Introduction: Free fatty acids (FFAs) affect pituitary function. While no effect of FFAs on ACTH and cortisol seems to exist in men, data in women are somewhat controversial. Therefore, we aimed to assess the effect of an acute increase of circulating FFA levels induced by the infusion of a lipid-heparin infusion on ACTH and cortisol secretion in healthy young women.
Methods: Following a 10-h overnight fast 13 healthy female volunteers were investigated in a randomised controlled cross-over trial. A 20% lipid/heparin (LHI) or saline/heparin (SHI) infusion was administered at a rate of 1.5 ml/min for 6 h. ACTH, cortisol and 24 h urinary excretion of glucocorticoids were measured to assess steroid metabolism, the overall daily cortisol secretion and the enzyme activities of 5α-reductase, 21-hydroxylase and 11β-hydroxysteroid dehydrogenase Type 1 and 2.
Results: During SHI, both serum cortisol and plasma ACTH showed a progressive decline according to the circadian rhythm. The cortisol levels were not altered by LHI, resulting in higher levels compared to SHI, while the decrease in plasma ACTH during LHI was comparable to the decline observed during SHI. No effects were found on daily urinary excretion rates of adrenal glucocorticoids, glucocorticoid precursors or calculated activity of 5α-reductase, 21-hydroxylase and 11β-HSD1 and 2.
Conclusion: FFAs seem to have no effect on ACTH secretion in normal weight young women. However the adrenal sensitivity to ACTH seems to be increased during LHI in women, as no change in neither in 21-hydroxylase activity nor in cortisol degradation, excretion or in peripheral conversion exists. This effect may have role in the development of obesity-associated complication.
03 - 07 May 2008
European Society of Endocrinology