Evidence for Renotropic Activity in Ovine Pituitaries*

A linear relationship was found for kidney weight vs. body weight in both intact and hypophysectomized male Sprague-Dawley rats, weighing 75–150 g; however, kidney weight was greater for a given body weight in intact animals. A partially purified extract of ovine pituitaries was prepared which had the heretofore undescribed property of stimulating renal growth in hypophysectomized animals to the level expected for intact rats of similar size. When rats, hypophysectomized 6 days previously, were given 10 daily injections of the pituitary extract, which was analyzed for GH, ACTH, and LH content, renal weight increased significantly. In contrast, kidney size in other hypophysectomized animals treated with a quantity of GH plus ACTH similar to that found in the extract did not increase beyond that expected for a hypophysectomized rat of comparable size. A possible indirect action of LH in the extract via androgen production was excluded by demonstrating that the extract produced similar renal growth in both hypophysectomized and hypophysectomized- castrated animals. A possible direct action of LH seemed equally unlikely, since hCG failed to stimulate renal growth in hypophysectomized-castrated animals. Significant increases in renal wet weight, dry weight, protein content, and DNA content were produced by the extract, strongly suggesting the presence of a renotropic factor(s) in pituitary tissue.