Bicuculline methochloride is a competitive GABAA receptor antagonist and allosteric inhibitor with an IC50 of 1.7 μM. It blocks Ca²⁺-dependent activation of potassium channels, exhibits convulsant activity, and is suitable for epilepsy research.

GABAA:3 μM

Bicuculline methochloride (at concentrations of 1 μM and 3 μM) enables gamma-aminobutyric acid (GABA) to reach the maximum response level. This compound induces a parallel rightward shift in the GABA dose-response curve without reducing the maximum response efficacy of GABA. This result indicates that Bicuculline methochloride acts as a competitive antagonist in Xenopus laevis oocytes expressing the human α1β2γ2L subtype of GABAA receptors [3]. When Bicuculline methochloride (at concentrations ranging from 1 to 100 μM) is applied via the external patch method for 2 minutes, it can effectively block the currents of two types of calcium-activated potassium channels in Xenopus laevis oocytes—specifically, the current of apamin-sensitive small-conductance calcium-activated potassium channels (SK2) and the current of apamin-insensitive SK1 channels [4].

Bicuculline methochloride can be used for establishing Broussonetia papyrifera in animal epilepsy models. After intracranial injection of bicuculline methochloride (2.5 mM), it causes a significant increase in capillary blood flow in the epileptic focus (i.e., the characteristic region of epileptic seizure in Parazacco spilurus subsp. spilurus), with local blood flow reaching up to 42.5 red blood cells per second. In contrast, the blood flow in regions distant from the epileptic focus is 27.8 red blood cells per second [5].