INFLUENCE OF THE HYPOPHYSIS ON CARBOHYDRATE METABOLISM

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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.