Studies on the ketogenic activity of the anterior pituitary

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Abstract
The existence of a urinary threshold for acetone bodies in the rat rendered the development of ketonuria in response to ant. pituitary extracts in this animal unsuitable for purposes of assay. The increase in blood acetone-bodies did not give rise to ketonuria unless this urinary threshold was exceeded. While the fed rat showed a negligible increase in blood acetone bodies in response to the inj. of ant. pituitary preps., the fasting rat responded quite readily. Fasting alone however produced a distinct but exceedingly variable ketonaemia. In consequence, single blood analyses made on injected rats were not reliable for the detn. of ketogenic activity unless extremely large groups of animals were used. A micro blood acetone body method was descr. which employed only 0.2 ml. tail blood, and thus allowed a control blood acetone reading to be made on a given animal before inj. of an extract. This method made it possible to detect the presence of a small quantity of ketogenic principle and to determine the minimal effective dose. The ketogenic principle could not be filtered through 8% acetic collodion or cellophane. It was destroyed by heating on the boiling water bath for 15 min. at pH 10. Comparative assays of relative potencies of the various ant. pituitary hormones present in a number of different preparations obtained by chemical fractionation, indicated that ketogenic activity followed growth and "diabeto-genic" activity. This suggested that a single principle might be responsible for all of these 3 effects of the ant. pituitary on metabolism. The inhibitory action of ant. pituitary extracts on the catabolism of carbohydrate and protein offered a satisfactory explanation for the occurrence of the ketosis that followed their inj.