Dihydrogenfated ergot compounds bind with to GABA A receptor-associated Cl − ionophore

Abstract

The binding of t-[ 3H]butylbicycloorthobenzoate ([ 3H]TBOB) to crude synaptosomal membranes of the mouse brain (cerebrum minus cortex) in the presence of dihydroergotoxine, dihydroergosine, dihydroergotamine and γ-aminobutyric acid (GABA) was studied in vitro. [ 3H]TBOB binding was inhibited by all drugs used. The rank order of potency was dihydroergotoxine > GABA > dihydroergosine > dihydroergotamine. This suggests that dihydrogenated ergot compounds, especially dihydroergotoxine, possess appreciable binding activity (comparable to that of benzodiazepines and barbiturates) at the GABA A receptor-associated Cl −1 ionophore.