The mechanisms of pain and hyperalgesia were examined in rats following cutaneous-heat and peripheral-nerve injury. Central mechanisms of hyperalgesia were indicated since a heat injury produced a decrease in foot-withdrawal latencies in the paw contralateral to the injury and an increase in autotomy of the injured paw following section of the sciatic and saphenous nerves. The reduced contralateral foot-withdrawal latencies were reversed by spinal anesthesia and subcutaneous guanethidine, but were unaffected by local anesthetics and capsaicin at the site of injury. The enhancement of autotomy produced by an injury was reduced by spinal anesthesia and a combination of intrathecal capsaicin and subcutaneous guanethidine. Both intrathecal substance P and systemic noradrenaline produced an increase in autotomy following nerve lesions; guanethidine, but neither capsaicin nor procaine, produced a decrease in autotomy. A reduction in inflammation and hyperalgesia within an injured paw was produced by local capsaicin, but not by guanethidine. The results suggest that central mechanisms, such as spinal hyperactivity, combined with peripheral neurogenic mechanisms are involved in the production of hyperalgesia following heat injury. Pain and hyperalgesia following nerve injury are proposed to be due to spinal cord plasticity resulting from deafferentation and abnormal sympathetic activity.

Doctor of Philosophy (PhD) / The investigation into the relationship between neural plasticity in the rat forebrain associated with opiate-induced behaviours yielded two major results. The major finding of the functional neuroanatomy of acute morphine dependence was that doses of naloxone that induced hyperalgesia following a brief exposure to morphine, in previously drug-naïve rats, caused a specific induction of the inducible transcription factor (itf) proteins c-Fos and zif268 in the extended amygdala. Moreover, doses of naloxone that caused a simple reversal in morphine analgesia failed to induce itf proteins in these same brain regions. This increase in itf proteins was specific to regions of the extended amygdala that receive and process nociceptive information relayed via the spino-parabrachio-amygdaloid pathway and was not observed in other regions that are involved in supraspinal pain modulation such as the rostral ventromedial medulla and the periaqueductal gray. We also found that acute morphine increased c-Fos protein in the basolateral amygdala and the major output nucleus of the central amygdala the medial subdivision. Acute morphine also up-regulated c-Fos protein in striatal, midbrain, and hypothalamic nuclei. A unique finding of the current study was that prolonged exposure to morphine was required to induce c-Fos in these brain regions, as the subsequent administration of naloxone 30-minutes after morphine either reversed or blocked this induction. These results indicate the potential role of the amygdala in analgesia following systemic morphine and in pain facilitation during acute morphine abstinence. Investigation into the neurons and circuitry that undergo long-term neuroplasticity in response to repeated morphine exposure revealed that network-level changes in the distribution of Fos protein in the nucleus accumbens and striatum predicted both tolerance to catalepsy and psychomotor sensitisation. Drug-naïve rats became profoundly cataleptic following morphine, an effect that rats with a drug-history became tolerant. Rats with a history of morphine exposure showed an increase in stereotyped behaviours compared to drug-naïve rats. The major finding of this study was that a shift in the induction of c-Fos protein from a matrix predominance in drug-naïve rats toward a patch predominance in drug-sensitised rats in the accumbens core predicted both tolerance to catalepsy and sensitisation of oral stereotyped behaviours. Acute injection of morphine in a drug-naïve rat induced catalepsy and increased the number of c-Fos-positive neurons in matrix striatopallidal projection neurons of the rostral accumbens core. An increase in activity of striatopallidal projection neurons, which give rise to the indirect pathway, could potentially increase inhibitory drive to the pedunculopontine nucleus (PPN). The PPN, long known as a site of termination for basal ganglia output, is thought to direct the outflow of incentive-motivational and sensorimotor information from the nucleus accumbens to pons, medullary, and spinal cord nuclei translating the incentive impact of the stimuli into appropriate motor, autonomic and emotive responses (Winn et al., 1997). Inhibition of this nucleus would cause the animal to be unable to initiate a movement and in effect lock up, which is precisely what cataleptic postures look like. In contrast c-Fos-positive neurons were decreased in the rostral matrix and increased in patch striatonigral projection neurons along the rostro-caudal extent of the accumbens core when morphine was administered to drug-sensitised rats. Striatonigral neurons located in the patch give rise to the direct pathway innervating the dopaminergic neurons in both substantia pars compacta and the dopamine rich islands in the substantia nigra pars reticulata (Berendse et al., 1992; Gerfen, 1992; Furuta et al., 2002). Activity of this pathway is thought to be involved in the initiation of movement (Gerfen, 1992; Gerfen and Wilson, 1996), however, when this pathway is overstimulated as is the case when morphine is injected in drug-sensitised rats this could potentially cause increased activity of PPN neurons leading to repetitive psychomotor behaviours or stereotypy. This data adds to the growing body of evidence that suggests that long-term neuroadaptations induced by drugs of abuse including morphine that lead to behavioural sensitisation involves the circuitry that includes the nucleus accumbens.

