Evaluation Of The Efficacy Of Ripe Pu-erh Tea In Alleviating Obesity And Depression-like Behaviors Based On Intestinal Flora

Ripe Pu-erh tea(RPT)is one of the six major tea groups in China,which has a special aroma and many health benefits due to its special ’post-fermentation’ process,and is rich in complex macromolecules that have a potential role in regulating intestinal microorganisms.The dysbiosis of the intestinal flora is closely related to the development of various chronic diseases.Regulation of the gut flora is an important target for improving the alleviation of chronic diseases such as obesity and depression.As storage period affects the bioactive substances of RPT,this study selected ripe Pu-erh tea produced in 2006(RPT2006)and ripe Pu-erh tea produced in 2020(RPT2020)as samples to compare their biochemical composition,in vitro antioxidant capacity,α-amylase inhibiting capacity and lipase inhibiting capacity.This study explored the alleviating effects of RPT and IF on obesity in mice and RPT on depression-like behaviors in mice based on the intestinal flora.The main results were as follows:1.The bioactive composition of RPT2006 and RPT2020 were explored by high performance liquid chromatography,and their in vitro antioxidant capacity,α-amylase inhibition capacity and lipase inhibition capacity were evaluated by in vitro experiments.The results showed that RPT2006 contained more tea polysaccharides and catechin content,which gave RPT2006 stronger in vitro antioxidant capacity,in vitro α-amylase inhibition capacity and lipase inhibition capacity.The results suggest that RPT2006 may have a better potential to regulate obesity and depression compared to RPT2020.2.The effect of RPT synergistically with IF on the alleviation of obesity was explored by high-fat diet induced obesity in female mice.The results showed that the synergistic effects of RPT and IF significantly reduced body weight in female mice,improved the ability of regulating glucose tolerance and blood lipid levels(TC,TG,LDL-C,HDL-C),restored liver function(ALT,AST,SOD,GSH)and regulated key proteins in the liver(PPARα,SREBP-1,FASN).IF caused an abnormal increase in serum follicle-stimulating hormone(FSH)levels.RPT and IF synergistically regulated FSH levels and enhance the expression of AMPK/PGC1α/UCP1 signalling pathway in white and brown fat.The synergistic effect of RPT and IF repaired the intestinal barrier by upregulating the protein expression of ZO-1 and Occludin,modulated the structure of intestinal microorganisms in obese mice,reduced the Firmicutes/Bacteroidetes ratio,promoted the growth of potentially probiotic bacteria Akkermansia and Lachnospiraceae＿NK4A136＿group,reduced potentially harmful bacteria norank＿f＿＿Lachnospiraceae and Bacillus,and promoted the production of short-chain fatty acids,especially butyric acid.The results showed that RPT and IF synergistically enhanced the adipogenic effect on obesity in female mice mainly by regulating the dysbiosis of intestinal flora and serum FSH levels.3.The effect of RPT intake on the alleviation of depression-like behaviors was explored by a depression model by blue light exposure in mice.The results showed that RPT intake alleviated the severity of depression-like behaviour induced by blue light exposure and modulated the release of neurotransmitters(5-HT,BDNF)in the brain.RPT alleviated blood-brain barrier damage and reduced neuroinflammation,inhibited the MYD88/NF-κB inflammatory pathway in the cerebral cortex,and reduced the release of pro-inflammatory factors IL-1β,IL-6,and TNFα in the cerebral cortex.RPT repaired the intestinal barrier by upregulating the tight junction protein ZO-1,Occludin,reduced the release of pro-inflammatory factors IL-1β,IL-6,TNF-α,LPS in the blood.RPT alleviated systemic inflammation by modulating the composition of intestinal microbes,increasing the potential probiotic bacteria Bifidobacterium and Dubosiella,decreased potentially harmful bacteria Alistipes and Bacteroides.RPT promoted the production of SCFAs,especially acetic acid and propionic acid,which could exert anti-inflammatory effects.Correlation analysis showed that RPT improved depression-like behaviours by increasing Bifidobacterium and Dubosiella,enhancing the communication of signals via the gut-brain axis and promoting the release of the neurotransmitter BDNF.These results suggested that RPT modulate gut microbes and promote the production of SCFAs through the microbial-gut-brain axis to alleviate depressive-like behaviours induced by blue light exposure.