Functional gastrointestinal disease(FGID)and inflammatory bowel disease(IBD)are two common gastrointestinal diseases in clinical practice.FGID refers to non-structural changes in gastrointestinal function,with irritable bowel syndrome(IBS)and functional dyspepsia(FD)being the common types.On the other hand,IBD is a group of chronic inflammatory bowel diseases with well-defined pathological features,mainly including Crohn's disease(CD)and ulcerative colitis(UC).Over the past decades,the incidence rates of both FG1D and IBD have increased with years,accompanied by high recurrence rates,and the clinical outcomes remain unsatisfactory,which seriously affect the physical and mental health of patients.Further research has revealed that neuropsychiatric abnormalities,including mental and psychological disorders,play important roles in the occurrence and development of FGID and IBD.The comorbidity of gastrointestinal and psychiatric diseases shares a common pathophysiological basis,that is,the abnormalities in the bidirectional communication between the gut and the central nervous system,and the theory of brain-gut axis has emerged as a research hotspot in this field.Better therapeutic outcomes can be achieved by screening and identifying key brain regions closely related to FGID and IBD through quantifiable assessments,and implementing combined pharmacotherapy on both the digestive system and the nervous system based on the theory of brain-gut axis.Current neuroimaging studies have provided the preliminary results for understanding the changes in the nervous system in FGID and IBD patients,but there is still a lack of systematic evaluation of the application of neuroimaging studies based on the brain-gut axis in gastrointestinal diseases.This paper reviewed the changes in brain structure and function associated with FGID and IBD,and the neuroimaging-based analysis of the brain-gut axis theory in the occurrence and development of these diseases,in order to provide theoretical basis for future personalized precision medicine of FGID and IBD based on the brain-gut axis.

Objective To explore the relationship between cellular rejection and the development of allo-or xenografted primordia from different gestational ages .Methods Whole rat metanephroi from embryonic day E14～ E19 were transplanted into omenta of outbred (SD → SD ,6 groups ,n≥10 each ;E15-E17SDCsA ,3 groups ,n=15 each) ,syngeneic (Lewis→Lewis ,5 groups ,n=8 each) ,allogeneic (Lewis→BN ,E15BN n= 6 each E15BNCsA n= 10 each ,E16BNCsA n= 10 each) rats and xenogeneic (Lewis→C57groups ,E15C57 n=10 each ,E15C57CsA ,n=8 each ;Lewis→Balb/c nude mice ,3 groups ,n=10 each) recipients .Histopathology ,Banff's grading and electron microscopy (EM ) were utilized for assessing the graft development .Similarly ,biochemical indicators and creatinine clearances were measured .Results At 4 weeks post-transplantation , in SD → SD groups ,E14-E17SD metanephroi developed with Banff ' s rejections . E14/E15SD was significantly lighter than E16/E17SD ( P< 0 .01 );E18/E19SD barely developed . After cyclosporine A (CsA , 8 mg·kg -1·d-1 )dosing ,Banff's rejection of E15-E17SDCsA group lessened significantly .In Lewis→BN ,E15BN metanephroi were completely rejected .After dosing CsA (12 mg·kg -1·d-1 ) ,E15BNCsA and E16BNCsA Banff ' s rejections became alleviated . Upon a discontinuation of CsA , both metanephroi were rejected . In Lewis → Lewis , E15 ～ E17Lewis metanephroi developed well . No significant difference existed in Banff's classification (P>0 .05) .E14Lewis and E18Lewis rats had significantly poorly differentiated metanephroi than those in E16 Lewis group .In Lewis→C57BL/6 , E15 metanephroi were rejected at Day 14 post-transplantation (n= 10) and no improvement was evident after CsA dosing (15 mg·kg -1·d-1 ,n=8) .In Lewis→Balb/c nude mice ,all E15～E17Balb/c metanephroi developed well .Both light microscopy and EM examination showed normal nephrons and collecting ducts and wet weight ,creatinine or urea nitrogen of effusion showed no significant difference (P>0 .05) .E15Lewis and E16Lewis had significantly different values of wet weight and creatinine clearances from those of E15SDCsA and E16SDCsA .E15SDCsA had the greatest wet weight and the lowest creatinine clearance rate (P< 0 .01) .Conclusions After controlling rejection during allo-and xenotransplantations ,E15 ,E16 and E17 rat metanephros have similar development characteristics . And cellular immunogenic factors still remain the major barriers to their developments .