Role of sensory afferent neurons in hypertonic damage and restitution of the rat gastric mucosa.

BACKGROUND & AIMS: Gastric mucosal hyperemia is a protective response mediated at least in part by the response of sensory afferent neurons to hydrogen ions. The aim of this study was to determine if other pathways to the hyperemic response are present and if these neurons have an effect exclusive of hyperemia on mucosal protection and repair.

METHODS

Rat sensory afferent neurons were ablated by capsaicin treatment. Chambered stomachs were damaged by hypertonic saline followed by either acidic or neutral isotonic saline. Blood flow was measured by laser Doppler velocimetry, and mucosal morphology was quantitatively evaluated by microscopy.

RESULTS

Mucosal damage alone evoked a strong hyperemic response in both control and ablated rats. Ablated rats lost gastric protection despite this hyperemic response. Acid exposure after damage sustained the hyperemic response. Rapid epithelial restitution occurred faster (even over hemorrhagic lesions) in control rats.

CONCLUSIONS

The hyperemic response to mucosal damage alone is not mediated by sensory neurons. Protection of the stomach by sensory afferent neurons occurs by mechanisms also unrelated to their elicitation of hyperemia. Restitution during acid challenge is enhanced by the sustained hyperemic response mediated through sensory afferent neurons.