Characterisation of substance P-induced endocytosis of NK1 receptors on enteric neurons

Abstract

Immunoreactivity for NK1 receptors is confined to specific nerve cell bodies in the guinea-pig ileum, including inhibitory motor neurons and secretomotor neurons. In the present work, endocytosis of NK1 receptors in these enteric neurons was studied following addition of substance P (SP) to isolated ileum. NK1 receptors were localised with antibodies against the C-terminus of this receptor. Some preparations were incubated with SP tagged with the fluorescent label, Cy3.18, so that the fate of SP bound to receptors could be followed. Preparations were analysed by confocal microscopy. In tissue that was incubated at 4°C in the absence of SP, most NK1 receptor immunoreactivity (IR) was confined..