GABA is a neurotransmitter—a brain chemical that is released by nerve cells (neurons) to transmit signals to neighboring neurons. GABA is a major inhibitory neurotransmitter in the nervous system. This means that GABA acts on its target neurons to prevent other nerve signals from being propagated across those neurons. To exert this inhibitory effect, GABA interacts with complex protein molecules (i.e., receptors) that are embedded in the membrane of the signal-receiving neurons. Several different types of GABA receptors exist, such as the GABAA and GABAB receptors. Each of these receptors, in turn, is comprised of several proteins that are encoded by a corresponding number of genes. For example, genes called GABRA2, GABRA4, GABRB1, and GABRG1 code for components of the GABAA receptor, and a gene called GABAB2 codes for one component of the GABAB receptor. Researchers previously had demonstrated that alcohol directly interacts with the GABAA receptor, enhancing the inhibitory effects of GABA and resulting in alcohol’s sedative effect (Davies 2003).