Submitted by MARCELLA FERRAZ PAZZINATTO null (ferraz_mar@hotmail.com) on 2016-05-13T17:13:57Z No. of bitstreams: 1 Dissertacao_final.pdf: 1372783 bytes, checksum: 82c520a2d6f64d7158d4001c043c712b (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-05-16T16:48:45Z (GMT) No. of bitstreams: 1 pazzinatto_mf_me_prud.pdf: 1372783 bytes, checksum: 82c520a2d6f64d7158d4001c043c712b (MD5) / Made available in DSpace on 2016-05-16T16:48:45Z (GMT). No. of bitstreams: 1 pazzinatto_mf_me_prud.pdf: 1372783 bytes, checksum: 82c520a2d6f64d7158d4001c043c712b (MD5) Previous issue date: 2016-04-29 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A dor femoropatelar (DFP) é considerada um “enigma ortopédico”, e uma das desordens musculoesqueléticas mais desafiadoras para se gerenciar. Isso porque até o presente momento não se tem definição acerca da(s) causa(s) que podem levar a esta desordem. Há mais de duas décadas têm-se investigado a presença de alterações biomecânicas em indivíduos com DFP durante as mais diversas atividades, como corrida, subida e descida de escada, agachamento e salto. Os parâmetros eletromiográficos (EMG) relacionados ao tempo e amplitude de ativação dos músculos vasto lateral (VL) e vasto medial (VM) são frequentemente abordados em estudos com essa população, no entanto, os resultados são controversos e acredita-se que uma das possíveis causas para essa inconsistência seja a característica intermitente dos sintomas. Ou seja, em determinados momentos a dor está presente e em outros não, independente da atividade que esteja sendo desenvolvida. Sabe-se que a dor recorrente pode levar a alterações no mecanismo central de controle da dor gerando respostas exageradas frente a estímulos dolorosos (hiperalgesia). Acredita-se que mulheres com DFP apresentam hiperalgesia tanto local quanto generalizada, no entanto, não se sabe o quanto a presença da dor no momento da avaliação pode alterar esses mecanismos de hiperalgesia. Diante disso, os objetivos gerais desta dissertação foram analisar o quanto a presença da dor afeta a hiperalgesia e os parâmetros EMG em mulheres com DFP, além de determinar pontos de corte para identificar a presença de hiperalgesia em mulheres com DFP. Os parâmetros EMG foram avaliados durante o gesto de subida de escada, e assim como os limiares pressóricos de dor (LPD) e a escala visual analógica (EVA) de dor, foram coletados em dois momentos antes e após um protocolo de esforço da articulação femoropatelar. Este protocolo foi realizado com o intuito de exacerbar os sintomas específicos da DFP e consistiu em 15 subidas de escada com 35% do peso corporal alocado em uma mochila e com ritmo demarcado por um metrônomo (96 degraus/min). Observou-se que mulheres com DFP apresentam LPDs reduzidos em comparação com mulheres assintomáticas e após o protocolo de esforço os LPDs avaliados ao redor do joelho, no grupo com DFP, reduziram significativamente comparado a avaliação prévia, no entanto, não houve diferença no LPD do ponto distante. Os pontos de corte encontrados apresentaram bons valores de acurácia diagnóstica, podendo ser úteis para a prática clínica na discriminação de indivíduos com e sem hiperalgesia. Já quanto aos parâmetros EMG avaliados em mulheres com DFP antes e após o protocolo de esforço, não houve diferença entre o início da ativação dos músculos VM e VL na presença da dor, mas houve aumento na amplitude do sinal EMG do VL e, consequentemente, redução na razão de ativação VM/VL após o protocolo de esforço. De acordo com estes resultados observa-se que a presença da dor é capaz de alterar os mecanismos centrais de modulação da dor, aumentando a hiperalgesia no local da desordem. A confirmação da presença de hiperalgesia local e generalizada em mulheres com DFP é de fundamental importância para traçar estratégias de tratamento, e a definição de pontos de corte capazes de discriminar os indivíduos quanto a presença de hiperalgesia facilita o gerenciamento desta desordem. E curiosamente os tratamentos visando o equilíbrio na ativação dos músculos VM e VL parecem não ser a melhor opção já que esse quesito não sofreu alteração diante do principal sintoma da DFP. / As there is no definition about etiological factors of patellofemoral pain (PFP), it is considered an “orthopaedic enigma” and one of musculoskeletal disorders most challenging to manage. More than two decades, researchers have investigated the presence of biomechanics alteration in individuals with PFP during different