Some networks of astrocytes, like these, appear to ship messages very similar to neurons do
RICCARDO CASSIANI-INGONI/SCIENCE PHOTO LIBRARY
A brand new kind of mind cell, referred to as a glutamatergic astrocyte, has been found. It may clarify how quite a lot of neurodegenerative circumstances, equivalent to Parkinson’s, develop.
Mind cells can largely be categorised into two varieties: neurons and glia. Neurons are usually thought-about to speak with one another throughout the synapses, or junctions, between them, whereas glia don’t use this sort of signalling.
Synaptic transmission happens when a neuron is electrically excited and releases a chemical, referred to as a neurotransmitter, into the hole between itself and one other neuron, which ends up in the activation of the second neuron. This potential was largely considered distinctive to neurons.
However 20 years in the past, Andrea Volterra, now on the College of Lausanne in Switzerland, and his colleagues introduced that they’d found that some glia may additionally use synaptic-like transmission to speak with different cells. Nevertheless, the findings proved controversial as different researchers struggled to copy the findings.
Now, Volterra and a special workforce have used trendy methods to lastly put this controversy to mattress.
The researchers analysed information on the manufacturing by genes in mouse cells of RNA molecules, that are intermediates in protein manufacturing, to see if they may discover the protein complexes required for synaptic transmission in cells apart from neurons. The workforce particularly checked out cells within the mind’s hippocampus area, as a result of that is the place the earlier analysis claimed to have noticed non-neuronal synaptic transmission.
The evaluation revealed a number of clusters of astrocytes, a kind of glia, that appeared to additionally possess the flexibility to participate in synaptic transmission. The cells appeared to launch the neurotransmitter glutamate, which is the most typical neurotransmitter within the mind. The researchers then confirmed the presence of the genes concerned on this by finding out mind slices from grownup mice. The researchers have coined these cells glutamatergic astrocytes.
“These cells are a little bit like astrocytes and a little bit like neurons,” says Volterra. “They are secreting neurotransmitters with a mechanism and speed that are usually only linked to neurons. It’s why we call it a kind of hybrid cell.”
The researchers then used a kind of fluorescent microscopy approach referred to as two-photon imaging to check glutamate launch by these cells within the brains of the mice. “The signals that we see are in the order of speed similar to neurons,” says Volterra.
He and his colleagues additionally discovered related protein signatures of synaptic transmission in non-neuronal cells in people by current datasets. “The findings suggest that these cells are conserved [in people],” says workforce member Ludovic Telley, additionally on the College of Lausanne.
The researchers don’t know what number of of those cells might be discovered within the mind, or if they’re primarily within the hippocampus.
It’s unclear why the mind wants glia that talk through synaptic transmission, says Volterra. He speculates that it may result in a larger coordination of indicators. “Often, we have neuronal information that needs to spread to larger ensembles and neurons are not very good for the coordination of this,” he says. One astrocyte can keep in touch with 100,000 synapses in mice, which may imply the indicators go additional in a extra coordinated trend, he says. They will attain thousands and thousands of synapses in people.
These cells additionally look like in mind circuits concerned in motion, which degenerate in Parkinson’s illness, says Volterra. A greater understanding of the cells may give us a larger perception into methods to sort out the situation, he says.
