Fig. 1

Postoperative gut microbiota and changes in microbiota metabolites that affect intestinal motility. Surgery may lead to gut microbiota disorders and changes in the levels of their metabolites, such as bile acid (BA), short-chain fatty acids (SCFAs), and indole propionic acid (IPA). The underlying mechanisms of these changes include the following. Dendritic cells (DC) are induced to produce interleukin (IL)-12 and T helper type I (Th1) cells, which secrete interferons (IFNs), thereby activating mast cells (MCs) and muscle macrophages (MMs) to generate pro-inflammatory cytokines, such as nitric oxide (NO), tumor necrosis factor (TNF), and IL-1β. It inhibits tryptophan hydroxylase 1 (TPH1) production of 5-hydroxytryptamine (5-HT) in enterochromaffin cells (ECs), and 5-HT can regulate the release of neurotransmitters, such as substance P. Activation of receptors on the surface of neurons, such as Toll-like receptor (TLR)2/TLR4, can be directly suppressed. Activation of neuronal nuclear receptors, such as aryl hydrocarbon receptor (AHR), can be suppressed to inhibit the transcription of neurotransmitters