Cellular and sub-cellular localisation of GABA and GABA

Following the recent discovery that GABA receptors expressed in cell lines are only functional when both GABA and GABA are B B1 B2 expressed, the present study reports on the development of polyclonal antisera specific for carboxyl-terminal portions of the two related GABA receptor components respectively. Western blotting indicated the specificity of affinity-purified antibodies for native or B recombinant expressed GABA and GABA , with no cross-reactivity, both antisera detecting the heterodimer in rat cerebellar BR1 BR2 membranes. Immunohistochemistry revealed a distinct distribution of both receptor proteins in rat cerebellum. GABA immunoreactivity B1 was primarily located in the granule cell layer and Purkinje cells, with discrete immuno-positive cell bodies being present in the molecular layer. GABA staining revealed intense immunoreactivity in the molecular layer, with weaker staining in the granule cell layer. Purkinje B2 cell bodies were less intensely immuno-positive for GABA . Co-localisation of both receptor proteins was observed using double B2 immunofluorescence techniques, consistent with the notion that both proteins are required for the formation of functional GABAB receptors in vivo. Immunofluorescence also indicated that GABA receptors did not co-localise with glial fibrillary acid protein, B confirming a neuronal localisation for GABA receptors. Electron microscopic analysis of the molecular layer revealed that the B distribution of immunolabelling for both GABA and GABA was mainly located on the membrane of Purkinje cell dendrites and B1 B2 spines and in parallel fibre terminals.  2000 Elsevier Science B.V. All rights reserved. Theme: Neurotransmitters, modulators, transporters and receptors Topic: GABA receptors