Ethanol extracts from Hemerocallis citrina attenuate the decreases of brain-derived neurotrophic factor, TrkB levels in rat induced by corticosterone administration.

ETHNOPHARMACOLOGICAL RELEVANCE: Hemerocallis citrina, a traditional herbal medicine, has been used for the improvement of behavioral and emotional status in Eastern-Asia countries. AIM OF THE STUDY: Our previous studies have demonstrated that the ethanol extracts of H. citrina flowers (HCE) reversed the behavioral alterations and monoamine neurotransmitter dysfunctions in stressed mice. However, the relation of its antidepressant-like action with neurotrophic molecular expressions remains unknown. MATERIALS AND METHODS: To clarify this, we explored the effect of HCE (32.5, 65, 130mg/kg, p.o.) on the behavior, brain-derived neurotrophic factor (BDNF) and its receptor (TrkB) in depression-like rats induced by exogenous administration of the stress hormone corticosterone (40mg/kg, s.c.). RESULTS: It was observed that repeated administration of corticosterone induced an elevation on the serum corticosterone levels, which caused the abnormalities observed in the sucrose preference test and forced swimming test (FST). Administration of HCE (65 and 130mg/kg) reversed the changes above and up-regulated the BDNF and TrkB receptor protein expressions in the brain region of frontal cortex and hippocampus. CONCLUSION: These findings confirm that HCE produce an antidepressant-like effect in corticosterone-induced depression-like model of rats and this effect is at least partly mediated by BDNF-TrkB signaling in the frontal cortex and hippocampus.

Antidepressant-like behavioral, neurochemical and neuroendocrine effects of naringenin in the mouse repeated tail suspension test.

Our previous study demonstrated that the citrus bioflavonoid naringenin ameliorated behavioral alterations via the central serotonergic and noradrenergic systems in the tail suspension test (TST) induced mice. To better understand its pharmacological activity, mice were submitted to three 6min-TSTs one week apart (Day 1: test, Day 7: retest 1, Day 14: retest 2) followed by hippocampal glucocorticoid receptor (GR), monoamine neurotransmitters and serum corticosterone measurement. The results suggested that repeated TST detected the gradual increase in the efficacy of naringenin over time, additionally 1-day (20 mg/kg), 7-day (10, 20 mg/kg) and 14-day (5, 10, 20 mg/kg) naringenin treatment markedly decreased the immobility time. Moreover, administration of naringenin for 14 days (20 mg/kg) increased hippocampal serotonin (5-HT), norepinephrine (NE) and GR levels, and reduced serum corticosterone levels in mice exposed to the repeated TST. Overall, the present study indicated that the re-exposure would facilitate the detection of the anti-immobility effects of antidepressant drugs in the mouse TST, and clearly demonstrated that the antidepressant-like effect of naringenin may be mediated by an interaction with neuroendocrine and neurochemical systems.