Impact of Antibiotics, Cadmium, and Melatonin on Gut Microbiome

The 6-week-old male mice weighing 21.79 ± 0.76 g were given a standard diet and antibiotic treatment (1 g/L streptomycin, 1 g/L gentamicin, 0.5 g/L ampicillin and 0.5 g/L vancomycin, diluted in drinking water, Meilun Bio, Dalian, China) for 1 week to clean their gut microbiota [14 (link)]. Afterwards, the mice were randomized into 3 treatment groups: the antibiotics (anti (CON)), antibiotics + CdCl₂ (anti (Cd)), and antibiotics + CdCl₂ + Mel (anti (Cd + Mel)) group (n = 12/group). Total bacterial 16S rRNA was measured through qPCR, which verified the successful depletion of gut microbiota after antibiotic treatment [16 (link)]. Identical treatments in CON, Cd and Cd + Mel mice were given to anti (CON), anti (Cd) and anti (Cd + Mel) mice. After 10 weeks of Mel, Cd and antibiotic treatments were given once daily, with each mouse subjected to overnight fasting before it was euthanized. Consequently, samples of liver, blood, colonic content and mucosa and ileal mucosa were collected and stored at −80 ℃ until subsequent analyses.