Time course of effect of capsaicin on ultrastructure and histochemistry of substance P-immunoreactive nerves associated with the cardiovascular system of the guinea-pig.

摘要: Abstract Capsaicin, a neurotoxin which depletes substance P from primary afferent nerve fibres, was injected systematically into adult guinea pigs. The effects of capsaicin were studied by immunohistochemistry, electron microscopy and radioimmunoassay at times 5 min to 1 year. Within after single injection (50 mg/kg) immunofluorescence appeared less intense homogeneous than normal (i.e. it granular). Large trunks remained evident, but there fewer fine fibres. With increasing time progressive decrease in the number immunoreactive fibres; 4 h marked reduction fibres 24 only an occasional fibre evident. In animals sacrificed 2 or more hours treatment large brightly fluorescent swellings seen many nerves. Depletion P-immunoreactivity persisted for as long 365 days treatment. Electron revealed alterations capsaicin-sensitive within Many swollen disruption their internal morphology, e.g. loss microtubules filaments presence amorphous flocculent material axons. treatment, electron-dense profiles, indicative degenerating commonly associated with Schwann cells. These findings demonstrate that systemic administration pigs occur rapidly lasting depletion P-containing is due degeneration.