Excitatory interneurons dominate sensory processing in the spinal substantia gelatinosa of rat
Excitatory interneurons dominate sensory processing in the spinal substantia gelatinosa of rat
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DOI：
10.1113/jphysiol.2006.126912
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发表时间：
2007-05-15
影响因子：
5.5
通讯作者：
Safronov, Boris V.
中科院分区：
文献类型：
--
作者：
Santos, Sonia F. A.;Rebelo, Sandra;Safronov, Boris V.
胶状质（Substantia gelatinosa，SG，lamina II）是脊髓的一个区域，大多数无髓初级传入终止于此，中枢伤害性处理开始于此。它由几组不同的中间神经元组成，其功能特性和突触连接知之甚少，部分原因是由于发现连接细胞的概率非常低，因此来自突触耦合的SG神经元对的记录非常具有挑战性。在这里，我们描述了一种有效的方法，用于识别大鼠脊髓切片中的突触耦合的中间神经元，并表征其兴奋或抑制功能。使用密封的全细胞记录和细胞贴附刺激技术，我们常规测试了约1500 SG interneurons，其中102个分类为单突触连接的神经元在板层I-III。令人惊讶的是，绝大多数SG中间神经元（n = 87）是兴奋性和兴奋性的，而只有15个神经元是抑制性的。根据其内在的放电特性，这102个SG神经元也被分为紧张性（n = 49），适应性（n = 17）和延迟放电神经元（n = 36）。除了两个紧张神经元和所有适应神经元是兴奋性中间神经元。在36个延迟放电神经元中，23个是兴奋性的，13个是抑制性的。我们的结论是，感觉整合的内在SG神经元网络的兴奋性中间神经元占主导地位。脊髓SG中神经元回路的这种组织对于伤害性编码可能是重要的。
Substantia gelatinosa (SG, lamina II) is a spinal cord region where most unmyelinated primary afferents terminate and the central nociceptive processing begins. It is formed by several distinct groups of interneurons whose functional properties and synaptic connections are poorly understood, in part, because recordings from synaptically coupled pairs of SG neurons are quite challenging due to a very low probability of finding connected cells. Here, we describe an efficient method for identifying synaptically coupled interneurons in rat spinal cord slices and characterizing their excitatory or inhibitory function. Using tight-seal whole-cell recordings and a cell-attached stimulation technique, we routinely tested about 1500 SG interneurons, classifying 102 of them as monosynaptically connected to neurons in lamina I-III. Surprisingly, the vast majority of SG interneurons (n = 87) were excitatory and glutamatergic, while only 15 neurons were inhibitory. According to their intrinsic firing properties, these 102 SG neurons were also classified as tonic (n = 49), adapting (n = 17) or delayed-firing neurons (n = 36). All but two tonic neurons and all adapting neurons were excitatory interneurons. Of 36 delayed-firing neurons, 23 were excitatory and 13 were inhibitory. We conclude that sensory integration in the intrinsic SG neuronal network is dominated by excitatory interneurons. Such organization of neuronal circuitries in the spinal SG can be important for nociceptive encoding.