Obesogenic cafeteria diet induces dynamic changes in gut microbiota, reduces myenteric neuron excitability, and impairs gut contraction in mice.

The cafeteria diet (CAF) is a superior diet model in animal experiments compared with the conventional high-fat diet (HFD), effectively inducing obesity, metabolic disturbances, and multi-organ damage. Nevertheless, its impact on gut microbiota composition during the progression of obesity, along with its repercussions on the enteric nervous system (ENS) and gastrointestinal motility has not been completely elucidated. To gain more insight into the effects of CAF diet in the gut, C57BL/6 mice were fed with CAF or a standard diet for 2 or 8 wk. CAF-fed mice experienced weight gain, disturbed glucose metabolism, dysregulated expression of colonic IL-6, IL-22, TNFα, and TPH1, and altered colon morphology, starting at week 2. Fecal DNA was isolated and gut microbiota composition was monitored by sequencing the V3-V4 16S rRNA region. Sequence analysis revealed that Clostridia and Proteobacteria were specific biomarkers associated with CAF-feeding at week 2, while Bacteroides and Actinobacteria were prominent at week 8. In addition, the impact of CAF diet on ENS was investigated (week 8), where HuC/D+ neurons were measured and counted, and their biophysical properties were evaluated by patch clamp. Gut contractility was tested in whole-mount preparations. Myenteric neurons in CAF-fed mice exhibited reduced body size, incremented cell density, and decreased excitability. The amplitude and frequency of the rhythmic spontaneous contractions in the colon and ileum were affected by the CAF diet. Our findings demonstrate, for the first time, that CAF diet gradually changes the gut microbiota and promotes low-grade inflammation, impacting the functional properties of myenteric neurons and gut contractility in mice.NEW & NOTEWORTHY The gut microbiota changes gradually following the consumption of CAF diet. An increase in Clostridia and Proteobacteria is a hallmark of dysbiosis at the early onset of gut inflammation and obesity. The CAF diet was effective in inducing intestinal low-grade inflammation and alterations in myenteric neuronal excitability in mice. CAF diet is a reliable strategy to study the interplay between gut dysbiosis and low-grade inflammation, in addition to the mechanisms underlying gastrointestinal dysmotility associated with obesity.