Anxiolytic-like effect of etazolate, a type 4 phosphodiesterase inhibitor in experimental models of anxiety

Etazolate is a selective inhibitor of type 4 phosphodiesterase (PDE4) class enzyme. Antidepressant-like effect of etazolate has been previously demonstrated in the rodent models of depression. The present study was designed to investigate the anxiolytic-like activity of etazolate in experimental mouse models of anxiety. The putative anxiolytic effect of etazolate (0.25-1 mg/kg, ip) was studied in mice by using a battery of behavioural tests of anxiety such as elevated plus maze (EPM), light/dark (L/D) aversion, hole board (HB) and open field (OFT) with diazepam (2 mg/kg, ip) as reference anxiolytic. Like diazepam (2 mg/kg, ip), etazolate (0.5 and 1 mg/kg, ip) significantly increased the percentage of both time spent and entries into open arms in the EPM test. In the L/D test etazolate (0.5 and 1 mg/kg, ip) increased the both total time spent in and latency time to leave the light compartment. Etazolate (0.5 and 1 mg/kg, ip) also significantly increased head dipping scores and time spent in head dipping, whereas significantly decreased the head dipping latency in HB test. In addition, etazolate (0.5 and 1 mg/kg, ip) significantly increased the ambulation scores (square crossed) and number of rearing in OFT. In conclusion, these findings indicated that etazolate exhibited an anxiolytic-like effect in experimental models of anxiety and may be considered an alternative approach for the management of anxiety disorder.