Drinking blocks a chemical that promotes attention

In a new article, researchers at the University of Texas at San Antonio Health Sciences Center (UT Health San Antonio) report brain chemistry that may explain why drinkers have trouble paying attention when they are under the influence.

The work is funded by generous support from the Robert J. Kleberg, Jr. and Helen C. Kleberg Foundation and by grants from the National Institute on Alcohol Abuse and Alcoholism and the National Institute of Mental Health. The results were published on December 2 in Communications of nature.

“When we want to focus on something, or when we get up from a chair and become active, a nucleus in the brainstem releases a chemical called norepinephrine. Acute exposure to alcohol inhibits this signal in the brain,” said senior author Martin Paukert, MD, assistant professor of cellular and integrative physiology at UT Health San Antonio. When attention is needed for a task, norepinephrine is secreted by a brain structure called the locus coeruleus. Previously, scientists weren’t quite sure what happened next, but Dr. Paukert and the team showed that norepinephrine attaches to receptors in cells called Bergmann glia. This leads to an increase in calcium in these cells.

Bergmann glia are astrocytes (care or support cells) in the cerebellum, a region near the brainstem. “To our knowledge, this article is the first description that norepinephrine in mammals binds directly to receptors in Bergmann’s glia and activates them by elevating calcium,” said Dr Paukert.

The researchers focused on Bergmann’s glia but also demonstrated that the same phenomenon occurs in cortical astrocytes. “The most likely vigilance-dependent activation of astrocytic calcium is inhibited throughout the brain by acute alcohol poisoning,” said Dr Paukert.

People under the influence are imbalanced when they walk. The researchers expected to find that inhibiting the increase in calcium in Bergmann’s glia would also explain this. It didn’t “The elevation of calcium in Bergmann’s glia is not critical for motor coordination, which is somewhat surprising because the cerebellum is classically known for its role in motor control”, said Dr Paukert. “However, our results are consistent with current suggestions that the cerebellum also plays a vital role in non-motor functions, and that astrocytes not only support basic brain maintenance, but they can actively participate in cognitive functions. “

Co-authors included Manzoor Bhat, Ph.D., professor and chair of cellular and integrative physiology at UT Health San Antonio. “The beauty of the studies reported by Paukert and his co-authors is that they were carried out in real time on living and breathing animals using cutting edge technologies,” said Dr Bhat. “The findings will open up new avenues for defining the brain circuits that ultimately determine the state of alertness, and how the chemicals that interfere with these circuits essentially dampen this brain-inherent alertness system.”

The team used a technique called two-photon imaging to study specialized mice obtained from collaborators at Johns Hopkins University and Heidelberg University.