[Inhibitory effect of cysteamine on nociceptive responses of dorsal horn neurons in spinal cord of cats].
The effect of somatostatin depletor cysteamine on the nociceptive responses of neurons in laminae IV-VI of spinal cord was studied in 16 pentobarbitone anesthetized and spinal cord transected (at L1) cats. Intravenous injection of cysteamine (50 mg/kg) markedly inhibited responses of the neurons produced by noxious heating (50 C) of glabrous skin of the plantar region, but not C fibre responses induced by electrical stimulation of unmyelinated fibers of the tibial nerve. However, C responses in 8/13 neurons tested were significantly inhibited by large dose cysteamine (100 mg/kg). Following micropressure ejection of cysteamine (20 psig) into the substantia gelatinosa where somatostatin-containing fibers terminate, heating responses were significantly inhibited in all laminae IV-VI neurons whereas C responses was only weakly inhibited in 7/13 neurons. The results suggest that depletion of spinal somatostatin may be involved in cysteamine-induced inhibition of spinal nociception. The possible mechanism underlying the stronger cysteamine-induced inhibition of heating response was discussed.
Yang
H Q
HQ
Shanghai Brain Research Institute, Chinese Academy of Sciences.
Zhao
Z Q
ZQ
Liu
Y
Y
D000818:Animals; D002415:Cats; D003543:Cysteamine / Q000494:pharmacology*; D004558:Electric Stimulation; D005260:Female; D006358:Hot Temperature; D008297:Male; D009412:Nerve Fibers / Q000187:drug effects; D009475:Neurons, Afferent / Q000187:drug effects; D009619:Nociceptors / Q000187:drug effects* / Q000502:physiology; D013004:Somatostatin / Q000037:antagonists & inhibitors; D013116:Spinal Cord / Q000187:drug effects* / Q000502:physiology
D013004:Somatostatin; D003543:Cysteamine