Peripheral injection of dexamethasone modulates anxiety related behaviors in mice: an interaction with opioidergic neurons

ABSTRACT

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 glucoc orticoids 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