkeys trained to respond to either tail-dip testing at various waterbath temperatures (capsaicin) or mechanical allodynia testing utilizing von Frey filaments
(carrageenan). Baseline tail-dip or von Frey testing was performed pre and post-administration (capsaicin into tip of tail; carrageenan into plantar surface of foot). Cohorts of the best responders are to be used for subsequent validation with a TRPV-1 antagonist and celecoxib. Results: Injection of capsaicin induces thermal hyperalgesia at 35 and 40ºC with maximal possible effect (MPE) of 40 and 60% respectively. Carrageenan-induced mechanical allodynia elicited foot-withdrawal thresholds of 300 g pre-carrageenan to 13 g postcarrageenan; with inflammation of between 10 and 40% observed. Inflammation to some batches of carrageenan required longer recovery periods before re-testing, therefore, we have sourced new carrageenan resulting in much improved recovery. Conclusions: Achieved inflammatory pain responses in NHP’s with minimal animal use and distress and no self-harm. We are currently testing sensitivity to both a TRPV-1 antagonist and celecoxib. 357 CONTRIBUTION OF PERIPHERAL AND CENTRAL OPIOID RECEPTORS TO ANTINOCICEPTION IN RAT MUSCLE PAIN MODELS Ma.I. Martin *, A. Bagues, ¨ E.Ma. Sanchez. Rey Juan Carlos University, Alcorcon (Madrid), Spain Pain of muscle origin is the major presenting symptom of many clinically defined conditions. Several animal models of pain also have been developed to investigate acute and chronic pain mechanisms. The aim of our study is to compare the role of central and peripheral opioid receptors on two muscle acute pain models (rat masseter and gastrocnemius). Effects of intraperitoneal (i.p.) administration of morphine and loperamide, a peripherally acting opioid receptor agonist, were examined. In order to reveal the peripheral components, naloxone and its quaternary derivate, naloxone methiodide, an opioid receptor antagonist that poorly penetrates into the brain were used. Male rats (250–300 g) were used. In masseter model, hypertonic saline (HS) was injected into muscle to evoke a paw shaking behaviour that is considered as an index of nociception. In gastrocnemius model, HS was injected into muscle and the time that rat spent with lifted or retracted paw was counted. The modification of these behaviours, induced by intramuscular injection of HS, after pharmacological treatments, was studied. Morphine and loperamide (0.6–2.5 mg/kg) reduced HS-induced nociceptive behaviours on masseter model and these effects were antagonized by naloxone and naloxone methiodide (1 mg/kg). However, on gastrocnemius model, morphine (2.5–10 mg/kg), but not loperamide (5–10 mg/kg), was able to avoid the pain behaviour induce by HS, and this effect only was antagonized by naloxone. Our results suggest that peripheral opioid receptors can be implicated in masseter pain, induced by HS injection, whereas on gastrocnemius pain, central, and not peripheral opioid receptors, are involved. 358 SKIN PIGMENTATION SIGNIFICANTLY CONFOUNDS MAPPING GENES FOR RADIANT HEAT PAIN IN MICE M. Mashregi *, S. Biton, J. Hu, B. Sessle, Z. Seltzer. University of Toronto Centre for the Study of Pain, Toronto, Canada Background: A/J (‘A’; albino) and C57BL/6J (‘B’; black) mice contrast on radiant heat pain. Our objective is to compare heat pain in recombinant lines of crossed A and B mice (AXB-BXA), map chromosomal regions that harbour pain genes (‘quantitative trait loci’, QTLs) and identify these genes. However, AXB-BXA lines inherit albino, agouti and black skin/fur that could confound comparison of pain sensitivity, since darker skin may absorb more radiant heat. Aim: To test if skin pigmentation affects radiant heatinduced nociception, and test ways to correct any such confound. Methods: A 0–4 pain scale was used to construct stimulus/response curves correlating ear pigmentation [in A, B and 23 AXB-BXA lines (8 mice/gender)] to diode laser pulses (270 msec, 6 pulses/intensity,