The Role of Gastric Acid in the H. pylori-induced Gastritis in Mouse / 대한소화기학회지

BACKGROUND/AIMS: This study was designed to investigate the role of gastric acid in the extent of H. pylori-induced gastritis. METHODS: Twenty eight mice were innoculated with live H. pylori. They were allocated into four groups. Mice in group I received no treatment, group II mice were treated with sham injection, group III received 125microgram/kg body weight of pentagastrin, while group IV received 250microgram/kg body weight of pentagastrin subcutaneously three times a week. After 7 months, the mucosal pH, H. pylori density, neutrophils and monocytes infiltration, and the degree of atrophy were assessed in the stomach. RESULTS: In the gastric body, the densities of H. pylori were not different among groups. The degree of neutrophil infiltration was significantly lower in group IV compared to other groups (p<0.05). The degree of monocyte infiltration was also significantly lower in group IV than group III (p<0.05). In the gastric antrum, there was no significant difference of the H. pylori density, neutrophil and monocyte infiltration, and degree of atrophy among the groups. The mice with the gastric mucosal pH lower than mean of 3.2 had significant lower level of H. pylori density (1.4 vs. 2.4, p=0.04), and infiltration of neutrophils (0.9 vs. 2.3, p=0.018), and monocytes (1.2 vs. 1.8; p=0.011) than the those with mucosal pH above 3.2 in the body of stomach. CONCLUSIONS: Gastric acid plays a role in suppressing the proximal propagation of H. pylori-induced gastritis to the body of stomach.

Efffects of Fluoxetine on ATP-induced Calcium Signaling in PC12 Cells

Fluoxetine, a widely used anti-depressant compound, has several additional effects, including blockade of voltage-gated ion channels. We examined whether fluoxetine affects ATP-induced calcium signaling in PC12 cells by using fura-2-based digital calcium imaging and assay for [3H]-inositol phosphates (IPs). Treatment with ATP (100microM) for 2 min induced [Ca2+]i increases. The ATP-induced [Ca2+]i increases were significantly decreased by removal of extracellular Ca2+ and treatment with the inhibitor of endoplasmic reticulum Ca2+ ATPase thapsigargin (1microM). Treatment with fluoxetine for 5 min blocked the ATP-induced [Ca2+]i increase concentration-dependently. Treatment with fluoxetine (30microM) for 5 min blocked the ATP-induced [Ca2+]i increase following removal of extracellular Ca2+ and depletion of intracellular Ca2+ stores. While treatment with the L-type Ca2+ channel antagonist nimodipine for 10 min inhibited the ATP-induced [Ca2+]i increases significantly, treatment with fluoxetine alone blocked the ATP-induced responses. Treatment with fluoxetine also inhibited the 50 mM K+-induced [Ca2+]i increases completely. However, treatment with fluoxetine did not inhibit the ATP-induced [3H]-IPs formation. Collectively, we conclude that fluoxetine inhibits ATP-induced [Ca2+]i increases in PC12 cells by inhibiting both an influx of extracellular Ca2+ and a release of Ca2+ from intracellular stores without affecting IPs formation.