Behavioral effect of naloxone on anxiolytic- like effect of noscapine in bulb/c mice

The effect of naloxone, a non-selective opioid antagonist on some anxiolytic and analgesic drugs is reported. Noscapine is an opioid alkaloid with antitussive effect that cannot be antagonized by naloxone. The anxiolytic-like effect of noscapine has been shown in light-dark model and elevated plus maze. In this study the effect of naloxone on anxiolytic effect of noscapine in light-dark model was investigated The measured parameters were time spent in light, time spent in dark, latency and number of tunnel transitions. Since locomotion could affect the behavioral pattern of the animals, locomotor activity was also measured. Our data show that naloxone alone has no effect on number of tunnel transition, latency, time spent in light and time spent in dark. However, naloxone could antagonize the anxiolytic-like effect of noscapine (1, 1.5 mg/kg) and decrease time spent in light area. The antagonistic effect of naloxone on anxiolytic-like effect of noscapine may be due to non-opioid receptors, involved in anxiety.