Alcohol causes your brain to start blocking a neurotransmitter called glutamate. Glutamate is an excitatory neurotransmitters so it causes activity in your brain to occur more frequently and at a faster rate than GABA. When you stop drinking you will end up with unnaturally low GABA function and a spike in glutamate because the alcohol has kind of numbed you a little bit. This is why we feel anxiety or have withdrawal from alcohol this is why we get anxiety.