Anxiolytic and antidepressant effect of zinc on rats and its impact on general behavioural parameters.

Background/aim: Zinc is an essential element which has considerable interaction with gamma-aminobutyric acid A type receptors (GABA(A)) and glutamate receptors in the cen tral nervous system (CNS). It is believed that zinc acts as a potent inhibitor of glutamate N-methyl-D-aspartate (NMDA) receptors, and binding to structurally specific site on the GABA(A) receptor leads to inhibition of GABA-dependent Cl-pass. The aim of our research was to test the anxiolytic and antidepressant effects of zinc after single application and its influence on general behavioural parameters after repeated administration.

Methods: Male Wistar rats were treated with increasing doses of zinc histidine dehydrate (10, 20, 30 mg/kg, i.p.). To determine anxiolytic and antidepressant properties of zinc two models were used: elevated plus maze (EPM) and forced swim test (FST). Behavioural parameters (stillness and mobility) were, also, recorded after single and repeated administration of active substance.

Results: Testing animals in the EPM showed a statistically significant difference as follows: dose of 20 mg/kg significantly increased the time animals spent in open arms, indicating an acute anxio lytic effect, while doses of 30 mg/kg significantly reduced the time in the open arms, indicating a potentially anxiogenic ef fect. Testing the animals by FST showed a statistically signifi cant difference in immobility time of animals treated with the lowest applied (10 mg/kg) and highest applied (30 mg/kg) doses of zinc, compared to the control group. The first day of testing behavioral parameters showed the tendency to in crease locomotor activity of the animals with the lowest dose of zinc (10 mg/kg), while the following day revealed a reduced activity with the highest dose applied (30 mg/kg).

Conclusion: Zinc has important effects on the CNS: After single application, in all doses zinc showed antidepressant ef fects. The effects of zinc on anxiety and locomotor activity showed dose-dependent bidirectional effects.