Reduction of intrinsic inhibitory enteric neurons in the antropyloric area in PPPD patients with delayed gastric emptying

Background/Aims: Intrinsic inhibitory enteric neurons are considered to play an important role in the regulation of antropyloroduodenum coordination for gastric emptying. This study is designed to investigate the change of enteric neurons in the pylorus and antrum muscle in PPPD patients who have delayed gastric emptying. Methodology: Muscle strips of the pylorus and antrum from 6 normal and 2 PPPD patients with delayed gastric emptying were used for contraction study, immunohistochemical staining for enteric neurons, and western blotting for expression of neuropeptides. Results: Under the stimulation of carbachol, the contraction profile of the muscle strip from patients who had PPPD was different from those of the normal strips: muscle power of the ED ₅₀ of the pylorus/antrum were 1270mg/1400mg in normal strips, 400mg/1000mg in case 1, and 50mg/500mg in case 2. The frequency of muscle contraction was 3 times per minute in the normal strips, but 2.5 and 2 times per minutes in case 1 and case 2. From immunohistochemical staining, the density of inhibitory enteric neurons; nNOS-, CGRP-, and SST-containing nerve fibers and cells of Cajal, were significantly reduced in the pylorus and antrum muscle from the patients having delayed gastric emptying after PPPD. The protein content of inhibitory enteric neuropeptides, nNOS and CGRP, were also significantly decreased. Conclusions: These results suggest that the early loss of inhibitory enteric neurons in the preserved pylorus and antrum may be correlated with delayed gastric emptying in patients receiving PPPD.