Effect of probiotics and melatonin on inflammatory cytokines and oxidative stress status in distant organs after local radiotherapy: An experimental study

Abdominopelvic radiotherapy (RT) can lead to inflammatory and oxidative changes in non-targeted organs, such as the lungs. This study aimed to investigate the protective effect of probiotic and melatonin administration on the inflammatory and oxidative changes in the lungs after abdominopelvic RT in Wistar albino rats.

Thirty female Wistar albino rats were divided into four groups: Group 1 (Control), Group 2 (RT) receiving a single dose of radiotherapy to the abdominopelvic region, Group 3 (RT + Melatonin) receiving a single dose of melatonin intraperitoneally before radiotherapy, and Group 4 (RT + Probiotic) receiving probiotic containing Lactobacillus rhamnosus GG and BB-12 (1010 CFU) via an orogastric feeding cannula before radiotherapy. After the rats were sacrificed, lung tissue samples were analyzed for the levels of Total Antioxidant Status (TAS), Total Oxidant Status (TOS), Oxidative Stress Index (OSI), Interleukin-1 beta (IL-1β), Interleukin-6 (IL-6), and Tumor Necrosis Factor-alpha (TNF-α).

TAS was lower in Group 2 compared to Group 3 or 4 (p<0.001). TOS was higher in Group 2 compared to Group 3 (p=0.007). IL-1β, IL-6, OSI, and TNF-α levels were lower in Group 3 or Group 4 compared to Group 2.

Abdominopelvic RT resulted in increased TOS and inflammatory cytokines and decreased TAS in non-targeted lung tissues. However, administration of melatonin or probiotics improved the antioxidant status and mitigated the increase in inflammatory cytokines and OSI caused by RT. Melatonin exhibited more prominent effects.