Microplastic exposure is associated with gut microbiota alterations, intestinal barrier impairment, and endotoxin-related inflammation in female rats

Microplastics (MPs) are emerging environmental pollutants, and the gastrointestinal tract represents a major site of exposure following oral intake. This study investigated the effects of polystyrene MP exposure on gut microbiota composition, intestinal barrier integrity, and endotoxin-related inflammatory responses in female rats. MP exposure was associated with compositional alterations in the gut microbiota, including changes in community structure and enrichment of specific bacterial taxa. These microbial changes were accompanied by intestinal mucosal abnormalities, reduced PAS-positive mucin area, decreased expression of the tight junction proteins ZO-1, occludin, and claudin-1, and elevated serum levels of lipopolysaccharide (LPS), interleukin-6 (IL-6), and interleukin-1β (IL-1β). These findings indicate that MP exposure was associated with intestinal barrier impairment and endotoxin-related systemic inflammation. Overall, the present study supports the intestine as a major target of oral MP exposure and suggests that intestinal barrier disruption may contribute to circulating endotoxin accumulation and inflammatory responses. Further studies using direct intestinal permeability assays and targeted mechanistic interventions are needed to clarify the causal relationships among gut microbiota dysbiosis, barrier dysfunction, and systemic inflammation.