Research can pave the way for the treatment of various forms of acquired epilepsy and seizures that occur as a result of brain injury caused by trauma, infection or brain tumors.
Since 1893, scientists knew of 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 led by Harald Sontheimer (Harald Sontheimer) has determined that these networks modulate electrical impulses in the brain. In addition, they found that seizures may occur in the event of network melting. The results of the work published in the journal Nature Communications.
Initially, the researchers made this discovery in mice suffering from epilepsy caused by fatal brain cancer, glioblastoma, whose first symptom is often convulsions. Glioblastoma is the only cancer that is limited in space. Because the skull blocks cancer from expanding to the outside, the tumor produces an excitatory excess chemical neurotransmitter (glutamate), 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 gelatinous substance that holds the brain cells in place. Glioblastomas are very malignant and are known to be able to spread in the body. The secreted enzyme is a kind of knife that cuts tumor cells, allowing them to move freely.
To their surprise, the scientists also observed how the enzyme attacks perineuronal nets wound around the inhibitory neurons of GABA (gamma-aminobutyric acid), which help prevent seizures.
The Italian neuroscientist Camillo Golgi (Camillo Golgi) discovered for the first time the perineuronal network in 1893, but then misunderstood their function. Golgi called the "corset" of the network and said that they probably prevented the exchange of messages between the neurons. Sontheimer's study refutes him. The scientist, on the other hand, has discovered that networks support messaging. The neurons covered by perineuronal networks have a lower membrane capacity and the ability to store electrical charge, which means that they can trigger an impulse and recharge up to two times faster than non-neuronal neurons.
When they suddenly lose their perineural networks, the results can be catastrophic: by applying this enzyme to the brain without a tumor, scientists have seen that the most enzymatic degradation of perineuronal networks has been sufficient to trigger convulsions – even when the neurons have remained intact .
The researchers' attention now focuses on the role that perineural networks can play in other forms of acquired epilepsy – for example, following a head injury or a brain infection – that will bring them closer to creating effective medicine.
"We've solved the 125-year secret of neurology!" This is what fundamental science is to keep an open mind and watch out for old and new questions, "says Sontheimer.
According to the World Health Organization, over 50 million people worldwide suffer from epilepsy, a third of which are not subject to known anti-epileptic procedures.
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