Microplastic-Induced Alterations in mouse fecal microbiota: Plastic Aging as a Modulating Factor

The aim of this study was to evaluate the in vivo intestinal toxicity of a subchronic oral exposure to MPs derived from everyday-use samples that have undergone an aging process. Female BALB/c mice were exposed to aged and non-aged PVC MPs via oral gavage for two months (0.02 mg/day). Intestinal toxicity was assessed through tissue oxidative stress [ROS/RNS, lipid peroxidation, reduced glutathione (GSH)] and inflammation (IL-1beta, TNF-alpha) markers, histological examination, microbiota composition and metabolism (short-chain fatty acids, SCFAs), and intestinal permeability. Daily ingestion of PVC MPs increased oxidative stress, with higher ROS/RNS and lipid peroxides, and promoted inflammation, with elevated IL-1beta and TNF-alpha levels. Histological analysis showed reduced crypt depth and increased mucus-secreting cells. MPs also altered gut microbiota composition and reduced SCFA levels, although intestinal permeability remained unchanged. These findings demonstrate that subchronic exposure to PVC MPs disturbs intestinal homeostasis through oxidative and inflammatory stress and microbiota alterations, even without compromising barrier integrity.