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Copyright ©The Author(s) 2021.
World J Gastrointest Pathophysiol. May 22, 2021; 12(3): 25-39
Published online May 22, 2021. doi: 10.4291/wjgp.v12.i3.25
Table 1 List of neuromediators and their role in gut inflammation
Neuromediator
Distribution
Binding receptor
Function
SPNeurons and inflammatory cells like lymphocytes, macrophages, and dendritic cellsNK-1RExerts pro-inflammatory effects in epithelial and immune cells and contributes to inflammatory diseases. In murine model of colitis, it plays regulatory role
NTNervous system and intestineNTR1Recognized as an immunomodulator. By interacting with immune cells, it enhances the chemotaxis and induces the cytokine release to modulate the immune response. In IBD, it exerts its pro-inflammatory effects by promoting the expression of miR-210 in intestinal epithelial cells
NPYCentral and peripheral nervous system and immune cellsOut of five receptors of NPY, NPYY1 is known to play a crucial role in immunomodulationRegulates various immune cell functions such as T helper cell differentiation, neutrophil chemotaxis, natural killer cell activity, and granulocyte oxidative burst and NO production. In the gut, NPY is known to exert pro-inflammatory effects
VIPNeuronal and lymphoid cellsVIPR1 and VIPR2Identified as an anti-inflammatory molecule. administration of VIP nanomedicine in the form of VIP-SSM are capable of alleviating the symptoms of DSS- induced mice model of colitis
GALVasculature, immune cells and colonic epithelial cellsGAL (1-3) receptorExerts anti-inflammatory effects in TNBS induced colitis model by reducing the expression and activity of iNOS
CRH Immune cellsCRH-R1 and CRH-R2It acts as a pro-inflammatory peptide. The expression pattern of CRH 1 and CRH 2 varies in ulcerative colitis. Inhibition of CRH1 and overexpression of CRH2 may have the therapeutic potential in IBD
CGRPSensory nerves projecting to the lymphoid organs, airways, and pulmonary neuroendocrine cellsCGRP receptorsCGRP negatively regulates innate immune responses and thus has potential anti-inflammatory effects. Its expression reduced in the colon of an animal model of colitis
NANerves innervating the peripheral lymphoid organsAdrenergic α and β receptors immunomodulatory effect of NA is administered via cAMP. Activation of NA receptors that stimulate cAMP resulting in a shift toward Th2 responses which are anti-inflammatory and neuroprotective whereas decreased cAMP stimulates Th1 responses resulting in cell destruction and inflammation
AcetylcholineCentral and peripheral nervous system, immune cells, keratinocytes, endothelial cells, urothelial cells of the urinary bladder, airways and epithelial cells of the placentaNicotinic and muscarinic receptorsMuscarinic receptors mediate pro-inflammatory responses and nicotinic receptors enhance anti-inflammatory responses. Treatment of UC via nicotine suggests the role of the cholinergic pathway in colonic inflammation
NONeuron synapses and immune cellsNO does not act via receptors. its specificity for target cell depends on its concentration, its activity and response, and territory of target cellsNO is oxidised to reactive nitrogen oxide species which mediate most of the immunological effects. It regulates the growth, functional activity, and death of immune cells. It acts as a biomarker for monitoring disease activity due to its increased serum concentration during the active phase of both UC and CD and reduced concentration during the inactive phase of the disease
Serotonin or 5-HTCentral nervous system and EC cells of GIT5-HT receptorIt promotes activation of lymphocytes and secretion of pro-inflammatory cytokines. It activates the signalling molecules of the NF-kB pathway during gut inflammation
GABANervous system and immune systemGABA- AR and GABA-BRGABA has several effects on immune cells, including modulation of cytokine secretion, regulation of cell proliferation, and migration. Activation of GABA-A receptor aggravates DSS induced mice model of colitis