HORMONAL HYPERTENSION RESULTING FROM PITUITARY IMBALANCE

Abstract

The removal of the posterior part of the pituitary gland in the rat leads to an elevation in blood pressure. The production of an anterior–posterior pituitary imbalance in hypophysectomized animals by the administration of certain hormones of target glands influenced by the anterior pituitary (thyroxine, testosterone, cortisone (TTC)) also produces an increase in mean arterial blood pressure. In the intact animal, too, the administration of the hormones of the target organs (TTC) will lead to an elevation of blood pressure, and 1 week after the cessation of this treatment the blood pressure is as high or higher than at the end of the administration period. Administration of anterior pituitary hormones TSH, LH, and ACTH both in hypophysectomized and in intact rats also produced elevations in blood pressure. In two female dogs, administration of pituitary target-organ hormones (TTC) consistently produced an elevation of blood pressure associated with a direct effect of the injected hormones, followed by a depression of blood pressure below previous resting values after hormone withdrawal, presumably because of an associated inhibition of anterior pituitary effects. When certain hormones of the posterior pituitary gland are administered along with TTC, in both hypophysectomized and intact rats, the blood pressure elevation is not as great as with TTC alone, though, by themselves, the posterior pituitary factors caused some elevation in blood pressure. It is concluded that an imbalance between the influences of the anterior and posterior parts of the pituitary gland can lead to a significant elevation in blood pressure. It seems likely that, depending on the dose, the effects observed after the injection of the agent is discontinued may be due to persistence of the action of the agent or, in some instances, to inhibition of the activity of part of the pituitary gland.