Qin Chao, Goodman Melanie D, Little Janine M, Farber Jay P, Foreman Robert D
Department of Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73190, USA.
Brain Res. 2010 Jul 30;1346:102-11. doi: 10.1016/j.brainres.2010.05.081. Epub 2010 Jun 2.
Previous studies have shown that the gracile nucleus in postsynaptic dorsal column pathway plays an important role in conveying nociceptive information from pelvic visceral organs. The purpose of this study was to compare effects of a noxious cardiac stimulus on neuronal activity in the cuneate nucleus and upper thoracic spinal cord in rats. Extracellular potentials of single neurons in the cuneate nucleus and upper thoracic (T3) spinal cord were recorded in pentobarbital anesthetized, ventilated and paralyzed male rats. To activate cardiac nociceptors, a silicone tube was placed in the pericardial sac over the left ventricle to administer a solution of bradykinin (10 microg/ml, 0.2 ml, 1 min). The number of cuneate neurons responding to intrapericardial bradykinin (IB, 15.6%, 17/109) was significantly less than for T3 neurons (43.2%, 48/111, P<0.05). IB excited 9/17 (52.9%) cuneate neurons and inhibited eight neurons. In contrast, IB excited a significantly higher percentage of responding spinal neurons than those in cuneate nucleus (43/48, 89.6%, P<0.01). The ratio of short latency/long-lasting responses of cuneate neurons to IB (14/3) were significant higher than responses of spinal neurons (26/22, P<0.05). Spontaneous activity (5.5+/-0.7 imp/s), response amplitudes (6.0+/-0.6 imp/s) and durations (83.4+/-10.8 sec) of cuneate neurons excited by IB were significantly less than for spinal neurons (11.5+/-1.3 imp/s, 20.4+/-2.0 imp/s and 104.9+/-7.0 imp/s, P<0.01, P<0.01, P<0.05), respectively. These results indicate that the cuneate nucleus neurons play a relatively minor role in transmission of cardiac nociceptive information in comparison to upper thoracic spinal neurons.
先前的研究表明，突触后背柱通路中的薄束核在传递来自盆腔内脏器官的伤害性信息方面发挥着重要作用。本研究的目的是比较有害心脏刺激对大鼠楔束核和上胸段脊髓神经元活动的影响。在戊巴比妥麻醉、通气和麻痹的雄性大鼠中记录楔束核和上胸段（T3）脊髓单个神经元的细胞外电位。为了激活心脏伤害感受器，将硅胶管置于左心室上方的心包囊中，以注入缓激肽溶液（10微克/毫升，0.2毫升，1分钟）。对心包内缓激肽（IB）有反应的楔束核神经元数量（15.6%，17/109）明显少于T3神经元（43.2%，48/111，P<0.05）。IB兴奋了17个楔束核神经元中的9个（52.9%），并抑制了8个神经元。相比之下，IB兴奋的脊髓反应神经元百分比明显高于楔束核中的神经元（43/48，89.6%，P<0.01）。楔束核神经元对IB的短潜伏期/长时反应比率（14/3）明显高于脊髓神经元（26/22，P<0.05）。由IB兴奋的楔束核神经元的自发活动（5.5±0.7次/秒）、反应幅度（6.0±0.6次/秒）和持续时间（83.4±10.8秒）分别明显低于脊髓神经元（11.5±1.3次/秒、20.4±2.0次/秒和104.9±7.0秒，P<0.01、P<0.01、P<0.05）。这些结果表明，与上胸段脊髓神经元相比，楔束核神经元在心脏伤害性信息传递中起相对较小的作用。
