Photobiostimulation in control of nociception in model of trigeminal neuralgia

Abstract

The trigeminal neuralgia (TN) is a common cause of facial pain. It has a significant impact on quality of life and socioeconomic functioning of the patient. The International Association for the Study of Pain (IASP) defines the NT as a painful unilateral disorder characterized by brief episodes of pain - like electric shocks - whose start or finish can be abrupt, and its distribution is limited to one or more trigeminal nerve divisions. Among the various models of neuropathy using body nerve damage, the trigeminal has also been an important target. Since the trigeminal nerve conducts information through three main branches: the ophthalmic, maxillary and mandibular and is largely responsible for conducting sensory information arising from the face and neck. In mice, we observed the same divisions, with the infraorbital nerve, maxillary division, greater emphasis to be composed almost by sensory fibers and is responsible for supplying the set of whiskers. The chronic constriction injury of the infraorbital nerve (CCI-NIo) which results in a chronic pain model that can be applied to the study of orofacial neuropathic pain has been described by VOS et al. (1994) subsequently being used in other studies, becoming a well-established model for the study of NT. The current NT treatment is not satisfactory, and pain control is the most widely used solution, and for some severe cases you can choose to remove or destroy the trigeminal ganglion. Among the main non-pharmacological techniques used for the treatment of neuropathies, we can highlight the low frequency electrical stimulation, active exercise, 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 changes in the trigeminal ganglion after CCI-NIO and how the laser can influence this process as well as in controlling the painful symptoms. For this we will use as immunoblotting analysis techniques, besides the use of behavioral testing, Orofacial Stimulation Test to assess whether after injury the animals develop neuropathy and as lower intensity laser therapy can change this condition. Furthermore, even we evaluate the expression of proteins associated with the pain process such as substance P and also the TRPV-1-type receptors in the trigeminal ganglion.