EFFECT OF ESTROGEN-RECEPTOR INTERACTION ON THE LEVELS OF FATTY ACID-BINDING PROTEINS AND SPECTRA OF FREE ACIDS IN SMALL INTESTINAL-MUCOSA OF RABBITS

Data on the possibility of estrogens to regulate absorption of free fatty acids (FFA) during absorption of lipids in small intestine with associated estrogen-receptor interaction and changes in fatty acid-binding protein (FABP) levels are reported. In particular, characteristics of cytoplasmic estrogen receptors, estradiol metabolism, FABP levels and spectra of FFA in FABP fraction were studied in small intestinal mucosa of sexually mature and immature female rabbits, intact or after ovariectomy and estradiol dipropionate administration. The dissociation constants (K(d)) and number of binding sites were determined in coordinates of Scatchard. FABP levels were demonstrated spectrophotometrically after ultracentrifugation (K-32M) and gel filtration (G-75). FFA composition of FABP fraction, chyme and enterocytes were analyzed by a chromatographic method (Tsvet-110). Levels of body estrogens were monitored by high-performance liquid chromatographic analysis (Tsvet-306) of estrogens in daily urine. The study has demonstrated a specific relation between FABP levels and their lipid component, FFA, on the one hand and endo- and exogenous estrogen levels on the other hand, in female rabbits maintained on a standard fat-free diet.