Peripheral nerve lesion-induced uptake and transport of choleragenoid by capsaicin-sensitive c-fibre spinal ganglion neurons.
In the present experiments the effect of systemic capsaicin treatment on the retrograde labelling of sensory ganglion cells was studied following the injection of choleratoxin B subunit-horseradish peroxidase conjugate (CTX-HRP) into intact and chronically transected peripheral nerves. In the control rats CTX-HRP injected into intact sciatic nerves labelled medium and large neurons with a mean cross-sectional area of 1,041 +/- 39 gm2. However, after injection of the conjugate into chronically transected sciatic nerves of the control rats, many small cells were also labelled, shifting the mean cross-sectional area of the labelled cells to 632 +/- 118 microm2. Capsaicin pretreatment per se induced a moderate but significant decrease in the mean cross-sectional area of the labelled neurons (879 +/- 79 microm2). More importantly, systemic pretreatment with capsaicin prevented the peripheral nerve lesion-induced labelling of small cells. Thus, the mean cross-sectional areas of labelled neurons relating to the intact and transected sciatic nerves, respectively, did not differ significantly. These findings provide direct evidence for a phenotypic switch of capsaicin-sensitive nociceptive neurons after peripheral nerve injury, and suggest that lesion-induced morphological changes in the spinal cord may be related to specific alterations in the chemistry of C-fibre afferent neurons rather than to a sprouting response of A-fibre afferents.
Jancsó
G
G
Department of Physiology, University of Szeged, Hungary. jancso@phys.szote.u-szeged.hu
Sántha
P
P
Gecse
Krisztina
K
D000818:Animals; D001693:Biological Transport, Active; D002211:Capsaicin / Q000494:pharmacology; D002772:Cholera Toxin / Q000493:pharmacokinetics*; D005727:Ganglia, Spinal / Q000187:drug effects / Q000378:metabolism*; D006735:Horseradish Peroxidase / Q000493:pharmacokinetics; D008297:Male; D036421:Nerve Fibers, Unmyelinated / Q000187:drug effects / Q000378:metabolism*; D009473:Neuronal Plasticity; D059348:Peripheral Nerve Injuries; D010525:Peripheral Nerves / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
D002772:Cholera Toxin; D006735:Horseradish Peroxidase; D002211:Capsaicin