Background: Radiation-induced enteritis and proctitis are common side effects
of abdominopelvic cancers among patients that undergo radiotherapy for prostate, colorectal
or urinary cancers. Exposure of these tissues to high doses of radiation leads to damage
to villous, inflammation, pain, ulcer and bleeding, which may cause malabsorption and
gastrointestinal disorders. To date, several procedures such as pharmaceutical treatment
have been proposed for protection and mitigation of gastrointestinal toxicity following radiotherapy.
Aims: In the current study, we aimed to investigate the possible radioprotection of ileum
and colon in rats using a combination of melatonin and metformin.
Methods: In this experimental study, 30 male Wistar rats were randomly assigned to six
groups: control, melatonin (100 mg/kg) treatment, melatonin (100 mg/kg) plus metformin
(100 mg/kg) treatment, radiation (10 Gy to whole body) group, radiation + melatonin (100
mg/kg) treatment, and radiation + melatonin (100 mg/kg) plus metformin (100 mg/kg)
treatment. After 3.5 days, rats were sacrificed and their ileum and colon tissues carefully
removed. Histopathological evaluations were conducted on these tissue samples.
Results: Histological evaluations reported moderate to severe damages to ileum and colon
following whole body irradiation. Melatonin administration was able to protect the ileum
remarkably, while the combination of melatonin and metformin was less effective. Interestingly,
for the colon, melatonin was less effective while its combination with metformin
was able to protect against radiation toxicity completely.
Conclusion: For the ileum, melatonin was a more effective radioprotector compared to its
combination with metformin. However, the combination of melatonin and metformin can
be proposed as an ideal radioprotector for the colon.