Abstract
Muscimol, a potent γ-aminobutyric acid (GABA) agonist, was used in a radioactively labeled form for the quantitative localization of GABA receptors in the rat's hippocampus (CA1 to CA4) and area dentata. [3H]Muscimol was injected directly in vivo or used in the incubation medium of tissue slices, and the tissues were then fixed and prepared for autoradiography. [3H]Muscimol-bound GABA receptors are weakly though evenly distributed over the fimbria of the fornix. There was a laminar distribution in CA1 to CA4 and the area dentata, with an increasing density of the GABA receptors in that order. The lowest density was found in the alveus of CA1 and CA2 and the highest in the stratum granulosum of the area dentata. The greatest density was found in the neuropil between granule cells, in which are found dendrites and the basket-like plexuses of the inhibitory GABA-containing local circuit neurons. The molecular layers of the area dentata, CA1, and CA2 also have a high density of GABA receptors, indicating a probable distribution over the dendrites of granule and pyramidal cells. The laminar distribution of GABA receptors in the hippocampus and area dentata is similar to the distributions of the GABA-synthesizing enzyme, glutamate decarboxylase, and of GABA previously published. Neurons with label of various density are found in the polymorphic cell layer of the area dentata, in the stratum radiatum of CA3, and in CA4. These are possibly the GABA-containing basket local circuit neurons.
Keywords: inhibition, granule, pyramidal cells, basket cells, lamination
Full text
PDF




Images in this article
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- ANDERSEN P., ECCLES J. C., LOYNING Y. LOCATION OF POSTSYNAPTIC INHIBITORY SYNAPSES ON HIPPOCAMPAL PYRAMIDS. J Neurophysiol. 1964 Jul;27:592–607. doi: 10.1152/jn.1964.27.4.592. [DOI] [PubMed] [Google Scholar]
- ANDERSEN P., ECCLES J. C., LOYNING Y. PATHWAY OF POSTSYNAPTIC INHIBITION IN THE HIPPOCAMPUS. J Neurophysiol. 1964 Jul;27:608–619. doi: 10.1152/jn.1964.27.4.608. [DOI] [PubMed] [Google Scholar]
- Andersen P., Blackstad T. W., Lömo T. Location and identification of excitatory synapses on hippocampal pyramidal cells. Exp Brain Res. 1966;1(3):236–248. doi: 10.1007/BF00234344. [DOI] [PubMed] [Google Scholar]
- Andersen P., Holmqvist B., Voorhoeve P. E. Entorhinal activation of dentate granule cells. Acta Physiol Scand. 1966 Apr;66(4):448–460. doi: 10.1111/j.1748-1716.1966.tb03223.x. [DOI] [PubMed] [Google Scholar]
- Brehm L., Hjeds H., Krogsgaard-Larsen P. The structure of muscimol, a GABA analogue of restricted conformation. Acta Chem Scand. 1972;26(3):1298–1299. doi: 10.3891/acta.chem.scand.26-1298. [DOI] [PubMed] [Google Scholar]
- Chan-Palay V. Autoradiographic localization of gamma-aminobutyric acid receptors in the rat central nervous system by using [3H]muscimol. Proc Natl Acad Sci U S A. 1978 Feb;75(2):1024–1028. doi: 10.1073/pnas.75.2.1024. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Curtis D. R., Duggan A. W., Felix D., Johnston G. A. Bicuculline, an antagonist of GABA and synaptic inhibition in the spinal cord of the cat. Brain Res. 1971 Sep 10;32(1):69–96. doi: 10.1016/0006-8993(71)90156-9. [DOI] [PubMed] [Google Scholar]
- Curtis D. R., Felix D., McLellan H. GABA and hippocampal inhibition. Br J Pharmacol. 1970 Dec;40(4):881–883. doi: 10.1111/j.1476-5381.1970.tb10663.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Enna S. J., Collins J. F., Snyder S. H. Stereospecificity and structure--activity requirements of GABA receptor binding in rat brain. Brain Res. 1977 Mar 18;124(1):185–190. doi: 10.1016/0006-8993(77)90878-2. [DOI] [PubMed] [Google Scholar]
- Eugster C. H. Chemie der Wirkstoffe aus dem Fliegenpilz (Amanita muscaria) Fortschr Chem Org Naturst. 1969;27:261–321. [PubMed] [Google Scholar]
- Johnston G. A., Krogsgaard-Larsen P., Stephanson A. L., Twitchin B. Inhibition of the uptake of GABA and related amino acids in rat brain slices by the optical isomers of nipecotic acid. J Neurochem. 1976 May;26(5):1029–1032. doi: 10.1111/j.1471-4159.1976.tb06488.x. [DOI] [PubMed] [Google Scholar]
- Johnston G. A., Krogsgaard-Larsen P., Stephanson A. Betel nut constituents as inhibitors of gamma-aminobutyric acid uptake. Nature. 1975 Dec 18;258(5536):627–628. doi: 10.1038/258627a0. [DOI] [PubMed] [Google Scholar]
- Krogsgaard-Larsen P., Johnston G. A., Curtis D. R., Game C. J., McCulloch R. M. Structure and biological activity of a series of conformationally restricted analogues of GABA. J Neurochem. 1975 Dec;25(6):803–809. doi: 10.1111/j.1471-4159.1975.tb04411.x. [DOI] [PubMed] [Google Scholar]
- Krogsgaard-Larsen P., Johnston G. A. Inhibition of GABA uptake in rat brain slices by nipecotic acid, various isoxazoles and related compounds. J Neurochem. 1975 Dec;25(6):797–802. doi: 10.1111/j.1471-4159.1975.tb04410.x. [DOI] [PubMed] [Google Scholar]
- Storm-Mathisen J. Choline acetyltransferase and acetylcholinesterase in fascia dentata following lesion of the entorhinal afferents. Brain Res. 1974 Nov 15;80(2):181–197. doi: 10.1016/0006-8993(74)90683-0. [DOI] [PubMed] [Google Scholar]
- Storm-Mathisen J., Fonnum F. Quantitative histochemistry of glutamate decarboxylase in the rat hippocampal region. J Neurochem. 1971 Jun;18(6):1105–1111. doi: 10.1111/j.1471-4159.1971.tb12039.x. [DOI] [PubMed] [Google Scholar]
- Storm-Mathisen J. Glutamate decarboxylase in the rat hippocampal region after lesions of the afferent fibre systems. Evidence that the enzyme is localized in intrinsic neurones. Brain Res. 1972 May 26;40(2):215–235. doi: 10.1016/0006-8993(72)90130-8. [DOI] [PubMed] [Google Scholar]
- Storm-Mathisen J., Guldberg H. C. 5-Hydroxytryptamine and noradrenaline in the hippocampal region: effect of transection of afferent pathways on endogenous levels, high affinity uptake and some transmitter-related enzymes. J Neurochem. 1974 May;22(5):793–803. doi: 10.1111/j.1471-4159.1974.tb04297.x. [DOI] [PubMed] [Google Scholar]
- Wolman M. A fluorescent histochemical procedure for gamma-aminobutyric acid. Histochemie. 1971;28(2):118–130. doi: 10.1007/BF00279856. [DOI] [PubMed] [Google Scholar]



