Injeção epidural de cetamina ou cetamina levógira no controle da dor pós-incisional, em eqüinos

The aim of this study was to evaluate the pre-emptive effect of epidural ketamine S (+) (SK) or racemic ketamine (RK) administration, in post-incisional pain in horses. Were used in a blinded, randomized experimental study, sixteen mixed breed mares, 6±2 years old, weighting 273.2±42.0 kg. An epidural catheter was inserted 24 hours before the trials. The thigh region was shaved bilaterally, and mechanical cutaneous sensibility was measured using von Frey filaments (T-30). Using the left side as the control one, local anesthesia was performed at the right side. Twenty-five minutes later, SK was injected in G1 or RK in G2 through the epidural catheter. Five minutes after the ketamine injection, a 10 cm skin incision was made on the right side, and then sutured. Mechanical post-incisional pain was measured using von Frey filaments, at 1, 3 and 5 cm around the incision at 15 minutes intervals, for 2 hours, then 4, 6 and 8 hours after suturing. No changes were observed in the heart and respiratory rate and rectal temperature among groups or times of each group. Hind limb ataxia was observed in 62.5% and 12.5% of G1 and G2 respectively. SK and RK reduced cutaneous sensibility in the right and the left sides to mechanical postincisional pain during all time of experiment. Epidural SK and RK produce similar post-incisional analgesic effects, did not interfere in the cardio-respiratory parameters. The SK induces more intense ataxia in mares and presents a larger analgesic potency in the first 60 minutes after the administration.

Avaliação da eficácia analgésica da farmacopuntura com meloxicam e da aquapuntura preemptivas em gatas submetidas à ovariosalpingohisterectomia (OSH)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efeito da arnica 6D e 30D administradas por via transmucosa oral e subcutânea no controle da dor pós-operatória de gatas submetidas à ovariossalpingohisterectomia

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Serotonergic modulation in neuropathy induced by oxaliplatin: Effect on the 5HT(2C) receptor

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Tumescent local anesthesia with ropivacaine in different concentrations in bitches undergoing mastectomy: plasma concentration and post-operative analgesia

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Synaptic plasticity and sensory-motor improvennent following fibrin sealant dorsal root reimplantation and mononuclear cell therapy

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estudos sobre atividade nociceptiva/antinociceptiva de peptídeos isolados do veneno bruto de abelha Apis mellifera

O veneno bruto de abelha Apis mellifera é composto por uma série de peptídeos, entre eles a melitina, adolapina, procamina A e B, apamina, tertiapina, secapina, peptídeos desgranuladores de mastócitos, entre outros. Estas substâncias apresentam diversos efeitos já estudadas, dentre elas, efeitos antitumorais, atividades hiperalgésicas ou analgésicas, inflamatórias ou anti-inflamatórias. O peptídeo secapina foi descrito há 35 anos atrás e, posteriormente nada mais foi relatado na literatura. Portanto, este é o primeiro trabalho que visa caracterizar o possível efeito hiperalgésico e/ou analgésico, inflamatório e/ou antiinflamatório, bem como analisar alguns dos mecanismos envolvidos nestes fenômenos. Para tanto, para caracterizar os possíveis efeitos hiperalgésicos/analgésicos da secapina, em diversas doses (0,005, 0,35, 1, 2, 10 e 30 μg / 50 μL), foi utilizado o teste de avaliação da sensibilidade dolorosa denominado teste do von Frey eletrônico. Para a caracterização do efeito inflamatório/anti-inflamatório da secapina foi utilizado o paquímetro digital determinando o volume da pata dos animais. Para investigar os possíveis mecanismos envolvidos nestes efeitos, foram realizados tratamentos farmacológicos utilizando indometacina, zileuton e zafirlikaste (inibidores da síntese da via da cicloxigenase, lipoxigenase e antagonista de receptor de leucotrieno, respectivamente). Os resultados mostraram que a secapina, em todas as doses testadas, induziu efeito hiperalgésico a partir dos primeiros 15 minutos após a administração deste peptídeo. Este efeito hiperalgésico persistiu por até 240 minutos nas doses de 0,005 e 0,35 μg/ 50μL e 480 minutos nas doses de 1 e 2 μg/ 50μL. O efeito edematogênico da secapina na dose de 0,35 μg/50 μL foi iniciado nos primeiros 15 minutos após a administração da secapina e persistiu por até 120 minutos, sendo... (Resumo completo, clicar acesso eletrônico abaixo)

Efeitos neuroprotetor e regenerativo do selante de fibrina derivado da peçonha de serpente combinado com células tronco mononucleares após reparo do nervo isquiático de ratos neonatos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Cytokine inhibition and time-related influence of inflammatory stimuli on the hyperalgesia induced by the nucleus pulposus

