In:
European Journal of Neuroscience, Wiley, Vol. 13, No. 3 ( 2001-02), p. 477-486
Abstract:
The neurotransmitter GABA (γ‐aminobutyric acid) functions as the major inhibitory neurotransmitter in the central nervous system of vertebrates and invertebrates. In vertebrates GABA signals both through ionotropic receptors (GABA A , GABA C ), which induce fast synaptic inhibitory responses, and through metabotropic receptors (GABA B ), which play a fundamental role in the reduction of presynaptic transmitter release and postsynaptic inhibitory potentials. Whilst GABA A and GABA C receptors have been cloned from vertebrates as well as invertebrates, GABA B receptors have only been identified in vertebrate species to date, although indirect evidence suggests their existence in arthropods, too. Here we report the cloning of three putative invertebrate GABA B receptor subtypes (D‐GABA B R1, R2 and R3) isolated from Drosophila melanogaster . Whilst D‐GABA B R1 and R2 show high sequence identity to mammalian GABA B R1 and R2, respectively, the receptor D‐GABA B R3 seems to be an insect‐specific subtype with no known mammalian counterpart so far. All three D‐GABA B R subtypes are expressed in the embryonic central nervous system. In situ hybridization of Drosophila melanogaster embryos shows that two of the D‐GABA B Rs (D‐GABA B R1 and R2) are expressed in similar regions, suggesting a coexpression of the two receptors, whilst the third D‐GABA B R (D‐GABA B R3) displays a unique expression pattern. In agreement with these results we have only been able to functionally characterize D‐GABA B R1 and R2 when the two subtypes are coexpressed either in Xenopus laevis oocytes or mammalian cell lines, whilst D‐GABA B R3 was inactive in any combination. The pharmacology of the coexpressed D‐GABA B R1/2 receptor was different from the mammalian GABA B Rs: e.g. baclofen, an agonist of mammalian GABA B Rs, showed no effect.
Type of Medium:
Online Resource
ISSN:
0953-816X
,
1460-9568
DOI:
10.1046/j.1460-9568.2001.01410.x
Language:
English
Publisher:
Wiley
Publication Date:
2001
detail.hit.zdb_id:
2005178-5
SSG:
12
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