Laboratory for Enteric Neuroscience, Translational Research Center for Gastrointestinal Disorders, ChroMeta, Katholieke Universiteit Leuven, Leuven, Belgium.
The Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, People's Republic of China.
Am J Physiol Gastrointest Liver Physiol. 2022 Oct 1;323(4):G341-G347. doi: 10.1152/ajpgi.00162.2022. Epub 2022 Aug 31.
Live calcium imaging is often used as a proxy for electrophysiological measurements and has been a valuable tool that allows simultaneous analysis of neuronal activity in multiple cells at the population level. In the enteric nervous system, there are two main electrophysiological classes of neurons, after-hyperpolarizing (AH)- and synaptic (S)-neurons, which have been shown to have different calcium handling mechanisms. However, they are rarely considered separately in calcium imaging experiments. A handful of studies have shown that in guinea pig, a calcium transient will accompany a single action potential in AH-neurons, but multiple action potentials are required to generate a calcium transient in S-neurons. How this translates to different modes of cellular depolarization and whether this is consistent across species is unknown. In this study, we used simultaneous whole-cell patch-clamp electrophysiology together with calcium imaging to investigate how enteric neurons respond to different modes of depolarization. Using both traditional (4 Hz) and also high-speed (1,000 Hz) imaging techniques, we found that single action potentials elicit calcium transients in both AH-neurons and S-neurons. Subthreshold membrane depolarizations were also able to elicit calcium transients, although calcium responses were generally amplified if an action potential was present. Furthermore, we identified that responses to nicotinic acetylcholine receptor stimulation can be used to distinguish between AH- and S-neurons in calcium imaging. Live calcium imaging is an important tool for investigating enteric nervous system (ENS) function. Previous studies have shown that multiple action potentials are needed to generate a calcium response in S-neurons, which has important implications for the interpretation of calcium imaging data. Here, we show that in mouse myenteric neurons, calcium transients are elicited by single action potentials in both AH- and S-neurons. In addition, nicotinic acetylcholine receptor stimulation can be used to distinguish between these two classes.
实时钙成像通常被用作电生理测量的替代物，是一种非常有价值的工具，可允许在群体水平上同时分析多个神经元的活动。在肠神经系统中，存在两种主要的电生理神经元类群，后超极化（AH）神经元和突触（S）神经元，它们被证明具有不同的钙处理机制。然而，在钙成像实验中很少将它们分开考虑。少数研究表明，在豚鼠中，AH 神经元中的单个动作电位伴随着钙瞬变，但 S 神经元中需要多个动作电位才能产生钙瞬变。这如何转化为不同的细胞去极化模式，以及这是否在不同物种中一致，目前尚不清楚。在这项研究中，我们使用同时进行的全细胞膜片钳电生理学和钙成像来研究肠神经元如何对不同的去极化模式做出反应。使用传统（4 Hz）和高速（1000 Hz）成像技术，我们发现单个动作电位会在 AH 神经元和 S 神经元中引发钙瞬变。亚阈膜去极化也能够引发钙瞬变，尽管如果存在动作电位，钙响应通常会被放大。此外，我们确定了烟碱型乙酰胆碱受体刺激的反应可用于在钙成像中区分 AH 和 S 神经元。实时钙成像对于研究肠神经系统（ENS）功能是一种重要的工具。先前的研究表明，S 神经元需要多个动作电位才能产生钙响应，这对钙成像数据的解释具有重要意义。在这里，我们表明在小鼠肌间神经元中，AH 和 S 神经元中的单个动作电位都能引发钙瞬变。此外，烟碱型乙酰胆碱受体刺激可用于区分这两种神经元。
