AIM:To observe the location of neurokinin receptor(NK3r)in the mouse gastrointestinal tract.METHODS:The abdomen of 8 male Kunming mice wereopened under anaesthesia with sodium pentobarbital.Theexposed gut organs were cleaned and kept moisture andtemperature.Then the esophagus,jejulum,ileum,colon,etc were respectively cut and the segments from thestomach to the distal colon were opened along themesenteric border.A circular 4mm～ 6mm enteric part(pieces of 1 cm~2 were to be prepared)and mucoea andsubmucosa were removed,then the longitudinal musclelayer was pulled off from the circular muscle layer undermicrophotography.They were rinsed in 50nmol·L~(-1)potassium phosphate-buffered saline(PBS).Immunohistochemistry and immunoreactive fluorescencewere used in the staining procedure.RESULTS:There was not NK3r-Like(-Li)positive material onthe smooth muscle cells of the esophagus,stomach,intestines and other regions.The nerve cell bodies withimmunoreactivity for NK3r were mainly distributed in thesubmucousal nerve plexus or myenteric nerve plexus of thegastrointestinal tract except for the esophagus,stomachand rectum.The reaction product was located on thesurface of the nerve cell plasma.It was observedoccasionally in the cell plasma endosomes,but was veryweakly stained.Among the NK3-1ike positive neurons in theplexus,the morphological type in many neurons’ appenaedlike Dogiel Ⅱ type cells.Some neuron cell bodies were big,having many profiles,Some were long ones or havinggrading structure.Cell bodiy diameter was about 10μm-46μmand 8μm-42μm in myenteric plexus and submucous plexus.CONCLUSION:This study not only described the distributionof neurokinin B receptor in the mouse gut,but alsoprovided a morphological basis for deducing the functionalidentity of the NK3r-LI immunoreactivity neurons,suggesting the possibility that these neurons were closelyrelated to gastrointestinal tract contraction and relaxingactivity. AIM: To observe the location of neurokinin receptor (NK3r) in the mouse gastrointestinal tract. METHODS: The abdomen of 8 male Kunming mice were opened under anaesthesia with sodium pentobarbital. Theexposed gut organs were cleaned and retained moisture and temperature. Of the esophagus, jejulum, ileum, colon, etc were respectively cut and the segments from the locomach to the distal colon were opened along themesenteric border. A circular 4mm ~ 6mm enteric part (pieces of 1 cm ~ 2 were to be prepared) and mucoea and submucosa were removed, then the longitudinal musclelayer was pulled off from the circular muscle layer under microprophotography. They were rinsed in 50 nmol·L -1 potassium phosphate-buffered saline (PBS). Immunohistochemistry and immunoreactive fluorescence were used in the staining procedure. RESULTS: There was not NK3r- Like (-Li) positive material on the smooth muscle cells of the esophagus, stomach, intestines and other regions. The nerve cell bodies withimmunoreactivity for NK3r were mainly distributed i n thesubmucousal nerve plexus or myenteric nerve plexus of thegastrointestinal tract except for the esophagus, stomachand rectum. The reaction product was located on the surface of the nerve cell plasma. It was observedoccasionally in the cell plasma endosomes, but was veryweakly stained. Amnon the NK3- 1ike positive neurons in theplexus, the morphological type in many neurons’ appenaedlike Dogiel Ⅱ type cells .ome neuron cell bodies were big, having many profiles, Some were long ones or havinggrading structure. Cell bodiy diameter was about 10μm-46μmand 8μm-42μmin myenteric plexus and submucous plexus. CONCLUSION: This study not only described the distribution of neurokinin B receptor in the mouse gut, but alsoprovided a morphological basis for deducing the functionalidentity of the NK3r-LI immunoreactivity neurons, suggesting that the may that these neurons were closelyrelated to gastrointestinal tract contraction and relaxingactivity.