activities as run, stair deambulation, squatting and jump. The electromyographic (EMG) parameters related to timing and amplitude of activation of vastus lateralis (VL) and vastus medialis (VM) muscles are often addressed in studies with PFP. However, the results are controversial and a plausible explanation may be the intermitent characteristic of the symptoms. In other words, at certain times the pain is present and not in others, regardless of the activity that is being developed. It is knowing that recurrent pain may result in dysfunctional analgesic control generating exaggerated responses to painful stimuli (hyperalgesia). Women with FPF present local and widespread hyperalgesia, however, it is unknown how the presence of pain at the moment of evaluation may alter the hyperalgesia. Thus, the overall aims were to analyze how the presence of pain affects hyperalgesia and EMG parameters in women with PFP, moreover, to determine cutoff points to identify the presence of hyperalgesia in women with PFP. EMG parameters were evaluated during stair climbing. EMG parameters, pressure pain thresholds (PPTs) and visual analogue scale of pain (VAS) were collected in two conditions: before and after a patellofemoral joint loading protocol. This protocol aimed to arouse the specific symptoms of PFP and it was composed to 15 stair deambulation with 35% of body mass allocated in a backpack and the rhythm was demarcated by a metronome (96 steps/min). The women presented lower PPTs compared to pain free group. After the protocol, the PPTs around the knee decreased, whereas the PPT at a remote site to the knee not changed in women with PFP. The PPT cutoff points presented good capability to discriminate women with and without PFP. There was no difference in VL and VM onset of activation in presence of pain, however, the VL amplitude increased and VM/VL activation ratio decreased after the patellofemoral joint loading protocol. According to these results, the presence of pain changed the central mechanisms of pain modulation, increasing hyperalgesia at the site of the disorder. The cutoff points can guide clinicians towards identifying the presence of local and widespread hyperalgesia in women with PFP. Thus, clinicians may be able to identify which patients would benefit from non-mechanical interventions focusing on components aimed at pain neuroscience education. Interestingly, the treatments aiming to reduce the imbalance between VM and VL muscles do not seem to be the best option insofar as this parameter did not change in the presence of the main symptom of PFP. / FAPESP: 2014/10839-0

Orientadores: Claudia Herrera Tambeli, Maria Claudia G. de Oliveira Fusaro / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-15T16:19:44Z (GMT). No. of bitstreams: 1 Teixeira_JulianaMaia_M.pdf: 2254823 bytes, checksum: cacfa6e93ba7783f863a22087d35a8a7 (MD5) Previous issue date: 2010 / Resumo: Dados obtidos recentemente em nosso laboratório demonstram que a ativação dos receptores P2X3 e P2X2/3 pelo ATP endógeno é essencial para o desenvolvimento da hiperalgesia mecânica induzida pela carragenina no tecido subcutâneo da pata de ratos. Além dos receptores P2X3, dos sete subtipos de receptores P2X, os receptores P2X7 também possuem um papel importante nos processos de dor e inflamação. No entanto, o papel desses receptores na hiperalgesia mecânica induzida pela carragenina no tecido subcutâneo da pata de ratos e o mecanismo pelo qual a ativação dos receptores P2X7 contribui para essas respostas hiperalgésicas ainda não eram conhecidos. Portanto, os objetivos desse trabalho foram (1) Estudar se o ATP endógeno, via ativação de receptores P2X7, contribui para a hiperalgesia mecânica induzida pela carragenina e caracterizar em que período de tempo o ATP endógeno, via ativação de receptores P2X7, contribui com o desenvolvimento dessa resposta hiperalgésica e (2) Testar a hipótese de que o mecanismo pelo qual a ativação dos receptores P2X7 contribui para a hiperalgesia mecânica induzida pela carragenina é através da sensibilização indireta dos nociceptores aferentes primários. De acordo com o objetivo (1): A co-administração da carragenina com os antagonistas de receptor P2X7, oATP e A-438079, reduziu significativamente a hiperalgesia mecânica induzida pela carragenina e essa resposta hiperalgésica foi reduzida 1, 2, 3 e 6 horas após as administrações. De acordo com o objetivo (2): A co-administração dos antagonistas de receptor P2X7, oATP