Substance P in the vagus nerve. Immunochemical and immunohistochemical evidence for axoplasmic transport.
1. The presence of immunoreactive substance P (I-SP) in the vagus nerve of 5 species was demonstrated by radioimmunoassay. Different amounts of SP per unit weight were found: Guinea pig greater than cat greater than rabbit, rat and cattle. 2. Infranodose ligations of the vagus nerve of cats and rabbits caused an accumulation of I-SP proximal but not distal to the ligation. The results obtained by radioimmunoassay and immunohistochemistry indicate a somatofugal axoplasmic transport of SP. 3. Double ligation experiments revealed that about 37% of I-SP of the cat vagus nerve are mobile. The transport rate of this mobile I-SP was found to be 170 mm per day. 4. Locally applied colchicine resulted in a similar accumulation of I-SP as after ligations. This is evidence favouring the involvement of microtubuli in the axoplasmic transport of SP. 5. Immunohistochemical data show that SP-fibers account for about 10% of the axons in the cat vagus nerve. Most of these SP-fibers seem to be unmyelinated. 6. Supranodose extracranial ligations of the cat vagus nerve led to an accumulation of I-SP on both sides of the ligature. Part of the SP-fibers are, therefore, afferent and their cell bodies are located in the nodose ganglion. The presence of efferent SP-fibers cannot be excluded.
D000818:Animals; D001370:Axonal Transport; D002415:Cats; D003078:Colchicine / Q000494:pharmacology; D005260:Female; D006168:Guinea Pigs; D006651:Histocytochemistry; D007120:Immunochemistry; D066298:In Vitro Techniques; D008297:Male; D011817:Rabbits; D051381:Rats; D013373:Substance P / Q000378:metabolism*; D014630:Vagus Nerve / Q000378:metabolism*
D013373:Substance P; D003078:Colchicine