Fig. 7: Gut microbiota was essential for the probiotic strain GR-1 to alleviate Cu toxicity in mice.

Cu levels in the feces (a) and tissue (b) samples of mice (n = 8 biologically independent animals). c The levels of ROS and MDA and activity of CAT and total SOD in the mouse liver sample (n = 8 biologically independent animals). d Representative images of hematoxylin and eosin–stained liver sections and Alcian blue and periodic acid–Schiff base–stained small intestinal sections (n = 3 biologically independent animals). The area within the solid square in 100× images of the small intestine has been magnified to 400×. Scale bars: 200 μm in 100× images and 50 μm in 400× images. The arrows and area circled using the dotted line indicate the liver damage. The liver tissue of the control exhibiting normal appearance; the liver tissue of the mice belonging to the Cu, Abx + Cu, and Abx + Cu + Pro groups showing cytoplasmic vacuolization, chromatin condensation, and pyknotic nuclei; the liver tissue of the mice belonging to the Cu+Pro group exhibiting preserved liver appearance, alleviated cytoplasmic vacuolization, and pyknotic nuclei. e Intergroup comparison of the averages of epithelial thickness, villus length, and muscle thickness of the ileum (n = 3 biologically independent animals). f Absolute copies of GR-1 in the feces sample of mice that were orally administered with GR-1 (n = 3 biologically independent animals). Data are expressed as means ± standard errors of the means. Statistical analysis was performed using one-way ANOVA with Tukey’s post hoc analysis using GraphPad Prism (version 8.0.1) (*p < 0.05, **p < 0.01, ***p < 0.001, and ****p < 0.0001, ns represents not significant). Source data are provided as a source data file.