Chunk #27 — Potential Biological Mechanism of Hippocampal Sensitivity to AUDs: Impact of Altered GluN and GABAR Signaling in the Hippocampus on Adult Neurogenesis — Regulation of Neurogenesis by GABAaRs
The granule cells of the hippocampus are maintained in a quiescent state by the mossy fibers of the hilus via GABA-ergic regulation [reviewed in Ref. (161)]. Evidence has demonstrated that these cells do express GABAaRs (162), as do the surrounding cells of the DG (163, 164); therefore, not only are the granule cells sensitive to enhanced GABA-ergic transmission during exposure to chronic alcohol but are also subject to secondary regulation due to the modulation of activity of surrounding cells by alcohol’s actions on the GABAaR. As specific subunit compositions of the GABAaR can modulate important stages of neurogenesis (particularly the maintenance of quiescent cells and proliferation), this could provide a potential mechanism by which alcohol could be modulating neurogenesis in dependent individuals. During periods of alcohol intake, GABAaR function would be supported and facilitated such that quiescent cells would be maintained (165, 166) as such and proliferation would be reduced (167–169). In the acute absence of alcohol, the facilitation of GABAaR activity would be lost and quiescent cells would be allowed to proliferate, and these effects could result in increase
