Amplified cold transduction in native nociceptors by M-channel inhibition.

Topically applied camphor elicits a sensation of cool, but nothing is known about how it affects cold temperature sensing. We found that camphor sensitizes a subpopulation of menthol-sensitive native cutaneous nociceptors in the mouse to cold, but desensitizes and partially blocks heterologously expressed TRPM8 (transient receptor potential cation channel subfamily M member 8). In contrast, camphor reduces potassium outward currents in cultured sensory neurons and, in cold nociceptors, the cold-sensitizing effects of camphor and menthol are additive. Using a membrane potential dye-based screening assay and heterologously expressed potassium channels, we found that the effects of camphor are mediated by inhibition of Kv7.2/3 channels subtypes that generate the M-current in neurons. In line with this finding, the specific M-current blocker XE991 reproduced the cold-sensitizing effect of camphor in nociceptors. However, the M-channel blocking effects of XE991 and camphor are not sufficient to initiate cold transduction but require a cold-activated inward current generated by TRPM8. The cold-sensitizing effects of XE991 and camphor are largest in high-threshold cold nociceptors. Low-threshold corneal cold thermoreceptors that express high levels of TRPM8 and lack potassium channels are not affected by camphor. We also found that menthol--like camphor--potently inhibits Kv7.2/3 channels. The apparent functional synergism arising from TRPM8 activation and M-current block can improve the effectiveness of topical coolants and cooling lotions, and may also enhance TRPM8-mediated analgesia.

The Foundational Data Initiative for Parkinson Disease: Enabling efficient translation from genetic maps to mechanism.

The Foundational Data Initiative for Parkinson Disease (FOUNDIN-PD) is an international collaboration producing fundamental resources for Parkinson disease (PD). FOUNDIN-PD generated a multi-layered molecular dataset in a cohort of induced pluripotent stem cell (iPSC) lines differentiated to dopaminergic (DA) neurons, a major affected cell type in PD. The lines were derived from the Parkinson's Progression Markers Initiative study, which included participants with PD carrying monogenic PD variants, variants with intermediate effects, and variants identified by genome-wide association studies and unaffected individuals. We generated genetic, epigenetic, regulatory, transcriptomic, and longitudinal cellular imaging data from iPSC-derived DA neurons to understand molecular relationships between disease-associated genetic variation and proximate molecular events. These data reveal that iPSC-derived DA neurons provide a valuable cellular context and foundational atlas for modeling PD genetic risk. We have integrated these data into a FOUNDIN-PD data browser as a resource for understanding the molecular pathogenesis of PD.

Automated Production of Human Induced Pluripotent Stem Cell-Derived Cortical and Dopaminergic Neurons with Integrated Live-Cell Monitoring.

Manual culture and differentiation protocols for human induced pluripotent stem cells (hiPSC) are difficult to standardize, show high variability and are prone to spontaneous differentiation into unwanted cell types. The methods are labor-intensive and are not easily amenable to large-scale experiments. To overcome these limitations, we developed an automated cell culture system coupled to a high-throughput imaging system and implemented protocols for maintaining multiple hiPSC lines in parallel and neuronal differentiation. We describe the automation of a short-term differentiation protocol using Neurogenin-2 (NGN2) over-expression to produce hiPSC-derived cortical neurons within 6‒8 days, and the implementation of a long-term differentiation protocol to generate hiPSC-derived midbrain dopaminergic (mDA) neurons within 65 days. Also, we applied the NGN2 approach to a small molecule-derived neural precursor cells (smNPC) transduced with GFP lentivirus and established a live-cell automated neurite outgrowth assay. We present an automated system with protocols suitable for routine hiPSC culture and differentiation into cortical and dopaminergic neurons. Our platform is suitable for long term hands-free culture and high-content/high-throughput hiPSC-based compound, RNAi and CRISPR/Cas9 screenings to identify novel disease mechanisms and drug targets.

The role of Nav1.7 in human nociceptors: insights from human induced pluripotent stem cell-derived sensory neurons of erythromelalgia patients.

