Assessment of laser photobiomodulation and polarized light on the healing of cutaneous wounds on euthyroid and hypothyroid induced rats

Luciana Maria Pedreira Ramalho; Barbara Mayoral Pedroso Weyll; Maíra Dória M. da Costa Lino; Maria Jose Pedreira Ramalho; Antonio Luis Barbosa Pinheiro

doi:10.1117/12.840508

25 February 2010 Assessment of laser photobiomodulation and polarized light on the healing of cutaneous wounds on euthyroid and hypothyroid induced rats

Luciana Maria Pedreira Ramalho, Barbara Mayoral Pedroso Weyll, Maíra Dória M. da Costa Lino, Maria Jose Pedreira Ramalho, Antonio Luis Barbosa Pinheiro

Author Affiliations +

Proceedings Volume 7552, Mechanisms for Low-Light Therapy V; 75520P (2010) https://doi.org/10.1117/12.840508
Event: SPIE BiOS, 2010, San Francisco, California, United States

Abstract

The aim of this study was to assess the influence of low-level laser therapy (LLLT) or polarized light (PL) in cutaneous wound healing of hypothyroid rats at dosages of 20 or 40J/cm². Bioestimulatory effects of Laser radiation and Polarized light are recognized alternative therapies to improve healing on systemic disease patients, but their usefulness in the improvement of hypothyroidism healing impairment is uncertain till date. Forty Wistar rats were used in this study. Hypothyroidism was propylthiouracil- induced. Standard excisional cutaneous wounds were created without suturing and LLLT (λ660nm, 30mW, φ 3mm) or PL (λ 400-2000nm, 40mW, φ 10mm) was applied every 48 hours up to seven days on experimental groups. The rats were killed on the eighth day when wound contraction was assessed. The healing features were evaluated by light microscopy (H/E and Sirius Red). The cutaneous wounds of hypothyroid rats showed delayed healing process characterized by reduced thickness of epithelial layers, incipient formation of disorganized collagen fibers and wound contraction to a lesser extent (FISHER, p=0.0276), when compared to the euthyroid group. The use of both the Laser and Polarized Light on hypothyroid rats increased the amount of fibroblasts and the thickness of collagen fibers, especially on the L 20J/cm² group. Euthyroid rats have still demonstrated more regular collagen fibers pattern than hypothyroid rats. It was therefore concluded that hypothyroidism delays wound healing and both Laser photobiomodulation and Polarized Light at 20j/cm² dosages had improved the healing process in hypothyroid rats.

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Luciana Maria Pedreira Ramalho, Barbara Mayoral Pedroso Weyll, Maíra Dória M. da Costa Lino, Maria Jose Pedreira Ramalho, and Antonio Luis Barbosa Pinheiro "Assessment of laser photobiomodulation and polarized light on the healing of cutaneous wounds on euthyroid and hypothyroid induced rats", Proc. SPIE 7552, Mechanisms for Low-Light Therapy V, 75520P (25 February 2010); https://doi.org/10.1117/12.840508

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