GABA receptor agonist

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g-Aminobutyric acid (GABA), a GABA receptor agonist. Gamma-Aminobuttersaure - gamma-aminobutyric acid.svg
γ-Aminobutyric acid (GABA), a GABA receptor agonist.

A GABA receptor agonist is a drug that is an agonist for one or more of the GABA receptors, producing typically sedative effects, and may also cause other effects such as anxiolytic, anticonvulsant, and muscle relaxant effects. [1]

Contents

There are three receptors of GABA. The GABAA and GABAA-ρ receptors are ion channels that are permeable to chloride ions which reduces neuronal excitability. The GABAB receptor belongs to the class of G protein-coupled receptors that inhibit adenylyl cyclase, therefore leading to decreased cyclic adenosine monophosphate (cAMP). The GABAA receptor mediates sedative and hypnotic effects and as well as anticonvulsant effects. The GABAB receptor mediates similar but differing effects.

Types

Many commonly used sedative and anxiolytic drugs that affect the GABA receptor complex are not agonists. These drugs act instead as positive allosteric modulators (PAMs) and while they do bind to the GABA receptors, they bind to an allosteric site on the receptor and cannot induce a response from the neuron without an actual agonist being present. Drugs that fall into this class exert their pharmacodynamic action by increasing the effects that an agonist has when potentiation is achieved.

General anesthetics act primarily as PAMs of GABA-A receptor. Positive allosteric modulators work by increasing the frequency with which the chloride channel opens when an agonist binds to its own site on the GABA receptor. The resulting increase in the concentration of Cl− ions in the postsynaptic neuron immediately hyperpolarizes this neuron, making it less excitable and thus inhibiting the possibility of an action potential. However, some general anesthetics like propofol and high doses of barbiturates may not only be positive allosteric modulators of GABA-A receptors but also direct agonists of these receptors.

Alcohol is an indirect GABA agonist. GABA is the major inhibitory neurotransmitter in the brain, and GABA-like drugs are used to suppress spasms. Alcohol is believed to mimic GABA's effect in the brain, binding to GABA receptors and inhibiting neuronal signaling.

GABAA receptor

Agonists

Positive allosteric modulators

GABAB receptor

Agonists

Positive allosteric modulators

GABAA-ρ receptor

Agonists

Positive allosteric modulators

References

  1. ↑ Brohan J, Goudra BG (October 2017). "The Role of GABA Receptor Agonists in Anesthesia and Sedation". CNS Drugs. 31 (10): 845–856. doi:10.1007/s40263-017-0463-7. PMID   29039138. S2CID   207486777.
  2. ↑ Petersen JG, Bergmann R, Møller HA, Jørgensen CG, Nielsen B, Kehler J, Frydenvang K, Kristensen J, Balle T, Jensen AA, Kristiansen U, Frølund B (February 2013). "Synthesis and biological evaluation of 4-(aminomethyl)-1-hydroxypyrazole analogues of muscimol as γ-aminobutyric acid(a) receptor agonists". J Med Chem. 56 (3): 993–1006. doi:10.1021/jm301473k. PMID   23294161.
  3. ↑ Löscher W, Rogawski MA (December 2012). "How theories evolved concerning the mechanism of action of barbiturates". Epilepsia. 53 (Suppl 8): 12–25. doi: 10.1111/epi.12025 . PMID   23205959. S2CID   4675696.
  4. 1 2 3 4 5 6 Ganellin CR, Triggle DJ, Macdonald F (1996). Dictionary of Pharmacological Agents. Boca Raton: Chapman & Hall/CRC. p. 608. ISBN   978-0-412-46630-4.
  5. 1 2 Ruesch D, Neumann E, Wulf H, Forman SA (January 2012). "An allosteric coagonist model for propofol effects on α1β2γ2L γ-aminobutyric acid type A receptors". Anesthesiology. 116 (1): 47–55. doi:10.1097/aln.0b013e31823d0c36. PMC   3261780 . PMID   22104494.
  6. ↑ Hales TG, Lambert JJ (November 1991). "The actions of propofol on inhibitory amino acid receptors of bovine adrenomedullary chromaffin cells and rodent central neurones". British Journal of Pharmacology. 104 (3): 619–628. doi:10.1111/j.1476-5381.1991.tb12479.x. PMC   1908220 . PMID   1665745.
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