The chronic pain syndrome inherited erythromelalgia (IEM) is attributed to mutations in the voltage-gated sodium channel (NaV) 1.7. Still, recent studies targeting NaV1.7 in clinical trials have provided conflicting results. Here, we differentiated induced pluripotent stem cells from IEM patients with the NaV1.7/I848T mutation into sensory nociceptors. Action potentials in these IEM nociceptors displayed a decreased firing threshold, an enhanced upstroke, and afterhyperpolarization, all of which may explain the increased pain experienced by patients. Subsequently, we investigated the voltage dependence of the tetrodotoxin-sensitive NaV activation in these human sensory neurons using a specific prepulse voltage protocol. The IEM mutation induced a hyperpolarizing shift of NaV activation, which leads to activation of NaV1.7 at more negative potentials. Our results indicate that NaV1.7 is not active during subthreshold depolarizations, but that its activity defines the action potential threshold and contributes significantly to the action potential upstroke. Thus, our model system with induced pluripotent stem cell-derived sensory neurons provides a new rationale for NaV1.7 function and promises to be valuable as a translational tool to profile and develop more efficacious clinical analgesics.

Crotalphine desensitizes TRPA1 ion channels to alleviate inflammatory hyperalgesia.

Crotalphine is a structural analogue to a novel analgesic peptide that was first identified in the crude venom from the South American rattlesnake Crotalus durissus terrificus. Although crotalphine's analgesic effect is well established, its direct mechanism of action remains unresolved. The aim of the present study was to investigate the effect of crotalphine on ion channels in peripheral pain pathways. We found that picomolar concentrations of crotalphine selectively activate heterologously expressed and native TRPA1 ion channels. TRPA1 activation by crotalphine required intact N-terminal cysteine residues and was followed by strong and long-lasting desensitization of the channel. Homologous desensitization of recombinant TRPA1 and heterologous desensitization in cultured dorsal root ganglia neurons was observed. Likewise, crotalphine acted on peptidergic TRPA1-expressing nerve endings ex vivo as demonstrated by suppression of calcitonin gene-related peptide release from the trachea and in vivo by inhibition of chemically induced and inflammatory hypersensitivity in mice. The crotalphine-mediated desensitizing effect was abolished by the TRPA1 blocker HC030031 and absent in TRPA1-deficient mice. Taken together, these results suggest that crotalphine is the first peptide to mediate antinociception selectively and at subnanomolar concentrations by targeting TRPA1 ion channels.

Vitamin B complex attenuated heat hyperalgesia following infraorbital nerve constriction in rats and reduced capsaicin in vivo and in vitro effects.

Vitamins of the B complex attenuate some neuropathic pain sensory aspects in various animal models and in patients, but the mechanisms underlying their effects remain to be elucidated. Herein it was investigated if the treatment with a vitamin B complex (VBC) reduces heat hyperalgesia in rats submitted to infraorbital nerve constriction and the possibility that TRPV1 receptors represent a target for B vitamins. In the present study, the VBC refers to a combination of vitamins B1, B6 and B12 at low- (18, 18 and 1.8mg/kg, respectively) or high- (180, 180 and 18mg/kg, respectively) doses. Acute treatment of rats with either the low- or the high-doses combination reduced heat hyperalgesia after nerve injury, but the high-doses combination resulted in a long-lasting effect. Repeated treatment with the low-dose combination reduced heat hyperalgesia on day four after nerve injury and showed a synergist effect with a single injection of carbamazepine (3 or 10mg/kg), which per se failed to modify the heat threshold. In naïve rats, acute treatment with the high-dose of VBC or B1 and B12 vitamins independently reduced heat hyperalgesia evoked by capsaicin (3µg into the upper lip). Moreover, the VBC, as well as, each one of the B vitamins independently reduced the capsaicin-induced calcium responses in HEK 293 cells transiently transfected with the human TRPV1 channels. Altogether, these results indicate that B vitamins can be useful to control heat hyperalgesia associated with trigeminal neuropathic pain and that modulation of TRPV1 receptors may contribute to their anti-hyperalgesic effects.

Comparison of two PBR ligands with classical antiinflammatory drugs in LPS-induced arthritis in rats.

