Research can open the way to the treatment of various forms of acquired epilepsy and seizures that occur as a result of brain lesions caused by trauma, infection or tumors in the brain.
Since 1893, scientists knew about mysterious structures called perineuronal networks wrapped around neurons, but the function of these networks remained unknown. However, a group of scientists from the University of Virginia headed by Harald Sontheimer (Harald Sontheimer) determined that these networks modulate electrical impulses in the brain. Moreover, they found that seizures can occur in the event of dissolution of the networks. The results 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, the first symptom of which is often convulsions. Glioblastoma is the only cancer that is limited in space. Because the skull blocks the cancer from expanding outward, the tumor produces an excitatory chemical neurotransmitter (glutamate) in excess, which kills adjacent healthy cells to make room for growth.
In addition to glutamate, the tumor secretes an enzyme aimed at destroying the surrounding extracellular matrix — a gel-like substance that holds the brain cells in place. Glioblastomas are very malignant and are known to be able to spread in the body. The enzyme secreted is a kind of knife that cuts cancer cells, allowing them to move freely.
To their surprise, scientists also observed how the enzyme attacks perineuronal networks wrapped around GABA-inhibiting neurons (Gamma-aminobutyric acid), which help prevent seizures.
Italian neuroscientist Camillo Golgi (Camillo Golgi) first discovered the perineuronal network in 1893, but then he misunderstood their function. Golgi called the network "corset" and said that they most likely prevented the exchange of messages between neurons. The study of Sontheimer refutes this. The scientist, on the contrary, found that networks support messaging. 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 recharge up to two times faster than non-neural neurons.
When they suddenly lose their perineural networks, the results can be catastrophic: applying this enzyme to the brain without a tumor, scientists saw that the most enzymatic degradation of the perineuronal networks was enough to provoke seizures — even when the neurons remained intact.
Now the attention of researchers is focused on the role that perineural networks can play in other forms of acquired epilepsy – for example, as a result of a head injury or a brain infection – which will bring them closer to creating an effective medicine.
“We have solved the 125-year secret of neurology! That's what fundamental science is to keep an open and observant mind and answer old and new questions, ”says Sontheimer.
According to the World Health Organization, more than 50 million people worldwide suffer from epilepsy, a third of whom are not susceptible to known anti-epileptic procedures.
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