ABLATION OF CAPSAICIN-SENSITIVE AFFERENT NERVES IMPAIRS DEFENSE BUT NOT RAPID REPAIR OF RAT GASTRIC-MUCOSA

Capsaicin sensitive afferent neurones have previously been reported to play a part in gastric mucosal protection. The aim of this study was to investigate whether these nociceptive neurones strengthen mucosal d efence against injury or promote rapid repair of the damaged mucosa, o r both. This hypothesis was examined in anaesthetised rats whose stoma chs were perfused with ethanol (25 or 50% in saline, wt/wt) for 30 min utes. The gastric mucosa was inspected 0 and 180 minutes after ethanol had been given at the macroscopic, light, and scanning electron micro scopic level. Rapid repair of the ethanol injured gastric mucosa (redu ction of deep injury, partial re-epithelialisation of the denuded surf ace) took place in rats anaesthetised with phenobarbital, but not in t hose anaesthetised with urethane. Afferent nerve ablation as a result of treating rats with a neurotoxic dose of capsaicin before the experi ment significantly aggravated ethanol induced damage as shown by an in crease in the area and depth of mucosal erosions. Rapid repair of the injured mucosa, however, as seen in rats anaesthetised with phenobarbi tal 180 minutes after ethanol was given, was similar in capsaicin and vehicle pretreated animals. Ablation of capsaicin sensitive afferent n eurones was verified by a depletion of calcitonin gene related peptide from the gastric corpus wall. These findings indicate that nociceptiv e neurones control mechanisms of defence against acute injury but are not required for rapid repair of injured mucosa.