Effect of thyroid hormones on distension-induced gastric and Pepsin secretion in the stomach of rat

Abstract: Thyroid hormones are known to influence acid and pepsin secretion, though exact mechanism(s) are not fully understood. In this study distension-stimulated acid and pepsin secretion of hypo and hyperthyroid rats were compared with controls. Each group consisted of 8 N-mari rats from both sexes, weighing 246.6±9.2 g. Hypo and hyperthyroid states were induced by administration of methimazole (500 mg/l H2O) and thyroxine (200 µg/l H2O) respectively in drinking water. All animals were deprived of food, but not of water 24 hours before the experiments. After anesthesiation with sodium thiopental (50 mg/kg body weight, ip), tracheostomy and laparatomy, gastric secretions were collected through a cannula introduced via duodenum. Gastric distension was induced by Ringer solution in stomach (1.5cm³/100gr 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 µmol/15min, respectively. Pepsin secretions were 4.4±0.5, 9.09±0.4 and 6.1±0.1 mg/15min in respective groups. Both series show statistically significant differences between control and the other two groups. The results from the measurements of TSH and T4 hormones show that increased or decreased thyroid function can significantly affect gastric distension-induced acid and pepsin secretion. Keywords: Thyroid hormones, Gastric acid secretion, Gastric pepsin secretion, Gastric distension, Ra