Bicuculline

Bicuculline
Systematic (IUPAC) name
(6R)-​6-​[(5S)-​6-​methyl-​5,​6,​7,​8-​tetrahydro​[1,3]dioxolo​[4,5-g]​isoquinolin-​5-​yl]​furo[3,4-e]​[1,3]​benzodioxol-​8(6H)-​one
Identifiers
CAS number	485-49-4
ATC code	none
PubChem	10237
ChemSpider	9820
Chemical data
Formula	C20H17NO6
Mol. mass	367.352 g/mol
SMILES	eMolecules & PubChem
Pharmacokinetic data
Bioavailability	?
Metabolism	?
Half life	?
Excretion	?
Therapeutic considerations
Pregnancy cat.	?
Legal status
Routes	?
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Bicuculline (BIC) is a light-sensitive competitive antagonist of GABA_A receptors. It was originally identified in 1932 in plant alkaloid extracts^[1] and has been isolated from Dicentra cucullaria, Adlumia fungosa, Fumariaceae, and several Corydalis species. Since it blocks the inhibitory action of GABA receptors, the action of bicuculline mimics epilepsy. This property is utilised 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.

The action of bicuculline is primarily on the ionotropic GABA_A 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 GABA_A receptors is 3 μM.

In addition to being a potent GABA_A receptor antagonist, bicuculine can be used to block Ca²⁺-activated potassium channels ^[2].

Sensitivity to bicuculline is defined by IUPHAR as a major criterion in the definition of GABA_A receptors — however in recent years a new class of ionotropic GABA receptor, defined variously as GABA_A or GABA_C has been characterised, which is insensitive to both benzodiazepines and bicuculline.

A water soluble form of bicuculline, bicuculline methiodide, is soluble in water to a concentration of 10 mg/mL.

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References