The combined effect of photobiomodulation therapy and chia seeds supplementation for the treatment of diabetic retinopathy in experimental rats

Background
Photobiomodulation (PBM) plays an essential role in accelerating wound healing and in the recovery of the retinal function. This study aimed to evaluate the efficacy of PBM therapy in combination with chia seeds as an antioxidant in the treatment of experimental diabetic retinopathy (DR).
Materials and methods
A total of 80 Wistar rats were divided into two groups: group 1 control (=8 rat), and group 2 streptozotocin (STZ)-induced DR group (72 rats), which were injected intraperitoneally with 55 mg/kg of STZ. After 6 weeks, the rats were examined for DR and divided into three subgroups (each 24 rats): (2a) STZ-induced DR group, (2b) STZ-induced DR group exposed to 670-nm diode laser for 6 successive weeks, and (2c) STZ-induced DR group was exposed to 670-nm diode laser and supplemented with 250 mg/kg of chia seeds for 2 weeks before induction of diabetes and continued till the end of the experiment. Electroretinogram (ERG), total protein concentration in retina, and Fourier transform infrared spectrum were assessed after 1, 2, 4, and 6 weeks (six rats each).
Results
DR group showed a progressive decrease (<0.05) in a-wave and b-wave of the ERG and retinal protein, in addition to distinct change in the amide I region during 6 weeks, whereas treatment with PBM showed improvement in ERG (a-wave and b-wave, <0.05), protein content (<0.05), and in the amide I region (<0.05). However, the group treated with PBM and chia seeds showed better improvement in the a/b ratio of ERG, retinal protein, and in structural component of amide I region compared with the control (α-helix: 37 vs. 34.3%, β-sheet first peak was 12.6 vs. 14.39%, and β-sheet second peak was 20 vs. 20.36%).
Conclusion
Chia seeds with PBM has more beneficial effects in the treatment of DR than by PBM alone.