Original Article

Melatonin reduces colon immunological injury in rats by regulating activity of macrophages.

Authors: Qiao MEI, Jie-Ping YU, Jian-Ming XU, Wei WEI, Li XIANG, Li YUE


AIM: To investigate the effects of melatonin on the colon immunological injury of
rats and the role of macrophages in this process.
METHODS: The rats colitis was established by intrarectal injection with
2,4,6-trinitrobenzenesulfonic acid (TNBS) and ethanol. The animals were
randomized into 6 groups: normal group, model group, 5-aminosalicylic acid group
(100 mg/kg), and melatonin group (2.5, 5.0, and 10.0 mg/kg), treated
intrarectally with saline, saline, 5-aminosalicylic acid, and melatonin,
respectively (once a day, from d 7 after colitis established to d 28). At the end
of the experiment, the colon mucosa damage index (CMDI), the score of histology
(HS), the level of myeloperoxidase(MPO), and the sore of occult blood test (OBT)
were evaluated. Meanwhile, the activity of interleukin-1 (IL-1), tumour necrosis
factor-alpha (TNF-alpha, and nitric oxide (NO) were also detected.
RESULTS: After treated with TNBS and ethanol, the extents of CMDI, HS, OBT, and
the level of MPO in model group were more higher than that in normal group.
Melatonin could alleviate the colon injury, and reduce the level of MPO and the
degree of OBT. The activity of IL-1, TNF-alpha, and NO which released mainly from
macrophages was elevated remarkably. Melatonin could depress all this parameters.
CONCLUSION: Melatonin could reduce the colon damage in the colitis rats by
regulating macrophage activity.

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