Background: Jejunum is one of the most radiosensitive parts of the gastrointestinal
system. This is the main issue, leading to several side effects to patients with abdominal cancers, in
addition to affecting their quality of life. Epithelial layer and clonogenic cells in the jejunum are the
most sensitive parts of the intestine, while damage to vascular may lead to chronic inflammation and
bleeding. Both melatonin and metformin have shown abilities to attenuate radiation toxicities
through the modulation of DNA damage responses, neutralization of free radicals and alleviation of
inflammation. In this study, we aimed to evaluate the possible radioprotective effects of melatonin
and metformin when administered either alone or as a combination, in rat’s jejunum against a high
dose of radiation.
Methods: 40 male rats were divided into 8 groups as G1: control; G2: metformin; G3: melatonin;
G4: melatonin + metformin; G5: radiation; G6: radiation + melatonin; G7: radiation + metformin;
G8: metformin + melatonin + radiation. Rats were irradiated with 10 Gy gamma rays, while
treatments were administered at 100 mg/kg. The ratio for melatonin and metformin was 1:1. 3.5 days
after irradiation, all rats were sacrificed, followed by histopathological evaluation of the jejunum.
Results: This study showed that whole body irradiation of rats led to severe injuries to the epithelial
and vascular of jejunum. A single administration of either melatonin or metformin was unable to
mitigate radiation toxicity. However, administering the combination of melatonin and metformin
could mildly mitigate radiation-induced jejunum injury.
Conclusion: From the results of this study, we suggest that the combination of melatonin and
metformin has superior radioprotective effect for jejunum compared with the single administration of