PERIPHERAL INJECTION OF DEXAMETHASONE MODULATES ANXIETY RELATED BEHAVIORS IN MICE: AN INTERACTION WITH OPIOIDERGIC NEURONS

Stress and anxiety initiates a cascade of biochemical and endocrine event which results in behavioral and electrophysiological effects in both animals and humans. in this study, we investigated the effects of dexamethasone (dex), as a synthetic glucocorticoid, and its interaction with opioidergic system on anxiety related behavior in mice. young adult male mice were used in this study. a standard elevated plus-maze was used to determine anxiety levels in animal. different doses of dex (0.1, 0.5, 1, 2 and 10 mg/kg, sc) or vehicle was injected 30 min before of evaluation. naloxone (1 and 2 mg/kg, ip) was injected 5 min before the dex (0.5 and 1 mg/kg) administration. results indicated that dex at doses of 0.5 and 1 reduced and in dose of 10 mg/kg increased anxiety related behaviors significantly (p<0.05 in all cases). also pretreatment of naloxone at doses of 1 and 2 mg/kg attenuated the effects of lower doses of dex on anxiety related behaviors. finding above indicated that peripheral administration of glucocorticoids induces biphasic effects on anxiety related behaviors: anxiolytic effects in lower doses and anxiogenic effects in a high dose. data also revealed an involvement of opioidergic system in anxiolytic effects of glucocorticoids.