Ji Yaping, Traub Richard J
Department of Oral and Craniofacial Biological Sciences, University of Maryland Dental School, 666 W Baltimore St, Baltimore, MD 21201, USA.
Pain. 2002 Sep;99(1-2):217-22. doi: 10.1016/s0304-3959(02)00106-9.
The present study examined the effect of a spinally administered excitatory amino acid antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX; 1, 2.5, 5 microg) on responses of spinal dorsal horn neurons to graded intensities (20, 40, 60, 80 mmHg) of colorectal distention (CRD). Extracellular single unit recordings were made from 28 dorsal horn neurons in the L6-S2 spinal cord. Neurons excited by CRD were subclassified as short latency abrupt (SLA) neurons and short latency sustained (SLS) neurons. The response to graded intensities of CRD was dose-dependently attenuated in 9/17 SLA neurons (53%). The response to CRD was also dose-dependently attenuated in 8/11 SLS neurons (73%). The response to CRD in the remaining eight SLA neurons and three SLS neurons was not attenuated by CNQX. Comparing only neurons that were significantly attenuated by the CNQX, it was found that the magnitude of attenuation of the response to noxious CRD (80 mmHg) produced by 5 microg CNQX was significantly greater in SLA (63 +/-6%) vs. SLS (40 +/- 6%) neurons. While CNQX produced a significant attenuation of the response to innocuous CRD (20 mmHg), there was no difference between the SLA and SLS neurons. The effects of CNQX on the response to somatic stimulation (touch, pinch) of the cutaneous receptive field of these 28 neurons were qualitatively examined in all neurons and quantitatively examined in nine neurons (five SLA and four SLS neurons). CNQX generally decreased the response to pinch or touch, even if CNQX did not attenuate the response to CRD. These results suggest that subpopulations of SLA and SLS neurons are differentially modulated by non-NMDA ionotropic excitatory amino acid receptors and that these neuronal subtypes contribute differently to visceral sensory processing. Furthermore, the lack of correlation between the effects of CNQX on visceral and somatic sensory processing in the same neuron underscores potential differences in processing of visceral and somatic pain.
本研究检测了脊髓给予兴奋性氨基酸拮抗剂6-氰基-7-硝基喹喔啉-2,3-二酮（CNQX；1、2.5、5微克）对脊髓背角神经元对不同强度（20、40、60、80毫米汞柱）结直肠扩张（CRD）反应的影响。对L6 - S2脊髓节段的28个背角神经元进行了细胞外单单位记录。被CRD兴奋的神经元被分为短潜伏期突发放电（SLA）神经元和短潜伏期持续放电（SLS）神经元。在17个SLA神经元中的9个（53%），对不同强度CRD的反应呈剂量依赖性减弱。在11个SLS神经元中的8个（73%），对CRD的反应也呈剂量依赖性减弱。其余8个SLA神经元和3个SLS神经元对CRD的反应未被CNQX减弱。仅比较被CNQX显著减弱反应的神经元，发现5微克CNQX对有害CRD（80毫米汞柱）反应的减弱幅度在SLA神经元（63±6%）显著大于SLS神经元（40±6%）。虽然CNQX对无害CRD（20毫米汞柱）的反应有显著减弱，但SLA和SLS神经元之间没有差异。对这28个神经元的皮肤感受野的躯体刺激（触摸、捏压）反应，在所有神经元中定性检测了CNQX的作用，在9个神经元（5个SLA和4个SLS神经元）中定量检测了该作用。即使CNQX未减弱对CRD的反应，它通常也会降低对捏压或触摸的反应。这些结果表明，SLA和SLS神经元亚群受到非NMDA离子型兴奋性氨基酸受体的不同调节，并且这些神经元亚型在内脏感觉处理中发挥不同作用。此外，同一神经元中CNQX对内脏和躯体感觉处理的影响缺乏相关性，这突出了内脏痛和躯体痛处理过程中的潜在差异。
