Effects of docosahexaenoic acid on annular lipid fluidity of the rat bile canalicular plasma membrane

Abstract

The role of docosahexaenoic acid (DHA) in the fluidity of the annular lipid regions and their associated membrane-bound proteins is still not as well understood as that in the global (bulk) lipid regions. We therefore studied the effects of dietary DHA on the relationship between annular and global lipid fluidity and membrane-bound enzymes such as 5 -nucleotidase and Mg 2 ؉ -ATPase in the rat bile canalicular membrane. Dietary DHA caused significant increases in 5nucleotidase and Mg 2 ؉ -ATPase activity and in global and annular lipid fluidity, a higher increase in fluidity in the annular lipids than the global lipids, and a decrease in the cholesterol-tophospholipid molar ratio in the canalicular membrane. Plasma total cholesterol and LDL cholesterol decreased, and fecal cholesterol increased in the DHA-fed rats. No changes were observed in oxidative markers, but glutathione peroxidase increased in the liver with DHA feeding. Annular lipid fluidity, but not global lipid fluidity, correlated remarkably well with DHA, synchronously with the activities of 5 -nucleotidase and Mg 2 ؉ -ATPase. The data indicate that the DHA-induced increase in annular lipid fluidity is responsible for the increases observed in the enzyme activity. We therefore concluded that the increased activity of membrane-bound enzymes and transporters induced by DHA and the concomitant increase in annular lipid fluidity comprise one of the mechanisms involved in DHA-induced clearance of plasma cholesterol. -

Lablab purpureus (L) bean flour ameliorates plasma proteins and accretion of docosahexaenoic acid (DHA, 22:6, ω‐3) in the plasma, liver, and brain of malnourished rats

“…The larger USI indicates a greater membrane fluidity, which plays a crucial role in many cellular and physiological functions. For example, an increase in membrane fluidity ameliorates hypertension (Hashimoto et al, ), platelet aggregation (Hossain et al, ; Hashimoto et al, ), hepatic secretory functions (Hashimoto et al, ), exo/endocytosis or neurotransmitter release from the synaptic plasma membranes/brain cognitions (Hashimoto et al, ), and cellular glucose transport (Weijers, ). These results thus demonstrate that LPS could be used not only in replenishment of protein‐energy malnutrition, it may also replenish essential DHA levels in brain and, consequently, may contribute positively to brain cognition impairments.…”

Review of Eukaryote Cellular Membrane Lipid Composition, with Special Attention to the Fatty Acids

“…This, in turn, leads to the displacement of raft-associated proteins and the removal of SM and CHOL from lipid rafts. These alterations result in shifts in membrane rigidity and permeability [483][484][485][486][487][488][489][490][491][492]. Therefore, the degree of unsaturation plays a crucial role in modulating the flip-flop rate and the asymmetry/distribution of membranes.…”