Alcohol increases the production of the neurotransmitter GABA, how are GABA levels returned back to normal?

a hangover

just kidding

In vertebrates, GABA acts at inhibitory synapses in the brain. GABA acts by binding to specific transmembrane receptors in the plasma membrane of both pre- and postsynaptic neurons. This binding causes the opening of ion channels to allow either the flow of negatively-charged chloride ions into the cell or positively-charged potassium ions out of the cell. This will typically result in a negative change in the transmembrane potential, usually causing hyperpolarization. Three general classes of GABA receptor are known. These include GABAA and GABAC ionotropic receptors, which are ion channels themselves, and GABAB metabotropic receptors, which are G protein-coupled receptors that open ion channels via intermediaries (G proteins).

Neurons that produce GABA as their output are called GABAergic neurons, and have chiefly inhibitory action at receptors in the adult vertebrate. Medium Spiny Cells are a typical example of inhibitory CNS GABAergic cells. GABA exhibits excitatory actions in insects, mediating muscle activation at synapses between nerves and muscle cells and also the stimulation of certain glands. In hippocampus and neocortex of the mammalian brain, GABA has primarily excitatory effects early in development, and is in fact the major excitatory neurotransmitter in many regions of the brain prior to the maturation of glutamate synapses - See developing cortex. Whether GABA is excitatory or inhibitory depends on the direction (into or out of the cell) and magnitude of the ionic currents controlled by the GABAA receptor. When net positive ionic current is directed into the cell, GABA is excitatory, when the net positive current is directed out of the cell, GABA is inhibitory. A developmental switch in the molecular machinery controlling the polarity of this current is responsible for the changes in the functional role of GABA between the neonatal and adult stages.

In spastic cerebral palsy in humans, GABA cannot be absorbed properly by the damaged nerve rootlets leading to certain muscles; this leads to hypertonia in those muscles.


[edit] Synthesis
Organisms synthesize GABA from glutamate using the enzyme L-glutamic acid decarboxylase and pyridoxal phosphate as a cofactor. It is worth noting that this involves converting the principal excitatory neurotransmitter (glutamate) into the principal inhibitory one (GABA).

what isnt used is taken out of the synaptic cleft and surrounding areas by astrocytes, basically the cleanup cells of the nervous system (they have lots of other functions though),