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J Vet Sci 2018; 19(4): 483-491  https://doi.org/10.4142/jvs.2018.19.4.483
Comparison of electrophysiological properties of two types of pre-sympathetic neurons intermingled in the hypothalamic paraventricular nucleus
Yiming Shen1, Seong Kyu Han2, Pan Dong Ryu1,*
1Department of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute of Veterinary Science, Seoul National University, Seoul 08826, Korea
2Department of Oral Physiology, School of Dentistry and Institute of Oral Bioscience, Chonbuk National University, Jeonju 54896, Korea
Correspondence to: Tel: +82-2-880-1254; Fax: +82-2-879-0378; E-mail: pdryu@snu.ac.kr
Received: January 24, 2018; Revised: March 6, 2018; Accepted: March 9, 2018; Published online: July 31, 2018.
The hypothalamic paraventricular nucleus (PVN) contains two types of neurons projecting to either the rostral ventrolateral medulla (PVNRVLM) or the intermediolateral horn (IML) of the spinal cord (PVNIML). These two neuron groups are intermingled in the same subdivisions of the PVN and differentially regulate sympathetic outflow. However, electrophysiological evidence supporting such functional differences is largely lacking. Herein, we compared the electrophysiological properties of these neurons by using patch-clamp and retrograde-tracing techniques. Most neurons (>70%) in both groups spontaneously fired in the cell-attached mode. When compared to the PVNIML neurons, the PVNRVLM neurons had a lower firing rate and a more irregular firing pattern (p < 0.05). The PVNRVLM neurons showed smaller resting membrane potential, slower rise and decay times, and greater duration of spontaneous action potentials (p < 0.05). The PVNRVLM neurons received greater inhibitory synaptic inputs (frequency, p < 0.05) with a shorter rise time (p < 0.05). Taken together, the results indicate that the two pre-sympathetic neurons differ in their intrinsic and extrinsic electrophysiological properties, which may explain the lower firing activity of the PVNRVLM neurons. The greater inhibitory synaptic inputs to the PVNRVLM neurons also imply that these neurons have more integrative roles in regulation of sympathetic activity.
Keywords: action potential, inhibitory postsynaptic current, patch-clamp techniques, rostral ventrolateral medulla, spinal cord lateral horn

© 2018 The Korean Society of Veterinary Science.

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