Effects of thyroid-stimulating hormone upon the regulation of serum insulin levels and on the blood sugar and serum free fatty acid responses to insulin [author's transl].

The effect of a chronic treatment with thyroid-stimulating hormone on the blood sugar, serum insulin and free fatty acid responses to exogenous insulin in dogs was studied comparatively. Either before or after thyroid-stimulating hormone treatment, the blood sugar levels were significantly below- and serum immunoreactive insulin above- their respective base line throughout the test. The blood sugar basal value was raised by the treatment, while the blood sugar levels at any time during the test were not affected. Neither were their respective serum insulin values, nor serum insulin base line. The rate of disappearance of exogenous insulin from blood was not affected either, and insulin space was hardly, significantly increased. Hypoglycaemia induced a mobilization of free fatty acids from lipid stores, which was more intense and prolonged after thyroid-stimulating treatment. These results are discussed, emphasizing the weak lipomobilizing effect of thyroid-stimulating hormone in this species, as well as taking into consideration the mild participation of an extra-pancreatic mechanism such as insulin space in the regulation of serum insulin levels in normal dogs as modified by thyroid-stimulating hormone.