LIPOPEROXIDATION OF ROD OUTER SEGMENTS OF BOVINE RETINA IS INHIBITED BY SOLUBLE BINDING-PROTEINS FOR FATTY-ACIDS

In the present study it was investigated if soluble-binding proteins f or fatty acids (FABPs) present in neural retina show protection from i n vitro lipoperoxidation of rod outer segment membranes (ROS). After i ncubation of ROS in an ascorbate-Fe++ system, at 37 degrees C during 9 0-120 min, the total cpm originated from light emission (chemiluminesc ence) was found to be lower in those membranes incubated in the presen ce of soluble binding proteins for fatty acids. The fatty acid composi tion of rod outer segment membranes was substantially modified when su bjected to non-enzymatic lipoperoxidation with a considerable decrease of docosahexaenoic acid (22:6 n-3) and arachidonic acid (20:4 n-6). A s a result of this, the unsaturation index, a parameter based on the m aximal rate of oxidation of specific fatty acids was higher in the nat ive and control membranes when compared with peroxidized ones. A simil ar decrease of chemiluminescence was observed with the addition of inc reasing concentrations of native or delipidated FABP retinal containin g fractions to rod outer segment membranes. These results indicate tha t soluble proteins with fatty acid binding properties may act as antio xidant protecting rod outer segment membranes from deleterious effect.