Apple polyphenol extract ameliorates sugary-diet-induced depression-like behaviors in male C57BL/6 mice by inhibiting the inflammation of the gut–brain axis

C57BL/6 mice were fed with control diet, sugary-diet, or sugary-diet with APE gavage for 8 weeks. After behavioral testing, the samples of serum, hippocampus, colon, and colonic contents were collected for further determination.