A famÃlia de receptores de potencial transitÃrio (TRP) incluindo o receptor de potencial transitÃrio anquirina, subtipo 1 (TRPA1) tem mostrado ser um alvo terapÃutico potencial para o tratamento da dor aguda e crÃnica. Alguns estudos tÃm demonstrado que a resposta nociceptiva somÃtica se deve à ativaÃÃo dos receptores TRPA1 e sÃo efetivamente modulados atravÃs da ferramenta experimental, HC-030031, um antagonista seletivo. Contudo, existem poucos estudos que avaliam o papel dos receptores TRPA1 na dor visceral. Portanto, investigamos o papel do TRPA1 em modelos animais de nocicepÃÃo visceral induzido por diferentes substÃncias e tambÃm exploramos os possÃveis mecanismos envolvidos. Camundongos Swiss, machos (N=6) receberam carboximetilcelulose 0,5% (veÃculo CMC 0,5%, 1 mL/Kg, v.o.), HC-030031 (75, 150 ou 300 mg/Kg, v.o.), ou L-NAME (10 e 40 mg/Kg, s.c.) ou somente L-Arginina (600 mg/Kg, i.p.), 1 h apÃs foi administrado uma Ãnica injeÃÃo de IFO (400 mg/Kg, i.p.). A nocicepÃÃo visceral foi avaliada atravÃs do teste de Von Frey eletrÃnico previamente (T0) e 12 h (T1) apÃs a injeÃÃo de IFO com estimulaÃÃo abdominal atravÃs de um analgesÃmetro digital. Os resultados foram obtidos em gramas (T0-T1) pela variaÃÃo da hiperalgesia. Em seguida as bexigas dos animais foram removidas para pesagem, anÃlise e foram atribuÃdos escores macro e microscopicamente. Investigou-se, tambÃm, o efeito antinociceptivo visceral do HC-030031 atravÃs do modelo de nocicepÃÃo visceral induzido por Ãleo de mostarda (OM). Os animais foram tratados com CMC 0,5%, HC-030031 (18,75; 37,5 ou 75 mg/kg, v.o.) ou Morfina (5 mg/Kg, s.c.) isoladamente ou receberam Naloxona (2 mg/Kg, i.p.) previamente a estas drogas. Em seguida, OM 0,75% (50 μL/colon) foi instilado localmente no cÃlon. A nocicepÃÃo visceral foi verificada atravÃs do teste de Von Frey previamente (T0) e 10 min. (T1) apÃs a injeÃÃo do OM. Em outro protocolo experimental, os animais foram tratados com CMC 0,5% (10 mL/kg, v.o.) ou HC-030031 (18,75; 37,5 ou 75 mg/Kg, v.o.) previamente a uma injeÃÃo intraperitoneal com Ãcido acÃtico 0,6% (AA, 10 mL/Kg,), zymosan (Zym, 1 mg/cavidade) ou misoprostol (MPT, 1 Âg/cavidade, um anÃlogo estÃvel de prostaglandinas). Imediatamente apÃs a injeÃÃo desses algogÃnicos, contabilizaram-se as contorÃÃes abdominais por 30 min. Adicionalmente, para investigar o papel de cÃlulas peritoneais residentes sobre o efeito do HC-030031, a cavidade peritoneal dos camundongos foi lavada com uma soluÃÃo de 30 mL (PBS + heparina) e os estÃmulos AA, Zym e MPT foram injetados i.p. Um grupo Sham foi incluÃdo tambÃm neste protocolo. Ao final do experimento, as contorÃÃes abominais foram registradas por 30 mim. Utilizou-se para a anÃlise estatÃstica, ANOVA/Student e Newman/Keul, foi considerado significativo um p < 0,05 (CEPA: Protocolo: 92/10). A IFO induziu significativa (p<0,05) nocicepÃÃo visceral (6,25Â1,08) e resposta inflamatÃria [escores edema 2(1-3); hemorragia 3(1-3) e peso bexiga (42,78 3,10)] comparado com o grupo salina (1,97Â0,89),[ 0(0-0); 0(0-0) e 20,01 0,7749] respectivamente. AlÃm disso, HC-030031(75 mg/Kg) e L-NAME (10 e 40 mg/Kg) preveniram de maneira significativa (p<0,05) da resposta nociceptiva (2,30Â1,07; 1,58Â0,86 e 0,2500  0,73) respectivamente quando comparado com o grupo IFO. O prÃ-tratamento com L-Arginina (6,844Â1,235) reverteu o efeito antinociceptivo do L-NAME 10 mg/Kg, (6,84Â1,23), mas foi ineficaz sobre o efeito do L-NAME 40 mg/Kg (1,500Â0,7361) e HC-030031 75 mg/Kg (0,7200Â0,6953). Contudo, o prÃ-tratamento com HC-030031 nÃo apresentou efeito antiinflamatÃrio. Adicionalmente, verificou-se que o OM induziu significativo (p<0,05) comportamento