Study of antidepressant-like activity of an enriched phloroglucinol fraction obtained from Hypericum caprifoliatum.

CONTEXT: Hypericum caprifoliatum Cham & Schlecht (Guttiferae) extracts have a potential antidepressant-like effect in rodents. However, the molecular mechanisms by which these extracts exert this effect remain unclear. OBJECTIVE: This study evaluated the effect of HC1, a fraction obtained from H. caprifoliatum enriched in phloroglucinol derivatives, on the Na⁺, K⁺ ATPase activity in mouse brain and verified the influence of veratrine on the effect of HC1 in the forced swimming test (FST). MATERIALS AND METHODS: Veratrine (0.06 mg/kg) and HC1 (360 mg/kg) were given alone or combined i.p. 60 and p.o. 30 min, respectively, before FST. The effect of single and repeated administration (once a day for 3 consecutive days) of HC1 (360 mg/kg) on Na⁺, K⁺ ATPase activity was evaluated ex vivo in the cerebral cortex and hippocampus of mice subjected or not to FST. RESULTS: HC1 reduced the immobility time (103.15 ± 18.67 s), when compared to the control group (183.6 ± 9.51 s). This effect was prevented by veratrine (151.75 ± 22.19 s). Mice repeatedly treated with HC1 presented a significant increase in Na⁺, K⁺ ATPase activity, both in cerebral cortex (46 ± 2.41 nmol Pi/min·mg protein) and hippocampus (49.83 ± 2.31 nmol Pi/min·mg protein), in relation to the respective controls (30 ± 2.66 and 29.83 ± 2.31 nmol Pi/min·mg protein respectively). DISCUSSION AND CONCLUSION: The HC1 antidepressant-like effect on FST might be related to its capacity to inhibit Na⁺ influx. HC1 increases hippocampal and cortical Na⁺, K⁺ ATPase activities possibly through long-term regulatory mechanisms.