抄録
The relation between plasma free fatty acids (FFA) and human growth hormone (HGH) levels was investigated in normal young male volunteers.
Nicotinic acid 200mg was administered intravenously in divided doses at 0 and 20 minutes in 10 subjects. Plasma FFA levels decreased to about 60% of the starting value within 30 minutes, followed by a marked rebound. Plasma HGH concentrations increased gradually and reached to 15.3±3.4ng/ml at 120 minutes. There were no significant changes in plasma glucose, insulin and alpha-amino nitrogen levels throughout the test periods. When nicotinic acid 200mg was administered in combination with 1,000 units of heparin, the initial depression of plasma FFA was abolished and the rise of plasma HGH was not observed.
In 7 subjects, heparin 1,000 units was administered intravenously. Plasma FFA levels elevated rapidly to about 300% of the basal level at 30 minutes after the injection and declined thereafter. Corresponding to the fall of plasma FFA from the peak value, a significant rise of plasma HGH occurred without any meaningful changes in plasma glucose. When the injections of heparin 500 units were repeated 60 and 90 minutes after the initial administration of heparin 1,000 units, plasma FFA levels were kept elevated above 200% of the starting level during 3 hours. Under these conditions, HGH rise was not observed.
Furthermore, analysis of the relationship between the changes in plasma FFA and HGH levels during 3 days fasting in 5 subjects (3 males and 2 females) revealed that the fall of plasma FFA was significantly associated with the rise of plasma HGH level.
From these results, we concluded that the fall of plasma FFA could be one of the stimuli to HGH secretion. At the present time, it is not clear why the fall of plasma FFA is linked with augumentation of HGH secretion, but this relation may be explained in the same manner as in the case of glucose deprivation (i. e. hypoglycemia or falling blood sugar).
It woud be reasonable to state that growth hormone is secreted when an energy substrate, whether glucose or FFA, is acutely deprived.
