Chandler M J, Zhang J, Foreman R D
Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73190, USA.
J Neurophysiol. 1998 Aug;80(2):628-37. doi: 10.1152/jn.1998.80.2.628.
Stimulation of cardiopulmonary sympathetic afferent fibers excites thoracic and cervical spinothalamic tract (STT) cells that respond primarily to noxious somatic stimuli. Neurons in dorsal column nuclei respond primarily to innocuous somatic inputs, but noxious stimulation of pelvic viscera activates gracile neurons. The purpose of this study was to compare effects of thoracic visceral input on cuneothalamic and STT neurons. Stellate ganglia of 17 anesthetized monkeys (Macaca fascicularis) were stimulated electrically to activate cardiopulmonary sympathetic afferent fibers. Somatic receptive fields were manipulated with brush, tap, and pinch stimuli. Extracellular discharge rate was recorded for neurons antidromically activated from ventroposterolateral (VPL) thalamus. Stimulation of the ipsilateral stellate ganglion increased activity of 17 of 38 cuneothalamic neurons and of 1 gracilothalamic neuron with an upper body somatic field. Spinal cord transections showed that cardiopulmonary input to cuneothalamic neurons traveled in ipsilateral dorsal column and probably in dorsolateral funiculus. One of eight gracilothalamic neurons with lower body fields was inhibited by cardiopulmonary input, and none were excited. Stimulation of the ipsilateral stellate ganglion increased activity in 10 of 10 T3-T4 STT neurons. Evoked discharge rates, latencies to activation and durations of peristimulus histogram peaks were significantly less for cuneothalamic neurons compared with STT neurons. Furthermore, additional long latency peaks of activity developed in histograms for 6 of 10 STT neurons but never for cuneothalamic neurons. Contralateral cardiopulmonary sympathetic input did not excite cuneothalamic neurons but increased activity of 7 of 10 T3-T4 STT neurons. Most cuneothalamic neurons (24 of 31 cells tested) responded primarily to innocuous somatic stimuli, whereas STT neurons responded primarily or solely to noxious pinch of somatic fields. Neurons that responded to cardiopulmonary input most often had somatic fields located on proximal arm and chest. Results of this study showed that cardiopulmonary input was transmitted in dorsal pathways to cuneate nucleus and then to VPL thalamus and confirmed that STT neurons transmit nociceptive cardiopulmonary input to VPL thalamus. Differences in neuronal responses to noxious stimulation of cardiopulmonary sympathetic afferent fibers suggest that dorsal and ventrolateral pathways to VPL thalamus play different roles in the transmission and integration of nociceptive cardiac information.
刺激心肺交感传入纤维会兴奋胸段和颈段脊髓丘脑束（STT）细胞，这些细胞主要对有害的躯体刺激作出反应。薄束核中的神经元主要对无害的躯体传入信号作出反应，但盆腔脏器的有害刺激会激活薄束神经元。本研究的目的是比较胸段内脏传入对楔丘脑和脊髓丘脑束神经元的影响。对17只麻醉的猕猴（食蟹猴）的星状神经节进行电刺激，以激活心肺交感传入纤维。用刷子、轻敲和捏压刺激来操控躯体感受野。记录从丘脑腹后外侧核（VPL）逆向激活的神经元的细胞外放电率。刺激同侧星状神经节增加了38个楔丘脑神经元中的17个以及1个具有上身躯体感受野的薄束丘脑神经元的活动。脊髓横断显示，楔丘脑神经元的心肺传入信号经同侧薄束传导，可能还经背外侧索传导。8个具有下身感受野的薄束丘脑神经元中有1个被心肺传入信号抑制，无神经元被兴奋。刺激同侧星状神经节增加了10个T3 - T4脊髓丘脑束神经元中10个的活动。与脊髓丘脑束神经元相比，楔丘脑神经元的诱发放电率、激活潜伏期和刺激后直方图峰值持续时间明显更短。此外，10个脊髓丘脑束神经元中有6个的直方图出现了额外的长潜伏期活动峰值，而楔丘脑神经元从未出现过。对侧心肺交感传入未兴奋楔丘脑神经元，但增加了10个T3 - T4脊髓丘脑束神经元中7个的活动。大多数楔丘脑神经元（31个受试细胞中的24个）主要对无害的躯体刺激作出反应，而脊髓丘脑束神经元主要或仅对躯体感受野的有害捏压作出反应。对心肺传入信号有反应的神经元，其躯体感受野大多位于上臂近端和胸部。本研究结果表明，心肺传入信号经背侧通路传至楔束核，再传至丘脑腹后外侧核，并证实脊髓丘脑束神经元将伤害性心肺传入信号传至丘脑腹后外侧核。神经元对心肺交感传入纤维有害刺激的反应差异表明，至丘脑腹后外侧核的背侧和腹外侧通路在伤害性心脏信息的传导和整合中发挥不同作用。
