Okay so obviously Ethanol augments GABA A through an allosteric binding site but is there any endogenous compound that interacts with the same site? I know it's fairly likely that Ethanol just happens to affect the receptor in a particular way (making wherever it tends to bind a binding site) but it's also possible that the site and its function have evolved in conjunction with a specific endogenous modulator, which is then hijacked by ethanol. I don't think there are many, if any, endogenous alcohols used for signaling and modulation so I'm leaning more towards the effect of Ethanol on GABA A being mainly coincidental .