High-voltage-activated Ca2+ currents and the excitability of pyramidal neurons in the hippocampal CA3 subfield in rats depend on corticosterone and time of day
Mhp. Kole et al., High-voltage-activated Ca2+ currents and the excitability of pyramidal neurons in the hippocampal CA3 subfield in rats depend on corticosterone and time of day, NEUROSCI L, 307(1), 2001, pp. 53-56
This study tested the time-of-day dependence of the intrinsic postsynaptic
properties of hippocampal CA3 pyramidal neurons. High-voltage-activated Ca2
+ currents and the Ca2+- and voltage-dependent afterhyperpolarizations were
examined in slices of rat brains obtained at four distinct time periods. J
ust after onset of the dark phase, the steady-state amplitude of the Ca2+ c
urrent (-1.24 +/- 0.11 nA) was significantly greater (P < 0.03) than that o
f the light phase (-0.84 +/- 0.06 nA). Over the entire time range, the ampl
itude of the Ca2+ current correlated with plasma corticosterone levels in a
U-shaped function. Furthermore, depolarization-induced excitability during
the dark phase exhibited an increased spike after depolarization (3.1 +/-
0.1 mV) and a slower adaptation of the firing frequency (146 +/- 18%). Thes
e findings point to a dynamic time-of-day dependence of the CA3 neuronal pr
operties and postsynaptic Ca2+ currents. (C) 2001 Published by Elsevier Sci
ence Ireland Ltd.