Recent research from Penn State has shed light on the relationship between anxiety-induced stress, reduced blood flow, and neurodegenerative diseases like Alzheimer’s and dementia.
While the exact causes of these diseases are still not fully understood, scientists have identified that one key feature of affected brains is reduced blood flow.
In this new study, researchers discovered that a rare type of neuron, which is especially vulnerable to stress, plays a critical role in regulating brain blood flow and coordinating neural activity.
The team, led by Patrick Drew, a professor of engineering science and mechanics at Penn State, focused on type-one nNOS neurons. These neurons make up less than 1% of the brain’s 80 billion neurons, yet they have a significant impact on brain functions such as blood flow regulation and neuronal communication.
The researchers found that when these neurons were eliminated in mice, both blood flow and electrical activity in the brain decreased, demonstrating how crucial these neurons are for maintaining proper brain function.
Type-one nNOS neurons are located in the somatosensory cortex, the brain region responsible for processing sensory input from the body, such as touch and temperature.
These neurons are responsible for regulating the “spontaneous oscillation” of brain blood vessels, including arteries, veins, and capillaries. This spontaneous oscillation refers to the constant dilation and constriction of blood vessels, which helps to move fluid around and maintain healthy circulation in the brain.
In the study, the team targeted type-one nNOS neurons by injecting mice with a toxin called saporin, which selectively kills these neurons.
Using a peptide that binds to genetic markers specific to type-one nNOS neurons, the researchers were able to eliminate only these neurons without affecting other brain cells. This method allowed the team to study the effects of losing these neurons in detail.
What the researchers found was striking. After eliminating type-one nNOS neurons, the mice showed a significant reduction in the oscillations of blood vessels in the brain, leading to decreased blood flow.
Furthermore, there was a noticeable reduction in neural activity across the brain, indicating that these neurons are also important for communication between brain cells. The effects were especially prominent during sleep, suggesting that these neurons play a crucial role in supporting brain function while the brain is resting.
Drew explained that while other studies have linked aging to reduced brain function and an increased risk of neurodegenerative diseases, there is less research on how stress can affect blood flow in the brain.
“Reduced blood flow is one of the contributing factors to poor brain health and conditions like Alzheimer’s,” he said. “We know aging is a major factor, but losing these rare neurons due to chronic stress could be an environmental cause of neurodegeneration.”
In addition to the changes in blood flow, the researchers also noted that the absence of type-one nNOS neurons led to weaker neural activity in the brain. This finding suggests that these neurons play a role in the brain’s ability to function properly, both in terms of maintaining circulation and enabling communication between brain cells.
The next steps in this research will focus on optimizing this method to study the loss of type-one nNOS neurons in more detail. Drew and his team are particularly interested in investigating how the loss of these neurons interacts with genetic risk factors for Alzheimer’s and dementia.
While it is too early to make a direct link between reduced type-one nNOS neurons and an increased risk of these neurodegenerative diseases, the team hopes that their findings will eventually lead to better treatments for these conditions.
This research, published in eLife, is a promising step toward understanding how stress affects the brain and contributes to neurodegenerative diseases. The findings may eventually help develop strategies for protecting the brain from stress-related damage, improving brain health, and reducing the risk of Alzheimer’s, dementia, and other cognitive disorders.
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