Astrocyte Responses to Olfactory Stimulation
Introduction
The brain requires the close collaboration of neurons and astrocytes to perceive smells such as coffee and cookies or to detect the scent of something burning. While research has focused on understanding the changes in neurons during olfactory perception, the contributions of astrocytes to the sensory experience remain unclear.
Findings
Researchers from Baylor College of Medicine and collaborating institutions have published a study in the journal Science, revealing the responses of astrocytes to olfactory stimulation. They have discovered a new mechanism that is essential for maintaining astrocyte-neuron communication and processing olfactory sensations.
Astrocyte-Neron Communication
Previous studies have shown that olfactory stimulation first activates neurons in the brain, causing changes in the genes these neurons express to mediate the olfactory sensation. This study aimed to investigate the changes that occur in astrocytes following neural activity during olfactory stimulation.
Serotonin Transport in Astrocytes
Results from the study demonstrate that olfactory stimulation triggers an increase in the serotonin transporter Slc22a3 on astrocytes, facilitating serotonin transport into the cells. Surprisingly, serotonin travels to the cell nucleus, where it binds to histones, assisting in the regulation of astrocyte gene expression.
Regulation of Astrocyte Genes
Serotonin regulates the expression of astrocyte genes involved in the production of the neurotransmitter GABA. This, in turn, influences neural circuits crucial for sensory perception.
Impact of Serotonin
The loss of the transporter Slc22a3 in astrocytes reduces serotonin levels in the cells, leading to alterations in serotonin-bound DNA. This reduction in gene expression affects the synthesis of GABA and decreases astrocytic GABA release, ultimately disturbing the neural circuits responsible for olfactory sensation.
Astrocyte Function and Plasticity
This project has revealed novel aspects of astrocyte function. Researchers have discovered that astrocytes, just like neurons, exhibit plasticity, meaning they can change their characteristics and functions in response to environmental stimuli. Astrocytes listen to neurons and respond, and their two-way communication is integral to sensory processing and animal behavior.
Conclusion
The responses of astrocytes to olfactory stimulation have been investigated, and a new mechanism has been uncovered that maintains astrocyte-neuron communication and processes olfactory sensation. Understanding these processes in astrocytes adds to the knowledge of sensory perception and may have relevance in conditions such as addiction and depression.
Acknowledgments
This research was supported by grants from the NIH, as well as awards from the Dan L Duncan Comprehensive Cancer Center, CPRIT Core Facility, NIH High End Instrument, and the National Institutes of Health Cancer Center Grant.