PAC1 Deficiency in a Murine Model Induces Gastric Mucosa Hypertrophy and Higher Basal Gastric Acid Output

Pituitary adenylate cyclase-activating polypeptide (PACAP) has been shown to increase the histamine release from gastric enterochromaffin-like (ECL) cells and promote gastric acid secretion in rats. In contrast, in mice, PACAP has been demonstrated to induce a decrease of gastric acid secretion, an effect presumably due to somatostatin release. To more clearly define the role of PACAP in the regulation of gastric acid output, a knockout mouse model for the PACAP-specific receptor PAC1 was applied in this study. Measurements of the basal and stimulated gastric acid secretion and morphological studies on the gastric mucosa were performed in both wild-type and PAC1-deficient mice. Compared with the wild-type mice, the PAC1-deficient mice showed a nearly threefold higher basal gastric acid output, increased gastric mucosa thickness and glands height, and proportional increases in parietal and total cell counts in the gastric mucosa. The PAC1-deficient mice also showed a trend of increased plasma gastrin levels and gastrin gene expression in the gastric mucosa. This study indicates that the expression of PAC1 is clearly important for maintaining the homeostasis of gastric acid secretion. Loss of PACAP receptor during development may lead to a compensatory mechanism regulating gastric acid secretion

PAC1 deficiency in a murine model induces gastric mucosa hypertrophy and higher basal gastric acid output.

Pituitary adenylate cyclase-activating polypeptide (PACAP) has been shown to increase the histamine release from gastric enterochromaffin-like (ECL) cells and promote gastric acid secretion in rats. In contrast, in mice, PACAP has been demonstrated to induce a decrease of gastric acid secretion, an effect presumably due to somatostatin release. To more clearly define the role of PACAP in the regulation of gastric acid output, a knockout mouse model for the PACAP-specific receptor PAC1 was applied in this study. Measurements of the basal and stimulated gastric acid secretion and morphological studies on the gastric mucosa were performed in both wild-type and PAC1-deficient mice. Compared with the wild-type mice, the PAC1-deficient mice showed a nearly threefold higher basal gastric acid output, increased gastric mucosa thickness and glands height, and proportional increases in parietal and total cell counts in the gastric mucosa. The PAC1-deficient mice also showed a trend of increased plasma gastrin levels and gastrin gene expression in the gastric mucosa. This study indicates that the expression of PAC1 is clearly important for maintaining the homeostasis of gastric acid secretion. Loss of PACAP receptor during development may lead to a compensatory mechanism regulating gastric acid secretion

Natural history of definitive diverticular hemorrhage based on stigmata of recent hemorrhage and colonoscopic Doppler blood flow monitoring for risk stratification and definitive hemostasis

Background and aimsFew prospective reports describe the short-term natural history of colon diverticular hemorrhage based on stigmata of recent hemorrhage, and none include blood flow detection for risk stratification or as a guide to definitive hemostasis. Our purposes were to report the 30-day natural history of definitive diverticular hemorrhage based on stigmata and to describe Doppler probe blood flow detection as a guide to definitive hemostasis.MethodsDifferent cohorts of patients with severe diverticular bleeding and stigmata on urgent colonoscopy are reported. For 30-day natural history, patients were treated medically. If severe rebleeding occurred, they had surgical or angiographic treatment. We report natural history with major stigmata (active bleeding, visible vessel, or adherent clot) and no stigmata or flat spots after clots were washed away. We also report Doppler probe detection of arterial blood flow underneath stigmata before and after hemostasis in a recent cohort.ResultsFor natural history, patients with major stigmata treated medically had 65.8% (25/38) rebleeding rates, and 44.7% (17/38) had intervention for hemostasis. Patients with spots or clean bases had no rebleeding. A Doppler probe detected arterial blood flow in 92% of major stigmata--none after hemostasis--and there was no rebleeding.Conclusions(1) Patients with major stigmata treated medically had high rates of rebleeding and intervention for hemostasis. (2) Patients with clean diverticula or only flat spots had no rebleeding. (3) High rates of arterial blood flow were detected under major stigmata with a Doppler probe, but with obliteration by hemostasis no rebleeding occurred