Voltage‐gated currents distinguish parvocellular from magnocellular neurones in the rat hypothalamic paraventricular nucleus

• DOI: 10.1111/j.1469-7793.2000.t01-1-00193.x
• Publication Date: 2004-08-13T07:40:14Z
• Authors: Jason A. Luther; Jeffrey G. Tasker
• Keywords: Parvocellular cell; Magnocellular cell

Magnocellular and parvocellular neurones of the hypothalamic paraventricular nucleus (PVN) differentially regulate pituitary hormone secretion autonomic output. Previous experiments have suggested that magnocellular, or type I neurones, parvocellular, II PVN express different electrophysiological properties. Whole‐cell patch‐clamp recordings were performed in slices to identify voltage‐gated currents responsible for differences between neurones. Type which display transient outward rectification lack a low‐threshold spike (LTS), generated large A‐type K + current ( A ) (mean ± s.e.m.: 1127.5 126.4 pA; range: 250–3600 voltage steps −25 mV) but expressed little no T‐type Ca 2+ T ). often an LTS, smaller (360.1 56.3 40–1100 mV), 75 % (‐402.5 166.9 −90 −2200 at peak). The dependence was shifted more negative values compared Thus, activation threshold (‐53.5 0.9 −46.1 2.6 half‐activation potential (‐25 1.9 −17.9 2.0 half‐inactivation (‐80.4 9.3 −67.2 3.0 became fully inactivated (‐57.4 2.1 −49.8 1.5 than respectively. activated −59.2 1.2 mV, peaked −32.6 1.7 half‐inactivated −66.9 2.2 −52.2 mV. Both cell types delayed rectifier with similar dependence, although it (389.7 39.3 pA) (586.4 76.0 pA). In reduced by 41.1 7.0 action delay caused 46.2 10.3 5 m 4‐aminopyridine. 66.8 10.9 LTS 76.7 7.8 100 μM nickel chloride, neither nor sensitive 50 cadmium chloride. properties I, putative magnocellular II, can be attributed differential expression currents. This diversity ion channel is likely profound effects on response these neurosecretory non‐neurosecretory