Gamma-aminobutyric acid

Gamma-aminobutyric acid (GABA) is a neurotransmitter present in widely divergent species of organism. In human beings, GABA acts at inhibitory synapsess in the brain. As in the other contexts where GABA figures as a transmitter, the inhibition results from a "hyperpolarization" of the inhibited neuron's cell potential, which is elicited by the binding of GABA molecules to their receptorss in the post-synaptic membrane. This binding opens ion channels to allow either the entry of chloride or the exit of potassium into or out of the cell. In insects GABA mediates muscle activation at synapses between nerves and muscle cells and also the stimulation of certain glands. So far three general classes of GABA receptor known, more than one of which is often represented in the same organisms. These include both so-called ionotropic receptors, which are ion channels themselves, and metabotropic receptors, which are G protein-coupled receptors that open ion channels via intermediaries (G proteins).

With regard to the human brain, it has been asserted that GABA signals interfere with the registration and consolidation stages of memory formation. As the GABA system is found in the hippocampus, which is thought to play a large role in memory formation, this is thought to be possible.

Three types of GABA receptors:

• GABA_A receptors
• GABA_B receptors
• GABA_C receptors

Drugs which affect GABA receptors:

• alcohol
• carbamazepine, phenytoin, valproate
• benzodiazepines and barbiturates
• baclofen
• add other drugs that affect the GABA receptors

External links

• http://www.vcu-cme.org/gaba/overview2.html