Ethanol extracts from Hemerocallis citrina attenuate the upregulation of proinflammatory cytokines and indoleamine 2,3-dioxygenase in rats.

ETHNOPHARMACOLOGICAL RELEVANCE

Hemerocallis citrina, a traditional herbal medicine, has been used for the improvement of behavioral and emotional status in Eastern-Asia countries. Previous studies in our laboratory demonstrated that ethanol extracts from Hemerocallis citrina (HCE) enhanced monoamines and brain-derived neurotrophic factor (BDNF) in depression-like model of rodents.

MATERIALS AND METHODS

The present study extends earlier works on the role of anti-inflammation in regulating the antidepressant-like actions of HCE in rats exposed to chronic unpredictable mild stress (CUMS). Frontal cortex and hippocampal proinflammatory cytokines levels and indoleamine 2,3-dioxygenase (IDO) activity were measured after 4-week HCE treatment in the CUMS an control rats.

RESULTS

Chronic administration of HCE reversed the decreased sucrose preference in sucrose preference test. In addition, we also found that HCE inhibited interleukin-1 beta (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) expression, as well as IDO activity in frontal cortex and hippocampus, which were increased in rats exposed to CUMS.

CONCLUSIONS

Combining with our previous studies, our present finding suggests that the anti-inflammatory property of HCE might play a crucial role in its antidepressant-like effect through, at least in part, the restoration or improvement of monoaminergic and neurotrophin systems.