Possible involvement of nitric oxide in antidepressant-like effect of silymarin in male mice

Abstract

Context: Silymarin (SM) is extracted from milk thistle Silybum marianum L. [Asteraceae (Compositae)] and known for antioxidative and anti-inflammatory effects.

Objective: The potential antidepressant-like effect of acute SM and possible involvement of nitric oxide (NO) were determined in male mice.

Material and methods: SM was administered orally (5, 10, 20, 50, 100, and 200?mg/kg; p.o.) 60?min before the tests. After assessment of locomotor activity, the immobility time was measured in forced swimming test (FST) and tail suspension test (TST). To assess the possible involvement of NO, a non-specific NO synthase inhibitor, l-NAME (10?mg/kg, i.p.), and a specific iNOS inhibitor, aminoguanidine (AG) (50?mg/kg, i.p.), were administered separately 30?min before SM (20 and 100?mg/kg).

Results: SM at its effective doses 10, 20, 50, and 100?mg/kg decreased the immobility time in a dose-dependent manner (p?p?p?p?p?p?p?p?50) of SM was around 10?mg/kg. The dose 100?mg/kg proved the most effective dose in both the tests. Further, this effect was not related to changes in locomotor activity. Moreover, l-NAME reversed the effect of SM (20 and 100?mg/kg) in FST and SM (100?mg/kg) in TST. However, AG did not influence this impact.

Conclusion: The antidepressant-like effect of SM is probably mediated at least in part through NO and SM may increase NO tune.