Effect of thyroxine and carbimazole treatments on basal and histamine stimulated gastric acid secretion in the common African Toad (Bufo regularis).

Several studies have confirmed that thyroid hormones influence acid secretion particularly in mammals, but little attention is given to the influence of thyroid hormone on gastric acid secretion in amphibians. In this study, the basal and stimulated gastric acid secretions in carbimazole and thyroxine-treated common Africa toads were compared with controls. Thirty toads (100-120g b.w) were divided into three groups of ten toads each; Group “A” the control, Group “B” the hypothyroid group given carbimazole (5mg/250g  b.w) and Group “C” the hyperthyroid group treated with thyroxine (5µg/100g b.w) treatments were carried out for 35 days by daily oral administration. Serum T₃, T₄ and TSH levels confirmed the thyroid status of the toads. The mean Basal Gastric Acid (GAS) secretion in the control toads was significantly (p<0.05) higher than that of the carbimazole treated group, while the basal GAS of the thyroxine treated group was significantly (p<0.05) increased compared to the control. Administration of histamine intramuscularly increased significantly (p<0.05) the basal GAS of hyperthyroid toads, and the increment is higher than the GAS in control animals and in carbimazole treated toads. The parietal cells counts were significantly (p<0.05) higher in thyroxine treatment and lowered in carbimazole treated toads compared with control animals. In conclusion, increased thyroid hormone is associated with a rise in the basal secretion of gastric acid which is associated with increased histaminergic and zymogenic cell activities.