title: 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.
abstract: 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 Ca(2+)- and voltage-dependent afterhyperpolarizations were examined in slices of rat brains obtained at four distinct time periods. Just after onset of the dark phase, the steady-state amplitude of the Ca2+ current (-1.24+/-0.11 nA) was significantly greater (P<0.03) than that of the light phase (-0.84+/-0.06 nA). Over the entire time range, the amplitude 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%). These findings point to a dynamic time-of-day dependence of the CA3 neuronal properties and postsynaptic Ca2+ currents.
authors.affiliation: Division of Neurobiology, German Primate Center, Kellnerweg 4, 37077 Göttingen, Germany.
authors.forename: M H
authors.initials: MH
authors.lastname: Kole
authors.forename: J M
authors.initials: JM
authors.lastname: Koolhaas
authors.forename: P G
authors.initials: PG
authors.lastname: Luiten
authors.forename: E
authors.initials: E
authors.lastname: Fuchs
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D002104:Cadmium / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002940:Circadian Rhythm / Q000502:physiology*; D003345:Corticosterone / Q000097:blood* / Q000494:pharmacology; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D017966:Pyramidal Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D015220:Calcium Channels; D002104:Cadmium; D003345:Corticosterone