Prior work from our laboratory has shown that the spinal cord is capable of supporting a simple form of instrumental (response-outcome) learning. In a typical experiment, animals are given a spinal transection at the second thoracic vertebra, and tested 24 h after surgery. If animals are given shock when their leg is in a resting position (controllable shock), they quickly learn to maintain the leg in a flexed position, thereby minimizing shock exposure. Animals exposed to shock that is independent of leg position (uncontrollable shock) fail to learn. This learning deficit can be induced by as little as 6 minutes of shock to either limb or to the tail, and lasts for up to 48 h. The aim of this dissertation was to explore whether the deficit shares behavioral features and pharmacological mechanisms similar to those involved in the induction of neuropathic pain. Work within the pain literature has identified a spinal hyperexcitability that is induced by intense stimulation of pain fibers. This phenomenon, known as central sensitization, is characterized by an increase in tactile reactivity (allodynia) that can be induced by shock or peripheral inflammation. Pharmacological findings have revealed that central sensitization depends on the activation of the N-methyl-D-aspartate (NMDA) and group I metabotropic glutamate receptors (mGluRs). Experiment 1 showed that uncontrollable shock induces a tactile allodynia similar to that observed in central sensitization. Experiment 2 showed that peripheral inflammation caused by a subcutaneous injection of formalin generates a dose-dependent deficit. Experiment 3 indicated that the formalin-induced deficit was observed 24 h after delivery of the stimulus. Experiments 4-8 revealed that the NMDA and group I mGluRs are involved in the deficit. The NMDA receptor was found to be necessary (Experiment 4), but only sufficient to induce a deficit at neurotoxic doses (Experiment 5). Both of the group I mGluRs (subtypes, mGluR1 and mGluR5) were found to be necessary (Experiments 6 & 7). A general group I mGluR agonist summated with a subthreshold intensity of shock to produce a robust deficit (Experiment 8), suggesting shock and mGluR activation produce a deficit through a common mechanism.

Hypersensitivity after tissue injury is an expression of neuronal plasticity in the central nervous system. This has been explored most extensively using in vitro preparations and animal models of inflammatory pain and chemical irritation. For pain after surgery, a similar process has been proposed. In the present study, we examined dorsal horn neuron (DHN) sensitization using the plantar incision model for post-operative pain. In behavioral experiments, the effect of a local anesthetic injection (or saline vehicle) 15min before plantar incision on pain behaviors several days after incision was studied. Bupivacaine injection before incision prevented pain behaviors until 4h afterwards; injection after incision produced the same effect. One day after incision, pain behaviors were not different between rats injected with saline or bupivacaine. In neurophysiologic experiments, however, bupivacaine injection blocked activation of DHNs during incision. One hour after incision, expansion of receptive fields (RFs) to pinch and increased background activity occurred in 14 of 16 neurons in the saline group but only in two of 22 neurons in the bupivacaine group. The difference was not due to a systemic effect of bupivacaine. Ten sensitized neurons were studied using the injection of bupivacaine 90min after incision. Increased background activity (n=7) and expanded RFs (n=7) were reversed by bupivacaine. Sensitization was re-established in seven of eight neurons 2h after injection as the local anesthetic dissipated. These results indicate that activation of DHNs during plantar incision and sensitization 1h later are not necessary for subsequent pain behaviors. Because sensitization was reversed 90min after plantar incision and then re-established as the local anesthetic effect diminished, enhanced responsiveness of DHN requires ongoing afferent input during the first day after incision.

