Pharmacological characteristics of zolpidem-induced catalepsy in the rat

Zolpidem is a non-benzodiazepine hypnotic drug acting preferentially at α1-containing GABAA receptors expressed in various parts of the brain, including the basal ganglia. The aim of the present study was to provide preliminary characteristics of zolpidem-induced catalepsy in Wistar rats. Zolpidem (2.5-10.0 mg/kg), but not diazepam and midazolam, produced dose-dependent cataleptic responses in the bar test, which were similar to those produced by a reference antipsychotic drug, haloperidol. Zolpidem-induced catalepsy was abolished by a benzodiazepine site antagonist, flumazenil (5.0 mg/kg), D2/3 receptor agonist, quinpirole (1.0 mg/kg), and a non-competitive NMDA receptor antagonist, MK-801 (0.1 mg/kg), but not by a non-selective opioid receptor antagonist, naltrexone (3.0 mg/kg). The present results indicate that systemic injections of zolpidem may produce short-lasting, neuroleptic-like catalepsy in the rat.