The antinociceptive and anti-edematogenic effects of peripheral benzodiazepine receptor (PBR) ligands, Ro5-4864 (7-chloro-5- (4-chlorophenyl)-1,3-dihydro-1-methyl-2-H-1,4-benzodiazepine-2) and PK11195 (1-(2-chlorophenyl)-N-methyl-N(1-methylpropyl)-3-isoquinoline carboxamide), were studied in an experimental model of carrageenan/LPS -induced arthritis in rats. These effects were compared with those of indomethacin and dexamethasone. Both pre and post-treatments with PK11195 were found to be anti-edematogenic and antinociceptive. The lower dose (0.01 mg/kg) exhibited the higher anti-edematogenic effect. On the other hand, the higher dose (0.5 mg/kg) produced antinociception, but with a decreased anti-edematogenic effect. Ro5-4864 produced a negligible antinociception and anti-edematogenic effect as pretreatment, but a pro-edematogenic effect when given as post-treatment. Dexamethasone and indomethacin presented parallel and dose-dependent antinociceptive and anti-edematogenic effects. In conclusion, PK11195 can effectively diminish arthritic nociception and edema elicited by LPS, but probably by mechanisms different from those of dexamethasone or indomethacin. RO5-4864 seemed to have opposite effect on this model.

Effects of one minute and ten minutes of walking activity in rats with arthritis induced by complete Freund's adjuvant on pain and edema symptoms.

This study evaluated the effects of two protocols of exercise on nociception, edema and cell migration in rats with CFA-induced arthritis. Female Wistar rats (200 - 250 g, n = 50) was monoarthritis-induced by complete Freund's adjuvant (CFA; Mycobacterium butyricum, 0.5 mg/mL; 50 µL) into the right knee joint (TF; n = 24) or right ankle joint (TT; n = 26). Incapacitation was measured by the paw elevation time (TEP; s) in 1-min periods of observation. The edema of the knee or ankle joints was evaluated by the variation of the articular diameter (DA, cm) and by the paw volume variation (EP, mL), respectively. Both were measured during 10 consecutive days. Two protocols of exercise were performed: (a) in the constant exercise group (TF, n = 6; TT, n = 6) performing 1 minute of daily exercise on the cylinder; (b) variable exercise group (TF, n = 6; TT, n = 7), the exercise increased by 1 minute per day. The control groups (TF, n = 12; TT, n = 13) didn't perform the exercise. After 10 days, the animals were euthanized for total (CT; cells/mm3) and differential leukocyte counts (mononuclear - MON, and polymorphonuclear - PMN, cells/mm3) of the articular inflammatory exudate. The variable exercise protocol inhibited incapacitation and edema for both joints. However, cell migration decreased only in the TF.The constant exercise reduced edema in both joints, and cell migration was decreased in the TT. However, the incapacitation was not reduced. Variable exercise seemed to be more effective in reducing the inflammatory parameters than constant exercise.

Standardization of an experimental model suitable for studies on the effect of exercise on arthritis.

OBJECTIVE: To standardize an experimental model of chronic monoarthritis induced by complete Freund's adjuvant appropriate for the analysis of the effect of walking on nociception and on joint edema. METHODS: The following factors were evaluated as to monoarthritis induction: route and site of administration, number and interval of inoculations, Mycobacterium species, and animal gender. Wistar male and female rats (200 to 250g) received two injections of complete Freund's adjuvant containing Mycobacterium tuberculosis (1.0mg/mL; 50µL) or Mycobacterium butyricum (0.5mg/mL; 50µL) intra-articularly in the tibiotarsal or tibiofemoral joints, or an injection of complete Freund's adjuvant (Mycobacterium butyricum or tuberculosis) intradermally at the base of the tail and another intra-articularly (tibiotarsal or tibiofemoral). The animals were submitted to evaluations of articular disability and edema. Articular disability was assessed by paw elevation time (in seconds) during the one-minute walk test. Edema of the tibiofemoral joint was assessed by variation of joint diameter (cm). Tibiotarsal joint edema was measured by the volume of the paw (mL). RESULTS: Administration of complete Freund's adjuvant containing Mycobacterium butyricum increased paw elevation time and edema in both joints. CONCLUSIONS: These data allow standardization of an animal model of chronic monoarthritis adequate for analysis of the effects of exercise on treatment of rheumatoid arthritis.

Evidence that LPS-reactive arthritis in rats depends on the glial activity and the fractalkine-TNF-α signaling in the spinal cord.

