Low intensity LASER therapy in the control of chronic neuropatic pain and the regeneration of the ischial nerve of rats.

A técnica de laserterapia é um método não invasivo utilizado por diversas áreas da saúde, e tem se mostrado eficaz no tratamento da diminuição da sensibilidade a dor. O presente estudo visa elucidar os efeitos desta terapia nas alterações moleculares induzida pela constrição crônica (CCI) do nervo isquiático de ratos. Esta técnica é aplicada em dias intercalados e tem a duração de 10 sessões. Ao finalizarmos o tratamento com laserterapia os animais foram eutanasiados e os gânglios das raízes posteriores (DRG L4L6) e o nervo isquiático foram retirados para posterior análise. Os DRGs foram processados para detecção da Substância P (SP) e do receptor de potencial transitório vanilóide tipo I (TRPV1). Ainda submetemos o nervo isquiático para a detecção do fator de crescimento neural (NGF) e proteína zero (P0). Nossos resultados demonstraram uma reversão da hipernocicepção dos animais tratados com LASER. Ainda, observamos um aumento da expressão de SP e TRPV1 nos animais com lesão e uma diminuição após o tratamento com LASER. Com relação aos ensaios referente ao nervo isquiático, podemos observar que houve um aumento da densidade óptica para o NGF e para a P0 após tratamento. Esses resultados podem ser observados de modo qualitativo por meio da técnica de imunohistoquímica de fluorescência. Nossos resultados em conjunto, demonstram a eficácia da laserterapia para reversão da hipernocicepção dos animais com lesão. Ainda, esta técnica é capaz de modular liberação de mediadores que participação do processo álgico, além de induzir a regeneração do nervo isquiático.The laser therapy technique is a noninvasive method used by several health areas, and has been shown to be effective in treat pain sensitivity. The present study aims to elucidate the effects of this therapy on molecular changes induced by chronic constriction (CCI) in rats. This technique was applied every other day, during 10 sessions. At the end of treatment, the animals were euthanized and the posterior root ganglia (DRG L4-L6) and sciatic nerve were removed for further analysis. The DRG\'s were processed for the detection of Substance P (SP) and transient potential receptor type I (TRPV1). In addition, we submit the sciatic nerve for the detection of neural growth factor (NGF) and zero protein (P0). Our results demonstrated a reversal of hypernociception in animals treated with LASER. Furthermore, we observed an increase in SP and TRPV1 expression in animals with lesion and a decrease after LASER treatment. With respect to the tests referring to the sciatic nerve, we could observe that there was an increase in the optical density for NGF and P0 after treatment. These results can be observed qualitatively by fluorescence immunohistochemistry. Our results together demonstrate the efficacy of laser therapy for the reversal of hypernociception of animals with lesions. Furthermore, this technique is able to modulate the release of mediators that participate in the algic process; in addition, this technique is also able to induce regeneration of sciatic nerve in rats

Evaluation of 904nm AsGa LASER radiation on the pain process in the neuropathic pain model in rats.

A técnica de laserterapia é um método não-invasivo que demonstra clinicamente ser eficaz na redução da sensibilidade à dor. O presente estudo visou examinar os efeitos da aplicação do LASER sobre a sensibilidade dolorosa induzida pela constrição crônica do nervo isquiático (CCI) de ratos. Os animais foram submetidos a ensaios comportamentais e a dez sessões de laserterapia. Observamos melhora para os testes comportamentais o que corrobora com os ensaios de imunoblotting no gânglio da raiz dorsal, onde observamos uma diminuição de Substância P no grupo de animais tratados com LASER. Com relação aos ensaios imunoenzimático de ELISA, observamos diminuição de citocinas pró-inflamatória e uma tendência ao aumento de citocina anti-inflamatória. Não observamos diferença estatística na análise dos receptores opióides MOR , DOR e KOR . Podemos concluir que o LASER é eficaz e age na modulação da dor neuropática.The technique of laser therapy is a not invasive method that demonstrates clinically to be effective in reducing sensitivity to pain. This study aimed to examine the effects of application of LASER on pain sensitivity induced by chronic constriction of the sciatic nerve (CCI) in rats. The animals were subjected to behavioral tests and the ten sessions of laser therapy. We observed and improvement for behavioral tests which corroborates with immunoblotting assays in the dorsal root ganglion, where we observes a decrease of substance P in the group of animals treated with LASER. Regarding immunoenzymatic ELISA assay, we observed a decrease of pro-inflammatory cytokines and a possible increase in anti-inflammatory cytokine. No statistical difference in the analysis of opioid receptor MOR, DOR and KOR

Neural Mobilization Treatment Decreases Glial Cells and Brain-Derived Neurotrophic Factor Expression in the Central Nervous System in Rats with Neuropathic Pain Induced by CCI in Rats

Background. Glial cells are implicated in the development of chronic pain and brain-derived neurotropic factor (BDNF) released from activated microglia contributes to the nociceptive transmission. Neural mobilization (NM) technique is a method clinically effective in reducing pain sensitivity. Here we examined the involvement of glial cells and BDNF expression in the thalamus and midbrain after NM treatment in rats with chronic constriction injury (CCI). CCI was induced and rats were subsequently submitted to 10 sessions of NM, every other day, beginning 14 days after CCI. Thalamus and midbrain were analyzed for glial fibrillary acidic protein (GFAP), microglial cell OX-42, and BDNF using Immunohistochemistry and Western blot assays. Results. Thalamus and midbrain of CCI group showed increases in GFAP, OX-42, and BDNF expression compared with control group and, in contrast, showed decreases in GFAP, OX-42, and BDNF after NM when compared with CCI group. The decreased immunoreactivity for GFAP, OX-42, and BDNF in ventral posterolateral nucleus in thalamus and the periaqueductal gray in midbrain was shown by immunohistochemistry. Conclusions. These findings may improve the knowledge about the involvement of astrocytes, microglia, and BDNF in the chronic pain and show that NM treatment, which alleviates neuropathic pain, affects glial cells and BDNF expression

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.\ud In irradiated animals, there was an enhanced expression of NGF (53%) and a decreased BDNF expression (40%) after\ud laser therapy. These results indicate that BDNF plays a locally crucial role in pain-related behavior development after IAN\ud injury, increasing after lesions (in parallel to the installation of pain behavior) and decreasing with laser therapy (in\ud parallel to the improvement of pain behavior). On the other hand, NGF probably contributes to the repair of nerve tissue,\ud in addition to improving the pain-related behavior.Fundação de Amparo a Pesquisa do Estado de São Paulo (FAPESP) nº 11/22268-0Fundação de Amparo a Pesquisa do Estado de São Paulo (FAPESP) nº 10/20026-6International Association For Study of Pain (IASP) – 2009 IAS