Enhanced responses of spinal dorsal horn neurons to heat and cold stimuli following mild freeze injury to the skin.
Enhanced responses of spinal dorsal horn neurons to heat and cold stimuli following mild freeze injury to the skin.
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DOI：
10.1152/jn.2001.86.2.986
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发表时间：
2001-08
影响因子：
2.5
通讯作者：
S. Khasabov;David M. Cain;Dinh Thong;P. Mantyh;D. Simone
中科院分区：
文献类型：
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作者：
S. Khasabov;David M. Cain;Dinh Thong;P. Mantyh;D. Simone
在麻醉大鼠上观察了轻度皮肤冻伤对背角伤害性神经元对冷热刺激反应的影响。电生理记录来自72个位于浅和深背角的伤害性脊髓神经元。所有神经元的感受野（RF）的无毛皮肤的后爪，神经元的功能分为宽动态范围（WDR）和高阈值（HT）神经元。44个神经元（61%）被归类为WDR，并对无害和有害的机械刺激（平均机械阈值为12.8 +/- 1.6 mN）作出反应。28个神经元（39%）被归类为HT，仅由伤害性机械刺激（平均机械阈值为154.2 +/- 18.3 mN）兴奋。神经元的特征在于其对施加到其RF的热（35至51摄氏度）和冷（28至-12摄氏度）刺激的敏感性。在WDR神经元中，86%的神经元对有害的热和冷刺激都有兴奋，而14%的神经元只对热有反应。对于HT神经元，61%对热和冷刺激有反应，32%仅对有害热有反应，7%仅对有害冷有反应。在30个WDR和22个HT神经元中检查了轻度冷冻损伤（-15 ° C施加到RF 20 s）对热和冷刺激反应的影响。皮肤冷冻被证实为由于与结晶相关的放热反应导致的损伤部位皮肤温度的突然升高。冷冻引起大多数WDR和HT神经元对热和冷刺激的反应阈值降低。WDR和HT神经元对冷的反应阈值分别平均降低9.0 +/- 1.3 ℃和10.0 +/- 1.6 ℃。WDR和HT神经元对热的平均反应阈值分别降低4.0 +/- 0.4 ℃和4.3 +/- 1.3 ℃。此外，对阈上冷刺激和热刺激的反应增加。WDR和HT神经元在所有冷刺激中的反应分别增加了89%和192%，在所有热刺激中诱发的反应分别增加了93%和92%。我们的研究结果表明，许多脊髓神经元编码强度的有害冷以及有害热在很宽的刺激温度范围。轻度冻伤后，WDR和HT神经元对冷和热刺激的反应增强，可能有助于人类类似冻伤后的热痛觉过敏。
The effects of a mild freeze injury to the skin on responses of nociceptive dorsal horn neurons to cold and heat stimuli were examined in anesthetized rats. Electrophysiological recordings were obtained from 72 nociceptive spinal neurons located in the superficial and deep dorsal horn. All neurons had receptive fields (RFs) on the glabrous skin of the hindpaw, and neurons were functionally divided into wide dynamic range (WDR) and high-threshold (HT) neurons. Forty-four neurons (61%) were classified as WDR and responded to both innocuous and noxious mechanical stimuli (mean mechanical threshold of 12.8 +/- 1.6 mN). Twenty-eight neurons (39%) were classified as HT and were excited only by noxious mechanical stimuli (mean mechanical threshold of 154.2 +/- 18.3 mN). Neurons were characterized for their sensitivity heat (35 to 51 degrees C) and cold (28 to -12 degrees C) stimuli applied to their RF. Among WDR neurons, 86% were excited by both noxious heat and cold stimuli, while 14% responded only to heat. For HT neurons, 61% responded to heat and cold stimuli, 32% responded only to noxious heat, and 7% responded only to noxious cold. Effects of a mild freeze injury (-15 degrees C applied to the RF for 20 s) on responses to heat and cold stimuli were examined in 30 WDR and 22 HT neurons. Skin freezing was verified as an abrupt increase in skin temperature at the site of injury due to the exothermic reaction associated with crystallization. Freezing produced a decrease in response thresholds to heat and cold stimuli in most WDR and HT neurons. WDR and HT neurons exhibited a mean decrease in response threshold for cold of 9.0 +/- 1.3 degrees C and 10.0 +/- 1.6 degrees C, respectively. Mean response thresholds for heat decreased 4.0 +/- 0.4 degrees C and 4.3 +/- 1.3 degrees C in WDR and HT neurons, respectively. In addition, responses to suprathreshold cold and heat stimuli increased. WDR and HT neurons exhibited an 89% and a 192% increase in response across all cold stimuli, and a 93 and 92% increase in responses evoked across all heat stimuli, respectively. Our results demonstrate that many spinal neurons encode intensity of noxious cold as well as noxious heat over a broad range of stimulus temperatures. Enhanced responses of WDR and HT neurons to cold and heat stimuli after a mild freeze injury is likely to contribute to thermal hyperalgesia following a similar freeze injury in humans.