Use of low-level laser for to assessment of painful sensitivity and the changes of substances involved in the genesis and maintenance of pain in rats undergoing to chronic constrictive lesion of infraorbital nerve

• Grant number: 13/08705-3
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate (Direct)
• Effective date (Start): July 01, 2013
• Effective date (End): December 31, 2013
• Field of knowledge: Biological Sciences - Morphology - Anatomy
• Principal Investigator: Marucia Chacur
• Grantee: Daniel de Oliveira Martins
• Supervisor: Barry John Sessle
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Research place: University of Toronto (U of T), Canada
• Associated to the scholarship: 10/20026-6 - Use of low-level laser and mechanisms in molecular and cellular repair process in peripheral nervous system, BP.DD

Abstract

The trigeminal neuralgia (TN) is a common cause of facial pain. She has a significant impact on quality of life and socioeconomic functioning of the patient. The International Association for the Study of Pain (IASP) defines NT as a unilateral painful disease that is characterized by episodes of pain like an electric shock, both its beginning and its ending may be abrupt. Many studies have been developed to analyze these mechanisms using more different experimental models in rats, for example, studies of complete transection or crush infraorbital nerve, inferior alveolar or lingual. Still, it is very difficult to define a definitive mechanism for trigeminal neuralgia, because even if the structural damage identify the pathologic process in progress, it is not enough to explain the pathophysiology of trigeminal neuralgia, that is, the mechanisms that give rise to this clinical phenomenon. The chronic constriction injury of the infraorbital nerve (CCI-NIO) which results in a model of chronic pain that can be applied to the study of orofacial neuropathic pain was described by VOS et al. (1994), and later used in other studies, making it a well-established model for the study of NT. The current treatment of the NT is not satisfactory, and pain control is the most used, and for some severe cases may choose to remove or destroy the trigeminal ganglion (TG). Among the main non-pharmacological techniques used for the treatment of neuropathies, we can emphasize the low-frequency electrical stimulation, active exercises, functional electrical stimulation, therapeutic ultrasound and LASER low power. In this study we propose the use of low-power laser, GaAs (904nm), to evaluate the cellular and molecular alterations in TG and brainstem (nucleus caudalis) after CCI-NIO and how the laser can influence this process, as well as in control of painful symptoms. For this we will use as immunoblotting analysis techniques, besides the use of behavioral test, Von Frey filaments to assess whether after injury the animals develop neuropathy and how low intensity laser therapy can change this condition. In addition, further evaluate the expression of proteins associated with painful process as substance P, BDNF, glia cells and also TRPV receptor type-1 and GT in the brain stem (nucleus caudalis). (AU)