GABA, or gamma-aminobutyric acid, is a neurotransmitter in the central nervous system that is involved in regulating neuronal activity. It is an inhibitory neurotransmitter, meaning that it reduces the activity of the neurons it acts upon.
Structure: GABA is an amino acid with a chemical structure similar to glutamate, another neurotransmitter in the brain. It consists of a carboxylic acid group, an amino group, and a side chain that contains a four-carbon chain terminated with an amino group.
Synthesis: GABA is synthesized from glutamate through the action of the enzyme glutamic acid decarboxylase (GAD), which removes a carboxyl group from glutamate. This process requires vitamin B6 as a cofactor. Once synthesized, GABA is packaged into synaptic vesicles and released into the synaptic cleft upon neuronal activation.
Function: GABA plays an important role in regulating neuronal activity and maintaining the balance between excitation and inhibition in the brain. When GABA binds to its receptors on the postsynaptic neuron, it opens chloride ion channels, which leads to hyperpolarization of the cell membrane and a decrease in the likelihood of the neuron firing an action potential.
Neurological diseases associated with GABA: Disruptions in GABAergic neurotransmission have been implicated in several neurological and psychiatric disorders, including anxiety, depression, epilepsy, and schizophrenia. For example, decreased GABA levels or function have been associated with anxiety disorders, while increased GABA levels have been observed in epilepsy. Altered GABAergic function has also been implicated in the development of drug addiction and withdrawal.