Dual effect of dexamethasone administration on anxiety and depression in adult male rats

Introduction: Dexamethasone is a synthetic glucocorticoid with possible effects on anxiety and depression because it has direct effects on the hypothalamus-pituitary-adrenal (HPA) and interacts with several neurotransmitter systems such as GABA and glutamate. Methods: Levels of anxiety and depression in rats were measured 40 minutes and 24 hours, respectively, after subcutaneous injection of Dexamethasone Sodium-Phosphate (DEX) 0.5, 1, 5, 10, 20, 30 mg/kg (saline 1ml/kg) in the elevated plus maze and forced swimming test. Results: The results of anxiety test showed a significant decrease in the percentage of open arm time and open arm entries in DEX (1 mg/kg) group compared to the saline groups. The percentage of time spent in the open arms significantly increased in DEX (20mg/kg) compared to the saline group. In terms of locomotor activity (total number of open and closed arms), significant decrease was observed in DEX (1 mg/kg) compared to the saline group. Also, a significant difference between DEX 1 and 20 mg/kg groups was observed. Comparative assessment of depression during total immobility time showed significant increase in DEX (1 mg/kg) compared to saline and also a significant decrease was observed in DEX (30 mg/kg) compared to the saline groups. A significant difference in latency to immobility was also detected between DEX 1 and 30 mg/kg groups. Conclusion: Our findings suggest that administration of DEX induced dual effects on anxiety and depression anxiogenic and depressant effects were observed at lower doses, while anxiolytic or antidepressant effects were detected at higher doses.