Syfte. Studiens syfte var att retrospektivt undersöka vilka kliniska variabler, bedömda under specialistundersökning av orofacial smärta, som kan förutsäga närvaro av en störd central smärtmodulering (DCPM). Material och metod. DC/TMD-data hämtades ur patientjournaler från 86 patienter som undersökts på Orofaciala smärtenheten på Malmö Universitet under perioden september 2012 till och med december 2013. Undersökta variabler omfattade smärtintensitet, smärtutbredning, smärtrelaterad nedsatthet, psykosociala variabler, refererad smärta samt kliniska fynd under somatosensoriska undersökningar. Baserat på denna data delades patienterna upp i en DCPM-grupp och en grupp utan DCPM. Allodyni, hyperalgesi, dysestesi, wind-up, regional/generell smärtutbredning samt eftersensation ansågs vara markörer för DCPM. Icke-parametriska statistiska analyser användes och en sannolikhetsnivå på P<0,05 ansågs vara signifikant. Resultat. Graden av ospecifika fysiska symptom och antalet refererande smärtor var signifikant högre i DCPM-gruppen. Den multivariata logistiska regressionen visade att ospecifika fysiska symptom, stress, smärtduration, smärtintensitet, smärtrelaterad nedsatthet, antalet refererande smärtpunkter, maximal gapning med och utan smärta, ångest samt antalet smärtinducerande käkrörelser var signifikanta marörer för DCPM (LR Chi2 = 26.89, p = 0.003, Pseudo R2 = 0.29). Slutsats. Denna studie indikerar att stress, ångest, smärtduration, smärtintensitet, smärtrelaterad nedsatthet, antalet refererande smärtpunkter, maximal gapning med och utan smärta samt antalet smärtinducerande käkrörelser är associerat med DCPM hos patienter med orofacial smärta. / Objective. To retrospectively investigate clinical variables that can predict the presence of disturbed central pain modulation (DCPM). Material and methods Medical records of 86 patients examined at the Orofacial Pain Unit at Malmö University from September 2012 to December 2013 were examined regarding pain intensity, pain distribution, pain-related disability, psychosocial variables, referred pain as well as somatosensory changes. Based on these variables, the patients were divided into a disturbed central pain modulation (DCPM) group and a non-DCPM group. Allodynia, hyperalgesia, dysesthesia, increased wind-up, regional/general pain distribution and aftersensation were considered as markers for DCPM. Non-parametric statistics were used and a probability level of P<0.05 was considered as significant. Results. The degree of unspecific physical symptoms and the number of sites eliciting pain referral were significantly higher in the DCPM group. In the multivariate regression model, the independent variables physical symptoms, stress, pain duration, characteristic pain intensity, pain-related disability, number of sites with referred pain, maximum mouth opening with and without pain, anxiety, and number of pain eliciting jaw movements significantly predicted DCPM (LR Chi2 = 26.89, p = 0.003, Pseudo R2 = 0.29). Conclusion. This study indicates that stress, anxiety, orofacial pain and its consequences, unspecific physical symptoms and jaw dysfunction are clinical signs of DCPM in patients with orofacial pain. Also, high number of palpations sites with referred pain over the masseter and temporal muscles and the TMJ indicate presence of DCPM.

INTRODUCTION: Altered walking patterns in individuals with knee osteoarthritis (OA) are a key driver of disease; however, mechanisms underlying this relationship are not clear. Central sensitization is now recognized as an important contributor to pain experience in people with knee OA. In the presence of chronic pain and central sensitization, there are alterations in activity and connectivity across multiple brain regions (e.g., prefrontal cortex, primary motor cortex) that could influence dynamic control of gait. However, the association of central sensitization with gait patterns in knee OA has not been studied. Our objective was