Thyroid hormone regulation of adrenergic receptors and beta-adrenergic responsiveness in the rat submandibular gland.

The effects of altered thyroid function on the sensitivity of isoproterenol induced secretion of saliva and in the characteristics of adrenergic receptors from the rat submandibular gland were examined. Hyperthyroidism produced an increased sensitivity to beta-adrenergic stimulation of the gland, and this phenomenon was associated with an increase in the number of beta and alpha 1-adrenoceptors. On the other hand, surgical thyroidectomy produced a decrease sensitivity to isoproterenol stimulation of the submandibular gland and a diminished density of beta-adrenoceptors. In this case, no changes in alpha-adrenoceptors were observed. These results are discussed emphasizing the correlation between the functional control of saliva secretion and the adrenergic receptors in different thyroid states.