Effect of phototherapy on gastrointestinal smooth muscle activity and oxidative stress

To evaluate the effect of phototherapy on gastrointestinal smooth muscle activity and oxidative stress.

Wistar albino rats (n = 18, in the first 7 days of life) weighing 7 ± 2 g with both sexes were included in the study. The animals were randomized into three groups. In control group (CG), median laparotomy was performed to obtain 1 cm of jejunum, terminal ileum and colonic segments. In the phototherapy group (PTG), led phototherapy with a wave density of 40 μw/cm(2)/nm were used (Bilitron 3006, Fanem, Brasil). The efficacy surface of phototherapy was 30-40 cm and the exposure distance was 30 cm. The duration of phototherapy was 24 h. Sham group (SG) received white light with the same wave density and exposure distance. The oxidative stress markers and contraction responses were investigated from intestinal segments obtained from experiments.

The jejunum segments showed significantly lowered contraction response to carbachol in SG when compared to CG and PTG (p < 0.05). Decreased contractile response to KCl was detected in both SG and PTG in terminal ileum segments. MDA levels showed no difference between groups (p > 0.05). Total sulfhydryl (T-SH) levels were found significantly increased in PTG when compared to CG and SG (p < 0.05). When NO levels were evaluated, NO levels were found decreased in PTG and SG with respect to CG (p < 0.05).

PT may cause various alterations in oxidant/antioxidant system in intestinal segments. Unlike to clinical findings, decreased contractile responses were detected in rat gastrointestinal smooth muscles after PT.