Study Title:

DHA and Stroke Damage

Study Abstract

Background and Purpose—Consumption of fish has been shown to reduce risk of coronary heart disease and, possibly, of ischemic stroke. Because docosahexaenoic acid (DHA) is the most likely neuroactive component within fish oil, we hypothesized that exposing mice to a DHA-enriched diet may reduce inflammation and protect neurons against ischemic injury.

Methods—To visualize the effects of DHA on neuroinflammation after stroke, TLR2-fluc-GFP transgenic mice were exposed to either a control diet, a diet depleted in n-3 polyunsaturated fatty acid, or a diet enriched in DHA during 3 months. Real-time biophotonic/bioluminescence imaging of the TLR2 response was performed before and after middle cerebral artery occlusion, whereas cytokines concentrations and stroke area analyses were performed at 3 and 7 days after middle cerebral artery occlusion, respectively.

Results—We show that a 3-month DHA treatment prevented microglial activation after ischemic injury, reduced the ischemic lesion size, and increased levels of the antiapoptotic molecule Bcl-2 in the brain. Additional analysis revealed a significant decrease in the levels of COX2 and IL-1β, but not in other proinflammatory cytokines. Importantly, long-term DHA supplementation significantly changed the n-3:n-6 polyunsaturated fatty acid ratio in the brain.

Conclusions—Collectively, these data indicate that diet-induced accumulation of DHA in the brain protects against postischemic inflammation and injury. Because DHA is widely available at low cost and has an excellent safety profile, our data suggest that increased DHA intake may provide protection against acute immune response/brain damage in ischemic stroke.

From press release:

A diet rich in omega-3s reduces the severity of brain damage after a stroke, according to a study conducted by Université Laval researchers. The team, co-directed by professors Jasna Kriz and Frédéric Calon, showed that the extent of brain damage following a stroke was reduced by 25% in mice that consumed DHA type omega-3s daily. Details of the study can be found on the website of the journal Stroke.

Researchers observed that the effects of stroke were less severe in mice that had been fed a diet rich in DHA for three months than in mice fed a control diet. In mice from the DHA group, they saw a reduction in the concentrations of molecules that stimulate tissue inflammation and, conversely, a larger quantity of molecules that prevent the activation of cell death.

"This is the first convincing demonstration of the powerful anti-inflammatory effect of DHA in the brain," underscored Frédéric Calon of Université Laval's Faculty of Pharmacy. This protective effect results from the substitution of molecules in the neuronal membrane: DHA partially replaces arachidonic acid, an omega-6 fatty acid known for its inflammatory properties.

"The consumption of omega-3s creates an anti-inflammatory and neuroprotective environment in the brain that mitigates damage following a stroke," summarized Jasna Kriz, of Université Laval's Faculty of Medicine. "It prevents an acute inflammatory response that, if not controlled, is harmful to brain tissue."

Professor Calon believes that this anti-inflammatory effect is likely transferable to humans. "Since DHA is readily available, inexpensive, and reduces the risk of a number of health problems without causing significant side effects, the risk-benefit ratio tends to favor the regular consumption of fish or DHA," he concluded.

In addition to Kriz and Calon, the study was co-authored by Mélanie Lalancette-Hébert, Pierre Cordeau, Carl Julien, Ivan Bohacek, and Yuan-Cheng Weng. The authors are all members of the CHUQ Research Center.

Study Information

M. Lalancette-Hebert, C. Julien, P. Cordeau, I. Bohacek, Y.-C. Weng, F. Calon, J. Kriz.
Accumulation of Dietary Docosahexaenoic Acid in the Brain Attenuates Acute Immune Response and Development of Postischemic Neuronal Damage
2011 August
CHUQ Research Centre–Laval University, 2705 boul. Laurier, Quebec City, QC, G1V 4G2 Canada.

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