Effects of locus coeruleus stimulation on the responses of SI neurons of the rat to controlled natural and electrical stimulation of the skin.
Effects of locus coeruleus stimulation on the responses of SI neurons of the rat to controlled natural and electrical stimulation of the skin.
复制标题
蓝斑刺激对大鼠 SI 神经元对皮肤受控自然刺激和电刺激反应的影响。
DOI：
10.4449/aib.v137i1.652
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发表时间：
1999
影响因子：
1
通讯作者：
O. Pompeiano
中科院分区：
文献类型：
--
作者：
P. Snow;P. Andre;O. Pompeiano
1.在26只乌拉坦麻醉的Sprague-Dawley大鼠上，观察了微刺激蓝斑（LC）区对SI神经元自发放电及对皮肤自然刺激和电刺激反应的影响。特别地，以1/秒的呈现速率在手腕或前爪的有毛皮肤上施加一次或两次空气抽吸，持续时间为5-10毫秒，1-2 psi，通常间隔40毫秒。对于对空气抽吸无反应的单元，通过插入皮肤的最有效区域上的两个针施加低强度电刺激（0.2- 5.0V，0.2-0.4毫秒脉冲）的类似呈现。在控制条件下以及在40 Hz的0.3毫秒脉冲的250毫秒序列之后的50毫秒，施加皮肤的自然刺激和电刺激。20-30微安通过钨微电极立体定向地施加到LC复合物。2.并不是所有的皮层单位表现出自发放电。然而，大多数的单位，这是自发活动，抑制电刺激的LC复合物，而其余的兴奋。刺激部位包括LC或蓝斑下核，根据解剖学和生理学标准确定。3.在皮层表面以下400至950微米的位置处记录的SI神经元，因此最可能是第III层和第IV层的颗粒细胞，其响应于皮肤刺激具有尖峰，所述尖峰响应于单次空气抽吸以20-30毫秒的潜伏期发生，并且响应于对皮肤的单次电脉冲以15-20毫秒的潜伏期发生。在这两种情况下，在40毫秒的刺激间隔施加的第二刺激的反应显着减少或取消由于后兴奋抑制后的第一刺激的反应（现场抑制）。相比之下，单位特别是位于或低于1000微米从皮质表面，这是非常大的尺寸可能对应于大的V层锥体细胞，往往难以激活与空气喷在中心的感受野（RF），并提交给皮肤的电刺激。4.在对空气抽吸（45个神经元）或电皮肤刺激（14个神经元）测试的59个分离的SI单位中，15个单位（即，25.4%）得到促进，而12个单位（即，20.3%）在LC复合物刺激后被抑制。5.易化效应的一个显著特征通常涉及对第一次空气抽吸的主要反应，但也涉及对第二次抽吸的较小反应，即每次刺激的尖峰数量的增加伴随着反应的时间集中，其特征在于潜伏期的明显收紧和活动峰值的缩小，这通常伴随着背景放电的一定程度的紧张性抑制。因此，LC刺激增加了SI神经元对皮肤刺激的反应的信噪比。当LC刺激诱导抑制效应时，它们明显影响了对第一次空气抽吸的单位反应，这是严重抑制的。然而，对第二次抽吸的反应可以被促进，这表明LC刺激可能已经产生了对那些负责检查中的单位的兴奋后抑制的抑制性中间神经元的抑制。空间集中的反应的证据并不容易记录。然而，在某些单位中，LC刺激产生的促进反应，在感受野中心和抑制反应，在边缘的感受野或反之亦然。6.由于LC复合物在大鼠中含有去甲肾上腺素能神经元的主要群体，因此上述效应可能主要是由于这些去甲肾上腺素能神经元的激活。7.（摘要截断）
1. The effects of microstimulation of the locus coeruleus (LC) region on the spontaneous discharge and the response of SI neurons to natural and electrical stimulation of the skin have been investigated in 26 urethane anesthetized Sprague-Dawley rats. In particular, one or two air puffs, 5-10 msec in duration, 1-2 psi, usually separated by an interval of 40 msec, were applied on the hairy skin of the wrist or the forepaw at the presentation rate of 1/sec. For units unresponsive to air puffs, similar presentation of low intensity electrical stimuli (0.2-5.0 V, 0.2-0.4 msec pulses) were applied through two needles inserted on the most effective area of the skin. Both natural and electrical stimulations of the skin were applied under control conditions, as well as 50 msec after a 250 msec train of 0.3 msec pulses at 40 Hz. 20-30 microA applied stereotaxically to the LC complex through a tungsten microelectrode. 2. Not all cortical units exhibited spontaneous discharge. Most of the units, however, which were spontaneously active, were inhibited by electrical stimulation of the LC complex, while the remaining ones were excited. The sites of stimulation, which included either the LC proper or the locus subcoeruleus, were identified following both anatomical and physiological criteria. 3. SI neurons recorded at sites between 400 and 950 microns below the surface of the cortex, thus being most likely granule cells of layers III and IV, responded to cutaneous stimuli with spikes which occurred with a latency of 20-30 msec in response to single air puffs and a latency of 15-20 msec in response to single electrical pulses to the skin. In both instances the response to the second stimulus applied at the interstimulus interval of 40 msec was markedly reduced or abolished due to postexcitatory inhibition following the response to the first stimulus (in-field inhibition). In contrast, units particularly located at or below 1000 microns from the cortical surface, which were of very large size probably corresponding to large layer V pyramidal cells, were often difficult to activate with air puffs applied at the centre of the receptive field (RF) and were submitted to electrical stimulation of the skin. 4. Among the 59 isolated SI units tested either to air puffs (45 neurons) or to electrical skin stimulation (14 neurons), 15 units (i.e., 25.4%) were facilitated, while 12 units (i.e., 20.3%) were inhibited following stimulation of the LC complex. 5. A marked feature of the facilitatory effects which usually involved the predominant response to the first air puff, but also the smaller response to the second puff, was that the increase in the number of spikes per stimulus was accompanied by a temporal focusing of the responses characterized by a clear tightening of the latency and narrowing of the peak of activity, which was often accompanied by some level of tonic inhibition of the background discharge. Thus, LC stimulation increased the signal-to-noise ratio of SI neuronal responses to skin stimulation. When inhibitory effects were induced by LC stimulation, they clearly affected the unit response to the first air puff, which was severely depressed. However, the response to the second puff could be facilitated, suggesting that LC stimulation might have produced inhibition of those inhibitory interneurons responsible for the postexcitatory inhibition of the units under examination. Evidence for spatial focusing of the response was not easily documented. In some units, however, LC stimulation produced either facilitation of the responses to puffs at the receptive field center and inhibition of the responses to puffs at the edge at the receptive field or vice versa. 6. Since the LC complex contains in the rat a predominant population of noradrenergic neurons, it is likely that the effects described above were mainly due to activation of these noradrenergic neurons. 7. (ABSTRACT TRUNCATED)