to investigate whether central sensitization in individuals with knee OA is associated with dynamic control of gait as assessed using wearable sensor-derived measures of gait complexity and dynamic stability. We hypothesized that a greater degree of sensitization would be associated with lower gait complexity and stability. METHODS: We used data from the 12th-year visit of the Multicenter Osteoarthritis Study, a longitudinal cohort study of individuals with and without knee OA. This was the first visit at which the relevant gait parameters were collected using wearable sensors. Individuals from this visit with valid data available for all measures contained in this analysis were included. Mechanical temporal summation (TS), an augmented response to repetitive mechanical stimulation, is a reliable and valid measure of central sensitization. To assess TS, participants’ pain ratings were assessed after a single wrist stimulus was applied with successively weighted probes until a pain rating of at least 4/10 was achieved (the highest weighted probe was used if that pain rating was not obtained), then was assessed again after 10 repeated stimuli at a rate of 1 Hz was applied with the same probe. A post-stimulation pain rating larger than the initial pain rating reflected facilitated TS. For gait analyses, participants completed 2 trials of a 20m walking test at their usual walking pace while wearing inertial sensors on their lower back and both feet. The lower back sensor was used to calculate sample entropy and Lyapunov exponent, both of which may provide a window into how dynamic control of gait is altered in disease. Sample entropy measures the inter-stride predictability or regularity of gait kinematics. Lower sample entropy represents a more regular or predictable (i.e., less complex) gait pattern and may reflect a reduced ability of the neuromotor system to adapt to ongoing changes experienced in daily walking. LE measures the inter-stride stability of gait kinematics. Large LE values represent more gait instability and may reflect a reduced ability of the motor system to recover from small perturbations. We averaged the gait outcomes across the two trials. Exposure variables were standardized. We determined the association between TS and gait parameters using linear regression while adjusting for age, sex, race, body mass index (BMI), depressive symptoms, education, and presence of radiographic knee OA. Analyses were not adjusted for pain or gait speed because we hypothesized that these impairments were on the causal pathway between our exposure and outcomes. RESULTS: Data from 2,179 participants (age = 62.4 ± 10.0 years, BMI = 29.1 ± 5.5 kg/m2, 56.3% female) were included in the analysis. One standard deviation (SD) increase in TS was associated with a -0.024 [95% Confidence intervals -0.038, -0.010] change in sample entropy (i.e., more regular gait) but not with a change in LE (-0.002 [95% Confidence intervals -0.008, 0.004]). CONCLUSION: Individuals with knee OA and central sensitization display a less complex or more predictable gait pattern, evidenced by lower sample entropy, likely reflecting a deterioration in dynamic control of gait. However, central sensitization was not associated with an individual’s ability to respond to natural fluctuations that occur in walking, as evidenced by a lack of association with LE. We propose a plausible mechanism in which central sensitization may cause a reduction in gait complexity via continuous nociceptor release of glutamate, NMDAR activation, and changes in motoneuron excitability and inhibition at multiple sites along the motor pathway. Although causality cannot be determined from this cross-sectional study, these findings provide support for an association between central sensitization and specific aspects of the walking pattern in people with knee OA. Interventions to mitigate central sensitization may be useful to improve gait quality in people with knee OA.

