Retinoic acid (RA) and glycolic acid (GA) are frequently used in the treatment of acne and skin aging, as well as improving skin healing after dermabrasion and in photoaged skin. Examples of histologic alterations caused by these substances are vascularization increase and interference with inflammatory as well as regenerative skin processes. The objective of this study was to evaluate the possible decrease of skin flap necrosis areas in rats, by applying both substances to the skin 14 and 30 days before surgery, and analyzing histopathologic skin alterations after treatment. Fifty Wistar rats were divided into five groups of 10 animals each. They received daily retinoic acid application for 14 and 30 days, daily glycolic acid application for 14 and 30 days, and vehicle application (control group) for 14 days. After treatment, each rat was submitted to random dorsal skin flap (10 × 3 cm) elevation; flaps were sutured back in place over isolating plastic strips. The rats were sacrificed after 7 days and flap necrosis areas were measured through transparency and then analyzed using computer scanning. Statistical analysis was carried out using monocaudal nonpaired t tests and histopathologic examination was performed in all cases. Compared with the control group, treatment with both acids did not decrease average flap necrosis areas. Though groups RA 30 days and GA 14 days presented larger necrosis area averages (p < 0.05), groups RA 14 days and GA 30 days showed no statistically significant difference (p > 0.05) when compared to the control group. Both substances caused spongiosis, stratum corneum thickening, and vascularization increase, with GA inducing greater granulomatous reaction and RA more spongiosis and queratinization. Group RA 30 days showed the most significant dermo-epithelial (including vascular) regenerative and proliferative effects. Retinoic and glycolic acid treatment led to significatuve and well-known skin alterations, with group RA 30 days showing most notable dermo-epithelial proliferative effects. In our experimental model, preoperatory RA and GA application did not decrease rat dorsal skin flap necrosis area when compared to the control group.
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