Zhu Lin, Selverston Allen I, Ayers Joseph
Department of Biology, Northeastern University, Boston, Massachusetts; and.
Department of Marine and Environmental Sciences, Marine Science Center, Northeastern University, Nahant, Massachusetts.
J Neurophysiol. 2016 Jun 1;115(5):2434-45. doi: 10.1152/jn.00737.2015. Epub 2016 Feb 24.
The hyperpolarization-activated inward cationic current (Ih) is known to regulate the rhythmicity, excitability, and synaptic transmission in heart cells and many types of neurons across a variety of species, including some pyloric and gastric mill neurons in the stomatogastric ganglion (STG) in Cancer borealis and Panulirus interruptus However, little is known about the role of Ih in regulating the gastric mill dynamics and its contribution to the dynamical bifurcation of the gastric mill and pyloric networks. We investigated the role of Ih in the rhythmic activity and cellular excitability of both the gastric mill neurons (medial gastric, gastric mill) and pyloric neurons (pyloric dilator, lateral pyloric) in Homarus americanus Through testing the burst period between 5 and 50 mM CsCl, and elimination of postinhibitory rebound and voltage sag, we found that 30 mM CsCl can sufficiently block Ih in both the pyloric and gastric mill neurons. Our results show that Ih maintains the excitability of both the pyloric and gastric mill neurons. However, Ih regulates slow oscillations of the pyloric and gastric mill neurons differently. Specifically, blocking Ih diminishes the difference between the pyloric and gastric mill burst periods by increasing the pyloric burst period and decreasing the gastric mill burst period. Moreover, the phase-plane analysis shows that blocking Ih causes the trajectory of slow oscillations of the gastric mill neurons to change toward the pyloric sinusoidal-like trajectories. In addition to regulating the pyloric rhythm, we found that Ih is also essential for the gastric mill rhythms and differentially regulates these two dynamics.
超极化激活内向阳离子电流（Ih）已知可调节多种物种心脏细胞和许多类型神经元的节律性、兴奋性和突触传递，包括北方黄道蟹和中断岩龙虾口胃神经节（STG）中的一些幽门和胃磨神经元。然而，关于Ih在调节胃磨动力学中的作用及其对胃磨和幽门网络动态分岔的贡献知之甚少。我们研究了Ih在美洲螯龙虾胃磨神经元（内侧胃磨、胃磨）和幽门神经元（幽门扩张肌、外侧幽门）的节律活动和细胞兴奋性中的作用。通过测试5至50 mM CsCl之间的爆发周期，并消除抑制后反弹和电压下垂，我们发现30 mM CsCl可以充分阻断幽门和胃磨神经元中的Ih。我们的结果表明，Ih维持幽门和胃磨神经元的兴奋性。然而，Ih对幽门和胃磨神经元慢振荡的调节方式不同。具体而言，阻断Ih通过增加幽门爆发周期和缩短胃磨爆发周期来减小幽门和胃磨爆发周期之间的差异。此外，相平面分析表明，阻断Ih会导致胃磨神经元慢振荡的轨迹向幽门正弦样轨迹变化。除了调节幽门节律外，我们还发现Ih对胃磨节律也至关重要，并且对这两种动态有不同的调节作用。
