γ-Aminobutyric acid or GABA) is the chief inhibitory neurotransmitter in the mammaliancentral nervous system. It plays the principal role in reducing neuronalexcitability throughout the nervous system. In humans, GABA is also directly responsible for the regulation of muscle tone.
γ Aminobutyric acid (GABA) is a kind of natural amino acid, which is the chief inhibitory neurotransmitter in the mammalian central nervous system. It plays a role in regulating neuronal excitability throughout the nervous system. In humans, GABA is also directly responsible for the regulation of muscle tone. When the level of GABA in the brain decreases below a certain level seizures and other neurological disorders may occur. GABA can act as a natural calming and antiepileptic agent in the brain, also increases levels , which is desirable to most adults since this hormone allows children and teenagers to grow and gain weight increase muscle mass without putting on extra pounds.
Neurotransmitter
In vertebrates, GABA acts at inhibitory synapses in the brain by binding to specific transmembrane receptors in the plasma membrane of both pre- and postsynaptic neuronal processes. This binding causes the opening of ion channels to allow the flow of either negatively charged chloride ions into the cell or positively charged potassium ions out of the cell. This action results in a negative change in the transmembrane potential, usually causing hyperpolarization. Two general classes of GABA receptor are known: GABAA in which the receptor is part of a ligand-gated ion channel complex, and GABAB metabotropic receptors, which are G protein-coupled receptors that open or close ion channels via intermediaries
Brain development
While GABA is an inhibitory transmitter in the mature brain, its actions are primarily excitatory in the developing brain. The gradient of chloride is reversed in immature neurons, and its reversal potential is higher than the resting membrane potential of the cell; Activation of a GABA-A receptor thus leads to efflux of Cl- ions from the cell, i. e. A depolarizing current. The differential gradient of chloride in immature neurons is primarily due to the higher concentration of NKCC1 co-transporters relative to KCC2 co-transporters in immature cells. GABA itself is partially responsible for orchestrating the maturation of ion pumps. GABA-ergic interneurons mature faster in the hippocampus and the GABA signalling machinery appears earlier than glutamatergic transmission. Således, GABA is the major excitatory neurotransmitter in many regions of the brain before the maturation of glutamatergic synapses.
