Gut microbiota mediates the pharmacokinetics of Zhi-zi-chi decoction for the personalized treatment of depression.

ETHNOPHARMACOLOGICAL RELEVANCE: Zhi-zi-chi decoction (ZZCD), from "Treatise on Febrile Diseases", is a typical traditional Chinese medicine herb pair, which consists of Gardeniae Fructus (GF) and Semen Sojae Praeparatu (SSP). In clinical research, ZZCD was widely used to fight depression, remove annoyance. Many studies have reported that gut microbiota is critical target for the influence of depress through gut-brain axis, and our previously studies have found that ZZCD exhibiting antidepressant effect was through the gut-brain axis. However, the specific mechanism by which gut microbiota mediates the pharmacokinetics parameters of active compounds from ZZCD during the process of depression treatment has not yet been studied. AIM OF THE STUDY: To explore the differences in pharmacokinetics characters of bioactive iridoids from ZZCD and study the changes of gut microbiota at different stages of depression with the personalized medicine of ZZCD. MATERIALS AND METHODS: A new strategy exploring the relationship among disease phenotypes (D), intestinal microbiota (I), enzymes (E) and traits of metabolism (T) named as "DIET" was established. Firstly, a fast, selective and sensitive ultra-performance liquid chromatography coupled with tandem mass spectrometer (UPLC-MS/MS) was established and validated to quality the main bioactive compounds from ZZCD and compare the pharmacokinetics and bioavailability of different iridoids prototypes and metabolites from ZZCD between normal and chronic unpredictable mild stress rats. Subsequently, the activity of corresponding metabolic enzymes of anti-depressive compounds, ß-glucosidases and sulfotransferases, were analyzed by ρ-nitrophenyl-ß -D-glucopyranoside and sulfotransferases ELISA kits, respectively. Finally, 16S rRNA gene sequencing was adopt to analyze intestinal bacteria composition for the treatment of depression by ZZCD. RESULTS: The antidepressant effect of ZZCD was promoted due to the increased exposures and reduced eliminations of anti-depressive compounds, especially geniposide and genipin 1-gentiobioside, under the depression state. With the ZZCD treatment, the depression was improved, but the exposures of anti-depressive compounds from ZZCD gradually decreased. Meanwhile, there were the corresponding decreased trends on the activity of ß-glucosidases and sulfotransferases. With the consumption of ZZDC and the improvement of depression, the exposures of anti-depressive iridoid glycosides decreased and the activity of metabolism enzymes restored. Meanwhile, the dysbiosis of pathogenic bacteria (Bacteroidota) induced by depression was ameliorated and the probiotics (Firmicutes) at the phylum and genus level raised, the two phyla are closely related to the production of ß-glucosidase and sulfotransferases. CONCLUSIONS: It is the first proposed that ZZCD could personalized to treat depression at different stages targeting gut microbiota and gut microbiome could emerged as a potential diagnostic and therapeutic biomarker in depression.

Zhi-Zi-Chi Decoction Reverses Depressive Behaviors in CUMS Rats by Reducing Oxidative Stress Injury Via Regulating GSH/GSSG Pathway.

Depression is one of the main diseases that lead to disability and loss of ability to work. As a traditional Chinese medicine, Zhi-zi-chi decoction is utilized to regulate and improve depression. However, the research on the antidepressant mechanism and efficacy material basis of Zhi-zi-chi decoction has not been reported yet. Our previous research has found that Zhi-Zi-chi decoction can reduce glutamate-induced oxidative stress damage to PC 12 cells, which can exert a neuroprotective effect, and the antidepressant effect of Zhi-Zi-chi decoction was verified in CUMS rat models. In this study, the animal model of depression was established by chronic unpredictable mild stimulation combined with feeding alone. The brain metabolic profile of depressed rats was analyzed by the method of metabolomics based on ultra-performance liquid chromatography-quadrupole/time-of-flight mass. 26 differential metabolites and six metabolic pathways related to the antidepressant of Zhi-zi-chi decoction were screened and analyzed. The targeted metabolism of the glutathione metabolic pathway was analyzed. At the same time, the levels of reactive oxygen species, superoxide dismutase, glutathione reductase, glutathione peroxidase in the brain of depressed rats were measured. Combined with our previous study, the antioxidant effect of the glutathione pathway in the antidepressant effect of Zhi-zi-chi decoction was verified from the cellular and animal levels respectively. These results indicated that Zhi-zi-chi decoction exerted a potential antidepressive effect associated with reversing the imbalance of glutathione and oxidative stress in the brain of depressed rats.

Butyrate emerges as a crucial effector of Zhi-Zi-Chi decoctions to ameliorate depression via multiple pathways of brain-gut axis.

Gut microbiota has emerged as a crucial target of gut-brain axis to influence depression. Zhi-Zi-Chi decoctions (ZZCD), as a classic oral formula in clinic, is widely applied in depression treatment nowadays. However, the underlying mechanism in the antidepressant activity of ZZCD remains unknown. A classic depression model of chronic mild unpredictable stress (CUMS) was established in rats based on the results of behavioral tests and hippocampal histomorphology. 16S rRNA sequencing analysis indicated that ZZCD could increase short-chain fatty acid-producing and anti-inflammatory bacteria and reduce inflammatory and tryptophan-metabolizing bacteria. Furthermore, ZZCD reversed the alterations of BDNF, TNF-α, pro-inflammatory cytokines and neurotransmitters in the gut, blood and brain along the brain-gut axis and restored the decrease of butyrate in cecal content caused by CUMS. Then, butyrate was utilized to validate its ameliorative effect on pathological characteristics of depressive rats. Taken together, these results show that ZZCD exhibits antidepressant effect through modulating gut microbiota to facilitate the production of butyrate, which further regulate anti-inflammation, neurotransmitters, endocrine and BDNF along the gut-brain axis. Hence, this study fills the gap of the antidepressive mechanism of ZZCD in the light of the brain-gut axis and established a multi-targets and multi-levels platform eventually for further research into the mechanism of other TCM efficacy.