Viatchenko-Karpinski Viacheslav, Gu Jianguo G
Department of Anesthesiology and Perioperative Medicine, College of Medicine, University of Alabama at Birmingham, 901 19TH Street South, BMR II 210, Birmingham, AL 35294 United States.
Department of Anesthesiology and Perioperative Medicine, College of Medicine, University of Alabama at Birmingham, 901 19TH Street South, BMR II 210, Birmingham, AL 35294 United States.
Neurosci Lett. 2016 Nov 10;634:70-75. doi: 10.1016/j.neulet.2016.10.011. Epub 2016 Oct 5.
Primary afferent fibers use mechanically activated (MA) currents to transduce innocuous and noxious mechanical stimuli. However, it is largely unknown about the differences in MA currents between the afferents for sensing innocuous and noxious stimuli. In the present study, we used dorsal root ganglion (DRG) neurons acutely dissociated from rats and studied their MA currents and also their intrinsic membrane properties. Recorded from small-sized DRG neurons, we found that most of these neurons were mechanically sensitive (MS) showing MA currents. The MS neurons could be classified into nociceptive-like mechanically sensitive (Noci-MS) and non-nociceptive-like mechanically sensitive (nonNoci-MS) neurons based on their action potential shapes. Noci-MS neurons responded to mechanical stimulation with three types of MA currents, rapidly adapting (RA), intermediately adapting (IA), and slowly adapting (SA) currents. In contrast, almost all nonNoci-MS neurons showed RA current type in response to mechanical stimulation. Mechanical thresholds had a broad range for both nonNoci-MS and Noci-MS neurons, and the thresholds were not significantly different between them. However, MA current densities were significantly smaller in Noci-MS than in nonNoci-MS neurons. Noci-MS and nonNoci-MS neurons also showed significant differences in their electrophysiological properties including action potential (AP) thresholds and AP firing patterns. These differences may contribute to the differential sensory encoding for innocuous and noxious mechanical stimuli.
初级传入纤维利用机械激活（MA）电流来传导无害和有害的机械刺激。然而，对于感知无害和有害刺激的传入纤维之间MA电流的差异，人们还知之甚少。在本研究中，我们使用从大鼠急性分离的背根神经节（DRG）神经元，研究了它们的MA电流及其内在膜特性。从小型DRG神经元记录发现，这些神经元中的大多数是机械敏感（MS）的，表现出MA电流。根据动作电位的形状，MS神经元可分为伤害性机械敏感（Noci-MS）和非伤害性机械敏感（nonNoci-MS）神经元。Noci-MS神经元对机械刺激有三种MA电流反应，即快速适应（RA）、中间适应（IA）和缓慢适应（SA）电流。相比之下，几乎所有的nonNoci-MS神经元对机械刺激都表现出RA电流类型。nonNoci-MS和Noci-MS神经元的机械阈值范围都很广，且两者之间的阈值没有显著差异。然而，Noci-MS神经元的MA电流密度明显小于nonNoci-MS神经元。Noci-MS和nonNoci-MS神经元在包括动作电位（AP）阈值和AP发放模式在内的电生理特性方面也存在显著差异。这些差异可能有助于对无害和有害机械刺激进行不同的感觉编码。
