Blocking the Aryl Hydrocarbon Receptor Could Limit Stroke Damage

Imagine the chaos inside a brain when oxygen levels plummet during a stroke. Cells begin to die rapidly, leading to permanent loss of function. Scientists have long looked for ways to stop this cascade. The culprit might be a protein called the aryl hydrocarbon receptor (AhR). Usually, this sensor helps the body handle environmental toxins. But in the hippocampus—the brain's memory centre—it appears to overreact when blood flow stops.

The role of the aryl hydrocarbon receptor in brain injury

In a recent laboratory study, researchers simulated a stroke in mice by blocking their carotid arteries. They compared normal mice against those genetically engineered to lack the AhR. The difference was stark. The mice missing the receptor suffered significantly less brain damage. Their blood-brain barrier—the strict filter protecting the brain from the rest of the body—remained intact.

Why does this happen? It comes down to how the cell responds to stress. If the AhR is active during an ischemic insult (loss of blood flow), then it seems to trigger a cascade of inflammation. The study measured increased levels of inflammatory markers in normal mice. However, if the receptor is silenced, the barrier holds strong. The researchers observed that the 'knockout' mice had reduced dysfunction in the blood-brain barrier and less cell death in the CA1 region of the hippocampus.

The team also tested Resveratrol, a compound found in grapes. When they used it to block the receptor, the protective effect was replicated. This suggests that the receptor contributes to the breakdown of the brain's defences. While this study measured specific protein markers and tissue health in rodents, the data implies that drugs designed to inhibit this receptor might one day help stroke victims recover with their memories preserved.