Li W-C, Higashijima Shin-ichi, Parry D M, Roberts Alan, Soffe S R
School of Biological Sciences, University of Bristol, Bristol BS8 1UG, United Kingdom.
J Neurosci. 2004 Jun 23;24(25):5840-8. doi: 10.1523/JNEUROSCI.1633-04.2004.
Understanding the neuronal networks in the mammal spinal cord is hampered by the diversity of neurons and their connections. The simpler networks in developing lower vertebrates may offer insights into basic organization. To investigate the function of spinal inhibitory interneurons in Xenopus tadpoles, paired whole-cell recordings were used. We show directly that one class of interneuron, with distinctive anatomy, produces glycinergic, negative feedback inhibition that can limit firing in motoneurons and interneurons of the central pattern generator during swimming. These same neurons also produce inhibitory gating of sensory pathways during swimming. This discovery raises the possibility that some classes of interneuron, with distinct functions later in development, may differentiate from an earlier class in which these functions are shared. Preliminary evidence suggests that these inhibitory interneurons express the transcription factor engrailed, supporting a probable homology with interneurons in developing zebrafish that also express engrailed and have very similar anatomy and functions.
哺乳动物脊髓中的神经元网络因其神经元及其连接的多样性而难以理解。发育中的低等脊椎动物中较为简单的网络可能有助于深入了解基本组织结构。为了研究非洲爪蟾蝌蚪脊髓抑制性中间神经元的功能，采用了配对全细胞记录法。我们直接表明，一类具有独特解剖结构的中间神经元会产生甘氨酸能负反馈抑制，这种抑制在游泳过程中可限制运动神经元和中枢模式发生器中间神经元的放电。这些相同的神经元在游泳过程中还会对感觉通路产生抑制性门控作用。这一发现增加了一种可能性，即某些在发育后期具有不同功能的中间神经元类别，可能是从早期具有这些共同功能的类别分化而来的。初步证据表明，这些抑制性中间神经元表达转录因子engrailed，这支持了它们与发育中的斑马鱼中间神经元可能存在同源性的观点，斑马鱼中的中间神经元也表达engrailed，并且具有非常相似的解剖结构和功能。
