In vivo responses of mouse superficial dorsal horn neurones to both current injection and peripheral cutaneous stimulation
In vivo responses of mouse superficial dorsal horn neurones to both current injection and peripheral cutaneous stimulation
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DOI：
10.1113/jphysiol.2004.072645
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发表时间：
2004-12-15
影响因子：
5.5
通讯作者：
Callister, RJ
中科院分区：
文献类型：
--
作者：
Graham, BA;Brichta, AM;Callister, RJ
在浅背角(SDH)中，伤害性和非伤害性刺激的加工与其组成神经元的输入输出关系密切相关。这种关系通常通过评估神经元对躯体电流注入或突触输入激活的反应来检查。通过比较同一神经元中这两种形式的激活对神经元输出的影响，可以更全面地理解输入-输出关系。因此，在成年小鼠脊髓的活体准备中，我们研究了SDH神经元如何通过外周皮肤刺激(后爪的刷动和挤压)将去极化电流注入和突触兴奋转化为一系列动作电位。在全细胞电流钳记录条件下，在去极化电流注入过程中观察到四种动作电位放电模式：紧张性放电神经元(21/93)在整个台阶过程中放出棘波；始发阵发性神经元(35/93)在台阶起始时放电多个峰；单峰神经元(16/93)在台阶起始时放电1~2个峰；延迟放电神经元(21/93)在台阶起始时延迟放电。在对伤害性和非伤害性皮肤刺激的反应中，观察到四个特征：伤害性神经元(20/37)对捏刺激的反应最大；轻触触神经元(9/37)对刷刺刺激的反应最大；阈值下神经元(4/37)出现无放电动作电位的去极化反应；超极化神经元(4/37)表现出持续的捏刺激诱导的超极化。电流诱发放电模式与外周诱发反应的比较表明，表达四种放电模式的SDH神经元都可以接收并参与有关伤害性或无害刺激的信息处理。这些数据表明，神经元对当前注射的反应不一定有助于、识别或预测同一神经元对生理或功能相关刺激的反应。
In the superficial dorsal horn (SDH) processing of noxious and innocuous stimuli is critically dependent on the input-output relationship of its component neurones. Such relationships are routinely examined by assessing neuronal responses to somatic current injection or activation of synaptic inputs. A more complete understanding of input-output relationships would be achieved by comparing, in the same neurone, how the two forms of activation contribute to neuronal output. Therefore, we examined how SDH neurones transform depolarizing current injections and synaptic excitation via peripheral cutaneous stimuli (brush and pinch of the hindpaw) into trains of action potentials, in an in vivo preparation of the adult mouse spinal cord. Under whole-cell current clamp recording conditions four action potential discharge patterns were observed during depolarizing current injection: tonic firing neurones (21/93) discharged spikes throughout the step; initial bursting neurones (35/93) discharged several spikes at step onset; single spiking neurones (16/93) discharged one or two spikes at step onset; and delayed firing neurones (21/93) discharged spikes delayed from the step onset. Four characteristic profiles were observed in response to application of noxious (pinch) and innocuous (brush) cutaneous stimuli: nociceptive neurones (20/37) responded maximally to pinch stimulation; light touch neurones (9/37) responded maximally to brush stimulation; subthreshold neurones (4/37) exhibited depolarizing responses without firing action potentials; and hyperpolarizing neurones (4/37) exhibited a sustained pinch-induced hyperpolarization. Comparisons of current-evoked discharge patterns with peripherally evoked responses indicate SDH neurones expressing each of the four discharge patterns could receive, and therefore participate in the processing of information concerning, either noxious or innocuous stimuli. These data suggest that a neurone's response to current injection does not necessarily help, identify or predict how the same neurone will respond to physiologically or functionally relevant stimuli.