Summary: Researchers shed light on the role of astrocytes, a type of brain cell, in olfactory perception, or the detection of odors.
The study revealed that during olfactory stimulation, the serotonin transporter Slc22a3 in astrocytes mediates the transport of serotonin into cells, influencing gene expression. This process contributes to the production of the neurotransmitter GABA, a key component in the neural circuitry for sensory perception.
The findings highlight the critical role of astrocytes in sensory processing and animal behavior.
Key facts:
- Olfactory stimulation leads to an increase in the serotonin transporter Slc22a3 in astrocytes, which allows the transport of serotonin into the cells.
- Once inside astrocytes, serotonin binds to histones, proteins attached to DNA that control gene expression. This process affects the production of the neurotransmitter GABA.
- The findings highlight the plasticity of astrocytes and their ability to change their characteristics and functions in response to environmental stimuli, playing a key role in sensory processing and behavior.
To enjoy the aroma of morning coffee and freshly baked pastries, or to smell the warning smell of something burnt, the brain needs two types of cells, neurons and astrocytes, to work closely together.
Research has shown much of the changes that occur in neurons during olfactory or olfactory perception, but what the responses of astrocytes are and how they contribute to sensory experience remains unclear.
Researchers from Baylor College of Medicine and collaborating institutions report in the journal Science astrocyte responses to olfactory stimulation, revealing a novel mechanism that is required to maintain astrocyte-neuron communication and olfactory processing.
Olfactory stimulation causes an increase in the serotonin transporter Slc22a3 on astrocytes, which mediates the transport of serotonin into cells. Credit: Neuroscience News“Previous studies have shown that under natural conditions in a living animal, olfactory stimulation of the brain first activates neurons, which changes the genes those neurons express so they can mediate olfactory sensation,” said first author Dr. Debosmita Sardar, a postdoctoral fellow in Dr. Benjamin Deneen’s lab at Baylor.
“In this study, we investigated what happens to astrocytes following neuronal activity during olfactory stimulation and revealed changes that have not been described before.”
Olfactory stimulation causes an increase in the serotonin transporter Slc22a3 on astrocytes, which mediates the transport of serotonin into cells.
“We tracked serotonin inside astrocytes and were surprised to find that it travels to the cell nucleus, where it binds to histones, proteins attached to DNA that help regulate astrocyte gene expression,” Sardar said.
“Serotonin bound to DNA acts as a switch that controls gene expression.”
Interestingly, serotonin regulates the expression of astrocyte genes involved in the production of the neurotransmitter GABA, which is then fed back to the neurons regulating the neural circuitry that is fundamental to sensory perception.
“We showed that loss of the Slc22a3 transporter in astrocytes reduces serotonin levels in the cells and leads to changes in serotonin-related DNA,” said Sardar.
“This, in turn, reduces the expression of genes involved in GABA synthesis and reduces astrocytic GABA release, which disrupts olfactory neural circuits.”
Serotonin is well known for its contribution to normal brain function, as well as its involvement in addiction and depression.
“Here we discovered a new function of serotonin in astrocytes. “Serotonin induces changes in astrocyte gene expression patterns, turning astrocytes into an olfactory processing center,” Sardar said.
“This project revealed new aspects of astrocyte function,” said Deneen, professor and Ph.D. Russell J. and Marian K. Blattner, chairman of the Department of Neurosurgery and director of the Baylor Cancer Neuroscience Center. He is also the corresponding author of the work.
“We are learning that astrocytes are highly plastic, just like neurons, which means that astrocytes can change their characteristics and functions in response to environmental stimuli. They listen to neurons and respond, and their two-way communication underlies sensory processing and ultimately animal behavior.
About this olfactory perception and neuroscience research news
Author: Debosmita Sardar
source: Baylor College of Medicine
Contact: Debosmita Sardar – Baylor College of Medicine
Image: Image credit: Neuroscience News
Original research: Closed access.
“Induction of astrocytic Slc22a3 regulates sensory processing through histone serotoninylation” by Debosmita Sardar et al. Science
Summary
Induction of astrocytic Slc22a3 regulates sensory processing through histone serotoninylation
Neuronal activity leads to changes in gene expression in neurons, but how it directs transcriptional and epigenomic changes in neighboring astrocytes in functioning circuits is unknown.
We found that neuronal activity induced widespread transcriptional up- and down-regulation in astrocytes, highlighted by the identification of Slc22a3 as an activity-inducible astrocyte gene that encodes a neuromodulatory transporter Slc22a3 and regulates sensory processing in the mouse olfactory bulb.
Loss of astrocytic Slc22a3 reduces serotonin levels in astrocytes, leading to changes in histone serotonylation. Inhibition of histone serotoninylation in astrocytes reduces γ-aminobutyric acid (GABA) biosynthetic gene expression and GABA release, culminating in olfactory deficits.
Our study reveals that neuronal activity orchestrates transcriptional and epigenomic responses in astrocytes, while illustrating new mechanisms for how astrocytes process neuromodulatory input to release neurotransmitter to gate sensory processing.