Masked trichothecene and zearalenone mycotoxins withstand digestion and absorption in the upper GI tract but are efficiently hydrolyzed by human gut microbiota in vitro.

SCOPE: Cereal grains are commonly contaminated with Fusarium mycotoxins and their plant-derived masked metabolites. The fate of masked mycotoxins in the human gut is poorly understood. Here we assess the metabolism and transport of glucoside metabolites of common trichothecenes (deoxynivalenol, nivalenol, T-2 toxin) and zearalenone compounds (zearalenone, α- and ß-zearalenol) in the human gut in vitro. METHODS AND RESULTS: Masked mycotoxins were incubated with artificial digestive juices and absorption was assessed in differentiated Caco-2/TC7 cells. Colonic metabolism was studied using fecal batch cultures from five donors and mycotoxins were detected using LC-MS/MS. All masked mycotoxins were stable under upper GI tract conditions and no absorption was observed. Free trichothecenes were absorbed intact whereas free zearalenone compounds were absorbed and metabolized to undetected compounds by Caco-2/TC7 cells. Human gut microbiota efficiently hydrolyzed all masked mycotoxins. Trichothecenes were fully recovered as parent mycotoxins whereas 40-70% of zearalenone compounds were further metabolized to unknown metabolites. CONCLUSION: Our results demonstrate that masked trichothecenes will reach the colon intact to be released as parent mycotoxins by gut microbiota, hence contributing to mycotoxin exposure. Masked zearalenone compounds are metabolized by gut microbiota and epithelial cells and the identity and toxicity of metabolites remain to be determined.

Incretin response to a standard test meal in a rat model of sleeve gastrectomy with diet-induced obesity.

BACKGROUND: Currently, the most effective treatment for obesity is bariatric surgery. Gastroduodenal bypass surgery produces sustained weight loss and improves glycemic control and insulin sensitivity. Previous studies have shown that sleeve gastrectomy (SG) produces similar results and implicate changes in incretin hormone release in these effects. METHODS: Male Sprague-Dawley rats were divided into four groups; lean control (lean), diet-induced obesity (DIO), DIO animals that had undergone SG (SG), and DIO animals that had undergone a sham operation (sham). RESULTS: After a 2-week recovery period, the incretin response to a standard test meal was measured. Blood sampling was performed in free-moving rats at various time points using chronic vascular access to the right jugular vein. There was a significant increase in the bodyweight of DIO animals fed a high-fat/high-sugar diet compared with the lean animals, which was reversed by SG. DIO caused an impairment of the GLP-1 response to a standard test meal, but not the GIP response. SG resulted in a dramatic increase in the GLP-1 response to a standard test meal but had no effect on the GIP response. CONCLUSIONS: A rapid rise in blood sugar was observed in the SG group following a standard test meal that was followed by reactive hypoglycemia. SG dramatically increases the GLP-1 response to a standard test meal but has no effect on GIP in a rat model of DIO.