Comparison of electrophysiological properties of two types of pre-sympathetic neurons intermingled in the hypothalamic paraventricular nucleus.

ABSTRACT: The hypothalamic paraventricular nucleus (PVN) contains two types of neurons projecting to either the rostral ventrolateral medulla (PVN_RVLM) or the intermediolateral horn (IML) of the spinal cord (PVN_IML). 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 PVN_IML neurons, the PVN_RVLM neurons had a lower firing rate and a more irregular firing pattern (p ? 0.05). The PVN_RVLM neurons showed smaller resting membrane potential, slower rise and decay times, and greater duration of spontaneous action potentials (p ? 0.05). The PVN_RVLM 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 PVN_RVLM neurons. The greater inhibitory synaptic inputs to the PVN_RVLM neurons also imply that these neurons have more integrative roles in regulation of sympathetic activity.

SUBMITTER: Shen Y 

PROVIDER: S-EPMC6070595 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature