title: Laser therapy and pain-related behavior after injury of the inferior alveolar nerve: possible involvement of neurotrophins.
abstract: 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 brain-derived 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.
authors.affiliation: Laboratory of Functional Neuroanatomy of Pain, Department of Anatomy, University of São Paulo, São Paulo, Brazil.
authors.forename: Daniel
authors.initials: D
authors.lastname: de Oliveira Martins
authors.forename: Fabio
authors.initials: F
authors.lastname: Martinez dos Santos
authors.forename: Mara
authors.initials: M
authors.lastname: Evany de Oliveira
authors.forename: Luiz R G
authors.initials: LR
authors.lastname: de Britto
authors.forename: José
authors.initials: J
authors.lastname: Benedito Dias Lemos
authors.forename: Marucia
authors.initials: M
authors.lastname: Chacur
mesh_terms: D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000096:biosynthesis*; D028022:Low-Level Light Therapy / Q000379:methods*; D008297:Male; D008340:Mandibular Nerve / Q000378:metabolism*; D020932:Nerve Growth Factor / Q000096:biosynthesis*; D009414:Nerve Growth Factors / Q000096:biosynthesis; D010146:Pain / Q000378:metabolism*; D059408:Pain Management / Q000379:methods; D051381:Rats; D017208:Rats, Wistar; D061221:Trigeminal Nerve Injuries / Q000378:metabolism* / Q000628:therapy
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D009414:Nerve Growth Factors; D020932:Nerve Growth Factor