e A-438079, com a carragenina reduziu significativamente o aumento na concentração tecidual das citocinas pró-inflamatórias TNF-_, IL-6 e CINC-1 mas não de IL-1_ induzida pela carragenina. Os resultados do primeiro objetivo demonstram que a ativação dos receptores P2X7 pelo ATP endógeno contribui para a hiperalgesia induzida pela carragenina e os resultados do segundo objetivo mostram que o mecanismo pelo qual os receptores P2X7 contribuem para a hiperalgesia mecânica induzida pela carragenina é através da sensibilização indireta dos nociceptores aferentes primários mediada pela liberação prévia de citocinas inflamatórias como TNF-_, IL-6 e CINC-1. Esses resultados sugerem que, como a ativação dos receptores P2X7 pelo ATP endógeno é fundamental para o desenvolvimento da hiperalgesia inflamatória, os receptores P2X7 podem ser alvos farmacológicos interessantes para o desenvolvimento de medicamentos usados no controle da dor inflamatória / Abstract: We have recently demonstrated that activation of P2X3 and P2X2/3 receptors by endogenous ATP is essential for the development of carrageenan-induced mechanical hyperalgesia in the subcutaneous tissue of the rat's hind paw. In addition to P2X3 receptors, among the seven subtypes of P2X receptors, P2X7 receptors also have an important role in pain and inflammation. However, the role of these receptors in carrageenan-induced mechanical hyperalgesia in the subcutaneous tissue of the rat's hind paw and the mechanism by which the activation of P2X7 receptors contributes to these hyperalgesic responses were not yet known. Therefore, the aim of this study were (1) To study whether endogenous ATP via activation of P2X7 receptors contributes to carrageenan-induced mechanical hyperalgesia and characterize the period of time in which endogenous ATP via activation of P2X7 receptors, contributes to the development of carrageenan-induced mechanical hyperalgesia and (2) To test the hypothesis that the mechanism by which activation of P2X7 receptors contributes to carrageenan-induced mechanical hyperalgesia is through an indirect sensitization of the primary afferent nociceptors. According to the first aim: Co-administration of carrageenan with the P2X7 receptor antagonists, oATP or A-438079, significantly reduced carrageenan-induced mechanical hyperalgesia. This hyperalgesic response was reduced 1, 2, 3 and 6 hours after administrations. According to the second aim: Co-administration of the P2X7 receptor antagonists, oATP or A-438079 with carrageenan significantly reduced the increase in tissue concentration of proinflammatory cytokines TNF-_, IL-6 and CINC-1, but not IL-1_ induced by carrageenan. The results of the first aim demonstrate that activation of P2X7 receptors by endogenous ATP contributes to the hyperalgesia induced by carrageenan and the results of the second aim show that the mechanism by which P2X7 receptors contribute to carrageenan-induced mechanical hyperalgesia is through indirect sensitization of the primary afferent nociceptors mediated by previous release of inflammatory cytokines such as TNF-_, IL-6 and CINC-1. Because the activation of P2X7 receptors by endogenous ATP is essential for the development of inflammatory hyperalgesia, P2X7 receptors may be potential pharmacological targets for developing drugs to control inflammatory pain / Mestrado / Fisiologia Oral / Mestre em Odontologia

Orientador: Maria Claudia Gonçalves de Oliveira Fusaro / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Aplicadas / Made available in DSpace on 2018-08-25T13:04:54Z (GMT). No. of bitstreams: 1 Santos_DiogoFranciscodaSilvados_M.pdf: 1159978 bytes, checksum: d14c7c199ca0e75686645ae3ca6a131c (MD5) Previous issue date: 2014 / Resumo: De todas as dores que acometem o ser humano ao longo da sua existência, a dor muscular, especialmente a induzida por contração isométrica sustentada, é uma das mais prevalentes e possui um importante impacto sócio-econômico. Entretanto, apesar da sua relevância clínica, os mecanismos moleculares envolvidos no desenvolvimento da dor muscular induzida pela contração isométrica sustentada são pouco conhecidos. Isto se deve, principalmente, à ausência de um modelo experimental mais realístico e com bom grau de predição do controle farmacológico desta dor. Portanto, o objetivo deste trabalho foi desenvolver um novo modelo de hiperalgesia muscular induzido por contração isométrica sustentada em ratos. A contração isométrica sustentada foi realizada