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Effects of stimulation of rabbit caudate nucleus on units responsive to noxious stimuli in the parafascicular nucleus of thalamus

Tong Zhenqing, Chen Shuicun, Zhang Fengtong

Department of Physiology, The First Medical College of PLA. Guangzhou, Guangdong, China

Abstract

The discharges of parafascicular units excited by noxious stimuli (PfPE) and inhibited by those (PfPI) in 51 conscious and curarized rabbits were recorded. The effects of stimulation of the dorsal part of the head of caudate nucleus (DHCN) on the spontaneous and nociceptive discharges of these units were studied. (1) Among the 28 PfPE units, the spontaneous discharges of 19 units were inhibited by caudate stimulation, those of 2 units were enhanced, while those of the remaining 7 units showed no change. Among the 6 PfPI units, the spontaneous discharges were enhanced in 5 units and unchanged in 1 unit. (2) Among the 38 PfPE units, the nociceptive discharges were enhanced in 2 units, inhibited in 30 units, while showed no change in 6 units. This inhibitory effect occurred immediately at the beginning of the stimulation of DHCN and lasted for 700-1600 ms in 8 out of 12 of the 30 inhibited units. Among the 10 PfPI units, nociceptive discharges were enhanced in 7 units and no effect was observed in 2 units. The results described above suggest that DHCN plays a modulatory action in the integration of pain information in PfPE and PfPI units and that this action may be carried out via both direct and indirect pathways, according to the relatively short latent period and long duration of this inhibitory effect.

Key words: Caudate nucleus;Parafascicular nucleus;Spontaneous discharges;Paindischarges;Modulatory action

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Citing This Article：

Tong Zhenqing, Chen Shuicun, Zhang Fengtong. Effects of stimulation of rabbit caudate nucleus on units responsive to noxious stimuli in the parafascicular nucleus of thalamus. Acta Physiol Sin 1985; 37 (2): (in Chinese with English abstract).