© Georg Thieme Verlag KG Stuttgart · New York
Action of Insulin on Thyroid Protein Synthesis in Dogs
23 December 2008 (online)
The study was performed on dog thyroid slices after in vivo administration of monocomponent insulin (carotid perfusion of a lobe: 25 mIU/kg/min for 15 min, the 2nd lobe perfused as control: saline) and after in vitro hormone addition (100 mIU/ml of glucose-free incubation medium). The 3H-leucine incorporation in thyroid proteins (dpm/mg) was determined following incubation of slices for 1 h and 2 h.
Insulin given in situ significantly increased the mean incorporation into homogenate and cytosol proteins: about 130% after 1 h of incubation, for an identical hypoglycemia in both lobes. When insulin was added to the medium, a similar response was observed after 1 h of incubation, the effect being less pronounced after 2 h but still significant. The sucrose gradient analysis of the soluble fraction showed that the stimulation affected all thyroid proteins.
Polyribosomes isolated from in vivo insulin-perfused thyroids exhibited an increased activity when tested in cell-free system.
These data suggest that insulin stimulated the thyroid protein synthesis in dogs through a direct action on the thyroid cell.
Insulin - Thyroid Protein Synthesis - Dog - In Vivo Perfusion - In Vitro Addition