It is known that primary afferent central terminal sensitization can influence peripheral inflammation, however, it remains to be understood whether spinal cord glia can also contribute to this process. Our aim was to investigate the effect of spinal cord glia inhibition on the pathogenesis of LPS-induced knee-joint monoarthritis in rats and also to investigate the role of fractalkine and TNF-α. LPS was injected into the knee-joint previously primed with carrageenan to cause articular incapacitation, edema, synovial leukocyte infiltration, and GFAP and CD11b/c spinal immunoreactivity (glia-IR) increase. Articular edema was more sensitive to the inhibition by intrathecal fluorocitrate and minocycline than nociception and synovial leukocyte content. The higher doses of both drugs were ineffective when given by intraperitoneal route. Corticosteroid synthesis inhibition by aminoglutethimide did not change the glia inhibitors effect. The inhibitory effect of the dorsal root potential inhibitor, furosemide, was not additive to that caused by fluorocitrate and minocycline. Intrathecal anti-fractalkine and anti-TNF-α inhibited edema, nociception, and synovial leukocytes, while fractalkine caused the opposite effects. The fractalkine effect was inhibited by fluorocitrate and anti-TNF-α. Finally, fluorocitrate, minocycline and anti-fractalkine attenuated, but fractalkine increased, GFAP and CD11b/c IR. The evidence reported herein supports the hypothesis that spinal fractalkine release is involved in glia activation, which via the spinal release of TNF-α, seems to be involved in the development and maintenance of this arthritis model. A possible modulation of the dorsal root reflexes is discussed. This article is part of a Special Issue entitled 'Post-Traumatic Stress Disorder'.

Ankle joint mobilization reduces axonotmesis-induced neuropathic pain and glial activation in the spinal cord and enhances nerve regeneration in rats.

An important issue in physical rehabilitation is how to protect from or to reduce the effects of peripheral nerve injury. In the present study, we examined whether ankle joint mobilization (AJM) would reduce neuropathic pain and enhance motor functional recovery after nerve injury. In the axonotmesis model, AJM during 15 sessions every other day was conducted in rats. Mechanical and thermal hyperalgesia and motor performance deficit were measured for 5 weeks. After 5 weeks, we performed morphological analysis and quantified the immunoreactivity for CD11b/c and glial fibrillary acidic protein (GFAP), markers of glial activation, in the lumbar spinal cord. Mechanical and thermal hyperalgesia and motor performance deficit were found in the Crush+Anesthesia (Anes) group (P<0.001), which was significantly decreased after AJM (P<0.001). In the morphological analysis, the Crush+Anes group presented reduced myelin sheath thickness (P<0.05), but the AJM group presented enhanced myelin sheath thickness (P<0.05). Peripheral nerve injury increased the immunoreactivity for CD11b/c and GFAP in the spinal cord (P<0.05), and AJM markedly reduced CD11b/c and GFAP immunoreactivity (P<0.01). These results show that AJM in rats produces an antihyperalgesic effect and peripheral nerve regeneration through the inhibition of glial activation in the dorsal horn of the spinal cord. These findings suggest new approaches for physical rehabilitation to protect from or reduce the effects of nerve injury.

LPS-induced knee-joint reactive arthritis and spinal cord glial activation were reduced after intrathecal thalidomide injection in rats.

AIMS: Thalidomide is thought to prevent TNF-α production, and such mechanism could be useful in a spinally delivered drug approach for the control of peripheral inflammation. This study aimed to evaluate the effect of intrathecal thalidomide, in comparison with that of intraperitoneal treatment, on articular incapacitation, edema, synovial leukocyte content, and spinal cord glial activation in a model of Escherichia coli lipopolysaccharide (LPS)-induced reactive arthritis in rats. MAIN METHODS: LPS (30ng) was injected into a knee-joint previously primed with carrageenan (300µg). Systemic (30 and 100mg/kg; intraperitoneal, i.p.) and intrathecal (10 and 100µg; i.t.) thalidomide were given 1h or 20min before LPS injection, respectively. Articular incapacitation and edema were evaluated hourly. After 6h, synovial fluid and lumbar spinal cords were collected for subsequent evaluations of cell migration and expression of CD11b/c and GFAP markers, respectively. KEY FINDINGS: Systemic (30 and 100mg/kg) or intrathecal (10 and 100µg) thalidomide reduced articular incapacitation, edema, and polymorphonuclear migration. In addition, i.p. and i.t. thalidomide reduced the expression of CD11b/c and GFAP markers in the lumbar spinal cord. These results suggest that thalidomide can also produce peripheral anti-inflammatory effects through action in the spinal cord that may involve glia inhibition. SIGNIFICANCE: This study provides new evidence that the direct spinal delivery of immunomodulators may be an alternative for the treatment of arthritic diseases, which require long systemic treatment with drugs associated with undesirable side effects.