por estimulações elétricas aplicadas diretamente no ventre do músculo gastrocnêmio de ratos wistar e os parâmetros foram de 19 milissegundos de duração de pulso, frequência em 50 Hertz, intensidade de 1,6 Volts (V) por um período de 1 hora. A hiperalgesia muscular mecânica foi avaliada com o método Randall Selitto nos tempos de meia hora até 48 horas após o término da contração isométrica sustentada. A contração isométrica sustentada, obedecendo o parâmetros supracitados, induziu hiperalgesia muscular mecânica por 1 hora, regredindo com valores próximos ao basal 2 horas após o término da contração. As respostas com 1,6V por 1 hora, foram significativamente maiores do que as induzidas por estimulações de 1,6V por 15 e 30 minutos; 0,5 e 1,0V por 1h ou sham. Demonstramos ainda que a hiperalgesia muscular mecânica induzida pela contração isométrica sustentada foi bloqueada pela dexametasona, evidenciando o caráter inflamatório desse novo modelo, respaldado pela presença de células inflamatórias no tecido muscular, confirmadas pela análise histológica. Juntos, estes dados sugerem que esse novo modelo de hiperalgesia muscular se aproxima de uma condição mais próxima da real encontrada nas dores musculares decorrentes das atividades diárias, além de possuir um grande potencial científico para os estudos dos mecanismos fisiopatológicos envolvidos na dor muscular relacionada à contração isométrica sustentada / Abstract: Among the types of pain that affect people throughout their lives, muscle pain, specially the one induced by sustained isometric contraction, is one of the most prevalent and has an important socio-economic impact. However, despite their clinical relevance, the molecular mechanisms involved in the development of muscle pain induced by sustained isometric contraction are unknown. This is mainly due to the absence of a more realistic experimental model that has a good degree of prediction of pharmacological control of pain. Therefore, the aim of this study was to develop a new model of muscle hyperalgesia induced by sustained isometric contraction in Wistar rats. The sustained isometric contraction was performed by the electrical stimulation directly to the belly of the gastrocnemius muscle of rats and the parameters were 19 millisecond of pulse duration, frequency of 50Hz, and intensity of 1.6 volts (V) for a period of 1 hour. Randall Selitto method was used to measure muscular hyperalgesia 30 minutes until 48 hours after the finish of sustained isometric contraction. This protocol induced mechanical muscle hyperalgesia for one hour and, after two hours, the responses were similar to the baseline. These responses were significantly higher than those induced by stimulation 1.6V for 15 and 30 minutes, 0.5 and 1.0 V for 1h or sham. We also demonstrated that the mechanical muscle hyperalgesia induced by sustained isometric contraction was blocked by dexamethasone, indicating the inflammatory nature of this new model, supported by the presence of inflammatory cells in muscle tissue, confirmed by histological analysis. Together, these data suggest that this new model of muscle hyperalgesia approaching a condition closest to the actual found in muscle pain resulting from daily activities, besides having a great scientific potential for the study of pathophysiological mechanisms involved in muscle pain related to contraction sustained isometric / Mestrado / Metabolismo e Biologia Molecular / Mestre em Ciências da Nutrição e do Esporte e Metabolismo

Orientador: Carlos Amilcar Parada / Texto em português e inglês / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-20T10:16:37Z (GMT). No. of bitstreams: 1 TorresChavez_KarlaElena_D.pdf: 3048246 bytes, checksum: 47a94680eba82c1f3eb36fe7add0a488 (MD5) Previous issue date: 2012 / Resumo: Os objetivos deste estudo foram: (1) Verificar se a administração local de prostaglandina E2 (PGE2) no tecido periférico aumenta o efeito anti-hiperalgésico da ativação do receptor opióide mu e se este efeito é mediado por um aumento da expressão de receptor opióide mu (2) Testar se o efeito anti-hiperalgésico da ativação do receptor opióide mu no tecido periférico está associada com a diminuição da excitabilidade das fibras-C. De acordo com o objetivo (1)... Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital / Abstract: The aims of this study were:(1) To verify whether local administration of E2 prostaglandin (PGE2) in peripheral tissue increases the anti-hyperalgesic effect of mu opioid receptor activation and whether this effect is mediated by an increased expression of mu opioid receptor (2) To test if the anti-hyperalgesic effect of the activation of mu opioid receptor in peripheral tissue is associated with the decrease of C-fibers excitability. According to the objective(1)... Note: The complete abstract is available with the full electronic document / Doutorado / Fisiologia Oral / Doutor em Odontologia

