Research can open the way to the treatment of various forms of acquired epilepsy and seizures that occur as a result of brain damage caused by trauma, infection or tumors in the brain.
Since 1893, scientists knew about mysterious structures called perineuronal networks wound around neurons, but the function of these networks remained unknown. However, a group of scientists from the University of Virginia, led by Harald Sontheimer (Harald Sontheimer), determined that these networks modulate electrical impulses in the brain. In addition, they found that seizures can occur in the event of dissolution of the networks. The result of the work, published in the journal Nature Communications.
Initially, researchers made this discovery in mice suffering from epilepsy caused by fatal brain cancer, glioblastoma, whose first symptoms are often convulsions. Glioblastoma is the only cancer that is limited in space. As the skull blocks the channel from expanding outward, the tumor produces an excitatory chemical neurotransmitter (glutamate) in excess that kills adjacent healthy cells to provide room for growth.
In addition to glutamate, the tumor secretes an enzyme that destroys the surrounding extracellular matrix – a gel-like substance that keeps the brain cells in place. Glioblastoma is very malignant and is known to spread in the body. The enzyme secreted is a kind of knife that cut cancer cells so that they can move freely.
To their surprise, researchers also observed how the enzyme attacks perineuronal networks that surround GABA inhibitory neurons (Gamma-aminobutyric acid), which helps prevent seizures.
The Italian neuroscientist Camillo Golgi (Camillo Golgi) first discovered the perineuronal network in 1893, but then he misunderstood his function. Golgi called the network "corset" and said that they probably hindered the exchange of messages between neurons. The study of Sontheimer opposes this. On the contrary, the researcher found that networks support messages. Neurons covered with perineuronal nets have a smaller membrane capacity and the ability to store electrical charge, which means they can trigger a pulse and charge up to twice faster than non-neural neurons.
When they suddenly lose their perineural networks, the results can be disastrous: applying this enzyme to the brain without tumor, the researchers saw that the most enzymatic breakdown of perineuronal networks was sufficient to provoke seizures – even when the neurons were intact.
Now the researchers' attention is focused on the role that perineural networks can play in other forms of acquired epilepsy – for example as a result of head injury or brain infection – which will make them more effective in creating effective medicine.
"We have solved the 125-year-old secret of neurology! That's what basic science is to keep an open minded mind and answer old and new questions," says Sontheimer.
According to the World Health Organization, more than 50 million people worldwide suffer from epilepsy, one-third of whom are not sensitive to known anti-epileptic procedures.
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