Objective To explore the effect of melatonin on gut microbiota of a mouse model of γ-ray-induced radiation intestinal injury.

Methods C57BL/6J male mice were divided into three groups using a simple random grouping method, namely, the control (without any treatment), irradiation (abdominal irradiation of mice at a dose of 13 Gy), and melatonin+irradiation groups (administration of melatonin to the mice for five consecutive days, followed by abdominal irradiation at a dose of 13 Gy), with five mice in each group. Mouse feces were collected 3 days after radiation, and gut microbiota analysis was conducted via 16S rDNA amplicon sequencing. Operational taxonomic units clustering and species annotation were analyzed using Uparse software. Sample complexity analysis and multisample comparative analysis were completed using the Qiime microbiome analysis platform.

Results Pasteurella, Candidatus Arthromitus, and Bacteroides were the most abundant bacteria in the intestines of mice in the melatonin+irradiation group. Compared with the control group, the melatonin+irradiation group showed decreased abundance and diversity of gut microbiota (both P<0.01) and increased community structure (P<0.001). From phylum to species, Proteobacteria phylum/class, Enterobacteriales order/family, Pasteurellales order/family/genus/species and Clostridiales class/order were the most abundant gut microbiota of mice in melatonin+irradiation group. In the construction of a symbiotic network of dominant species in mouse gut microbiota, the dominant interacting species under Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes and their interacting relationships were identified.

Conclusion The dominant species in the intestines of mice from melatonin+irradiation group might contribute to the relief of γ-ray-induced radiation intestinal injury mediated by melatonin.