The GABA
A receptor provides the majority of inhibitory neurotransmission in the adult central nervous system but in immature brain is responsible for much of the excitatory drive, a requirement for normal brain development. It is well established
that GABA
A receptor subunit expression changes across the course of brain development. In the present study, we have
identified a splice variant of the GABAA receptor α3 subunit which appears unique to the developing brain, referred to here
as the GABA
A receptor α3 subunit neonatal variant (GABAA receptor α3N). RT-PCR and sequence analysis revealed splicing of exon 8 of the α3 subunit. Western blot analysis showed expression of GABAA receptor α3N in the cortex of several
neonatal species and significantly reduced expression of this splice variant in the corresponding adult brains. Expression was
evident in multiple brain regions and decreased across development in the pig. Fractionation revealed differential cellular
localisation in the parietal cortex, hippocampus and thalamus of the full-length GABAA receptor α3 and GABAA receptor
α
3N. Immunoprecipitation showed direct interaction with the GABAA receptor subunits α1 and γ2 but not with gephyrin.
Keywords GABAA receptor · Development · Neonatal

• Identification and expression of a unique neonatal variant of the GABA A receptor α3