No / Chronic pain is currently under-diagnosed and under-treated, partly because doctors' training in pain management is often inadequate. This situation looks certain to become worse with the rapidly increasing elderly population unless there is a wider adoption of best pain management practice. This paper reviews current knowledge of the development of chronic pain and the multidisciplinary team approach to pain therapy. The individual topics covered include nociceptive and neuropathic pain, peripheral sensitization, central sensitization, the definition and diagnosis of chronic pain, the biopsychosocial model of pain and the multidisciplinary approach to pain management. This last section includes an example of the implementation of a multidisciplinary approach in Belgium and describes the various benefits it offers; for example, the early multidimensional diagnosis of chronic pain and rapid initiation of evidence-based therapy based on an individual treatment plan. The patient also receives continuity of care, while pain relief is accompanied by improvements in physical functioning, quality of life and emotional stress. Other benefits include decreases in catastrophizing, self-reported patient disability, and depression. Improved training in pain management is clearly needed, starting with the undergraduate medical curriculum, and this review is intended to encourage further study by those who manage patients with chronic pain.

Introdução: A fibromialgia (FM) é uma síndrome de dor crônica musculoesquelética difusa, cuja etiologia não está totalmente conhecida. A síndrome cursa com dor, alterações do humor e sintomas de ruptura do ritmo circadiano. Sabe-se que seu processo fisiopatogênico envolve um desbalanço entre os sistemas de modulação excitatório e inibitório da dor. A capacidade do sistema modulatório inibitório está enfraquecida, com hiperativação de neurônios e da neuroglia, constituindo um quadro de sensibilização central. Portanto, estudos adicionais são necessários para compreender a relação entre possíveis marcadores séricos da hiperativação neuronal, tais como o Brain Derived Neurotrophic Factor (BDNF) e a proteína S100 beta (S100B). Além disso, estudos que busquem opções terapêuticas com efeito em vias neurobiológicas alternativas, tais como a melatonina, uma indolamina com efeitos ressincronizador, analgésico, anti-inflamatório e em sistemas moduladores da dor, como o gabaérgico, opioidérgico e glutamatérgico. Objetivos: 1) Primário: Avaliar se os níveis séricos de BDNF e S100B teriam associação com a FM e se ambos os mediadores sorológicos poderiam ser associados com o limiar de dor à pressão. 2) Secundário: Testar o tratamento com melatonina isolada ou em combinação com amitriptilina é melhor que amitriptilina isolada para modificar o sistema modulatório da dor. Assim, para provar tais hipóteses, neste estudo foram quantificados a modulação condicionada da dor e níveis de BDNF sérico em pacientes que receberam tratamento com melatonina isolada ou associada com amitriptilina. Foi também testado se melatonina melhoraria os sintomas clínicos como dor, limiar de dor à pressão e qualidade do sono relacionado à FM. Métodos: Foram selecionadas pacientes com diagnóstico de FM de acordo com o American College of Rheumatology (ACR) 2010. No primeiro estudo, de desenho transversal, foram incluídas 56 mulheres com FM, com idades entre 18 e 65 anos. Foram avaliados o limiar de dor à pressão e dosagem sérica de BDNF e S100B. No segundo estudo, foram incluídas 63 pacientes com os mesmos critérios de inclusão descritos no estudo transversal. As pacientes foram randomizadas e receberam, ao deitar, amitriptilina (25mg) (n=21), melatonina (10mg) (n=21) ou melatonina (10 mg) + amitriptilina (25mg) (n=21), durante seis semanas. O sistema modulatório descendente da dor foi acessado pela modulação condicionada da dor, através da mensuração da escala numérica de dor (NPS(0-10)) durante aferição do limiar de dor ao calor. Resultados: O resultado do estudo transversal mostrou que BDNF e S100B séricos foram correlacionados. BDNF e S100B foram inversamente correlacionados com limiar de dor à pressão. BDNF sérico foi associado com limiar de dor à pressão, idade