AJP - Endocrinology and Metabolism, Vol 269, Issue 6 E1067-E1075, Copyright © 1995 by American Physiological Society
Postprandial free fatty acids stimulate activity of human corticosteroid binding globulin
M. Haourigui, S. Sakr, M. E. Martin, N. Thobie, A. Girard-Globa, C. Benassayag and E. A. Nunez
U-224 Institut National de la Sante et de la Recherche Medicale, Faculte de Medecine Xavier Bichat, Laboratoire de Biochimie, Paris, France.
The effect of postprandial variation of free fatty acids (FFA) on serum
corticosteroid binding globulin (CBG) properties and cortisol
(hydrocortisone) concentrations were explored in 11 women (20-30 yr) during
8 h after an oral load of tallow (26% C16:0, 18% C18:0, and 43% C18:1),
oleic-sunflower (oleic-SF; 73% C18:1), sunflower (SF; 67% C18:2), and mixed
oil (MO; 39% C18:1 and 48% C18:2). Serum FFA increased little after SF and
MO but more than doubled in the late postprandial period (6 and 8 h) after
oleic-SF (due to monounsaturated FFA) or tallow (due to saturated and
monounsaturated FFA). CBG concentrations remained unchanged, but in
relation with the postprandial elevation of serum FFA, CBG binding activity
was increased after tallow or oleic-SF as a result of a combined two- to
threefold increase in affinity constant and a 50% reduction in binding
sites. Immunological and in vitro binding studies showed the changes in CBG
behavior to be conformational and to be mediated mainly by monounsaturated
FFA, especially C18:1. The modifications of CBG properties were associated
with sustained high concentrations of cortisol (suppression of midday
decrease) 6 and 8 h after tallow or oleic-SF. Thus dietary FFA may have an
impact on bioavailability of glucocorticoids.
