INFLUENCE OF THE HYPOPHYSIS ON CARBOHYDRATE METABOLISM

Abstract

An ant. pituitary extract (Phyone), capable of maintaining the carbohydrate levels of fasting, hypophysectomized animals, did not influence the rate of sugar utilization by the extra-hepatic tissues of normal dogs, as detd. by direct balance expts. after abdominal evisceration. The extra-hepatic tissues of hypophysectomized dogs utilized sugar at a considerably lower rate than normal. The decrease in carbo-hydrate levels exhibited by fasting hypophysectomized ani-mals is due to a decreased rate of hepatic gluconeogenesis. insufficient to meet even the reduced sugar utilization of the extra-hepatic tissues. Conversely, the increased carbo-hydrate levels resulting from the adm. of ant. pituitary extracts ("glycostatic effect") is not due to a greater stability of the tissue glycogen, but to stimulation of hepatic gluco-neogenesis to a rate in excess of the sugar utilization of the extra-hepatic tissues. The reduction of hyperglycemia, glyco-suria and ketosis in the depancreatized animal following hypophysectomy, is due to a decrease in the rate of hepatic gluconeogenesis, and not to a greater utilization of sugar by the extra-hepatic tissues.