An electrical signal travels down one nerve cell, causing it to release the neurotransmitter into a small gap between cells called the synapse . The neurotransmitter and receptor are specific to each other, like a lock and key. Neurotransmitters can either excite the receiving cell to cause a response or inhibit the receiving cell from stimulation.
Alcohol acts primarily on the nerve cells within the brain.
Enhancing an inhibitor would have the effect of making things sluggish, which matches the behavior you see in a drunk person. Glutamine is an excitatory neurotransmitter that alcohol weakens. By making this excitatory neurotransmitter less effective, you also get sluggishness. Alcohol does this by interacting with the receptors on the receiving cells in these pathways. Alcohol affects various centers in the brain, both higher and lower order.