Endothelins as pronociceptive mediators of the rat trigeminal system: role of ETA and ETB receptors.

The trigeminal nerve is comprised of three main divisions, ophthalmic, maxillary and mandibular, each providing somatosensory innervation to distinct regions of the head, face and oral cavity. Recently, a role for endothelins in nociceptive signaling in the trigeminal system has been proposed. The present study aimed to gain better insight into the participation of the endothelin system in trigeminal nociceptive transmission. Herein ET-1 and ET-3 mRNA was detected in the rats' trigeminal ganglion (TG). Fluorescent labeling of TG neurons revealed that ET(A) and ET(B) receptors are distributed along the entire TG, but ET(A) receptor expression slightly predominated within the three divisions. TRPV1 receptors were also detected throughout the entire TG, and a significant proportion of TRPV1-positive neurons (approximately 30%) co-expressed either ET(A) or ET(B) receptors. Our behavioral data showed that ET-1 (3 to 30 pmol/site) induced overt nociceptive responses after injection into the upper lip or temporomandibular joint (TMJ) and hyperalgesic actions when applied to the eye, while ET-3 and the selective ET(B) receptor agonist IRL-1620 (each at 3 to 30 pmol/site) showed only the first two effects. Injection of BQ-123, but not BQ-788 (ET(A) and ET(B) receptor antagonists, respectively, 10 nmol/site each, 30 min beforehand), into the ipsilateral upper lip abolished ET-1 induced facial grooming, but both antagonists markedly reduced the nociceptive responses induced by ET-1 injected into the TMJ. Taken together, these findings suggest that endothelins, acting through ET(A) and/or ET(B) receptors, may play an important role in mediating pain resulting from activation of most trigeminal nerve branches.

Efeitos de um minuto e dez minutos de deambulação em ratos com artrite induzida por adjuvante completo de Freund sobre os sintomas de dor e edema / Effects of one minute and ten minutes of walking activity in rats with arthritis induced by complete Freund's adjuvant on pain and edema symptoms

Este estudo avaliou o efeito de dois protocolos de exercício na nocicepção, edema e migração celular em ratos com artrite induzida por CFA. Ratos Wistar fêmeas (200 - 250 g, n = 50) foram induzidos à monoartrite por adjuvante completo de Freund (CFA, Mycobacterium butyricum; 0,5 mg/mL; 50 μL) na articulação do joelho direito (TF; n = 24) ou tornozelo direito (TT; n = 26). A incapacitação articular foi mensurada pelo tempo de elevação da pata (TEP; s) em 1 minuto de avaliação. O edema do joelho ou tornozelo foi avaliado pela medida do diâmetro articular (AD, cm) e pelo edema de pata (EP, mL), respectivamente. Ambos foram avaliados durante 10 dias consecutivos. Dois protocolos de exercício foram realizados: (a) exercício constante (TF, n = 6; TT, n = 6), realizando 1 minuto diário de exercício no cilindro (3 r.p.m.); (b) exercício variável (TF, n = 6; TT, n = 7), exercício com aumento de 1 minuto por dia, totalizando 10 minutos no último dia. Os grupos-controle (TF, n = 12; TT, n = 13) não realizaram exercício. Após 10 dias, os animais foram eutanasiados para contagem total (células/mm3) e diferencial (mononucleares e polimorfos nucleares; células/mm3) de leucócitos do tecido inflamado. O exercício variável inibiu a incapacitação e o edema em ambas as articulações. Entretanto, reduziu a migração total de leucócitos apenas na articulação TF. O exercício constante inibiu o edema nas duas articulações e reduziu a migração total de leucócitos da articulação TT. Porém, não reduziu a incapacitação. O exercício variável pareceu ser mais efetivo em reduzir os parâmetros inflamatórios em comparação com o exercício constante.

