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. Author manuscript; available in PMC: 2020 Jan 15.
Published in final edited form as: Brain Res. 2018 Feb 23;1703:31–40. doi: 10.1016/j.brainres.2018.02.031

Figure 4. Neurosteroid modulation of synaptic and extrasynaptic receptors of DGCs.

Figure 4

A: A schematic diagram showing the expression of γ2 subunit-containing receptors at the synaptic and extrasynaptic sites on the membrane of DGCs where they are exposed to GABA released from the presynaptic terminal. The excess GABA in the synaptic cleft can spread to extrasynaptic sites to activate α4βxδ subunit-containing receptors. B: A representative averaged miniature inhibitory post-synaptic current showing prolongation of decay after application of allopregnanolone (10 nM, red trace). C: A trace illustrating allopregnanolone modulation of tonic current. Allopregnanolone (10 nM) bath application was started at the arrowhead and it increased the holding current. Once a stable response was obtained, bath application of the GABAR blocker picrotoxin (50 μM) was started (arrow), and it reduced the holding current. Traces below (a′, b′ and c′) show membrane noise, which is another measure of tonic current, at baseline (a), after application of allopregnanolone (b), and after application of picrotoxin (c).