Anxiolytic-Like Activity of Pregabalin in the Vogel Conflict Test in α₂δ-1 (R217A) and α₂δ-2 (R279A) Mouse Mutants

Abstract

The ␣ 2 ␦ auxiliary subunits (␣ 2 ␦-1 and ␣ 2 ␦-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 ␣ 2 ␦-1 and ␣ 2 ␦-2 subunits. Two independent point mutant mouse strains were generated in which either the ␣ 2 ␦-1 subunit (arginine-to-alanine mutation at amino acid 217; R217A) or the ␣ 2 ␦-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 ␣ 2 ␦-1 (R217A) mutants up to a dose of 320 mg/kg. In contrast, pregabalin was active in the ␣ 2 ␦-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 ␣ 2 ␦-1 subunit.

α2δ Ligands Act as Positive Modulators of Adult Hippocampal Neurogenesis and Prevent Depression-Like Behavior Induced by Chronic Restraint Stress

“…In the PGB long-term administration experiments, behavioral tests were performed 24 h after the last drug (or vehicle) injection. In the PGB short-term administration experiments, tests were performed 2 h after the drug (or vehicle) injection, a time reported to correspond to peak behavioral effects (Lotarski et al, 2011). For the first 5 days of the experimental procedure, animals were given BrdU (150 mg/kg i.p., once daily).…”

“…Although multiple sites and modes of action have been proposed for GBP and PGB, at present one mechanism is considered primary for their clinical efficacy, namely, high-affinity drug interactions with the ␣2␦1/2 subunits of voltage-gated calcium channels (VGCCs) (Gee et al, 1996;Bian et al, 2006). Studies demonstrated that drug binding to the ␣2␦1 subunit is necessary for antihyperalgesic effects in a preclinical model of pain (Field et al, 2006), as well as anxiolytic effects in rodents (Lotarski et al, 2011).…”

The Physiology, Pathology, and Pharmacology of Voltage-Gated Calcium Channels and Their Future Therapeutic Potential

“…Using the a 2 d-1 knock-in mouse model, it was found that binding of gabapentin and pregabalin to the a 2 d-1 subunit is essential for their therapeutic effect, both in neuropathic pain and in several epilepsy models (Field et al, 2006;Lotarski et al, 2014). Furthermore, anxiolyticlike effects of pregabalin in mice were also mediated by Pharmacology of Voltage-Gated Calcium Channels drug binding to a 2 d-1 rather than a 2 d-2 (Lotarski et al, 2011). Nevertheless, gabapentin and pregabalin show similar affinities for a 2 d-1 and a 2 d-2 (Gong et al, 2001;Li et al, 2011); therefore, a 2 d-1-selective ligands might show an improved side effect profile.…”

“…As mentioned above, it is possible that selective ligands of a 2 d-1 might be of therapeutic use, with fewer side effects, because the therapeutic antiepileptic, anxiolytic, and antihyperalgesic effects in animal models of gabapentin and pregabalin were via binding to a 2 d-1 (Field et al, 2006;Lotarski et al, 2011Lotarski et al, , 2014. Nevertheless, a 2 d-2 binds these drugs with similar affinity and is expressed in brain regions associated with movement and other behaviors (Barclay et al, 2001).…”

“…Mutation of RRR to RRA reduced the affinity of gabapentin binding, for both a 2 d-1 (Wang et al, 1999) and a 2 d-2 . Knock-in mice were created with the same point mutation in either a 2 d-1 or a 2 d-2, such that gabapentin binding affinity was markedly reduced (Field et al, 2006;Lotarski et al, 2011). Using the a 2 d-1 knock-in mouse model, it was found that binding of gabapentin and pregabalin to the a 2 d-1 subunit is essential for their therapeutic effect, both in neuropathic pain and in several epilepsy models (Field et al, 2006;Lotarski et al, 2014).…”