Tian-Huang Formula, a Traditional Chinese Medicinal Prescription, Improves Hepatosteatosis and Glucose Intolerance Targeting AKT-SREBP Nexus in Diet-Induced Obese Rats

Tianhuang formula regulates adipocyte mitochondrial function by AMPK/MICU1 pathway in HFD/STZ-induced T2DM mice

BACKGROUND

Tianhuang formula (THF) is a Chinese medicine prescription that is patented and clinically approved, and has been shown to improve energy metabolism, but the underlying mechanism remains poorly understood. The purpose of this study is to clarify the potential mechanisms of THF in the treatment of type 2 diabetes mellitus (T2DM).

METHODS

A murine model of T2DM was induced by high-fat diet (HFD) feeding combined with low-dose streptozocin (STZ) injections, and the diabetic mice were treated with THF by gavaging for consecutive 10 weeks. Fasting blood glucose (FBG), serum insulin, blood lipid, mitochondrial Ca²⁺ (mCa²⁺) levels and mitochondrial membrane potential (MMP), as well as ATP production were analyzed. The target genes and proteins expression of visceral adipose tissue (Vat) was tested by RT-PCR and western blot, respectively. The underlying mechanism of the regulating energy metabolism effect of THF was further explored in the insulin resistance model of 3T3-L1 adipocytes cultured with dexamethasone (DXM).

RESULTS

THF restored impaired glucose tolerance and insulin resistance in diabetic mice. Serum levels of lipids were significantly decreased, as well as fasting blood glucose and insulin in THF-treated mice. THF regulated _mCa²⁺ uptake, increased MMP and ATP content in VAT. THF increased the mRNA and protein expression of AMPK, phosphorylated AMPK (p-AMPK), MICU1, sirtuin1 (SIRT1) and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α). THF could increase the _mCa²⁺ level of 3T3-L1 adipocytes and regulate mitochondrial function. The protein expression of AMPK, p-AMPK, _mCa²⁺ uniporter (MCU) and MICU1 decreased upon adding AMPK inhibitor compound C to 3T3-L1 adipocytes and the protein expression of MCU and MICU1 decreased upon adding the MCU inhibitor ruthenium red.

CONCLUSIONS

These results demonstrated that THF ameliorated glucose and lipid metabolism disorders in T2DM mice through the improvement of AMPK/MICU1 pathway-dependent mitochondrial function in adipose tissue.

Tianhuang formula reduces the oxidative stress response of NAFLD by regulating the gut microbiome in mice

Background

The gut microbiome affects the occurrence and development of NAFLD, but its mechanism has not yet been fully elucidated. Chinese medicine is a new treatment strategy to improve NAFLD by regulating the gut microbiome. Tianhuang formula (TH) has been proved to have a lipid-lowering effect in which constituents of ginsenoside Rb1, ginsenoside Rg1, ginsenoside Rb, ginsenoside Re, and ginsenoside R1 from Panax notoginseng and berberine, palmatine, and coptisine from Coptis chinensis have low drug permeability, which results in poor intestinal absorption into the human body, and are thus able to come into contact with the gut microflora for a longer time. Therefore, it might be able to influence the gut microbial ecosystem, but it still needs to be investigated.

Method

The characteristics of the gut microbiome were represented by 16S rRNA sequencing, and the metabolites in intestinal contents and liver were discovered by non-targeted metabolomics. Correlation analysis and fermentation experiments revealed the relationship between the gut microbiome and metabolites. Blood biochemical indicators, liver function indicators, and oxidation-related indicators were assayed. H&E staining and Oil Red O staining were used to analyze the characteristics of hepatic steatosis. RT-qPCR and western blotting were used to detect the expression of genes and proteins in liver tissues, and fecal microbial transplantation (FMT) was performed to verify the role of the gut microbiome.

Results

Gut microbiome especially Lactobacillus reduced, metabolites such as 5-Methoxyindoleacetate (5-MIAA) significantly reduced in the liver and intestinal contents, the level of hepatic GSH and SOD reduced, MDA increased, and the protein expression of Nrf2 also reduced in NAFLD mice induced by high-fat diet (HFD). The normal diet mice transplanted with NAFLD mice feces showed oxidative liver injury, indicating that the NAFLD was closely related to the gut microbiome. TH and TH-treated mice feces both can reshape the gut microbiome, increase the abundance of Lactobacillus and the content of 5-MIAA in intestinal contents and liver, and improve oxidative liver injury. This indicated that the effect of TH improving NAFLD was related to the gut microbiome, especially Lactobacillus. 5-MIAA, produced by Lactobacillus, was proved with fermentation experiments in vitro. Further experiments proved that 5-MIAA activated the Nrf2 pathway to improve oxidative stress in NAFLD mice induced by HFD. TH reshaped the gut microbiome, increased the abundance of Lactobacillus and its metabolite 5-MIAA to alleviate oxidative stress, and improved NAFLD.

Conclusion

The study has demonstrated a mechanism by which the gut microbiome modulated oxidative stress in NAFLD mice induced by HFD. The traditional Chinese medicine TH improved NAFLD by regulating the gut microbiome, and its mechanism was related to the “Lactobacillus-5-MIAA-Nrf2” pathway. It provided a promising way for the intervention of NAFLD.