| Objective:Based on the theory of brain-gut interaction and intestinal microecology,the study explores the effects of hygrothermal environment on the hypothalamus appetite regulation center,neuroendocrine and gastronintestinal digestion function,in order to clarify the mechanism and interactive relationship between appetite decreases,gastrointestinal dysfunction and intestinal microecology caused by exogenous damp-heat.Methods:The normal and hygrothermal environments were set for modeling,while Sanren decoction was used to verify the exogenous etiological model.The model of environmental and biological pathogenic factors was used to further improved exogenous pathogeny modeling.Microflora transplantation was used to study the interaction between brain and intestine.The quality of life and general conditions of mice in different feeding environments were observed.gastric emptying rate,intestinal propulsion rate and gastrin expression were detected to compare the gastronintestinal digestion function,and histopathology and electron microscopy of small intestine were used to observe the local pathological changes.Local pathological changes of the hypothalamus were observed,and the m RNA expression of AGRP,NPY,POMC and CART neurons in the hypothalamus arcuate nucleus were detected,as well as the expression of brain-gut peptides Ghrelin and Leptin in serum.Changes in intestinal microenvironment were detected by16 Sr RNA sequencing technology,and the content of short-chain fatty acids in feces was detected by gas chromatography,while their receptors FFAR2/FFAR3 was detected using PCR.Results:1.The animal model of exogenous damp-heat with digestive system function decline was successfully established.In the hygrothermal environment,mice were listless,unresponsive,reduced in food intake and slow in weight gain.Their foul feces were soft and texture.Pathological examination showed that defects appeared on the surface of villi of small intestine,and the arrangement of columnar cells was relatively disorderly with deformed or broken nuclei,while some of the microvilli were prostrate or absent.Besides,the gastrointestinal propulsion rate,intestinal absorption rate and gastrin of mice were significantly decreased.The Chinese medicinal formulae Sanren decoction could significantly improve the health status and gastrointestinal motility.2.Exogenous damp-heat could have effect on the intestinal microecology of mice.The results of 16 S r RNA sequencing showed that there were significant differences in the number and abundance of OTU in mice living in the hygrothermal environment,compared to these in normal environment.Alpha diversity of intestinal flora,including observed species index,chao index,ace index and shannon index,were increase with statistical significance.The flora with obvious difference from the normal control group was Helicobacteraceae,Turicibacteraceae,Odoribacteraceae and Bifidobacteriaceae.In addition,the expression of short-chain fatty acids and their receptors FFAR2 and FFAR3 were increased.3.Exogenous damp-heat could have effect on the appetite-related neurons and brain-gut peptides of mice.The pathological changes of hypothalamus in hygrothermal environment were not obvious.However,the expression of NPY/Ag RP m RNA neurons in the hypothalamus was found decreased,while the expression of POMC/CART neurons was significantly increased.The expression of serum Ghrelin decreased,while Leptin and Insulin increased significantly.4.As the exogenous damp-heat combined with influenza virus infection,pulmonary virus amplification of mice was enhanced.The intestinal microecological balance was broken,leading to an increase of Staphylococcus and Coryneaceae and other pathogenic bacteria.Humid and hot environment combined with biological pathogenic factors could aggravate the gastrointestinal dysfunction of mice,but the effect was not significant compared with influenza in the normal environment.5.Microflora transplantation to normal mice could change appetite and digestion.After flora transplantation,the microflora structure of the mice in the normal environment showed a high similarity with that in the hygrothermal environment,and the alpha diversity of intestinal flora,including observed species index,chao index,ace index and shannon index,were significantly increased.The abundance of intestinal bacteria,such as Bacteroidales,Dehalobacteriaceae,Ruminococcus and Porphyromonadaceae were increased,while Lactobacillus,Bifidobacteriaceae and Verrucomicrobiaceae have decreased.The expression of short-chain fatty acids and their receptors FFAR2 and FFAR3 were increased.Compared with the normal group,the m RNA expression of Ag RP/NPY was reduced,while the m RNA expression of POMC/CART was significantly increased.The changes of brain-intestinal peptides and hormones were consistent with the damp-heat model,as the serum Ghrelin expression was decreased,while Leptin and Insulin expression were significantly increased.In addition,intestinal propulsion rate and gastric emptying rate of the transplanted mice were significantly reduced.Conclusion:1.Hygrothermal environment could change the structure and composition of intestinal flora of mice,and have a significant impact on the expression of short-chain fatty acids and their receptors.Thus,exogenous heat and humidity could affect the intestinal microenvironment of the body and disrupt the intestinal microecological balance,which might be related to the changes in fecal traits in hygrothermal environment.2.Exogenous hot and humid could lead to loss of appetite,which might because it could change the expression of appetite regulating neurons in the hypothalamus,and affect the expression of appetite-related brain and intestinal peptides.The morphological changes of small intestinal mucosa and reduce of gastrointestinal digestion function might lead to the indigestion changes caused by hygrothermal environment.3.Exogenous hot and humid could decreased appetite and cause gastrointestinal digestive disorders.The mechanism might be hygrothermal environment could change the intestinal microenvironment of mice,which might affect the expression of appetite regulating neurons in hypothalamus and the expression of brain-gut peptides through brain-gut interaction,and eventually led to a decrease in appetite and a reduce in gastrointestinal digestion function. |
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