Biomodulative effects of visible and IR laser light on the healing of cutaneous wounds of nourished and undernourished wistar rats

Abstract

Aim: We evaluated histologically the differences in the healing of cutaneous wounds on nourished or undernourished rats following laser phototherapy (LPT) (20 or 40 J/cm2). Background: Wound healing occurs due to a competitive mechanism between the synthesis and lysis of collagen. Any factor that increases the lysis or reduces the synthesis of collagen may change the healing process. Nutritional deficiencies have a great effect on wound healing. Methods: Fifty nourished or undernourished Wistar rats had one standardized wound created on the dorsum and were divided into 10 subgroups: Control (standard diet); Control [Northeastern Brazilian basic diet (DBR)]; Standard diet + LPT (λ635 nm; spatial average energy fluence (SAEF) 20 J/cm2); Standard diet + LPT (λ635 nm; SAEF 40 J/cm2); Standard diet + LPT (λ780 nm; SAEF 20 J/cm2); Standard diet + LPT (λ780 nm; SAEF 40 J/cm2); DBR + LPT (λ635 nm; SAEF 20 J/cm2); DBR + LPT (λ635 nm; SAEF 40 J/cm2); DBR + LPT (λ780 nm; SAEF 20 J/cm2); DBR + LPT (λ780 nm; SAEF 40 J/cm2). The first application of the treatment was carried out immediately and repeated daily for seven days. The specimens were routinely processed to wax, cut, stained with H&E and Sirius Red stains, and analyzed using light microscopy. The analyses included re-epithelization, inflammatory infiltrate, and fibroblastic proliferation. Sirius Red stained slides were used to perform descriptive analyses of the collagen fibers. Results: The results showed that LPT with λ635 wavelength was more effective for the treatment of undernourished subjects, treated with either LPT with λ730 nm with SAEF of 20 J/cm2 or λ780 nm with SAEF of 40 J/cm2. Conclusion: Nutritional status influenced the progression of the healing process as well as the quality of the healed tissue. In addition, the use of both wavelengths resulted in a positive biomodulatory effect on both nourished and undernourished subjects.