Effect of fish oils on rat plasma lipoproteins

Plasma high (HDL) and low (LDL) density lipoproteins were isolated from rats fed a diet supplemented with either fish (menhaden) oil or hydrogenated coconut oil (control). Fluorescence polarization and electron spin resonance of labelled fatty acid probe molecules incorporated into the outer amphiphilic monolayer of HDL indicate molecular motion is restricted in the upper portion of the acyl chain following the fish oil diet, which is consistent with a 'hook' conformation predicted by preliminary molecular model calculations for n-3 fatty acids (the predominant component of fish oil). Negligible dependence on diet was observed in LDL. Thus, a HDL specific effect of dietary fish oil on molecular fluidity and order in the outer monolayer of rat lipoproteins is suggested.