e transtorno obsessivo compulsivo, enquanto que S100B sérica foi apenas associada com limiar de dor à pressão. O ensaio clínico randomizado demonstrou que a melatonina aumentou a potência do sistema modulatório da dor inibitório e que a modulação condicionada da dor foi negativamente correlacionada com BDNF sérico. Conclusões: Os estudos desta tese demonstram que S100B e BDNF, ambos mediadores chave no processo de sensibilização central, foram inversamente correlacionados com o limiar de dor à pressão. BDNF sérico foi, ainda, inversamente correlacionado com a redução da dor. Portanto, a avaliação sérica de BDNF e S100B merece estudos adicionais para determinar seu potencial papel sinalizador no espectro da sensibilização central nessa doença. / Introduction: Fibromyalgia (FM) is a syndrome of chronic diffuse musculoskeletal pain whose etiology is not fully known. This syndrome causes pain, mood swings and symptoms of rupture of the circadian rhythm. Its pathophysiological process involves an imbalance between excitatory and inhibitory pain modulatory systems. The ability of inhibitory systems is weakened, providing a framework of central sensitization, with dysfunction in the descending pain modulatory system, hyper-activation of neurons and neuroglia. Therefore, additional studies are needed to understand the possible relationship between serum markers of neuronal hyperactivity, such as Brain Derived Neurotrophic Factor (BDNF) and S100B. Particularly, studies seeking therapeutic options with effect in neurobiological alternative pathways such as melatonin, a indolamine with resynchronization, analgesic, and anti-inflammatory effects and actions on the modulatory pain systems such as GABAergic, opiodergic and glutamatergic. Objectives: 1) Primary: Evaluate whether the serum levels of BDNF and S100B have association with FM and if both serological mediators could be associated with pressure pain threshold. 2) Secondary: To test the hypothesis that treatment with melatonin alone or in combination with amitriptyline is better than amitriptyline alone to modify the endogenous pain modulatory system. Thus, to prove these hypothesis, it was quantified the conditioned pain modulation and serum BDNF levels in FM patients receiving treatment with melatonin alone or in combination with amitriptyline. Also, it was tested whether melatonin would improve clinical symptoms such as pain, pressure pain threshold and quality of sleep related to FM. Methods: Patients with FM according to the American College of Rheumatology (ACR) 2010 were selected. In the first study, a cross-sectional design, 56 women aging 18-65 years old, with FM were included. It was evaluated the pressure pain threshold, and serum levels of BDNF and S100B. In the second study, 63 patients were included with the same inclusion criteria described in the cross-sectional study. Patients were randomized and received at bedtime amitriptyline (25 mg) (n = 21), melatonin (10 mg) (n = 21) or melatonin (10 mg) + amitriptyline (25 mg) (n = 21) for six weeks. The descending pain modulatory system was accessed by the conditioned pain modulation, measuring the numerical pain scale [NPS (0-10)] during the heat pain threshold. Results: On the cross-sectional study serum BDNF and S100B were correlated. Serum BDNF and S100B were correlated with the pressure pain threshold. Serum BDNF was associated with pressure pain threshold, age and obsessive compulsive disorder, while serum S100B was associated with pressure pain threshold, only. The randomized clinical trial showed that melatonin increased the efficacy of inhibitory pain modulatory system and the conditioned pain modulation was negatively correlated with serum BDNF. Conclusions: The studies of this thesis show that both key mediators of the central sensitization process, BDNF and S100B, were inversely correlated with the pressure pain threshold. They also showed that melatonin increased the inhibitory pain modutalory system. Furthermore, it emphasizes that serum BDNF was inversely correlated with pain reduction. Therefore, assessment of serum BDNF and S100B deserve further studies to determine their potential as a proxy for the central sensitization spectrum in FM.