The symptoms of lumbar disc herniation, such as low back pain and sciatica, have been associated with local release of cytokines following the inflammatory process induced by the contact of the nucleus pulposus (NP) with the spinal nerve. Using an animal experimental model of intervertebral disc herniation and behavioral tests to evaluate mechanical (electronic von Frey test) and thermal (Hargreaves Plantar test) hyperalgesia in the hind paw of rats submitted to the surgical model, this study aimed to detect in normal intervertebral disc the cytokines known to be involved in the mechanisms of inflammatory hyperalgesia, to observe if previous exposure of the intervertebral disc tissue to specific antibodies could affect the pain behavior (mechanical and thermal hyperalgesia) induced by the NP, and to observe the influence of the time of contact of the NP with the fifth lumbar dorsal root ganglion (L5-DRG) in the mechanical and thermal hyperalgesia. The cytokines present at highest concentrations in the rat NP were TNF-alpha, IL-1 beta and CINC-1. Rats submitted to the disc herniation experimental model, in which a NP from the sacrococcygeal region is deposited over the right L5-DRG, showed increased mechanical and thermal hyperalgesia that lasted at least 7 weeks. When the autologous NP was treated with antibodies against the three cytokines found at highest concentrations in the NP (TNF-alpha, IL-1 beta and CINC-1), there was decrease in both mechanical and thermal hyperalgesia in different time points, suggesting that each cytokine may be important for the hyperalgesia in different steps of the inflammatory process. The surgical remotion of the NP from herniated rats 1 week after the implantation reduced the hyperalgesia to the level similar to the control group. This reduction in the hyperalgesia was also observed in the group that had the NP removed 3 weeks after the implantation, although the intensity of the hyperalgesia did not decreased totally. The removal of the NP after 5 weeks did not changed the hyperalgesia observed in the hind paw, which suggests that the longer the contact of the NP with the DRG, the greater is the possibility of development of chronic pain. Together our results indicate that specific cytokines released during the inflammatory process induced by the herniated intervertebral disc play fundamental role in the development of the two modalities of hyperalgesia (mechanical and thermal) and that the maintenance of this inflammation may be the most important point for the chronification of the pain.

Percutaneous sciatic nerve block with tramadol induces analgesia and motor blockade in two animal pain models

Local anesthetic efficacy of tramadol has been reported following intradermal application. Our aim was to investigate the effect of perineural tramadol as the sole analgesic in two pain models. Male Wistar rats (280-380 g; N = 5/group) were used in these experiments. A neurostimulation-guided sciatic nerve block was performed and 2% lidocaine or tramadol (1.25 and 5 mg) was perineurally injected in two different animal pain models. In the flinching behavior test, the number of flinches was evaluated and in the plantar incision model, mechanical and heat thresholds were measured. Motor effects of lidocaine and tramadol were quantified and a motor block score elaborated. Tramadol, 1.25 mg, completely blocked the first and reduced the second phase of the flinching behavior test. In the plantar incision model, tramadol (1.25 mg) increased both paw withdrawal latency in response to radiant heat (8.3 +/- 1.1, 12.7 +/- 1.8, 8.4 +/- 0.8, and 11.1 +/- 3.3 s) and mechanical threshold in response to von Frey filaments (459 +/- 82.8, 447.5 +/- 91.7, 320.1 +/- 120, 126.43 +/- 92.8 mN) at 5, 15, 30, and 60 min, respectively. Sham block or contralateral sciatic nerve block did not differ from perineural saline injection throughout the study in either model. The effect of tramadol was not antagonized by intraperitoneal naloxone. High dose tramadol (5 mg) blocked motor function as well as 2% lidocaine. In conclusion, tramadol blocks nociception and motor function in vivo similar to local anesthetics.

Joint NOD2/RIPK2 Signaling Regulates IL-17 Axis and Contributes to the Development of Experimental Arthritis

Intracellular pattern recognition receptors such as the nucleotide-binding oligomerization domain (NOD)-like receptors family members are key for innate immune recognition of microbial infection and may play important roles in the development of inflammatory diseases, including rheumatic diseases. In this study, we evaluated the role of NOD1 and NOD2 on development of experimental arthritis. Ag-induced arthritis was generated in wild-type, NOD1(-/-)!, NOD2(-/-), or receptor-interacting serine-threonine kinase 2(-/-) (RIPK2(-/-)) immunized mice challenged intra-articularly with methylated BSA. Nociception was determined by electronic Von Frey test. Neutrophil recruitment and histopathological analysis of proteoglycan lost was evaluated in inflamed joints. Joint levels of inflammatory cytokine/chemokine were measured by ELISA. Cytokine (IL-6 and IL-23) and NOD2 expressions were determined in mice synovial tissue by RT-PCR. The NOD2(-/-) and RIPK2(-/-), but not NOD1(-/-), mice are protected from Ag-induced arthritis, which was characterized by a reduction in neutrophil recruitment, nociception, and cartilage degradation. NOD2/RIPK2 signaling impairment was associated with a reduction in proinflammatory cytokines and chemokines (TNF, IL-1 beta, and CXCL1/KC). IL-17 and IL-17 triggering cytokines (IL-6 and IL-23) were also reduced in the joint, but there is no difference in the percentage of CD4(+) IL-17(+) cells in the lymph node between arthritic wild-type and NOD2(-/-) mice. Altogether, these findings point to a pivotal role of the NOD2/RIPK2 signaling in the onset of experimental arthritis by triggering an IL-17-dependent joint immune response. Therefore, we could propose that NOD2 signaling is a target for the development of new therapies for the control of rheumatoid arthritis. The Journal of Immunology, 2012, 188: 5116-5122.

