title: Calbindin-D28k content and firing pattern of hippocampal granule cells in amygdala-kindled rats: a perforated patch-clamp study.
abstract: The dentate gyrus is believed to play an important pathophysiological role during experimentally induced kindling. In this study, we investigated whether an altered content of the calcium binding protein calbindin-D(28k) or an increased intrinsic excitability of hippocampal granule cells contribute to the induction of the kindling phenomenon. We determined the firing pattern of granule cells in hippocampal slices using perforated patch-clamp recordings in current clamp mode. The expression of calbindin-D(28k) and glutamic acid decarboxylase (GAD(67)) by granule cells was analyzed immunohistochemically. Rats developed secondarily generalized limbic seizures within approximately 11 days of twice-daily stimulation of the amygdala. As reported for other kindling paradigms, this protocol induced a clear up-regulation of GAD(67) in granule cells, indicating their involvement in the induced neuronal activity. However, when comparing kindled and control rats, we could not detect any differences in intrinsic excitability: Firing frequency, after-hyperpolarisations, action potentials, input resistance and membrane potentials were nearly identical between both groups. Furthermore, we did not observe any differences in the calbindin-D(28k) immunoreactivity between groups. In every slice, virtually all granule cells were found to be strongly calbindin-D(28k) positive, and there was no apparent reduction in the general level of calbindin-D(28k) expression. We conclude that changes in intrinsic membrane properties or in the calbindin-D(28k) content of granule cells are not necessary for the development of amygdala kindling.
authors.affiliation: Experimental Neurophysiology, Department of Neurosurgery, NCH U1 R035, University Clinic Bonn, Sigmund-Freud-Strasse 25, D-53105 Bonn, Germany. dirk.dietrich@ukb.uni-bonn.de
authors.forename: D
authors.initials: D
authors.lastname: Dietrich
authors.forename: M
authors.initials: M
authors.lastname: Podlogar
authors.forename: G
authors.initials: G
authors.lastname: Ortmanns
authors.forename: H
authors.initials: H
authors.lastname: Clusmann
authors.forename: T
authors.initials: T
authors.lastname: Kral
mesh_terms: D000200:Action Potentials / Q000502:physiology* / Q000528:radiation effects; D000679:Amygdala / Q000528:radiation effects; D000818:Animals; D064092:Calbindin 1; D064026:Calbindins; D002452:Cell Count / Q000379:methods; D004558:Electric Stimulation / Q000379:methods; D005968:Glutamate Decarboxylase / Q000378:metabolism; D006624:Hippocampus / Q000166:cytology*; D007150:Immunohistochemistry / Q000379:methods; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000378:metabolism; D007696:Kindling, Neurologic / Q000502:physiology*; D008297:Male; D009474:Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D064030:S100 Calcium Binding Protein G / Q000378:metabolism*
chemical_list: C576500:Calb1 protein, rat; D064092:Calbindin 1; D064026:Calbindins; D007527:Isoenzymes; D064030:S100 Calcium Binding Protein G; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1