Introdução: A fibromialgia (FM) é uma síndrome de dor crônica musculoesquelética difusa, cuja etiologia não está totalmente conhecida. A síndrome cursa com dor, alterações do humor e sintomas de ruptura do ritmo circadiano. Sabe-se que seu processo fisiopatogênico envolve um desbalanço entre os sistemas de modulação excitatório e inibitório da dor. A capacidade do sistema modulatório inibitório está enfraquecida, com hiperativação de neurônios e da neuroglia, constituindo um quadro de sensibilização central. Portanto, estudos adicionais são necessários para compreender a relação entre possíveis marcadores séricos da hiperativação neuronal, tais como o Brain Derived Neurotrophic Factor (BDNF) e a proteína S100 beta (S100B). Além disso, estudos que busquem opções terapêuticas com efeito em vias neurobiológicas alternativas, tais como a melatonina, uma indolamina com efeitos ressincronizador, analgésico, anti-inflamatório e em sistemas moduladores da dor, como o gabaérgico, opioidérgico e glutamatérgico. Objetivos: 1) Primário: Avaliar se os níveis séricos de BDNF e S100B teriam associação com a FM e se ambos os mediadores sorológicos poderiam ser associados com o limiar de dor à pressão. 2) Secundário: Testar o tratamento com melatonina isolada ou em combinação com amitriptilina é melhor que amitriptilina isolada para modificar o sistema modulatório da dor. Assim, para provar tais hipóteses, neste estudo foram quantificados a modulação condicionada da dor e níveis de BDNF sérico em pacientes que receberam tratamento com melatonina isolada ou associada com amitriptilina. Foi também testado se melatonina melhoraria os sintomas clínicos como dor, limiar de dor à pressão e qualidade do sono relacionado à FM. Métodos: Foram selecionadas pacientes com diagnóstico de FM de acordo com o American College of Rheumatology (ACR) 2010. No primeiro estudo, de desenho transversal, foram incluídas 56 mulheres com FM, com idades entre 18 e 65 anos. Foram avaliados o limiar de dor à pressão e dosagem sérica de BDNF e S100B. No segundo estudo, foram incluídas 63 pacientes com os mesmos critérios de inclusão descritos no estudo transversal. As pacientes foram randomizadas e receberam, ao deitar, amitriptilina (25mg) (n=21), melatonina (10mg) (n=21) ou melatonina (10 mg) + amitriptilina (25mg) (n=21), durante seis semanas. O sistema modulatório descendente da dor foi acessado pela modulação condicionada da dor, através da mensuração da escala numérica de dor (NPS(0-10)) durante aferição do limiar de dor ao calor. Resultados: O resultado do estudo transversal mostrou que BDNF e S100B séricos foram correlacionados. BDNF e S100B foram inversamente correlacionados com limiar de dor à pressão. BDNF sérico foi associado com limiar de dor à pressão, idade e transtorno obsessivo compulsivo, enquanto que S100B sérica foi apenas associada com limiar de dor à pressão. O ensaio clínico randomizado demonstrou que a melatonina aumentou a potência do sistema modulatório da dor inibitório e que a modulação condicionada da dor foi negativamente correlacionada com BDNF sérico. Conclusões: Os estudos desta tese demonstram que S100B e BDNF, ambos mediadores chave no processo de sensibilização central, foram inversamente correlacionados com o limiar de dor à pressão. BDNF sérico foi, ainda, inversamente correlacionado com a redução da dor. Portanto, a avaliação sérica de BDNF e S100B merece estudos adicionais para determinar seu potencial papel sinalizador no espectro da sensibilização central nessa doença. / Introduction: Fibromyalgia (FM) is a syndrome of chronic diffuse musculoskeletal pain whose etiology is not fully known. This syndrome causes pain, mood swings and symptoms of rupture of the circadian rhythm. Its pathophysiological process involves an imbalance between excitatory and inhibitory pain modulatory systems. The ability of inhibitory systems is weakened, providing a framework of central sensitization, with dysfunction in the descending pain modulatory system, hyper-activation of neurons and neuroglia. Therefore, additional studies are needed to understand the possible relationship between serum markers of neuronal hyperactivity, such as Brain Derived Neurotrophic Factor (BDNF) and S100B. Particularly, studies seeking therapeutic options with effect in neurobiological alternative pathways such as melatonin, a indolamine with resynchronization, analgesic, and anti-inflammatory effects and actions on the modulatory pain systems such as GABAergic, opiodergic and glutamatergic. Objectives: 1) Primary: Evaluate whether the serum levels of BDNF and S100B have association with FM and if both serological mediators could be associated with pressure pain threshold. 2) Secondary: To test the hypothesis that treatment with melatonin alone or in combination with amitriptyline is better than amitriptyline alone to modify the endogenous pain modulatory system. Thus, to prove these hypothesis, it was quantified the conditioned pain modulation and serum BDNF levels in FM patients receiving treatment with melatonin alone or in combination with amitriptyline. Also, it was tested whether melatonin would improve clinical symptoms such as pain, pressure pain threshold and quality of sleep related to FM. Methods: Patients with FM according to the American College of Rheumatology (ACR) 2010 were selected. In the first study, a cross-sectional design, 56 women aging 18-65 years old, with FM were included. It was evaluated the pressure pain threshold, and serum levels of BDNF and S100B. In the second study, 63 patients were included with the same inclusion criteria described in the cross-sectional study. Patients were randomized and received at bedtime amitriptyline (25 mg) (n = 21), melatonin (10 mg) (n = 21) or melatonin (10 mg) + amitriptyline (25 mg) (n = 21) for six weeks. The descending pain modulatory system was accessed by the conditioned pain modulation, measuring the numerical pain scale [NPS (0-10)] during the heat pain threshold. Results: On the cross-sectional study serum BDNF and S100B were correlated. Serum BDNF and S100B were correlated with the pressure pain threshold. Serum BDNF was associated with pressure pain threshold, age and obsessive compulsive disorder, while serum S100B was associated with pressure pain threshold, only. The randomized clinical trial showed that melatonin increased the efficacy of inhibitory pain modulatory system and the conditioned pain modulation was negatively correlated with serum BDNF. Conclusions: The studies of this thesis show that both key mediators of the central sensitization process, BDNF and S100B, were inversely correlated with the pressure pain threshold. They also showed that melatonin increased the inhibitory pain modutalory system. Furthermore, it emphasizes that serum BDNF was inversely correlated with pain reduction. Therefore, assessment of serum BDNF and S100B deserve further studies to determine their potential as a proxy for the central sensitization spectrum in FM.

