Neurons secreting gamma aminobutyric acids (GABA) as their primary neurotransmitter are called GABA neurons. GABA is an inhibitory neurotransmitter i.e., it inhibits whichever neurons its binds to. These neurotransmitters are binded with membrane proteins called receptors. Neurotransmitter binds only to a specific receptor thereby GABA neurotransmitters bind with only GABA Receptors. Subclasses of GABA likely play distinct roles in regulating cortical circuitry. Three general classes of GABA receptor are known as GABA A, GABAB and GABA C receptors. The GABA A and GABA C are ionotropic receptors and GABA B metabotropic receptors.
In the nurons of vertebrate, chloride ions are pumped out of the You do not have access to view this node. On activating GABA A receptors chloride ions diffuse into You do not have access to view this node, hyperpolarize the membrane and decrease the excitability of the You do not have access to view this node. This inhibition is called hyperpolarizing inhibition. In some You do not have access to view this node, internal chloride concentration is higher than the equilibrium potential. In these cases, opening chloride channels caused an efflux of this anion, creating an inward current, and depolarizing the membrane. This type of inhibition is called depolarizing inhibition. Thus, activation of GABA A receptors will inhibit cell activity whether it hyperpolarizes or depolarizes the You do not have access to view this node.
The GABA A receptors is typical ligand-gated (ionotropic) receptors. The GABA A receptors is made up of five protein subunits set in a circle to form a pore, or channel, that remains closed until its specific ligand binds to the specific site. Each protein subunit is in fact a string of amino acids which passes in and out of the cell membrane four times. At the extracellular end of this string is a large N-terminal. This end-chain will mediate GABA-channel communications. In the center of the string is a large intracellular loop of amino acids with four sites.
The five subunits named as alpha, beta, gamma and delta. GABA A receptors are typically made up of two alphas and two beta subunits among the five subunits, though the particular subunit composition usually varies among brain regions and species.
The GABA A receptors is important parts of neuronal feedback loops; GABA A receptors keeps a check on the effects of excitatory neurotransmitters. They also monitor and balance neural responses. GABA feedback controls muscle tone by inhibiting spastic uncontrolled movements. When muscle relaxants bind to GABA A receptors this feedback loop are activated to stop cramps and spasms.