Caspase-1 is involved in the genesis of inflammatory hypernociception by contributing to peripheral IL-1β maturation

Abstract Background Caspase-1 is a cysteine protease responsible for the processing and secretion of IL-1β and IL-18, which are closely related to the induction of inflammation. However, limited evidence addresses the participation of caspase-1 in inflammatory pain. Here, we investigated the role of caspase-1 in inflammatory hypernociception (a decrease in the nociceptive threshold) using caspase-1 deficient mice (casp1-/-). Results Mechanical inflammatory hypernociception was evaluated using an electronic version of the von Frey test. The production of cytokines, PGE2 and neutrophil migration were evaluated by ELISA, radioimmunoassay and myeloperoxidase activity, respectively. The interleukin (IL)-1β and cyclooxygenase (COX)-2 protein expression were evaluated by western blotting. The mechanical hypernociception induced by intraplantar injection of carrageenin, tumour necrosis factor (TNF)α and CXCL1/KC was reduced in casp1-/- mice compared with WT mice. However, the hypernociception induced by IL-1β and PGE2 did not differ in WT and casp1-/- mice. Carrageenin-induced TNF-α and CXCL1/KC production and neutrophil recruitment in the paws of WT mice were not different from casp1-/- mice, while the maturation of IL-1β was reduced in casp1-/- mice. Furthermore, carrageenin induced an increase in the expression of COX-2 and PGE2 production in the paw of WT mice, but was reduced in casp1-/- mice. Conclusion These results suggest that caspase-1 plays a critical role in the cascade of events involved in the genesis of inflammatory hypernociception by promoting IL-1β maturation. Because caspase-1 is involved in the induction of COX-2 expression and PGE2 production, our data support the assertion that caspase-1 is a key target to control inflammatory pain.

Laser therapy and pain-related behavior after injury of the inferior alveolar nerve: possible involvement of neurotrophins

Nerve-related complications have been frequently reported in dental procedures, and a very frequent type of occurrence involves the inferior alveolar nerve (IAN). The nerve injury in humans often results in persistent pain accompanied by allodynia and hyperalgesia. In this investigation, we used an experimental IAN injury in rats, which was induced by a Crile hemostatic clamp, to evaluate the effects of laser therapy on nerve repair. We also studied the nociceptive behavior (von Frey hair test) before and after the injury and the behavioral effects of treatment with laser therapy (emitting a wavelength of 904 nm, output power of 70 Wpk, a spot area of *0.1 cm2, frequency of 9500 Hz, pulse time 60 ns and an energy density of 6 J/cm2). As neurotrophins are essential for the process of nerve regeneration, we used immunoblotting techniques to preliminarily examine the effects of laser therapy on the expression of nerve growth factor (NGF) and brainderived neurotrophic factor (BDNF). The injured animals treated with laser exhibited an improved nociceptive behavior. In irradiated animals, there was an enhanced expression of NGF (53%) and a decreased BDNF expression (40%) after laser therapy. These results indicate that BDNF plays a locally crucial role in pain-related behavior development after IAN injury, increasing after lesions (in parallel to the installation of pain behavior) and decreasing with laser therapy (in parallel to the improvement of pain behavior). On the other hand, NGF probably contributes to the repair of nerve tissue, in addition to improving the pain-related behavior.

