Anxiolytic effects of the novel α2δ ligand mirogabalin in a rat model of chronic constriction injury, an experimental model of neuropathic pain.

RATIONALE: Psychiatric disorders such as anxiety and depression are frequently observed in neuropathic pain patients, and negatively impact their quality of life. Mirogabalin is a novel ligand for the α2δ subunit of voltage-gated calcium channels and has unique binding characteristics to α2δ subunits and potent and long-lasting analgesic effects in neuropathic pain models.
OBJECTIVES: To provide further information on the pharmacological profile of mirogabalin and its utility for chronic pain therapy, we investigated its anxiolytic effects in an experimental animal model for neuropathic pain.
METHODS: In chronic constriction injury (CCI) model rats, mechanical hypersensitivity was determined by the von Frey test. Anxiety- and depression-related behaviours were evaluated using the elevated plus maze test and forced swimming test, respectively.
RESULTS: CCI model rats showed sustained tactile allodynia followed by anxiety-related behaviours, not depression-related behaviours. The tactile allodynia (significant decreases in paw withdrawal threshold) developed within 2 weeks after model preparation, whereas the anxiety-related behaviours (significant decreases in the number of entries and time spent in open arms and significant increases in time spent in closed arms) were observed at 5 weeks but not 4 weeks after model preparation. Single oral administration of mirogabalin (3 or 10 mg/kg) dose-dependently alleviated the above-mentioned anxiety-related behaviours and tactile allodynia.
CONCLUSIONS: CCI model rats showed anxiety-related behaviours in a time-dependent manner in the elevated plus maze test. Mirogabalin alleviated both the anxiety-related behaviours and tactile allodynia in CCI model rats. Mirogabalin may provide effective anxiety relief as well as pain relief in patients with neuropathic pain.