Introdução: A fibromialgia (FM) é uma síndrome de dor crônica musculoesquelética difusa, cuja etiologia não está totalmente conhecida. A síndrome cursa com dor, alterações do humor e sintomas de ruptura do ritmo circadiano. Sabe-se que seu processo fisiopatogênico envolve um desbalanço entre os sistemas de modulação excitatório e inibitório da dor. A capacidade do sistema modulatório inibitório está enfraquecida, com hiperativação de neurônios e da neuroglia, constituindo um quadro de sensibilização central. Portanto, estudos adicionais são necessários para compreender a relação entre possíveis marcadores séricos da hiperativação neuronal, tais como o Brain Derived Neurotrophic Factor (BDNF) e a proteína S100 beta (S100B). Além disso, estudos que busquem opções terapêuticas com efeito em vias neurobiológicas alternativas, tais como a melatonina, uma indolamina com efeitos ressincronizador, analgésico, anti-inflamatório e em sistemas moduladores da dor, como o gabaérgico, opioidérgico e glutamatérgico. Objetivos: 1) Primário: Avaliar se os níveis séricos de BDNF e S100B teriam associação com a FM e se ambos os mediadores sorológicos poderiam ser associados com o limiar de dor à pressão. 2) Secundário: Testar o tratamento com melatonina isolada ou em combinação com amitriptilina é melhor que amitriptilina isolada para modificar o sistema modulatório da dor. Assim, para provar tais hipóteses, neste estudo foram quantificados a modulação condicionada da dor e níveis de BDNF sérico em pacientes que receberam tratamento com melatonina isolada ou associada com amitriptilina. Foi também testado se melatonina melhoraria os sintomas clínicos como dor, limiar de dor à pressão e qualidade do sono relacionado à FM. Métodos: Foram selecionadas pacientes com diagnóstico de FM de acordo com o American College of Rheumatology (ACR) 2010. No primeiro estudo, de desenho transversal, foram incluídas 56 mulheres com FM, com idades entre 18 e 65 anos. Foram avaliados o limiar de dor à pressão e dosagem sérica de BDNF e S100B. No segundo estudo, foram incluídas 63 pacientes com os mesmos critérios de inclusão descritos no estudo transversal. As pacientes foram randomizadas e receberam, ao deitar, amitriptilina (25mg) (n=21), melatonina (10mg) (n=21) ou melatonina (10 mg) + amitriptilina (25mg) (n=21), durante seis semanas. O sistema modulatório descendente da dor foi acessado pela modulação condicionada da dor, através da mensuração da escala numérica de dor (NPS(0-10)) durante aferição do limiar de dor ao calor. Resultados: O resultado do estudo transversal mostrou que BDNF e S100B séricos foram correlacionados. BDNF e S100B foram inversamente correlacionados com limiar de dor à pressão. BDNF sérico foi associado com limiar de dor à pressão, idade e transtorno obsessivo compulsivo, enquanto que S100B sérica foi apenas associada com limiar de dor à pressão. O ensaio clínico randomizado demonstrou que a melatonina aumentou a potência do sistema modulatório da dor inibitório e que a modulação condicionada da dor foi negativamente correlacionada com BDNF sérico. Conclusões: Os estudos desta tese demonstram que S100B e BDNF, ambos mediadores chave no processo de sensibilização central, foram inversamente correlacionados com o limiar de dor à pressão. BDNF sérico foi, ainda, inversamente correlacionado com a redução da dor. Portanto, a avaliação sérica de BDNF e S100B merece estudos adicionais para determinar seu potencial papel sinalizador no espectro da sensibilização central nessa doença. / Introduction: Fibromyalgia (FM) is a syndrome of chronic diffuse musculoskeletal pain whose etiology is not fully known. This syndrome causes pain, mood swings and symptoms of rupture of the circadian rhythm. Its pathophysiological process involves an imbalance between excitatory and inhibitory pain modulatory systems. The ability of inhibitory systems is weakened, providing a framework of central sensitization, with dysfunction in the descending pain modulatory system, hyper-activation of neurons and neuroglia. Therefore, additional studies are needed to understand the possible relationship between serum markers of neuronal hyperactivity, such as Brain Derived Neurotrophic Factor (BDNF) and S100B. Particularly, studies seeking therapeutic options with effect in neurobiological alternative pathways such as melatonin, a indolamine with resynchronization, analgesic, and anti-inflammatory effects and actions on the modulatory pain systems such as GABAergic, opiodergic and glutamatergic. Objectives: 1) Primary: Evaluate whether the serum levels of BDNF and S100B have association with FM and if both serological mediators could be associated with pressure pain threshold. 2) Secondary: To test the hypothesis that treatment with melatonin alone or in combination with amitriptyline is better than amitriptyline alone to modify the endogenous pain modulatory system. Thus, to prove these hypothesis, it was quantified the conditioned pain modulation and serum BDNF levels in FM patients receiving treatment with melatonin alone or in combination with amitriptyline. Also, it was tested whether melatonin would improve clinical symptoms such as pain, pressure pain threshold and quality of sleep related to FM. Methods: Patients with FM according to the American College of Rheumatology (ACR) 2010 were selected. In the first study, a cross-sectional design, 56 women aging 18-65 years old, with FM were included. It was evaluated the pressure pain threshold, and serum levels of BDNF and S100B. In the second study, 63 patients were included with the same inclusion criteria described in the cross-sectional study. Patients were randomized and received at bedtime amitriptyline (25 mg) (n = 21), melatonin (10 mg) (n = 21) or melatonin (10 mg) + amitriptyline (25 mg) (n = 21) for six weeks. The descending pain modulatory system was accessed by the conditioned pain modulation, measuring the numerical pain scale [NPS (0-10)] during the heat pain threshold. Results: On the cross-sectional study serum BDNF and S100B were correlated. Serum BDNF and S100B were correlated with the pressure pain threshold. Serum BDNF was associated with pressure pain threshold, age and obsessive compulsive disorder, while serum S100B was associated with pressure pain threshold, only. The randomized clinical trial showed that melatonin increased the efficacy of inhibitory pain modulatory system and the conditioned pain modulation was negatively correlated with serum BDNF. Conclusions: The studies of this thesis show that both key mediators of the central sensitization process, BDNF and S100B, were inversely correlated with the pressure pain threshold. They also showed that melatonin increased the inhibitory pain modutalory system. Furthermore, it emphasizes that serum BDNF was inversely correlated with pain reduction. Therefore, assessment of serum BDNF and S100B deserve further studies to determine their potential as a proxy for the central sensitization spectrum in FM.

