Figure 4.

Effects of GABAergic signaling in oligodendroglial differentiation and myelination. OPCs express GABA_A and GABA_BRs. Activation of GABA_ARs causes depolarization in these cells (Kirchhoff and Kettenmann, 1992; Baraban et al., 2018). In absence of axons (top), they lose GABA_AR expression as they differentiate into mature OLs (Berger et al., 1992; Arellano et al., 2016); however, expression of GABA_BRs is largely stable over time (Serrano-Regal et al., 2020). In the presence of axons (low), GABA_AR expression is modulated by neurons, as OPCs maintain their expression towards the myelinating stage (Arellano et al., 2016). Moreover, oligodendroglial cells express GAT-1 transporter and synthesize GABA, which may be released by reverse GAT-1 operation and activate GABA receptors (GABARs) in an autocrine manner. Exogenous GABA or baclofen promotes oligodendroglial differentiation and myelination in vitro (Serrano-Regal et al., 2020).