THE EFFECTS OF FASTING AND OF GROWTH HORMONE ADMINISTRATION ON PLASMA FATTY ACID CONCENTRATION IN NORMAL AND HYPOPHYSECTOMIZED RHESUS MONKEYS1

The effects of growth hormone and of fasting on the concentration of plasma nonesterified fatty acids (NEFA) in hypophysectomized and intact monkeys (Macaca mulatta) were studied. NEFA concentration was determined by the method of Dole. Small doses (0.05 nig./kg.) of simiangrowthhormone caused an increase in plasma NEFA concentrations in fasting hypophysectomized and intact monkeys. Bovine and porcine growth hormone preparations were ineffective in this regard as were LTH, TSH, ACTH and Pituitrin. The effect of simian growth hormone was absent or diminished if the animals were allowed access to food during the experiment. Fasting caused a marked increase in plasma NEFA concentrations within a few hours. Hypophysectomized as well as normal monkeys showed increased NEFA concentrations in response to fasting, suggesting that the NEFA mobilization during fasting is not mediated by an increased secretion of growth hormone by the pituitary gland.