Disturbed glucose metabolism by perfluorobutanesulfonate pollutant and benefit of young fecal transplantation in aged zebrafish

Perfluorobutanesulfonate (PFBS) is an environmental pollutant of emerging concern, which significantly impacts the metabolism and health of animals. Because of the loss of functional capacity, the aged animals are regarded more susceptible to the toxicity of environmental pollutants. In the present study, aged zebrafish were employed as the toxicological animal and transplanted with the feces collected from young donors for 14 days, after which the acclimated elderly were exposed to PFBS at environmentally relevant concentrations (0 and 100 μg/L) for another 14 days. When the exposure was concluded, glucose metabolic disturbances of PFBS in the aged and efficacy of young fecal transplant to mitigate the toxicity of PFBS were explored along the gut-liver axis. The results showed that PFBS exposure significantly inhibited the enzymatic activity of α-amylase in the gut, but increased the alanine aminotransferase (ALT) activity in the blood of the aged zebrafish, suggesting the impairment of intestinal digestive functions of carbohydrates and the induction of liver damage by PFBS. However, young fecal transplantation successfully ameliorated the toxicity of PFBS on α-amylase and ALT, underlining the benefits conveyed to the health of the elderly. In addition, transplantation of young feces was efficient to alleviate the hyperglycemia symptom in the elderly via stimulating the secretion of insulin. PFBS exposure increased blood glucagon level, disrupted insulin receptor transcription, and depleted hepatic glycogen store, which were all mitigated by young fecal transplant. Hepatic proteomic analysis also found dynamic interactions between young fecal transplantation and PFBS pollutant on the metabolic pathways of glucose and glycogen, involving glycolysis, gluconeogenesis, glycogenesis, and glycogenolysis. Overall, the present findings highlighted the beneficial effects of young fecal transplantation to protect the aged from the glucose metabolism toxicity of PFBS, thus providing a plausible measure to improve the health aging status.