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Effects of stimulation of SI cortex and cerebral peduncle on the nociceptive responses of spinal dorsal horn neurons in the rat

Yuan Bin, Wang Gexin, Pang Tianci, Liu Xinling

Research Laboratory of Neurophysiology, Xian Medical University. Xian 710061, China

Abstract

Single spinal dorsal horn neurons were recorded extracellularly with glass micropipettes，and the effect of stimulation of SI cortex or cerebral 'peduncle (CP) was observed on the long latency discharges (C-fiber evoked response) of the wide dynamic range (WDR)neurons induced by intense electrical skin stimulation. Inhibition was the predominant effect of SI cortex stimulation on the C-fiber evoked responses of WDR neurons. The effect of CP stimulation was similar to that of SI cortex stimulation，except that the former was much more effective than the latter. The inhibition lasted a period of time. varying from 400 ms to more than 10 min after CP stimulation in different neurons. Systemic naloxone had no significant effect on the inhibition produced by CP stimulation. Systemic methysergide reduced or eliminated the inhibition in a part of the neurons tested，suggesting that 5-HT，but not opioid peptides，is involved partially in mediation of the descending inhibitory effect originating from the cortex.

Key words: Somatosensory cortex;Cerebral peduncle;Descending control;Spinal dorsal horn;Nociceptive neurons

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Citing This Article：

Yuan Bin, Wang Gexin, Pang Tianci, Liu Xinling. Effects of stimulation of SI cortex and cerebral peduncle on the nociceptive responses of spinal dorsal horn neurons in the rat. Acta Physiol Sin 1993; 45 (1): (in Chinese with English abstract).