Volume 16, Number 21,
Issue of November 1, 1996
pp. 6766-6774
Copyright ©1996 Society for Neuroscience
Hippocampal Cell Responses in Mice with a Targeted Glucocorticoid
Receptor Gene Disruption
Received June 5, 1996; revised July 26, 1996; accepted Aug. 20, 1996.
Wouter Hesen1,
Henk Karst1, 2,
Onno Meijer2,
Tim J. Cole3,
Wolfgang Schmid3,
E. Ronald de
Kloet2,
Gunther Schütz3, and
Marian Joëls1
1 Department of Experimental Zoology, University of
Amsterdam, 1098 SM Amsterdam, The Netherlands, 2 Division
of Medical Pharmacology, Leiden Amsterdam Center for Drug Research,
Leiden University, 2300 RA Leiden, The Netherlands, and
3 German Cancer Research Institute, DE-69009 Heidelberg,
Germany
Previous studies in rats have shown that cellular properties
of hippocampal CA1 neurons are under coordinative control of
mineralocorticoid and glucocorticoid receptors (MRs and GRs,
respectively). In the present study, we examined electrical properties
under conditions of exclusive MR occupation, by using mice with a
genetic defect in GRs obtained by homologous recombination techniques.
It appeared that in the animals homozygous for the genetic defect, the
properties studied, i.e., the voltage-gated Ca currents and responses
to serotonin and the cholinergic analog carbachol, resembled the
effects observed in adrenalectomized mice, i.e., when no steroid
receptors are activated. This may point to the necessity of functional
GRs for the development of MR-induced actions. Ca current amplitude and
transmitter responses in the heterozygous animals, which combine a
reduced amount of GRs in the hippocampus with relatively high
circulating levels of corticosterone, were large compared with those in
the wild-type controls; this resembles the responses that were observed
previously in rats subjected to a very high dose of corticosterone.
These findings exemplify the use of GR knockout mice for the study of
cellular properties in the brain. Further substantiation of the
observations, however, awaits the development of site-specific,
inducible GR knockouts.
Key words:
calcium currents;
serotonin;
carbachol;
hexokinase;
electrophysiology;
quantitative enzyme histochemistry