GABAA receptor subunits in the rat hippocampus I: Immunocytochemical distribution of 13 subunits
Section snippets
Animals and tissue preparation
Male Sprague–Dawley rats (250–350 g, Forschungsinstitut für Versuchstierzucht, Himberg, Austria) were injected with a lethal dose of thiopental (150 mg/kg, i.p., Sanabo, Austria) and perfused immediately through the ascending aorta with 50 ml ice-cold phosphate-buffered saline (PBS; 50 mM phosphate buffer, pH 7.4 in 0.9% NaCl) followed by 200 ml chilled 4% paraformaldehyde in PBS. The brains were removed from the skulls and divided by coronal cuts into three parts. They were postfixed in the same
Antibodies
In the present experiments the antibodies appeared highly specific, revealing staining patterns characteristic for each subunit in different brain areas (data not shown). Notably, subunits which were less prominently expressed in the hippocampus were detected at considerable concentrations in other brain regions: e.g., α3 in the cortex, striatum and tuberculum olfactorium, α6 in granule cells of the cerebellum, β1 in the cerebral cortex, tuberculum olfactorium and cerebellum, γ1 in the ventral
Discussion
The present data provide a detailed survey of the immunocytochemical distribution of 13 GABAA receptor subunits in the hippocampal formation in the rat.
Conclusion
A heterogeneous distribution of GABAA receptor subunits has been found within the hippocampus. The predominant subunits within the molecular layer of the dentate gyrus are α1, α2, α4, β1, β3, γ2 and δ. Within the dendritic areas of the hippocampus proper the α1-, α2-, α5-, β3- and the γ2- subunits predominate. GABAA receptors within local circuit neurons of the hippocampus consist mainly of α1, β2, and of either γ2- or δ-subunits (or both γ2 and δ). These data imply heterogeneously constituted
Acknowledgements
We would like to thank C. Wanzenböck and E. Kirchmair for technical assistance and C. Trawöger for preparing the photographs. We also thank Dr U. Berresheim for critically reading the manuscript. The work was supported by grants from the Austrian Science Foundation (to G.S. and W.S.), the Jubiläumsfoolns of the Austrian National Bank (to G.S.) and of the Japanese Foundation for Aging and Health (to K.T.). For information concerning antibodies contact Dr W. Sieghart. We would like to dedicate
References (50)
- et al.
Kynurenine pathway enzymes in a rat model of chronic epilepsy: immunohistochemical study of activated glial cells
Neuroscience
(1993) - et al.
A prominent epitope on GABAA receptors is recognized by two different monoclonal antibodies
Brain Res.
(1992) - et al.
Early degeneration of calretinin-containing neurons in the rat hippocampus after ischemia
Neuroscience
(1993) - et al.
Identification of α2- and α3-subunits of the GABAA-benzodiazepine receptor complex purified from the brains of young rats
Fedn Eur. biochem. Socs Lett.
(1990) - et al.
Regulation of GABAA receptor function by protein kinase C phosphorylation
Neuron
(1994) - et al.
Microglial and astrocytic cell responses in the rat hippocampus after an intracerebroventricular kainic acid injection
Expl Neurol.
(1993) - et al.
Bridging the cleft at GABA synapses in the brain
Trends Neurosci.
(1994) - et al.
Immunoaffinity purification of γ-aminobutyric acidA (GABAA) receptors containing γ1-subunits
J. biol. Chem.
(1994) - et al.
Proliferative astrocytes may express fibrinonectin-like protein in the hippocampus of epileptic rats
Neurosci. Lett.
(1994) - et al.
Mapping of the β2 subunit gene (GABRB2) to microdissected human chromosome 5q34-q35 defines gene cluster for the most abundant GABAA receptor isoform
Genomics
(1994)