Photobiostimulation reverses allodynia and peripheral nerve damage in streptozotocin-induced type 1 diabetes
For better evaluation of the efficacy of low-level laser therapy in treating painful diabetic neuropathy and in protecting nerve fiber damage, we conducted a study with type 1 diabetic rats induced by streptozotocin. It is well known that diabetic peripheral neuropathy is the leading cause of pain in those individuals who suffer from diabetes. Despite the efficacy of insulin in controlling glucose level in blood, there is no effective treatment to prevent or reverse neuropathic damage for total pain relief.Male Wistar rats were divided into saline, vehicle, and treatment groups. A single intraperitoneal (i.p.) injection of streptozotocin (STZ) (85 mg/kg) was administered for the induction of diabetes. The von Frey filaments were used to assess nociceptive thresholds (allodynia). Behavioral measurements were accessed 14, 28, 48, and 56 days after STZ administration. Rats were irradiated with GaAs Laser (Gallium Arsenide, Laserpulse, Ibramed Brazil) emitting a wavelength of 904 nm, an output power of 45 mWpk, beam spot size at target 0.13 cm2, a frequency of 9500 Hz, a pulse time 60 ns, and an energy density of 6,23 J/cm2.The application of four sessions of low-level laser therapy was sufficient to reverse allodynia and protect peripheral nerve damage in diabetic rats.The results of this study indicate that low-level laser therapy is feasible to treat painful diabetic condition in rats using this protocol. Although its efficacy in reversing painful stimuli and protecting nerve fibers from damage was demonstrated, this treatment protocol must be further evaluated in biochemical levels to confirm its biological effects.
KeywordsDiabetes mellitus Sciatic nerve Nociception Myelin sheath Rat Streptozotocin
All authors made substantial contributions to the following tasks of research: initial conception (Rocha, I.R.C; Martins, D.O. Chacur, M.); design (Rocha, I.R.C; Martins D.O., Chacur M); provision of resources (Chacur M); collection of data (Rocha, I.R.C; Rosa, S. Ciena A.P); analysis and interpretation of data (Rocha, I.R.C; Chacur M.); writing the first draft of the paper or important intellectual content (Rocha, I.R.C; Martins D.O., Chacur M.); and revision of the paper (Rocha, I.R.C; Martins D.O., Chacur M).
Compliance with ethical standards
Ethics approval and consent to participate
All procedures were approved by the Institutional Animal Care Committee of the University of São Paulo (protocol number 123/2015) and performed in accordance with the guidelines for the ethical use of conscious animals in pain study published by the International Association for the Study of Pain.
Consent for publication
Availability of data and materials
The authors declare that they have no competing interests.
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