nociceptivo (6,333Â0,9458) quando comparado ao grupo salina (1,250Â0,9204). AlÃm disso, o HC-030031 preveniu de maneira significativa da resposta nociceptiva provocada pelo OM (1,536 Â0,7653). Avaliou-se tambÃm o envolvimento do sistema opiÃide no efeito antinociceptivo do HC-030031. Verificou-se que a morfina apresentou uma importante atividade antinociceptiva (0,07143Â0,07143) contra a nocicepÃÃo induzida por OM a qual foi significativamente revertida pelo prÃ-tratamento com naloxona (3,125 1,302). Por outro lado, o efeito antinociceptivo do HC-030031 nÃo foi afetado pela naloxona (2,240Â1,263). Adicionalmente, AA, Zym e MPT induziram respostas de contorÃÃes abdominais significativas (43,71Â4,43; 11,00Â2,11 e 9,00Â2.30, respectivamente) as quais foram significativamente inibidas com HC-030031 (18,75, 37,5 ou 75 mg/kg, v.o.) em todas as doses utilizadas no teste com AA (29,07%; 53,35% e 41,59%), no teste com Zym (55,85%; 61,03% e 71,20%) e no teste com MPT (63,88%; 83,33% e 88,88%). Uma vez que a prostaglandina ativa o nociceptor diretamente, demonstrou-se que o HC-030031 possivelmente inibe a nocicepÃÃo visceral atravÃs da estabilizaÃÃo direta de nociceptores. O efeito antinociceptivo do HC-030031 parece ser independente da inibiÃÃo de cÃlulas residentes inflamatÃrias, do Ãxido nÃtrico ou do sistema opiÃide. Este estudo fornece perspectivas para o manuseio da dor visceral atravÃs da modulaÃÃo dos canais TRPA1. / The description of the TRP family of receptors including TRPA1 has provided potential therapeutic targets for treating acute and chronic pain. Some studies have shown a somatic nociceptive response due to the TRPA1 receptors activation which is effectively modulated with the experimental tool, HC-030031, a TRPA1 antagonist. However, there are a few studies evaluating the role of TRPA1 receptors in visceral pain. Then aimed to investigate the role of TRPA1 in the animal models of visceral nociception induced by different substances and to explore the possible mechanisms involved. Swiss male mice (n=6) were given only Carboxymethyl cellulose (vehicle CMC 0.5%, 1 mL/kg, p.o.), the compound HC-030031 (75, 150 or 300 mg/Kg, p.o.) or L-NAME (10 or 40 mg/Kg, s.c.) alone or with L-arginine (600mg/Kg, i.p.) 1h previously a alone injection of IFO (400 mg/kg, i.p.). Visceral nociception was assessed through the von Frey test previously (T0) and 12h (T1) later IFO injection by the abdominal stimulation with a pressure meter. The results were obtained in grams (T0-T1). The bladder of these animals were also removed to weighted (BWW), analyzed and after given scores macro and microscopically. We also investigated the antinociceptive effect of HC-030031 in the model of mustard oil-induced visceral nociception. The animals were treated with CMC 0.5% or HC-030031 (18.75, 37,5 or 75 mg/kg) or Morphine (5 mg/Kg, s.c.) alone or with Naloxone (2 mg/Kg, i.p.) 1h previously the injection of Mustard oil (MO) 0,75% (MO, 50 ul/colon). Visceral nociception was assessed through the von Frey test previously (T0) and 10 min (T1) after MO injection by the abdominal stimulation with a pressure meter. The results were obtained in grams (T0-T1). In another experimental setting, the animals were treated with CMC 0.5% (1 mL/kg, p.o) or HC-030031 (18.75; 37.5 or 75mg/Kg, p.o.) previously an intraperitoneal injection with acetic acid 0.6% (AA, 10 mL/kg), zymosan (Zym, 1 mg/cavity) or misoprostol (MPT, a stable prostaglandin analogous, 1μg/cavity) and immediately had the writhing responses counted for 30 min. In order to investigate the role of resident peritoneal cells on the effect of HC-030031, we washed the peritoneal