Transmission ability of "support" cells in brain could help understand disorders better

NEW DELHI: The discovery of neurotransmission ability of "support" cells in the brain have led neuroscientists to believe that it could help understand pathologies of epilepsy and Parkinson's disease, new research published in the journal Nature said.

The brain is known to be made of neurons and glial cells, or cells of the glia, which is the tissue surrounding and supporting neurons (nerve cells) in the central nervous system.

Some of these glial cells, called astrocytes and surrounding synapses, which are neuronal junctions where neurotransmitters are released to transmit information between neurons, have been found to play an active role in synaptic transmission and in information processing, the study from the University of Lausanne (UNIL), Switzerland, said.

Earlier research has established the role of astrocytes in supporting neurons, but not in releasing neurotransmitters.

To confirm or refute the hypothesis that astrocytes can release neurotransmitters, the researchers first scrutinised the molecular content of astrocytes in mice to find traces of the machinery necessary for the rapid secretion of glutamate, the main neurotransmitter used by neurons.

"We also identified other specialised proteins in these cells, which are essential for the function of glutamatergic vesicles and their capacity to communicate rapidly with other cells," said Ludovic Telley, assistant professor at UNIL, co-director of the study.

Next, the neuroscientists tried to find out if these hybrid cells were able to actually release glutamate with a speed comparable to that of synaptic transmission. They used advanced imaging techniques that could map glutamate released by vesicles in brain tissues and in living mice.

"We have identified a subgroup of astrocytes responding to selective stimulations with rapid glutamate release, which occurred in spatially delimited areas of these cells reminiscent of synapses," said Andrea Volterra, honorary professor at UNIL and co-director of the study.

Further, this glutamate release also regulated neuronal circuits without which, the study showed, memory consolidation was impaired and that the memory of mice is impacted.

The implications of this discovery extend to brain disorders, the researchers said.

This is because, they said, the team observed links by disrupting these glutamatergic astrocytes with pathologies such as epilepsy, whose seizures were exacerbated.

They further found these astrocytes were found to be involved in regulating brain circuits related to movement control and could offer therapeutic targets for Parkinson's disease.

"Our next studies will explore the potential protective role of this type of cell against memory impairment in Alzheimer's disease, as well as its role in other regions and pathologies than those explored here," said Volterra.