Cloning and characterization of GABAA α subunits and GABAB subunits in Xenopus laevis during development.

Gamma-aminobutyric acid (GABA), the major inhibitory neurotransmitter in the adult nervous system, acts via two classes of receptors, the ionotropic GABA(A) and metabotropic GABA(B) receptors. During the development of the nervous system, GABA acts in a depolarizing, excitatory manner and plays an important role in various neural developmental processes including cell proliferation, migration, synapse formation, and activity-dependent differentiation. Here we describe the spatial and temporal expression patterns of the GABA(A) and GABA(B) receptors during early development of Xenopus laevis. Using in situ hybridization and qRT-PCR, GABA(A) α2 was detected as a maternal mRNA. All other α-subunits were first detected by tailbud through hatching stages. Expression of the various subunits was seen in the brain, spinal cord, cranial ganglia, olfactory epithelium, pineal, and pituitary gland. Each receptor subunit showed a distinctive, unique expression pattern, suggesting these receptors have specific functions and are regulated in a precise spatial and temporal manner.