Even though majority of people would never think about it, balance of excitation and inhibition in our brain is very important. Scientists say it can be compared to a thermostat and has to work perfectly throughout our lives.
Now team of scientists from Japan and France have figured out how this balance is maintained. Researched demonstrated how inhibitory synapses are stabilized when the neurotransmitter glutamate triggers stored calcium to be released from the endoplasmic reticulum in neurons.
Although it sounds extremely complicated process, which may not be interesting for everyone, it is very important and getting to understand it better is a significant achievement. Hiroko Bannai, lead author of the study, said: “Imbalances in excitation and inhibition in the brain has been linked to several disorders. In particular, forms of epilepsy and even autism appear to be related to dysfunction in inhibitory connections”. One of the key molecules in this process is the inhibitory neurotransmitter, called GABA. In short, GABA binds to GABAa receptors on the outside of a neuron, which prevents the neuron from sending signals to other neurons.
Normally GABAa are clustered together, but some processes may make them spread out, which reduces how much the neuron can be inhibited by GABA. Therefore, the receptors have to be re-clustered often, which is exactly what maintains the proper excitatory/inhibitory balance in the brain. Scientists wanted to understand how it happens and set out to research another signalling pathway that also begins with glutamate. In this pathway, glutamate binds to another receptor, called mGluR, which leads to the release of calcium from internal storage into the neuron’s internal environment.
Scientists used quantum dot-single particle tracking and managed to show this calcium interacts with protein kinase C to promote clustering of GABAa receptors at the postsynaptic membrane. In other words, this complex process re-clusters GABAa receptors. Scientists were surprised to see that dispersion of GABAa and stabilization of it is both caused by the same neurotransmitter. This shows once again how complex our bodies are and how little we know about them.
Now scientists will try to understand what controls which pathway is activated by glutamate and why calcium is involved in such wide variety of biological functions of our bodies. Even though it is understandable researches like this are not going to be that interesting to common public, they are very important and are majority of the work of scientists around the globe.