Mechanosensitivity in the myenteric plexus of the guinea pig ileum

The enteric nervous system regulates autonomously from the central nervous system all the reflex pathways that control blood flow, motility, water and electrolyte transport and acid secretion. The ability of the gut to function in isolation is one of the most intriguing phenomenons in neurogastroenterology. This requires coding of sensory stimuli by cells in the gut wall. Enteric neurons are prominent candidates to relay mechanosensitivity. Surprisingly, the identity of mechanosensitive neurons in the enteric nervous system as well as the appropriate stimulus modality is unknown despite the evidence that enteric neurons respond to sustained distension. Objectives: The aim of our study was to record from mechanosensitive neurons using physiological stimulus modalities. Identification of sensory neurons is of central importance to understand sensory transmission under normal conditions and in gut diseases associated with sensorimotor dysfunctions, such as Irritable Bowel Syndrome. Only then it will be possible to identify novel targets that help to normalise sensory functions. Methods: We used guinea-pig ileum myenteric plexus preparations and recorded responses of all neurons in a given ganglion with a fast neuroimaging technique based on voltage sensitive dyes. To evoke a mechanical response we used two different kinds of stimuli: firstly we applied a local mechanical distortion of the ganglion surface with von Frey hair. Secondarily we mimic the ganglia deformation during physiological movements of myenteric ganglia in a freely contracting ileal preparation. We were able to reliably and reproducibly mimic this distortion by intraganglionic injections of small volumes of oxygenated and buffered Krebs solution using stimulus parameters that correspond to single contractions. We also performed in every ganglion tested, electrical stimulations to evoke fast excitatory postsynaptic potentials. Immunohistochemistry reactions were done with antibodies against Calbindin and NeuN, considered markers for sensory neurons. Results: Recordings were performed in 46 ganglia from 31 guinea pigs. In every ganglion tested we found from 1 to 21 (from 3% to 62%) responding cells with a median value of 7 (24% of the total number of neurons). The response consisted of an almost instantaneous spike discharge that showed adaptation. The median value of the action potential frequency in the responding neurons was 2.0 Hz, with a recording time of 1255 ms. The spike discharge lasted for 302 ± 231 ms and occurred only during the initial deformation phase. During sustained deformation no spike discharge was observed. The response was reproducible and was a direct activation of the enteric neurons since it remained after synaptic blockade with hexamethonium or ω-conotoxin and after long time perfusion with capsaicin. Muscle tone appears not to be required for activation of mechanosensory neurons. Mechanosensory neurons showed a response to mechanical stimulation related to the stimulus strength. All mechanosensory neurons received fast synaptic inputs. There was no correlation between mechanosensitivity and Calbindin-IR and NeuN-IR (44% of mechanosensitive neurones Calb-IR-/NeuN-IR-). Conclusions: We identified mechanosensitive neurons in the myenteric plexus of the guinea pig ileum which responded to brief deformation. These cells appear to be rapidly accommodating neurons which respond to dynamic change. All mechanosensitive neurons received fast synaptic input suggesting that their activity can be highly modulated by other neurons and hence there is a low stimulus fidelity which allows adjusting the gain in a sensory network. Mechanosensitivity appears to be a common feature of many enteric neurons belonging to different functional classes. This supports the existence of multifunctional enteric neurons which may fulfil sensory, integrative and motor functions.

Diskriminationsleistungen des Schmerzsinnes und deren Korrelate in Laser-evozierten Potenzialen

In der vorliegenden Arbeit sollte die Fähigkeit untersucht werden, Schmerzreize auf der Haut zu lokalisieren und deren Intensität zu differenzieren. Während dieser Diskriminationsaufgaben wurde die elektrische Aktivität des Gehirns gemessen.Traditionell werden dem nozizeptiven System nur geringe Diskriminationsleistungen zugeschrieben. In einer ersten Versuchsreihe sollten daher die räumlichen Diskriminationsleistungen für nozizeptive und taktile Reize verglichen werden. Auf dem Handrücken konnten schmerzhaft Laserhitzereize genauso gut lokalisiert werden wie taktile Reize (von-Frey-Haar). Nur ein mechanischer Nadelreiz, der taktiles und nozizeptives System koaktivierte, konnte noch besser lokalisiert werden. In der zweiten Versuchsreihe wurden während verschiedener Diskriminationsaufgaben (räumliche Diskrimination, Intensitätsdiskrimination) und einer Ablenkungsaufgabe (mentale Arithmetik) Laser-evozierte Potenziale von der Kopfhaut abgeleitet. Eine Dipolquellenanalyse zeigte als erstes eine Aktivierung des frontalen Operculums, entsprechend einem zur Zeit noch umstrittenen Projektionsgebiet eines nozizeptiven Thalamuskerns (VMpo), gefolgt vom primären somatosensorische Kortex (SI) und dem Gyrus cinguli. Im Gegensatz zum taktilen System wurde SI signifikant später aktiviert als SII (bzw. das Operculum). Die Diskriminationsaufgaben erhöhten die Aktivität aller Quellen im Vergleich zu der Ablenkungsbedingung. Dies konnte sogar für die früheste Quelle im Operculum gezeigt werden.Die frühe sensorisch-diskriminative Komponente der Schmerzverarbeitung im Operculum zeigte eine Hemisphärenasymmetrie, mit stärkerer Aktivierung der linken Hemisphäre unabhängig von der Stimulationsseite.