Modulation of C-nociceptive Activities by Inputs from Myelinated Fibers.
Adv Exp Med Biol
; 904: 33-40, 2016.
Article
en En
| MEDLINE
| ID: mdl-26900061
ABSTRACT
To understand the mechanisms of neuropathic pain caused by demyelination, a rapid-onset, completed but reversible demyelination of peripheral A-fibers and neuropathic pain behaviors in adult rats by single injection of cobra venom into the sciatic nerve, was created. Microfilament recording revealed that cobra venom selectively blocked A-fibers, but not C-fibers. Selective blockade of A-fibers may result from A-fiber demyelination at the site of venom injection as demonstrated by microscope examination. Neuropathic pain behaviors including inflammatory response appeared almost immediately after venom injection and lasted about 3 weeks. Electrophysiological studies indicated that venom injection induced loss of conduction in A-fibers, increased sensitivity of C-polymodal nociceptors to innocuous stimuli, and triggered spontaneous activity from peripheral and central terminals of C-fiber nociceptors. Neurogenic inflammatory responses were also observed in the affected skin via Evans blue extravasation experiments. Both antidromic C-fiber spontaneous activity and neurogenic inflammation were substantially decreased by continuous A-fiber threshold electric stimuli applied proximally to the venom injection site. The data suggest that normal activity of peripheral A-fibers may produce inhibitory modulation of C-polymodal nociceptors. Removal of inhibition to C-fiber polymodal nociceptors following demyelination of A-fibers may result in pain and neurogenic inflammation in the affected receptive field.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Nervio Ciático
/
Enfermedades Desmielinizantes
/
Fibras Nerviosas Amielínicas
/
Nocicepción
/
Fibras Nerviosas Mielínicas
/
Neuralgia
Límite:
Animals
Idioma:
En
Revista:
Adv Exp Med Biol
Año:
2016
Tipo del documento:
Article
País de afiliación:
China