Short-chain fatty acids augment rat duodenal mucosal barrier function.

Area of Science:

• Gastroenterology
• Physiology
• Molecular Biology

Background:

• Short-chain fatty acids (SCFAs) are microbial metabolites found in the small intestine, primarily from oral bacteria or supplements.
• The precise role of SCFAs in regulating small intestinal mucosal barrier function and motility remains incompletely understood.
• SCFAs are crucial for energy metabolism and have diverse physiological effects throughout the gastrointestinal tract.

Purpose of the Study:

• To investigate the effects of luminal and systemic acetate and propionate on duodenal mucosal barrier function, bicarbonate secretion, and motility in rats.
• To elucidate the mechanisms by which SCFAs influence duodenal physiology.
• To explore the potential contribution of SCFA signaling to gastrointestinal disorders.

Main Methods:

• Anesthetized rats underwent perfusion of a proximal duodenal segment with intact blood supply.
• Measurements included duodenal bicarbonate secretion, mucosal paracellular permeability (using 51Cr-EDTA clearance), transepithelial net fluid flux, and duodenal motility.
• SCFAs were administered either luminally via perfusion or systemically via intravenous infusion.

Main Results:

• Luminal perfusion with acetate or propionate significantly decreased duodenal paracellular permeability and net fluid flux while increasing bicarbonate secretion.
• Intravenous administration of SCFAs decreased mucosal permeability but also significantly reduced bicarbonate secretion.
• Luminal SCFAs shifted duodenal motility patterns from migrating motor complexes to fed patterns, an effect partially modulated by GLP-2.

Conclusions:

• Short-chain fatty acids exert differential effects on duodenal barrier function and bicarbonate secretion depending on their route of administration (luminal vs. systemic).
• Luminal SCFAs enhance barrier function and bicarbonate secretion, promoting a 'fed' motility state.
• Aberrant SCFA signaling or chemosensing may play a role in conditions characterized by impaired mucosal barrier function.