This study evaluated the effects of two protocols of exercise on nociception, edema and cell migration in rats with CFA-induced arthritis. Female Wistar rats (200 - 250 g, n = 50) was monoarthritis-induced by complete Freund's adjuvant (CFA; Mycobacterium butyricum, 0.5 mg/mL; 50 μL) into the right knee joint (TF; n = 24) or right ankle joint (TT; n = 26). Incapacitation was measured by the paw elevation time (TEP; s) in 1-min periods of observation. The edema of the knee or ankle joints was evaluated by the variation of the articular diameter (DA, cm) and by the paw volume variation (EP, mL), respectively. Both were measured during 10 consecutive days. Two protocols of exercise were performed: (a) in the constant exercise group (TF, n = 6; TT, n = 6) performing 1 minute of daily exercise on the cylinder; (b) variable exercise group (TF, n = 6; TT, n = 7), the exercise increased by 1 minute per day. The control groups (TF, n = 12; TT, n = 13) didn´t perform the exercise. After 10 days, the animals were euthanized for total (CT; cells/mm3) and differential leukocyte counts (mononuclear - MON, and polymorphonuclear - PMN, cells/mm3) of the articular inflammatory exudate. The variable exercise protocol inhibited incapacitation and edema for both joints. However, cell migration decreased only in the TF.The constant exercise reduced edema in both joints, and cell migration was decreased in the TT. However, the incapacitation was not reduced. Variable exercise seemed to be more effective in reducing the inflammatory parameters than constant exercise.

Evidências de que um protocolo de atividade física pode reduzir a contagem de leucócitos sinoviais de ratos artríticos / Evidence that a physical activity protocol can reduce synovial leukocyte count in arthritic rats

INTRODUÇÃO: O exercício físico apresenta potenciais benefícios na artrite, retardando a incapacidade funcional e melhorando a função das articulações. Estudos in vivo utilizando modelos experimentais de artrite podem fornecer informações úteis sobre estes benefícios. OBJETIVO: O propósito deste estudo foi avaliar os efeitos do exercício de baixa intensidade em um modelo de artrite induzida por CFA em ratos. MÉTODOS: A incapacitação articular foi mensurada pelo tempo de elevação da pata em uma deambulação estimulada no período de um minuto. O edema foi avaliado pela medida do diâmetro articular do joelho. O exsudato inflamatório foi coletado após dez dias para contagem de leucócitos. O protocolo de exercício consistiu de dois minutos de deambulação no primeiro dia, dez minutos de deambulação no segundo dia e 20 minutos de deambulação do terceiro ao décimo dia. O grupo controle foi submetido a um minuto de deambulação uma vez ao dia através de dez dias. O envolvimento de corticosteroide foi avaliado pelo tratamento dos animais por aminoglutetimida. RESULTADOS: O protocolo de exercício produziu uma pequena, mas sustentada redução da incapacitação e do edema articulares, associada a uma grande redução na contagem de leucócitos sinoviais. A aminoglutetimida preveniu apenas o efeito na contagem de leucócitos sinoviais. CONCLUSÃO: Esses resultados sugerem que uma atividade física de baixa intensidade não agrava a sintomatologia dos animais artríticos, de fato apresentando leve melhora, e ainda pode reduzir acentuadamente a migração de leucócitos para o espaço sinovial.

INTRODUCTION: Physical activity is thought to be beneficial to arthritis, delaying disability and/or improving joint function. In vivo studies using experimental models of arthritis may provide useful information about such benefits. OBJECTIVE: The aim of the present study was to evaluate the effects of the low-intensity exercise on a model of CFA-induced arthritis in rats. METHODS: Articular incapacitation was measured by the paw elevation time in 1-min periods of stimulated walk. Edema was evaluated by the knee-joint diameter. Synovial exudate was sampled after 10 days for leukocyte count. The exercise protocol consisted of a 2-min period of stimulated walk in the 1st day, 10 min in the 2nd day, and 20 min from the 3rd to the 10th day; The control animals were submitted to 1-min period of stimulated walk once a day over 10 days. Corticosteroid involvement was assessed by treating the animals with aminoglutethimide. RESULTS: The exercise protocol produced a slight but sustained reduction of disability and joint swelling associated with a large reduction in the synovial leukocyte count. Aminoglutethimide only prevented the effect on synovial leukocyte count. CONCLUSION: These results suggest that a low-intensity physical activity does not aggravate the symptoms of arthritic animals, in fact showing a slight improvement, and still can markedly reduce the migration of leukocytes into the synovial space.

