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Direct influence of low-level laser irradiation on neurons: an electrophysiological study to helping comprise analgesic effects of infrared light in diabetic neuropathy

Grant number: 18/05108-8
Support type:Scholarships abroad - Research Internship - Doctorate
Effective date (Start): October 01, 2018
Effective date (End): September 30, 2019
Field of knowledge:Health Sciences - Physiotherapy and Occupational Therapy
Principal Investigator:Carlos Amilcar Parada
Grantee:Willians Fernando Vieira
Supervisor abroad: Rodney Philip Oconnor
Home Institution: Instituto de Biologia (IB). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
Local de pesquisa : École des Mines de Saint-Étienne, Gardanne (MINES Saint-Étienne), France  
Associated to the scholarship:15/12673-5 - Effects of low-level laser therapy (LLLT) in experimental diabetic neuropathy, BP.DR

Abstract

Approximately 50% of the diabetic patients develop peripheral neuropathy with irreversible complications to the peripheral nervous system. Hyperglycemia is the majoritarian cause of oxidative stress and promotes a suitable environment to damage peripheral nerves and neurotransmitter pathways. Nociceptors could be selectively affected by low-level laser therapy (LLLT), and it has been proposed that this effect underpins the pain-relieving effects of LLLT in the treatment of acute and chronic pain. In cell culture studies using rat DRG, 830, 808, and 650 nm LLLT resulted in reversible neurophysiological changes of significantly decreased mitochondrial membrane potential (MMP). However, no study showed the direct effect of the infrared laser irradiation on sensitized neurons in a condition of hyperglycemic oxidative stress environment that mimics a diabetic neuropathy situation. Thus, the general goal of this study is to comprise the direct influence of LLLT in the electrical activity of HT22 mouse hippocampal and rat DRG neurons. Firstly, we will use immortalized cell cultures of HT22 mouse hippocampal neurons and after testing, DRG will be collected from male LEW/HsdUnib (Lewis) isogenic rats (4-weeks-old). HT22 mouse hippocampal neurons and rat DRG neurons on culture dishes will be exposed to GaAs 904 nm infrared laser irradiation using an Endophoton LLT-1307 laser device (KLD Biosystems® - Brazil), class IIIB; continuous wave; energy 2.03 joule; 29 seconds; 70 mW power; 0.001 cm² output beam; 7,000 mW/cm² irradiance. During laser irradiation, the neurons will be submitted to electrophysiological recordings. Neurons will be transfer into a recording chamber through which oxygenated artificial cerebrospinal fluid (ACSF) will be constantly perfused (2 mL/min) at room temperature. We also will investigate the MMP by using tetramethyl rhodamine methyl ester (TMRM - Invitrogen/Molecular Probes). HT22 and DRG neurons, exposed to LLLT, will be label by Hoechst Stain solution (Sigma-Aldrich). Cells will also be loaded with FluoVolt in the physiological solution supplemented with the dye and with the PowerLoad Concentrate. The PowerLoad Concentrate (a component of the FluoVolt Kit) is an optimized formulation of pluronic surfactant polyols, which help the solubilization of the dye. These experiments will help comprise the possible effects of LLLT in the electrical activity of neurons, once we believe in a "hyperpolarizing effect" promoted by infrared laser irradiation. (AU)

Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
VIEIRA, WILLIANS F.; DE MAGALHAES, SILVIANE F.; FARIAS, FELIPE H.; DE THOMAZ, ANDRE A.; PARADA, CARLOS A. Raman spectroscopy of dorsal root ganglia from streptozotocin-induced diabetic neuropathic rats submitted to photobiomodulation therapy. Journal of Biophotonics, v. 12, n. 11 JULY 2019. Web of Science Citations: 0.

Please report errors in scientific publications list by writing to: cdi@fapesp.br.