Low gastric acid and high plasma gastrin in high-anxiety Wistar Kyoto rats.
Wistar Kyoto (WKY) rats are more susceptible to stress-evoked ulcerations than Sprague-Dawley (SPD) rats. We have already demonstrated that gastrin cells are more active and ghrelin cells less active in WKY rats than in SPD rats. The purpose of this study was to compare endocrine cell activity and gastric acid output in WKY and SPD rats. Gastric acid output was determined in conscious rats with gastric fistula. Plasma gastrin and ghrelin levels were measured after an overnight fast. Acid secretagogues (gastrin, histamine and carbachol) were given by continuous subcutaneous infusion. The volume of gastric juice, and the acidity and acid output were all significantly lower (p <0.05) in fasted WKY rats than in fasted SPD rats. Gastrin evoked a 4-fold (p <0.01) and 3-fold (p <0.05) increase in gastric acid output in SPD rats and WKY rats, respectively. Histamine raised the acid output 1.6-fold in SPD rats (p=0.06) and 3-fold in WKY rats (p <0.05), while carbachol failed to affect the acid output (weak increase, p >0.05). Fasting plasma ghrelin levels were 2-fold higher in SPD rats than in WKY rats (p <0.01) while fasting gastrin levels were 10-fold higher in WKY rats than in SPD rats (p <0.05). Neither the parietal-cell density nor the oxyntic mucosal thickness differed between the two strains. The results of the present study suggest that a high gastrin cell activity in WKY rats is secondary to a low gastric acidity. Whether the high gastrin cell activity is linked to susceptibility to stress ulcer in WKY rats warrants further investigation.