Bicuculline

Bicuculline is a phthalide-isoquinoline compound that is a light-sensitive competitive antagonist of GABAA receptors.[1] It was originally identified in 1932 in plant alkaloid extracts[2] and has been isolated from Dicentra cucullaria, Adlumia fungosa, and several Corydalis species (all in subfamily Fumarioideae, previously known as family Fumariaceae). Since it blocks the inhibitory action of GABA receptors, the action of bicuculline mimics epilepsy; it also causes convulsions. This property is utilized in laboratories across the world in the in vitro study of epilepsy, generally in hippocampal or cortical neurons in prepared brain slices from rodents. This compound is also routinely used to isolate glutamatergic (excitatory amino acid) receptor function.

Bicuculline
Clinical data
ATC code
  • none
Identifiers
CAS Number
PubChem CID
IUPHAR/BPS
ChemSpider
UNII
ChEBI
ChEMBL
PDB ligand
CompTox Dashboard (EPA)
ECHA InfoCard100.006.927
Chemical and physical data
FormulaC20H17NO6
Molar mass367.357 g·mol−1
3D model (JSmol)
Melting point215 °C (419 °F)
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The action of bicuculline is primarily on the ionotropic GABAA receptors, which are ligand-gated ion channels concerned chiefly with the passing of chloride ions across the cell membrane, thus promoting an inhibitory influence on the target neuron. These receptors are the major targets for benzodiazepines and related anxiolytic drugs.

The half-maximal inhibitory concentration (IC50) of bicuculline on GABAA receptors is 3 μM.

In addition to being a potent GABAA receptor antagonist, bicuculline can be used to block Ca2+-activated potassium channels.[3]

Sensitivity to bicuculline is defined by IUPHAR as a major criterion in the definition of GABAA receptors 

See also

References
  1. Johnston, Graham AR (2013). "Advantages of an antagonist: bicuculline and other GABA antagonists". British Journal of Pharmacology. 169 (2): 328–336. doi:10.1111/bph.12127. ISSN 1476-5381. PMC 3651659. PMID 23425285.
  2. Manske RH (1932). "The Alkaloids of Fumaraceous Plants. II. Dicentra cucullaria (L.) Bernh". Canadian Journal of Research. 7 (3): 265–269. Bibcode:1932CJRes...7..265M. doi:10.1139/cjr32-078.
  3. Khawaled R, Bruening-Wright A, Adelman JP, Maylie J (August 1999). "Bicuculline block of small-conductance calcium-activated potassium channels". Pflugers Archiv. 438 (3): 314–21. doi:10.1007/s004240050915. PMID 10398861.
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