Nutrients activate distinct patterns of small-intestinal enteric neurons

Area of Science:

• Neurogastroenterology
• Sensory biology
• Digestive system physiology

Background:

• Detecting nutrients is vital for survival and meeting metabolic needs.
• The enteric nervous system (ENS) uses gut signals for digestion and absorption.
• Cellular pathways for initial nutrient sensing and chemical discrimination by the ENS are not well understood.

Purpose of the Study:

• To identify specific enteric pathways activated by luminal nutrients in the mouse jejunum.
• To determine if the ENS can distinguish between different luminal chemicals.
• To elucidate the cellular mechanisms underlying nutrient detection in the gut.

Main Methods:

• Utilized calcium imaging techniques to monitor neuronal activity.
• Applied various luminal nutrients to isolated mouse jejunum segments.
• Investigated neurochemical profiles of activated neuronal populations.

Main Results:

• Specific nutrients activated distinct neurochemically defined neuronal ensembles in the myenteric and submucosal plexuses.
• Enteric neurons do not directly sense nutrients; they detect chemicals indirectly through the intestinal epithelium.
• A serotonin signaling pathway is a primary route for nutrient detection by the epithelium.
• Luminal information is spatially distributed along the intestine's radial axis, with signals relayed from villus epithelium to myenteric and then submucosal plexuses.

Conclusions:

• The ENS differentiates between various nutrients by activating specific neuronal circuits.
• Nutrient sensing is an indirect process involving epithelial cells and serotonin signaling.
• A hierarchical pathway transmits luminal information from the villus to deeper enteric plexuses.