Padronização de modelo experimental adequado a estudos do efeito do exercício na artrite / Standardization of an experimental model suitable for studies on the effect of exercise on arthritis

OBJETIVO: Padronizar um modelo experimental de monoartrite crônica induzida por adjuvante completo de Freund apropriado à análise do efeito da deambulação na nocicepção e no edema articular. MÉTODOS: Foram avaliados os seguintes fatores para a indução da monoartrite: via e local de administração, número e intervalo das inoculações, espécie de micobactéria e gênero dos animais. Para tanto, ratos Wistar machos e fêmeas (200 a 250g) receberam duas injeções de adjuvante completo de Freund contendo Mycobacterium tuberculosis (1,0mg/mL; 50µL) ou Mycobacterium butiricum (0,5mg/mL; 50µL) intra-articular nas articulações tibiotársica ou tibiofemural ou, ainda, uma injeção de adjuvante completo de Freund (Mycobacterium butiricum ou tuberculosis) intradérmica na base da cauda e outra intra-articular (tibiotársica ou tibiofemural). Os animais foram submetidos à avaliação da incapacitação e edema articulares. A incapacitação articular foi avaliada pelo tempo de elevação da pata (em segundos) durante a marcha de 1 minuto. O edema da articulação tibiofemural foi avaliado pela variação do diâmetro articular (cm). O edema da articulação tibiotársica foi medido pelo volume da pata (mL). RESULTADOS: A administração de adjuvante completo de Freund, contendo Mycobacterium butiricum, aumentou o tempo de elevação da pata e o edema, em ambas as articulações. CONCLUSÃO: Esses dados possibilitaram a padronização de um modelo animal de monoartrite crônica, adequado à análise dos efeitos do exercício no tratamento da artrite reumatoide.

OBJECTIVE: To standardize an experimental model of chronic monoarthritis induced by complete Freund's adjuvant appropriate for the analysis of the effect of walking on nociception and on joint edema. METHODS: The following factors were evaluated as to monoarthritis induction: route and site of administration, number and interval of inoculations, Mycobacterium species, and animal gender. Wistar male and female rats (200 to 250g) received two injections of complete Freund's adjuvant containing Mycobacterium tuberculosis (1.0mg/mL; 50µL) or Mycobacterium butyricum (0.5mg/mL; 50µL) intra-articularly in the tibiotarsal or tibiofemoral joints, or an injection of complete Freund's adjuvant (Mycobacterium butyricum or tuberculosis) intradermally at the base of the tail and another intra-articularly (tibiotarsal or tibiofemoral). The animals were submitted to evaluations of articular disability and edema. Articular disability was assessed by paw elevation time (in seconds) during the one-minute walk test. Edema of the tibiofemoral joint was assessed by variation of joint diameter (cm). Tibiotarsal joint edema was measured by the volume of the paw (mL). RESULTS: Administration of complete Freund's adjuvant containing Mycobacterium butyricum increased paw elevation time and edema in both joints. CONCLUSIONS: These data allow standardization of an animal model of chronic monoarthritis adequate for analysis of the effects of exercise on treatment of rheumatoid arthritis.

Contribution of TNFalpha, IL-1beta and CINC-1 for articular incapacitation, edema and cell migration in a model of LPS-induced reactive arthritis.

The protective effect of anti-CINC-1, -TNFalpha and -IL-1beta antisera on articular inflammatory incapacitation, articular diameter and synovial fluid cell content, which are correlated to nociception, edema and cell migration, respectively, were evaluated in a rat model of LPS-induced reactive arthritis. In this model, Escherichia coli lipopolysaccharide (LPS; 30 ng) was injected in a knee-joint previously primed with carrageenan (300 microg). Articular incapacitation was evaluated hourly by the automated registering of the knee-joint function during animal walking, and the knee-joint edema was evaluated by measuring the articular diameter increase. After 6 h, the animals were euthanized for collecting synovial fluid for the evaluation of cell migration. LPS produced dose-dependent incapacitation and edema. Anti-TNFalpha, -IL-1beta, and -CINC-1 antisera (20 and 40 microl) were used as pretreatment into knee-joint before LPS injection. At higher dose, Anti-TNFalpha and anti-CINC-1 were able to inhibit incapacitation, articular edema and mononuclear (MON) migration. Anti-IL1beta did not affect incapacitation at any dose, although inhibited edema and cell migration. Surprisingly, the higher dose of anti-IL1beta antisera did not inhibit cell migration, although inhibited articular edema. These findings corroborate the role TNFalpha has in different forms of arthritis, but points out the idea that CINC-1 (the homologue for human IL-8) may constitute a promising target for reactive arthritis management. Indeed, the potent antiedematogenic effect, and principally the anti-migration effect of anti-CINC-1, raises the possibility of a better control of disease progression than with anti-IL-1beta therapies.