EFFECT OF GROWTH HORMONE AND INSULIN ON BODY WEIGHT AND NITROGEN RETENTION IN PANCREATECTOMIZED RATS

Abstract

Female rats, weighing about 145 gm, were deprived of 95% of the pancreas and were tube-fed 7 gm of food per day; pancreatin was not required. When given 12 units of insulin daily, the amount needed for the control of glycosuria (less than 0.1 gm/day), they gained 0.4 gm/day in body weight and retained 6% of the nitrogen fed. Administration of 0.1 mg of growth hormone/day produced a body weight gain of 1.6 gm/day and retention of 28% of the nitrogen fed; 21% of the weight gain was protein. Extra food and extra insulin were not necessary for the growth hormone effect. Reduction of the dosage of insulin to 8 units/day impaired the growth response to growth hormone. This growth disturbance occurred before there was any significant increase in glycosuria or urine volume. When given 6 and then 4 units daily the rats treated with growth hormone continued to retain nitrogen but gained no weight. Although the growth hormone treated rats retained very little nitrogen when given 2 and 1 units daily, they retained significantly more nitrogen than did the pancreatectomized controls receiving the same amounts of insulin. Raising the insulin dosage from 1 to 4 units immediately abolished the nitrogen retaining effect of growth hormone. After increasing the insulin dosage to 12 units daily, which controlled glycosuria, both groups of rats gained body weight at a slow rate but neither retained nitrogen. There was no direct relation between the amount of nitrogen retained, with or without growth hormone, and the insulin dosage or glycosuria. When insulin was withheld two-thirds of the rats died in diabetic coma. Growth hormone (3.0 mg/day) had no effect on the insulin requirement of the diabetic rats.