cavity of mice with heparin added PBS (30 mL) and then AA, Zym or MPT were injected i.p. A Sham group was included. Eventually, the writhing responses were recorded. Statistical analysis was performed with ANOVA/Student Newman Keul as appropriate. p<0.05 was accepted. (CEPA: Protocol 92/10). IFO induced significant (p<0.05) visceral nociception (6.25Â1.08) and inflammatory response [scores to edema 2(1-3); hemorrhage 3(1-3); and bladder wet weight (42.78  3.1)] in comparison with saline treated group (1.97Â0.89), [0(0-0); 0(0-0); 20.01 0.7749] respectively. Moreover, HC-030031(75) and L-NAME (10 or 40 mg/Kg) prevented in a significant manner (p<0.05) the nociceptive response (2.30Â1.07; 1.58Â0.860 and 2500Â0.7361) respectively when compared with IFO-treated group. Although the pretreatment with L-arginine (6.844Â1.235) was able to reverse the antinoceceptive effect of L-NAME 10 mg/Kg, (6.84Â1.23), it failed to do the same (p>0.05) with L-NAME 40 mg/Kg (1.500Â0.7361) and HC-0300031 75 mg/Kg (0.72Â0.69). The same reversible effect of L-Arginine was observed for the anti-inflammatory activity of L-NAME (p<0.05). However, HC-030031 presented no anti-inflammatory effect. The antinociceptive activity of HC-030031 was also assessed in the MO nociception model. We verified that MO induced a significant (p<0.05) nociceptive behavior (6.333Â0.9458) when compared to saline injected mice (1.250Â0.9204). Moreover, HC-030031 prevented in a significant manner the nociceptive response elicited by MO (1.536Â0.7653). Furthermore, the involvement of opioid system in the antinociceptive effect of HC-030031 as tested. We observed that morphine presented an important antinociceptive activity (0.07143Â0.07143) against MO-induced nociception which was significantly reverted by naloxone pre-treatment (3.125 1.302). On the other hand, the antinociceptive effect of HC-030031 remained in spite the injection of naloxone (2.240Â1.263). In addition to that, AA, Zym and MPT induced significant writhing responses (43.71Â4.43; 11.00Â2.11; 9.00Â2.30; respectively) which was significantly inhibited with HC-030031(18.75, 37.5 e 75 mg/kg, p.o.) treated mice in all the doses tested (29.07%, 53.35% and 41.59%, in the AA test, 55.85%, 61.03% and 71.20%, in the Zym test, 63.88%, 83.33% and 88.88%, in the MPT induced nociception, respectively to 18.75, 37.5 and 75 mg/kg doses. Eventually, the reduction of cell population in the peritoneal cavity prevented the development of writhing responses in both AA and Zym injected mice, with no effect was visualized on MPT treated mice. We the conclude that, since prostaglandin activates the nociceptor directly, it was shown that HC-030031 inhibits visceral nociception possibly through the stabilization of the neuronal ends. The antinociceptive effect of HC-030031 seems to be independent of the inhibition of inflammatory resident cells, opioid and nitric oxide pathways. This study provides perspective for the effective management of visceral pain through the modulation of TRPA1 channels.
| Identifer | oai:union.ndltd.org:IBICT/oai:www.teses.ufc.br:5366 |
| Date | 12 August 2012 |
| Creators | Lus Mario da Silva Pereira |
| Contributors | Ronaldo de Albuquerque Ribeiro, Roberto CÃsar Pereira Lima JÃnior, Vietla Satyanarayana Rao, Herbert Arlindo Trebien |
| Publisher | Universidade Federal do CearÃ, Programa de PÃs-GraduaÃÃo em Farmacologia, UFC, BR |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Biblioteca Digital de Teses e Dissertações da UFC, instname:Universidade Federal do Ceará, instacron:UFC |
| Rights | info:eu-repo/semantics/openAccess |
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