As a first step, scientists tried to determine the expression pattern of glycine receptors in the developing cortex by focusing principally on one of the sub-units of these receptors: the alpha 2 sub-unit. Glycine receptors are composed of five subunits. These can be identical, in which case they are known as homomeric receptors, or they can be different as in the case of heteromeric receptors. “During development, the alpha 2 sub-unit is the most represented and it has previously been explained that the homomeric receptors composed of five sub-units of this type are involved in extrasynaptic development functions throughout the entire nervous system”, states Laurent Nguyen.

A small amino acid that triggers a torrent of reactions

In order to detect glycine receptors in the interneurons, the researchers performed immunohistochemistry and electrophysiology. “The use of antibodies and the recording of electric currents that cross the cells enabled us to show the presence of glycine receptors. Subsequently, we were also able to analyze the type of subunits that these receptors are composed of, thanks to specific pharmacological agents”, continues Laurent Nguyen. This is how scientists realized that most of the glycine receptors present in the immature interneurons were homomeric alpha 2 receptors. The latter are activated by the surrounding glycine probably arising from projection neurons that are already in place. “The glycine receptors are functional in migrating interneurons and give rise to currents that cause a modification of membrane potential”, continues the scientist.