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1The Queensland Brain Institute and School of Biomedical Sciences, The University of Queensland, Brisbane, Australia; and 2Department of Biology, Science Faculty, The University of Isfahan, Isfahan, Iran
Submitted 3 September 2008; accepted in final form 31 October 2008
-Aminobutyric acid (GABA) is the primary inhibitory transmitter in the mammalian brain. This inhibition is mediated by type A (GABAA) receptors that are pentameric proteins assembled from 14 different subunits. Although inhibitory synaptic transmission has been studied in the amygdala, the subunit composition of receptors present at different synapses is not well understood. In this study we examined the subunit composition of GABAA receptors at synapses in the basolateral and central amygdala. Using receptors expressed in HEK293 cells we first determined the pharmacology of receptors of different subunit compositions. We then used this pharmacological profile to test the properties of receptors present at synapses in the central and basolateral amygdala. These results show that the GABAA receptor subunits are differentially distributed in the amygdala. Our data indicate that in the basolateral amygdala, GABAergic synapses are likely composed of receptors that contain
2βx
2 subunits. In the central amygdala receptors at the medial input, carrying afferents from the bed nucleus of the stria terminalis contain similar receptors, whereas in the lateral input GABA receptors likely contain
1 subunits. These inputs arise from the intercalated cells masses, thought to be responsible for mediating extinction of conditioned fear, raising the possibility of new targets for the treatment of anxiety-related disorders.
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