Orientadores: Maria Cláudia Gonçalves de Oliveira Fusaro, Andrea Maculano Esteves / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Aplicadas / Made available in DSpace on 2018-08-27T04:11:06Z (GMT). No. of bitstreams: 1 Jorge_CarolinaOcanha_M.pdf: 1325403 bytes, checksum: 6635807ae28ce8dbb49ec5d1bcc74a75 (MD5) Previous issue date: 2015 / Resumo: A dor musculoesquelética é um importante problema de saúde mundial. Dentre todos os tipos de dor, àquela induzida pela contração isométrica sustentada está relacionada com os movimentos corporais nas atividades da vida diárias e apresenta um alto impacto socioeconômico. Apesar da sua relevância clínica, os mecanismos moleculares envolvidos no desenvolvimento da dor muscular induzida pela contração isométrica sustentada são pouco conhecidos. Portanto, o objetivo deste estudo foi avaliar o envolvimento dos receptores TRPV1 e TRPA1 na hiperalgesia muscular mecânica induzida pela contração isométrica sustentada no músculo gastrocnêmio de ratos machos, da linhagem wistar. O antagonista seletivo do receptor TRPV1, AMG9810, reduziu significativamente a hiperalgesia muscular mecânica induzida pela contração isométrica sustentada quando administrado no músculo gastrocnêmio ipsilateral, mas não no contralateral. A administração intratecal de AMG9810 apresentou a mesma resposta. Similar ao TRPV1, a administração intramuscular e intratecal do antagonista seletivo do receptor TRPA1, HC030031, reduziu significativamente a hiperalgesia muscular induzida pela contração isométrica sustentada. No entanto, não foi observado modificação da expressão proteica dos receptores TRPV1 e TRPA1 no tecido muscular após a contração isométrica sustentada. Os dados sugerem que os receptores TRPV1 e TRPA1 expressos no músculo gastrocnêmio e corno dorsal da medula espinhal estão envolvidos na hiperalgesia muscular mecânica induzida pela contração isométrica sustentada em ratos. Sugerimos, portanto, que os receptores TRPV1 e TRPA1 co-expressos nas fibras aferentes primárias trabalhem juntos para ativar os nociceptores das fibras aferentes durante a contração isométrica sustentada. Além disso, nós sugerimos que os receptores TRPV1 e TRPA1 sejam potenciais alvos para o controle da dor muscular inflamatória / Abstract: Musculoskeletal pain is an important health issue in the world. Among the kinds of muscle pain, the one induced by sustained isometric contraction is associated with body movements of the daily life and has a high socio-economic impact. Despite its clinical relevance, the molecular mechanisms involved in the development of muscle pain induced by sustained isometric contraction are poorly understood. Therefore, the aim of this study was to evaluate the involvement of TRPV1 and TRPA1 receptors in the mechanical muscle hyperalgesia induced by sustained isometric contraction of the gastrocnemius muscle of rats. The selective TRPV1 receptor antagonist AMG 9810 reduced the mechanical muscle hyperalgesia induced by sustained isometric contraction when administered in the ipsilateral but not in the contralateral gastrocnemius muscle. Also, the intratecal administration of AMG9810 reduced the same response. Similar to TRPV1, intramuscular and intrathecal administration of selective TRPA1 receptor antagonist HC030031 reduced the mechanical muscle hyperalgesia induced by sustained isometric contraction. Finally, the sustained isometric contraction did not modify the protein expression of TRPV1 and TRPA1 receptors in muscle tissue. We concluded that TRPV1 and TRPA1 receptors expressed in gastrocnemius muscle and spinal cord dorsal horn are involved with the mechanical muscle hyperalgesia induced by sustained isometric contraction in rats. We suggest that TRPV1 and TRPA1 receptors co-expressed in primary afferent fibers work together to activate nociceptive afferent fibers during sustained isometric contraction. Also, we suggest that TRPV1 and TRPA1 receptors are potential target to control inflammatory muscle pain / Mestrado / Biodinâmica do Movimento Humano e Esporte / Mestra em Ciências da Nutrição e do Esporte e Metabolismo

