Researchers at Tohoku University have conducted a groundbreaking study on the intricate interactions between neurons and astrocytes within the brain, specifically within the region known as the habenula. The habenula is associated with emotional processing and has been linked to anxiety. The findings of this study provide valuable insights into the mechanisms behind anxiety and may pave the way for new therapeutic strategies.
The researchers subjected mice to an anxiety-inducing scenario involving a floor scattered with marbles. They observed behavioral responses in the mice that were indicative of anxiety. The results of the study were published in the journal Neuroscience Research on February 10, 2024.
The habenula is a pair of small nuclei located above the thalamus and is one of the few brain regions that control both dopaminergic and serotonergic systems. These neuromodulators play crucial roles in various motivational and cognitive functions, making the neuronal circuits of the habenula potentially relevant to the regulation of anxiety.
Professor Ko Matsui, who led the research at Tohoku University’s Super-network Brain Physiology Lab, explains that anxiety, while often seen as an irrational and negative emotion, actually serves a purpose in guiding us away from potential dangers. The habenula plays a role in fine-tuning anxiety, ensuring that it remains within a beneficial range.
In the study, the researchers created a chamber filled with marbles, creating an inescapable environment that induces maximum anxiety in the mice. They observed increased neuronal activity in the theta band (5 to 10 Hz) frequency, an increase in local brain blood volume, and acidification occurring in the astrocytes of the habenula when the mice were placed in the all-marble cage. Interestingly, when the habenular astrocytes were artificially alkalized to counter the acidification, the theta band neuronal activity decreased.
Additionally, when given a choice between a brightly lit all-marble cage and a dark and comfortable cage, the mice naturally chose to stay in the dark cage. However, when the habenular astrocytes were opto-genetically alkalized, the mice showed more interest in the bright cage, indicating a reduction in anxiety-related behavior.
Astrocytes are non-neuronal cells that make up approximately half of the brain. They control the local ionic and metabotropic environment in the brain and release transmitters that can impact nearby neuronal activity. This study suggests that the activity of astrocytes regulates theta band neuronal activity in the habenula, thus playing a crucial role in anxiety regulation.
Lead study investigator Wanqin Tan believes that this research opens up new possibilities for the treatment of anxiety disorders. By developing therapeutic strategies that target and adjust astrocyte activity in the habenula, it may be possible to alleviate anxiety symptoms. Tan refers to the habenular astrocytes as the “marble blues” tuners, and hopes that this discovery will lead to the development of effective anxiety management methods in the future.
