GABAergic signaling in the developing cerebellum.

In the adult central nervous system (CNS), GABA is a predominant inhibitory neurotransmitter that regulates glutamatergic activity. Recent studies have revealed that GABA serves as an excitatory transmitter in the immature CNS and acts as a trophic factor for brain development. Furthermore, synaptic transmission by GABA is also involved in the expression of higher brain functions, such as memory, learning and anxiety. These results indicate that GABA plays various roles in the expression of brain functions and GABAergic roles change developmentally in accordance with alterations in GABAergic transmission and signaling. We have investigated morphologically the developmental changes in the GABAergic transmission system and the key factors important for the formation of GABAergic synapses and networks using the mouse cerebellum, which provides an ideal system for the investigation of brain development. Here, we focus on GABA and GABA(A) receptors in the developing cerebellum and address the processes of how GABA exerts its effect on developing neurons and the mechanisms underlying the formation of functional GABAergic synapses.