Docosahexaenoic acid (22:6n‐3) enrichment of membrane phospholipids increases gap junction coupling capacity in cultured astrocytes

Abstract

Although it is agreed that n-3 polyunsaturated fatty acids (PUFAs) are important for brain function, it has yet to be demonstrated how they are involved in precise cellular mechanisms. We investigated the role of enhanced n-3 PUFA in astrocyte membranes on the gap junction capacity of these cells. Astrocytes isolated from newborn rat cortices were grown in medium supplemented with docosahexaenoic acid (DHA), the main n-3 PUFA in cell membranes, or arachidonic acid (AA), the main n-6 PUFA, plus an antioxidant (alpha-tocopherol or N-acetyl-cystein) to prevent peroxidation. The resulting three populations of astrocytes differed markedly in their n-3:n-6 PUFA ratios in phosphatidylethanolamine and phosphatidylcholine, the main phospholipids in membranes. DHA-supplemented cells had a physiological high n-3:n-6 ratio (1.58), unsupplemented cells had a low n-3:n-6 ratio (0.66) and AA-supplemented cells had a very low n-3:n-6 ratio (0.36), with excess n-6 PUFA. DHA-supplemented astrocytes had a greater gap junction capacity than unsupplemented cells or AA-supplemented cells. The enhanced gap junction coupling of DHA-enriched cells was associated with a more functional distribution of connexin 43 at cell interfaces (shown by immunocytochemistry) and more of the main phosphorylated isoform of connexin 43. These findings suggest that the high n-3:n-6 PUFA ratio that occurs naturally in astrocyte membranes is needed for optimal gap junction coupling in these cells.

Dietary n-3 Polyunsaturated Fatty Acids and Direct Renin Inhibition Improve Electrical Remodeling in a Model of High Human Renin Hypertension

“…31 We are the first to show that there is also a direct link between the antiarrhythmic properties of n-3 PUFAs and restoration of proper Cx43 localization to the intercalated disks. DHA also improved the functional localization of Cx43 in astrocytes, 32 indicating the existence of common mechanisms of how n-3 PUFAs may improve gap junction coupling in heart and brain cells.…”

Omega‐3 fatty acids deficiency aggravates glutamatergic synapse and astroglial aging in the rat hippocampal CA1

“…The astrogliosis and the associated changes in astrocyte function that gradually take place during aging are more severe in x3-deficient rats, indicating that astroglial aging is one of the processes influenced by x3 deficiency. We previously used in vitro models to show that x3 modulates important properties of astroglia, such as gap junction coupling (Champeil-Potokar et al, 2006) and glutamate uptake (Grintal et al, 2009), which also points to the preeminent influence of x3 status on astrocyte function. We believe that x3 deficiency exacerbates the evolution of these cells towards astrogliosis by altering some of their properties.…”

Docosahexaenoic Acid Reduces Amyloid-β1-42 Secretion in Human AβPP-Transfected CHO-Cells by Mechanisms Other than Inflammation Related to PGE2

“…DHA was added to 10% FCS after which glutamine and geneticin were added (see above). α-Tocopherol (20 µM) (> 96% pure, Sigma) was added standard to the culture medium as a protective agent [23]. Twenty-four hours later cells were harvested, Aβ 42 content was measured (see Aβ 42 assay below), and the fatty acid composition of the cell membranes was analyzed.…”