The Antidepressant-like Effect of Hyperbrasilol B, A Natural Dimeric Phloroglucinol Derivative is Prevented by Veratrine, a Sensitive-Voltage Na+ Channel Opener

Aims: South Brazilian Hypericum species are a source of dimeric structures, constituted of filicinic acid and phloroglucinol moieties, which present antidepressant-like effects mediated by monoaminergic neurotransmission in rodents. Here, we show that hyperbrasilol B, a phloroglucinol derivative from Hypericum caprifoliatum, presents antidepressant-like activity in mice forced swimming test (FST). The aim of this study was to determinate if Na+ channels are important to the antidepressant-like effect of hyperbrasilol B and also verify the effect of this compound on Na+, K+ ATPase activity in the cerebral cortex and hippocampus of mice.

Methodology: We assessed the effects of veratrine, a Na+ channel opener on antidepressant-like effect of hyperbrasilol B by using mice FST. Veratrine (0.06 mg/kg) and hyperbrasilol B (10 mg/kg) were given i.p. 60 and p.o. 30 min, respectively, before the test. In another batch of experiments different groups of mice were treated with hyperbrasilol B 10 mg/kg, p.o. (Single administration or once a day during 3 days). Two hours after the acute or after the last of the three treatments, the brain structures were removed for measuring Na+, K+ ATPase activity.

Results: Veratrine was able to prevent the anti-immobility effect of hyperbrasilol B on the FST, suggesting that its antidepressant-like effect might be due to Na+ influx modifying properties. Animals treated for 3 consecutive days with hyperbrasilol B presented a significant increase in the hippocampus Na+, K+ ATPase activity. The acute treatment was ineffective.

Conclusion: Alterations in the Na+ gradient may be implicated in the antidepressant-like effect of hyperbrasilol B.