Neural Control of the Thyroid Gland: Studies on the Role of Extrapyramidal and Rhinencephalon Areas in the Development of the Goiter

Abstract

Bilateral electrolytic lesions placed on the extrapyramidal—globus pallidum— area, and in the rhinencephalon—septal area—resulted in a marked release of thyrotropic hormone (TSH) both in goiter-free rats and in those with goiters induced by a low iodine diet. In some of the groups the average weight of the thyroid gland increased by 400%. The height of thyroid acinar cells, microfollicular hyperplasia, radioiodine (I¹³¹) uptake, I¹³¹ concentration in the thyroid, protein-bound radioiodine (PBI¹³¹), and I¹³¹ uptake by red cells were also noticed to increase. A parallelism was found to exist between most of the parameters in radioiodine metabolism and the weight of the thyroid and its histologic picture. These findings point to the presence of centers inhibiting TSH secretion in these areas, and are suggestive of the existence of other areas in addition to the anterior hypothalamus, which significantly interfere with TSH release.