Neurons bearing NK(3) tachykinin receptors in the guinea-pig ileum revealed by specific binding of fluorescently labelled agonists.
The localisation of NK(3) tachykinin receptors in guinea-pig ileum was studied using the fluorescently labelled agonists, Cy3. 5-neurokinin A and Cy3.5-kassinin. Binding to nerve cell bodies in the myenteric and submucosal plexuses was visualised using confocal microscopy. Binding to NK(1) receptors was blocked by the NK(1) receptor antagonist, CP-99994. NK(3) receptors, demonstrated by binding in the presence of CP-99994, occurred in 72% of myenteric and 38% of submucosal neurons. Colocalisation with other markers was examined to deduce the classes of neurons with NK(3) receptors. In myenteric ganglia, NK(3) receptors were present on the following: 73% of calbindin-immunoreactive (IR) intrinsic primary afferent neurons, 63% of calretinin-IR excitatory motor neurons and ascending interneurons, 63% of nitric oxide synthase-IR inhibitory motor neurons and descending interneurons, 79% of strongly neuropeptide Y (NPY)-IR secretomotor neurons, 67% of weakly NPY-IR descending interneurons and motor neurons, and 46% of NK(1) receptor-IR neurons. In submucosal ganglia, NK(3) receptors were on 65% of calretinin-IR secretomotor/vasodilator neurons, 81% of NPY-IR cholinergic secretomotor neurons, 2% of vasoactive intestinal peptide-IR non-cholinergic secretomotor neurons and were completely absent from substance P-IR intrinsic primary afferent neurons. The results support physiological studies suggesting that NK(3) receptors mediate tachykinin transmission between myenteric sensory neurons and to interneurons and/or motor neurons in descending inhibitory and ascending excitatory pathways.
Jenkinson
K M
KM
Department of Anatomy and Cell Biology, University of Melbourne, Parkville, Victoria 3052, Australia, k.Jenkinson@anatomy.unimelb.edu.au
Morgan
J M
JM
Furness
J B
JB
Southwell
B R
BR
D000818:Animals; D002232:Carbocyanines / Q000737:chemistry; D002452:Cell Count; D005260:Female; D005456:Fluorescent Dyes / Q000737:chemistry; D006168:Guinea Pigs; D007082:Ileum / Q000378:metabolism*; D066298:In Vitro Techniques; D015286:Kassinin / Q000737:chemistry / Q000378:metabolism*; D008297:Male; D018613:Microscopy, Confocal; D009197:Myenteric Plexus / Q000166:cytology / Q000378:metabolism; D015288:Neurokinin A / Q000737:chemistry / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D010880:Piperidines / Q000494:pharmacology; D018042:Receptors, Neurokinin-3 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013368:Submucous Plexus / Q000166:cytology / Q000378:metabolism
D002232:Carbocyanines; D005456:Fluorescent Dyes; D010880:Piperidines; D018042:Receptors, Neurokinin-3; C089187:cyanine dye 3; C080755:3-(2-methoxybenzylamino)-2-phenylpiperidine; D015286:Kassinin; D015288:Neurokinin A; C091554:SR 142801