AN EXTRA-ADRENAL DIABETOGENIC RESPONSE TO CORTICOTROPHIN IN THE RAT

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Abstract
Sham-operated and adrenalecto-mized rats primed by tube-feeding a high carbohydrate diet and the daily administration of 5 mg of cortisone acetate were challenged at intervals with corticotrophin (ACTH) or growth hormone and suitable inert proteins as controls. Blood glucose levels, measured 1, 2, 3 and 4 hours after the ACTH, which was administered 3 1/2 hours after the morning meal, showed a marked hyperglycaemic response in both intact and adrenalectomized rats tested up to the fifty-fifth day of forced-feeding and cortisone treatment. Oxidation of ACTH with H2O2 abolished the hyperglycaemic response, whereas reduction with cysteine restored activity. Growth hormone did not elicit hyper-glycaemia in these experiments, in keeping with previous experience showing that several days of growth hormone treatment are required to elicit hyperglycaemia. Sham-operated and adrenalectomized rats receiving deoxycorticosterone responded to ACTH with hypoglycaemia, confirming earlier results. The conditions necessary to elicit the hyper- and hypoglycaemic extra-adrenal effects of ACTH are contrasted and discussed.