Abstract

The α₂δ auxiliary subunits (α₂δ-1 and α₂δ-2) of voltage-sensitive calcium channels are thought to be the site of action of pregabalin (Lyrica), a drug that has been shown to be anxiolytic in clinical trials for generalized anxiety disorder. Pregabalin and the chemically related drug gabapentin have similar binding and pharmacology profiles, demonstrating high-affinity, in vitro binding to both α₂δ-1 and α₂δ-2 subunits. Two independent point mutant mouse strains were generated in which either the α₂δ-1 subunit (arginine-to-alanine mutation at amino acid 217; R217A) or the α₂δ-2 subunit (arginine-to-alanine mutation at amino acid 279; R279A) were rendered insensitive to gabapentin or pregabalin binding. These strains were used to characterize the activity of pregabalin in the Vogel conflict test, a measure of anxiolytic-like activity. Pregabalin showed robust anticonflict activity in wild-type littermates from each strain at a dose of 10 mg/kg but was inactive in the α₂δ-1 (R217A) mutants up to a dose of 320 mg/kg. In contrast, pregabalin was active in the α₂δ-2 (R279A) point mutants at 10 and 32 mg/kg. The positive control phenobarbital was active in mice carrying either mutation. These data suggest that the anxiolytic-like effects of pregabalin are mediated by binding of the drug to the α₂δ-1 subunit.