Syfte. Att retrospektivt undersöka relationen mellan central sensitisering i det orofacialaområdet och refererad smärta, som kliniskt fynd, samt psykosociala faktorer hos patienter medDC/TMD-muskeldiagnosen myofasciell smärta med refererad smärta (MPR). Studien syftadeäven till att undersöka skillnader gällande psykosociala faktorer mellan patienter somdiagnostiserats med DC/TMD muskeldiagnoserna myofasciell smärta med refererad smärta(MPR), lokal myalgi (LM) och patienter med orofacial smärta eller käkdysfunktion men ejkäkmuskeldiagnos (WMD) som kontrollgrupper.Material och metod. Information från 85 patienters DC/TMD-undersökning utförd påOrofaciala smärtenheten vid Malmö högskola mellan september 2012 till årsslutet 2013insamlades retrospektivt. Undersökta variabler inkluderade smärtintensitet, smärt-relateraddysfunktion, psykosociala faktorer (depression, ångest och stress) samt refererad smärta.Patienterna indelades i grupper baserade på muskeldiagnos enligt DC/TMD samt utbredning avsmärta. Non-parametrisk statistik användes och P < 0,05 betraktades som signifikant.Resultat. Patienter med MPR uppvisade en signifikant korrelation mellan totala antaletrefererade smärtlokalisationer och smärt-relaterad dysfunktion (rs = 0,43, n = 49, p = 0,002),depression (rs = 0,32, n = 49, p = 0,023) och stress (rs = 0,39, n = 49, p = 0,006). Patienter meden generell smärtutbredning uppvisade en signifikant högre grad av stress (p = 0,020) samt flerantal refererade smärtlokalisationer (p = 0,019) jämfört med patienter med lokal och/ellerregional orofacial smärta.Konklusion. Studien indikerar att grad av central sensitisering kan bedömas med hjälp avutbredningen av refererad smärta, undersökt enligt DC/TMD, hos patienter med diagnosenmyofasciell smärta med refererad smärta i det orofaciala området. Studien kunde inte påvisaskillnader gällande psykosociala faktorer mellan de undersökta grupperna. / Objective. The aim of this study was to retrospectively investigate the relation between referredpain, as a clinical finding, and psychosocial factors versus central sensitization in patients withmyofascial pain with referral (MPR) as assessed according to DC/TMD. The study also aimedto investigate differences regarding psychosocial factors between patients demonstratingmyofascial pain with referral (MPR) and patients diagnosed with the DC/TMD muscle diagnoselocal myalgia (LM) as well as OFP/TMD patients without masticatory muscular diagnose(WMD) as control patients.Material and methods. Patients’ medical records of 85 patients examined at the Orofacial PainUnit at Malmö University during September 2012 till the end of 2013 were retrospectivelyexamined for DC/TMD data. Examined variables included pain intensity, pain-related disability,psychosocial factors (depression, anxiety and stress) and referred pain. The patients weredivided into groups based on DC/TMD muscle diagnosis as well as extension of pain. Nonparametricstatistics were used and a probability level of P < 0.05 was considered as significant.Results. Patients with MPR demonstrated significant correlations between the total number ofreferred pain sites and disability score (rs = 0.43, n = 49, p = 0.002), depression (rs = 0.32, n =49, p = 0.023) as well as stress (rs = 0.39, n = 49, p = 0.006). Patients with generalized paindistribution demonstrated a significantly higher degree of stress (p = 0.020) as well as highernumber of referred pain sites (p = 0.019) than patients with local and/or regional orofacial pain.Conclusion. This study indicates that the degree of central sensitization can be estimated bythe extent of referred pain, as assessed according to DC/TMD, in patients with myofascial painwith referred pain in the orofacial region. This study could not detect a difference inpsychosocial factors between the three groups, myofascial pain with referral (MPR), localmyalgia (LM) and no masticatory muscle diagnosis (WMD).

The effect of interleukin-1 beta (IL-1β) on the electrical properties of sensory neurons was assessed at comparable levels and exposure times to those found in animal models of neuropathic pain. Experiments involved whole cell current- or voltage-clamp recordings from rat dorsal root ganglion (DRG) neurons in defined medium, neuron enriched cultures. 5-6 days exposure to 100 pM IL-1β produced neuron specific effects. These included an increase in the excitability of medium diameter and small diameter isolectin B4 (IB4)-positive neurons that was comparable to that found after peripheral nerve injury. By contrast, a reduction in excitability was observed in large diameter neurons, while no effect was found in small diameter IB4-negative neurons. Further characterization of changes in medium and small IB4-positive neurons revealed that some, but not all, effects of IL-1β were mediated through its receptor, IL-1RI. Using appropriate voltage protocols and/or ion substitutions, it was found that neuron specific changes in several ionic currents, including alterations in hyperpolarization activated inward current (IH) and decreases in various K+ currents contribute to the increased excitability produced by IL-1β. Overall, these studies revealed that: 1. The effects of long-term exposure of DRG neurons to IL-1β are reflective of the enduring increase in primary afferent excitability reported after peripheral nerve injury. This expands the recognized role of IL-1β in acute inflammatory pain to neuropathic pain. 2. Hyperexcitability in medium neurons exposed to IL-1β likely includes mixed populations of neurons corresponding to nociceptive and non-nociceptive primary afferent fibres and, therefore, has relevance to hyperalgesia and allodynia, respectively. 3. The responsiveness of small IB4-positive neurons, but not IB4-negative, to prolonged IL-1β exposure is consistent with the suggestion that small IB4-negative afferents are involved in inflammatory pain, while small IB4-positive afferents are involved neuropathic pain. 4. The identification of receptor mediated effects and several contributing ionic mechanisms, may have relevance to the development of new therapeutic approaches to neuropathic pain. 5. IL-1β can contribute to increased neuronal excitability by mechanisms that are independent of IL-1RI signalling. This should be taken into account when targeting IL-1β, or more specifically IL-1RI, in the management of neuropathic pain.