Neurogenic colonic motility patterns and gut transit disrupted in a mouse model of Rett Syndrome

Gastrointestinal dysfunction is a prominent feature of neurodevelopmental disorders and contributes significantly to visceral discomfort, but the specific etiology is unclear. In particular, it is unknown which cell types within central, autonomic or enteric nervous systems, gut muscle, epithelium or immune system are the principal drivers of gut dysfunction. We report that the Mecp2 mouse model of Rett syndrome, a neurodevelopmental disorder with profound gut dysmotility, exhibits impaired whole gut transit times and constipation in vivo as well as striking alterations to propagating neurogenic contractions in ex vivo colons. Selective elimination of Mecp2 in neurons, but not glia or smooth muscle, recapitulates these dysmotility phenotypes. Bulk RNA sequencing of colonic external muscle, containing the myenteric compartment of the enteric nervous system, showed significant expression changes in specific neurochemical signaling pathways. Pharmacological modulation of one, the M1 acetylcholine receptor, modified the aberrant neurogenic contractile phenotype in mutant mice and reproduced it in wild-type mice. These results identify disruptions to neuronal muscarinic signaling in the enteric nervous system in a mouse model of Rett syndrome and provide an experimental strategy to identify translationally relevant cellular and molecular pathways underlying gastrointestinal dysmotility in neurodevelopmental disorders.