L’utilisation des opioïdes est à l’origine de phénomènes de tolérance et d’hyperalgésie induite (HIO) aussi bien chez l’animal qu’en utilisation clinique. Ces phénomènes surviennent avec tous les opioïdes de manière dose-dépendante. Les mécanismes qui les sous-tendent sont complexes et imparfaitement connus. Le rémifentanil et le sufentanil sont les opioïdes les plus utilisés en France en anesthésie-réanimation. Leur utilisation s’accompagne d’une HIO qui majore la douleur postopératoire et peut être responsable de la persistance de la douleur à long terme. La perception des stimuli nociceptifs chez un patient sous anesthésie générale n’est pas aisée et repose encore sur des signes cliniques indirects d’activation du système sympathique. Ces signes peu sensibles et peu spécifiques conduisent à sous doser ou sur-doser les patients en opioïdes. Récemment, un nouvel outil de monitorage de la nociception est apparu, l’analgesia nociception index (ANI). L’ANI reflète le tonus parasympathique et de ce fait permettrait aux anesthésistes de mieux adapter le dosage des opioïdes. Dans cette thèse, nous avons d’abord évalué la sensibilité et la spécificité de l’ANI à détecter les stimuli nociceptifs, puis montré qu’elles étaient supérieures à celles des signes cliniques, et supérieures à d’autres indices de monitorage proposés. Ensuite nous avons validé la capacité de l’ANI à guider l’analgésie peropératoire du rémifentanil dans différentes situations.Sur le plan expérimental, nous avons exploré, après une exposition courte ou prolongée à différentes doses de rémifentanil et de sufentanil, les mécanismes associés à l’hyperalgésie thermique in vivo, chez la souris, et ex vivo, sur la voie des MAP kinases ERK1/2 et sur le trafic membranaire des récepteurs opioïdes de type µ (MOR) dans différentes cultures cellulaires. Chez la souris, nous avons mis en évidence une hyperalgésie précoce au saut sur plaque chaude, après exposition aux doses les plus élevées de rémifentanil, mais pas avec le sufentanil. De plus, nous n’avons pas observé d’HIO sur le léchage des pattes.Sur les cultures cellulaires, le rémifentanil comme le sufentanil activent la voie des MAPK ERK1/2 lors d’une exposition courte, avec apparition d’une désensibilisation lorsque l’exposition se prolonge. Le rémifentanil comme le sufentanil induisent une internalisation précoce et progressive des récepteurs MOR. / The use of opioids is associated with tolerance and induced hyperalgesia (OIH). Tolerance and OIH occur with all opioids and have been demonstrated both, in animals and in humans and are likely to be dose-dependent. The underlying mechanisms are complex and partially known. Remifentanil and sufentanil are the most used opioids in France in anesthesia and intensive care. Their use is associated with OIH that increases postoperative pain and may be responsible for persistent pain. In anesthetized patients, nociceptive stimuli are still detected according to clinical signs of sympathetic activation. These signs lack sensitivity and specificity and lead to underdosing or overdosing opioids. Recently, the analgesia nociception index (ANI), has been proposed as surrogate marker of nociception. The ANI reflects the parasympathetic tone and thus may allow anesthetists to better adapt the opioid dosage. In this thesis, we first evaluated the sensitivity and specificity of ANI to detect nociceptive stimuli, and showed that it better detects them than do clinical signs or than other currently available monitoring tools. Subsequently, we validated the ability of the ANI to adequately guide the intraoperative dosing of remifentanil in different clinical setting.After acute and sustained exposure to different doses of remifentanil and sufentanil we investigated, in vivo, the mechanisms associated with thermal hyperalgesia in mice, and ex vivo, the effect on the MAP kinase ERK1/2 pathway and the μ-type opioid receptor (MOR) membrane trafficking in human neuroblastoma and embryonic kidney cell cultures. In mice, high-dose remifentanil induced early hyperalgesia assessed by the jumping latency in a hot-plate test, but not the sufentanil. We did not observe OIH for the hind paw licking test. On cell cultures, after short exposure, both remifentanil and sufentanil produced activation of the MAP kinase ERK1/2 pathway, and rapid desensitization and internalization of the MOR.

No description available.

