Optimal Ratio of Rehmanniae Radix and Lilii Bulbus in Baihe Dihuangtang Based on Antidepressant Activity and Its Mechanism / 中国实验方剂学杂志

ABSTRACT

ObjectiveBased on the antidepressant activity， the optimal ratio of Rehmanniae Radix and Lilii Bulbus in Baihe Dihuangtang was optimized and its possible mechanism was preliminarily explored. MethodA total of 100 male mice were randomly divided into normal group， model group， Rehmanniae Radix single decoction group， Lilii Bulbus single decoction group， and 5 different ratios of Baihe Dihuangtang group （Rehmanniae Radix-Lilii Bulbus 5∶6， 5∶5 ， 5∶4， 5∶3， 5∶2）， fluoxetine hydrochloride group. Except for the normal group， the remaining 9 groups were treated with chronic unpredictable mild stress method （CUMS） for 21 consecutive days to establish the depression mouse model.The Rehmanniae Radix single decoction group， Lilii Bulbus single decoction group and 5 different ratios of Baihe Dihuangtang group were administered with corresponding drugs at a dose of 2 g·kg-1 respectively， and fluoxetine hydrochloride group was administered fluoxetine hydrochloride at a dose of 0.01 g·kg-1， the normal group and the model group were respectively given an equal volume of normal saline by gavage for 21 consecutive days. The antidepressant effect of Baihe Dihuangtang with different ratios was evaluated by behavioral experiments. Western blot was used to detect the expression levels of brain-derived neurotrophic factor （BDNF） and tyrosine kinase receptor B （TrkB） in hippocampus. The level of total superoxide dismutase （SOD） in hippocampus was detected by hydroxylamine method. The level of reduced glutathione （GSH） in hippocampus was detected by spectrophotometric method. The levels of glutathione peroxidase （GPX） and glutathione S-transferase （GST） in hippocampus was detected by colorimetric method. The level of malondialdehyde （MDA） in hippocampus was detected by thiobarbituric acid method， and preliminary exploration of its antidepressant mechanism. ResultCUMS caused a significant decrease in the preference rate of sugar water and a significant prolongation of forced swimming and tail suspension immobility time （P<0.01）， while the different ratios of Baihe Dihuangtang and the single decoction of Rehmanniae Radix and Lilii Bulbus were significantly reversed to varying degrees. Abnormalities of the above indicators were observed （P<0.05， P<0.01）， especially when the ratio of 5∶6 had the most obvious effect on the above indicators， Moreover， CUMS caused the hippocampal BDNF and the expression of TrkB， SOD and glutathione antioxidant-related indexes were significantly decreased （P<0.01）， and the levels of lipid peroxidation product MDA was significantly increased （P<0.01）. However， the superior ratio of Baihe Dihuangtang （Rehmanniae Radix-Lilii Bulbus 5∶6， 5∶5， 5∶4） and the single decoction of Rehmanniae Radix and Lilii Bulbus significantly reversed the abnormality of the above indicators to varying degrees （P<0.05， P<0.01）. ConclusionIn summary， 5 different ratios of Baihe Dihuangtang and the single decoction of Rehmanniae Radix and Lilii Bulbus can produce antidepressant effect， especially when the ratio of 5∶6 had the most obvious effect on the above indicators， and the antidepressant effect gradually weakens with the proportion of Lilii Bulbus in the recipe decreases， and its mechanism may involve enhancing the nutritional level and antioxidant defense ability of hippocampal central nervous system.