Antidepressant-like effects of acute and chronic treatment with zinc in forced swim test and olfactory bulbectomy model in rats

The activity of zinc administered intraperitoneally, acutely (in single dose), sub-chronically (in triple doses) or chronically (once daily for 14 days) were assessed in the forced swim test (FST) and olfactory bulbectomy (OB) model of depression in rats. Previously, we have demonstrated that acute administration of zinc sulfate is active in FST in rats and mice. In the present study, zinc hydroaspartate in a dose of 65 mg/kg (11.5 mg Zn/kg), all: acute, sub-chronic and chronic administration, reduced the immobility time in the FST in rats. Removal of olfactory bulbs (OB surgery) in rats is associated with variety of behavioral abnormalities such as deficit in a step-down passive avoidance or hyperactivity in the "open field" test. Both acute and chronic administration of zinc hydroaspartate reduced the number of trials needed to the leaming passive avoidance and reduced the OB-induced hyperactivity in rats. At the time schedule following zinc hydroaspartate administration, when behavioral experiments were performed, the serum zinc concentrations were significantly higher than control-physiological values. These results confirm activity of zinc in the FST, show its antidepressant-like activity in the OB rat model of depression, demonstrate the lack of tolerance to these effects and suggest relationship of these antidepressant-like effects with the rise in serum zinc. These animal data further suggest antidepressant activity of zinc in human depression. (C) 2003 Elsevier Science Inc. All fights reserved.