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, dat is de belangrijkste remmende neurotransmitter in het centrale zenuwstelsel van zoogdieren. Het speelt een rol bij het reguleren van de neuronale prikkelbaarheid in het hele zenuwstelsel. In humans, GABA is also directly responsible for the regulation of muscle tone. Wanneer het niveau van GABA in de hersenen onder een bepaald niveau daalt, kunnen epileptische aanvallen en andere neurologische aandoeningen optreden. GABA kan werken als een natuurlijk kalmerend en anti-epileptisch middel in de hersenen, verhoogt ook het niveau , wat voor de meeste volwassenen wenselijk is, omdat dit hormoon kinderen en tieners in staat stelt te groeien en aan te komen en de spiermassa te vergroten zonder extra kilo's aan te komen.
Neurotransmitter
Bij gewervelde dieren, GABA werkt op remmende synapsen in de hersenen door zich te binden aan specifieke transmembraanreceptoren in het plasmamembraan van beide- en postsynaptische neuronale processen. 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. Thus, GABA is the major excitatory neurotransmitter in many regions of the brain before the maturation of glutamatergic synapses.
