The Effect of Ablation of the Hypophysis upon the Weight of the Kidney of the Rat *

Unilateral nephrectomy of an animal is normally followed by hypertrophy of the remaining kidney, providing the animal consumes sufficient protein in its diet.'0 22 This interesting reaction, which also occurs with certain other paired organs, may conceivably be utilized for further experiments on the physiology of the kidney. The excision of one lobe of the thyroid or one adrenal cortex, as will be recalled, normally causes hypertrophy of the remaining gland, but this does not occur if the hypophysis is absent.3 6 23 Ample evidence has been produced to show that in addition to a factor which causes somatic growth the pituitary supplies "tropic hormones" without which the subsidiary glands atrophy. The present report describes experiments which indicate that hypophysectomy also causes a decrease in the weight of the kidneys and prevents compensatory renal hypertrophy. These effects of hypophysectomy on the kidney were scarcely unexpected, in view of the profound depression in many metabolic functions which sets in after ablation of this "master gland." Especially notable after this operation is the atrophy of the thyroid, together with a lowering of the metabolic rate and a marked decrease iin appetite, any one of which might be taken to indicate diminished "work" of the kidney and therefore cause for its atrophy. For controls of these most obvious factors, then, it was necessary also to study compensatory renal hypertrophy in a group of thyroidectomized animals and in a group of normals on feedings paired with those of hypophysectomized rats. In preliminary observations we noted a striking diminution in the size of the hearts and livers of the hypophysectomized animals, and therefore the scope of the experiment was subsequently enlarged to include weighing of these organs in all the animals.