Neurosecretory and Non‐Neurosecretory Parvocellular Neurones of the Hypothalamic Paraventricular Nucleus Express Distinct Electrophysiological Properties

Parvocellular neurones of the hypothalamic paraventricular nucleus (PVN) comprise neurosecretory and non‐neurosecretory subpopulations. We labelled neurosecretory neurones with intravenous injection of the retrograde tracer, fluoro‐gold, and recorded from fluoro‐gold‐positive and negative PVN parvocellular neurones in hypothalamic slices. Non‐neurosecretory parvocellular neurones generated a low‐threshold spike (LTS) and robust T‐type Ca2+ current, whereas neurosecretory neurones showed no LTS and a small T‐current. LTS neurones were located in non‐neurosecretory regions of the PVN, and non‐LTS neurones were located in neurosecretory regions of the PVN. These findings indicate that neurosecretory and non‐neurosecretory subtypes of parvocellular PVN neurones express distinct membrane electrical properties.