Ultra-low doses (ULD) of the opioid receptor antagonists, naloxone and naltrexone, augment the analgesic actions of morphine, block the induction of tolerance, and reverse established tolerance by an unknown mechanism. Preclinical studies demonstrate that chronic morphine administration induces spinal gliosis and that inhibition of gliosis prevents the development of analgesic tolerance to opioids. Thus, this thesis investigated the inhibition of spinal gliosis as a mechanism by which ULD antagonists attenuate analgesic tolerance and opioid-induced hyperalgesia. Immune cell activation is implicated in the etiology of morphine tolerance and intrathecal catheterization, a technique commonly used to study the spinal effects of drugs, causes profound gliosis. Thus, the first study investigated the effects of catheter-induced gliosis on acute and chronic morphine analgesic tolerance. Catheterization-induced gliosis did not alter antinociceptive responses to acute intrathecal morphine; however, tolerance to chronic morphine was exacerbated in catheterized rats compared to sham and surgery-naïve controls. The potentiation of analgesic tolerance to chronic morphine by spinal gliosis provided evidence that glia modulate opioid analgesia; therefore, inhibition of opioid-induced activation of glia was explored as a potential mechanism by which ULD antagonists prevent tolerance. The second series of experiments reported morphine-induced activation of spinal microglia and astrocytes was blocked by co-administering ULD naltrexone with morphine. These findings prompted us to elucidate the specific molecular target through which ULD antagonists attenuate opioid analgesia. Activation of glial Toll-like receptor 4 (TLR4) induces gliosis and may contribute to analgesic tolerance and/or morphine-induced hyperalgesia (MIH). Antagonism of TLR4 by the opioid receptor-inactive (+) stereoisomer of naloxone was identified as a potential mechanism by which ULD antagonists modulate opioid analgesia. Tolerance and MIH developed in mice expressing non-functional TLR4 and in wildtype controls. Analgesic tolerance was stereoselectively blocked by ULD (-)naloxone, whereas MIH was blocked by both naloxone enantiomers. Collectively, these studies demonstrate analgesic tolerance and MIH occur through distinct mechanisms. ULD naloxone attenuates analgesic tolerance likely via an opioid receptor-mediated mechanism that is TLR4-independent. ULD antagonists do not attenuate tolerance via inhibition of spinal gliosis as hypothesized. In contrast, ULD antagonists prevent MIH by inhibiting opioid-induced gliosis in an opioid receptor- and TLR4-independent manner. Immune cell activation is implicated in the etiology of morphine tolerance and intrathecal catheterization, a technique commonly used to study the spinal effects of drugs, causes profound gliosis. Thus, the first study investigated the effects of catheter-induced gliosis on acute and chronic morphine analgesic tolerance. Catheterization-induced gliosis did not alter antinociceptive responses to acute intrathecal morphine; however, tolerance to chronic morphine was exacerbated in catheterized rats compared to sham and surgery-naïve controls. The potentiation of analgesic tolerance to chronic morphine by spinal gliosis provided evidence that glia modulate opioid analgesia; therefore, inhibition of opioid-induced activation of glia was explored as a potential mechanism by which ULD antagonists prevent tolerance. The second series of experiments reported morphine-induced activation of spinal microglia and astrocytes was blocked by co-administering ULD naltrexone with morphine. These findings prompted us to elucidate the specific molecular target through which ULD antagonists attenuate opioid analgesia. Activation of glial Toll-like receptor 4 (TLR4) induces gliosis and may contribute to analgesic tolerance and/or morphine-induced hyperalgesia (MIH). Antagonism of TLR4 by the opioid receptor-inactive (+) stereoisomer of naloxone was identified as a potential mechanism by which ULD antagonists modulate opioid analgesia. Tolerance and MIH developed in mice expressing non-functional TLR4 and in wildtype controls. Analgesic tolerance was stereoselectively blocked by ULD (-)naloxone, whereas MIH was blocked by both naloxone enantiomers. Collectively, these studies demonstrate analgesic tolerance and MIH occur through distinct mechanisms. ULD naloxone attenuates analgesic tolerance likely via an opioid receptor-mediated mechanism that is TLR4-independent. ULD antagonists do not attenuate tolerance via inhibition of spinal gliosis as hypothesized. In contrast, ULD antagonists prevent MIH by inhibiting opioid-induced gliosis in an opioid receptor- and TLR4-independent manner. / Thesis (Ph.D, Pharmacology & Toxicology) -- Queen's University, 2013-04-25 15:06:50.731