The purpose of this study was to examine the effects of short-term caloric restriction (CR) for 4, 8 and 16 weeks on gastric acid secretion in rats. CR rats were fed 60% of normal food intake for 4, 8 or 16 weeks and then prepared with gastric fistulas. Histamine- and carbachol-stimulated gastric acid secretion were significantly (P < 0.05) decreased after more than 4 weeks and 8 weeks of caloric restriction, respectively. In contrast, gastrin-stimulated acid secretion was unaffected by CR. The 1-h-integrated acid output to a submaximal dose of gastrin (40 μg · kg-1) was significantly higher than that of histamine (5 mg · kg-1) after 8 weeks of CR (63 ± 13 and 27 ± 4 μEq · h-1, respectively). Gastrin treatment (5 μg · kg-1 · h-1) of CR rats restored the gastric acid responses to both histamine and carbachol. These results suggest that CR can selectively decrease the gastric acid responses to both histamine and carbachol by depletion of the endogenous tissue stores of gastrin. More importantly, these results indicate that under an in vivo gastrin-diminished condition, histamine is not the final secretagogue for gastric acid secretion.
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