Long-term effects of neonatal capsaicin on C-fiber excitability and dorsal horn C-input processing in the rat.
The effects of neonatal capsaicin treatment (50 mg/kg, SC, at day 2 of postnatal life) on C-fiber excitability and dorsal horn C-input processing were studied through recording of a C-fiber-evoked spinal flexor reflex in 55-60-day-old rats, anesthetized with urethane (1.1 g/kg, IP) and spinalized at Th9-10. Neonatal capsaicin resulted in decreased C-fiber excitability, as revealed by increased chronaxie values determined in a strength-duration paradigm. Besides, capsaicin-treated rats exhibited a reduced potentiation of the C-reflex discharge in response to repetitive stimulation. The results indicate that capsaicin given to rats early in life leads to both functional disturbances of surviving C-fibers and altered temporal synaptic processing of the C-input in the spinal cord.
Pérez
H
H
Laboratorio de Neurofisiología y Biofísica, Universidad de Chile, Santiago.
Hernández
A
A
Ruiz
S
S
Paeile
C
C
Soto-Moyano
R
R
D000344:Afferent Pathways / Q000187:drug effects / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D002211:Capsaicin / Q000494:pharmacology*; D004558:Electric Stimulation; D005260:Female; D006614:Hindlimb / Q000294:innervation; D008297:Male; D009412:Nerve Fibers / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012018:Reflex / Q000187:drug effects; D012044:Regression Analysis; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology*; D013497:Sural Nerve / Q000187:drug effects / Q000502:physiology*
D002211:Capsaicin