Aim: To observe the location of neurokinin receptor (NK3r) in the mouse gastrointestinal tract.
Methods: The abdomens of 8 male Kunming mice were opened under anaesthesia with sodium pentobarbital. The exposed gut organs were kept moisture and temperature at the same time. Then the esophagus,jejulum, ileum, and colon, etc were respectively cut and the segments from the stomach to the distal colon were opened along the mesenteric border. A circular 4mm-6mm enteric part(pieces of 1 cm(2) were to be prepared) and mucosa and submucosa were removed, then the longitudinal muscle layer was pulled off from the circular muscle layer under microphotograph. They were rinsed in 50 nmol x L(-1) potassium phosphate-buffered saline(PBS). Immunohistochemistry and immunoreactive fluorescence were used in the staining procedures.
Results: There was NK3r-Like(-Li) positive material on the smooth muscle cells of the esophagus, stomach, and intestines and other regions. The nerve cell bodies with immunoreactivity for NK3r were mainly distributed in the submucousal nerve plexus or myenteric nerve plexus of the gastrointestinal tract except for the esophagus, stomach and rectum. The reaction product was located on the surface of the nerve cell plasma. It was occasionally observed in the cell plasma endosomes, but was very weakly stained. Among the NK3-like positive neurons in the plexus,the morphological type in many neurons appeared like Dogiel II type cells. Some neuron cell bodies were big, having many profiles, some were long ones or having grading structure. Cell body diameter was about 10 microm-46 microm and 8 microm-42 microm in myenteric plexus and submucous plexus.
Conclusion: This study not only described the distribution of neurokinin B receptor in the mouse gut, but also provided a morphological basis for deducing the functional identity of the NK3r-LI immunoreactivity neurons, suggesting the possibility that these neurons were closely related to gastrointestinal tract contraction and relaxing activity.