People with epilepsy suffer from involuntary seizures, which affect about 1% of the population. These seizures are often repetitive and involve excessive neuronal firing, and the triggers behind these are poorly understood.
Now, researchers at Northeastern University have used fluorescent calcium sensors to monitor astrocyte activity and found that astrocyte activity begins about 20 seconds before the onset of epileptic neuronal hyperactivity. This suggests that astrocytes play an important role in initiating epileptic seizures and promoting neural circuit overdrive.
The results are detailed in a journal Glial cells April 9, 2024.
Astrocytes are non-neuronal glial cells that make up about half of the brain. They have been shown to regulate the local ionic and metabolic environment in the brain. However, because they do not exhibit easily monitored electrical activity, their role in brain function has been largely overlooked. Fluorescent sensor proteins are changing this, revealing more about the fascinating activity of astrocytes.
“Astrocytes play a decisive role in regulating the state of neuronal activity and synaptic plasticity under physiological and pathophysiological conditions,” said Professor Ko Matsui of Tohoku University’s Supernetwork Brain Physiology Laboratory, who explained the study. “Therefore, astrocytes can be considered as a new therapeutic target for the treatment of epilepsy.”
When brain tissue is exposed to metals such as copper, inflammation is induced, leading to severe symptomatic seizures, which occur several times a day in mice. Matsui and his team observed these events and found that astrocyte activity can be a trigger for neuronal overactivity. Astrocytes can also be activated by low-amplitude direct current stimulation. The researchers observed that this stimulation caused a sharp increase in astrocyte calcium, followed by an epileptic seizure of neuronal hyperactivity. When fluorocitrate was used to block the metabolic activity of astrocytes, the degree of hyperactivity of epileptic neurons was significantly reduced. These indicate that astrocytes have the potential to regulate neuronal activity.
Shun Araki, the study’s lead researcher, emphasized that with proper guidance, the function of astrocytes could be used to combat various neurological diseases. This includes not only epilepsy, but also potential cognitive enhancement beyond natural limitations.
