GABA Receptors
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psychology
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date published 26/11/2007
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SummaryGABAA Receptor The GABAA receptor is a member of the superfamily of ligand-activated ion channels in the cell membrane. GABA type A (GABAA) receptors are most closely related to strychnine-sensitive glycine receptors, more distantly related to acetylcholine nicotonic receptors and serotonin 5-hydroxytryptamine (5-HT) [5-HT] type receptors, and even more distantly related to glutamate ionotropic receptors (AMPA and kainate receptors and NMDA receptors). GABAA receptors are heteropentameric protein complexes, which when activated undergo a series of conformational changes that form an open channel (pore) selectively permeable to anions, specifically chlorine anion (Cl–) and to a lesser degree (HCO–3). Receptor activation normally results in an influx of Cl– which rapidly and transiently hyperpolarizes the membrane, a process generally referred to as the generation of an inhibitory postsynaptic potential. The increase in Cl– flux also decreases the resistance of the membrane, which acts as a shunt to impede the ability of depolarizing excitatory postsynaptic potentials to elicit action potentials (nerve impulses).
Table of Contents
- GABAA receptors are heteromeric in that the receptor can comprise at least four types of subunit proteins, termed a, b, g, and d. It is pentameric in that each receptor has a total of five proteins
- A variety of pharmacological agents can influence the activity of GABAA receptors
- GABAB Receptors The metabotropic GABAB receptors are a member of the superfamily of G-protein-coupled receptors expressed in the cell membrane.
- However, it is likely that a breakdown in the regulation of glutamate is a major factor.
- Epilepsy Epilepsy is a group of neurological disorders characterized by spontaneous recurrent seizures.
- Although many neurobiological factors may contribute to seizure formation, a prominent feature of most seizures is an abnormal and excessive firing of glutamatergic neural pathways.
- Kindling, which is a gradual induction of a hyperexcitable neuronal state, can occur by focal repetitive subconvulsive stimulation of the hippocampus, amygdala, or some other brain areas.
- Neuropathic Pain Activation of afferent C fibers with nociceptive stimuli produces pain sensations that are enhanced during pathological conditions.
- A pregnane-derived synthetic neurosteroid is in clinical trials for treatment of epilepsy.
- Substance Abuse Ethanol enhances GABA receptor function in some in vitro preparations potentially via a protein-binding site.
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