Objective:To assess the effects of free fatty acids on adrenocorticotropin and cortisol secretion in healthy male adults.Methods:In six young male volunteers

ACTH

cortisol

FFAs and glucose level were measured during the following procedures for 51h:iv Saline-Heparin(SH)infusion;iv Intralipid-Heparin emulsion(LHE)infusion.All tests were started in the morning after an overnight fasting.Results:1.Circulating FFAs level increased 2 to 3 times at 60min after LHE infusion beginning in comparison with SH infusion

and it maintained this high level to the endpoint.2.ACTH level after LHE infusion was significantly lower than that during SH infusion in the first test morning(8am to 11am)(P=0.048).But there was no statistical difference in ACTH level between the two groups in the second morning and the third morning.3.Cortisol level after LHE infusion was also significantly lower than that during SH infusion in the first morning(P=0.042).But there was still no statistical difference between the two groups in the second morning and the third morning.4.No significant difference was found in ACTH or cortisol circadian rhythm between the two groups(P>0.05).Conclusions:1.The acute rise in FFAs level for a short term can inhibit ACTH and cortisol secretion in healthy male adults

but with prolonged FFA elevation this inhibition last less than 24 hours.2.The acute FFAs rise has no influence on ACTH or cortisol circadian rhythm.