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-1 beta), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) 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. (C) 2014 Elsevier Ireland Ltd. All rights reserved.