Effect of thyroid hormones on distension-induced gastric acid and pepsin secretion in rats

Thyroid hormones are known to influence acid and pepsin secretion, though the exact mechanism is not fully understood. In this study, distension-stimulated acid and pepsin secretions in hypo- and hyperthyroid rats were compared with controls.

Each group consisted of 8 N-mari rats of both sexes, weighing 246.6+/-9.2 g. Hypo- and hyperthyroid states were induced by administration of methimazole (500 mg/L H2O) and thyroxin (200 microg/L H2O) respectively, in drinking water. All animals were deprived of food, but not of water 24 hours before the experiments. After anesthetization with sodium thiopental (50 mg/kg body weight, ip), tracheotomy and laparatomy, gastric secretions were collected through a cannula introduced via the duodenum. Gastric distension was induced by the injection of Ringer solution in stomach (1.5 cm(3)/100 g body weight).

Acid secretions, which were measured by automatic titrator in the hypothyroid, hyperthyroid and control groups were 8+/-0.2, 14.6+/-1.9 and 10.2+/-0.1 micromol/15 min, respectively. Pepsin secretions were 4.4+/-0.5, 9.09+/-0.4 and 6.1+/-0.1 mg/15 min. in respective groups. There were statistically significant differences in both series between control and the other two groups.

The results from the measurements of thyroid-stimulating hormones and T4 hormones showed that increased or decreased thyroid function can significantly affect gastric distension-induced acid and pepsin secretion.