Butyrylated modification of corn starch alleviates autism-like behaviors by modulating 5-hydroxytryptamine metabolism and gut-brain neural activity

This study was conducted to elucidate the effects of different degrees of substitution (DS) on the properties of propionylated and butyrylated starches and to investigate their efficacy and mechanisms in ameliorating autism-like phenotypes. Fourier transform infrared spectra of propionylated and butyrylated starches revealed the presence of the CO absorption peak at 1730 cm^-1. Additionally, as the DS increased, the surface of the starch granules became rougher, and the crystallinity decreased. Moreover, in vitro digestion tests demonstrated that propionylated and butyrylated starches with a DS of approximately 0.25 exhibited enhanced resistance to digestion. Animal experiments indicated that butyrylated starch significantly improved abnormal behaviors in autism-like rats and increased butyrate accumulation in the colon. Furthermore, butyrylated starch normalized aberrant expression of G protein-coupled receptor 41 and tryptophan hydroxylase 1 in the colon, promoting 5-hydroxytryptamine metabolism and suppressing the expression of ionized calcium binding adaptor molecule 1 and glial fibrillary acidic protein in the gut and brain. These findings demonstrate that butyrylated starch effectively alleviates autism-like phenotypes in rats, supporting strategies to mitigate autism and develop new applications for natural corn starch.