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. 2008 Oct 14;6(10):1–18. doi: 10.1371/journal.pbio.0060249

Figure 8. GABA Acts through GABAA and GABAC Receptors.

Figure 8

(A) Coapplication of the GABAA receptor agonist muscimol (200 μM) and the GABAC receptor agonist CACA (50 μM) to retinal explants mimicked the inhibitory action of 1 mM GABA on retinal PER2::LUC rhythms.

(B) The GABAA and GABAC receptor agonist TACA (80 μM) inhibited PER2::LUC expression rhythms in a way similar to 1 mM GABA.

(C) The GABAA receptor antagonist SR-95531 (40 μM) and the GABAC receptor antagonist TPMPA (100 μM) greatly attenuated the action of GABA when they were coapplied with 1 mM GABA.

(D) Coapplication of SR-95531 (40 μM) and TPMPA (100 μM) increased the amplitude of retinal PER2::LUC rhythms.

Bars in (A–D) indicate the duration of treatment.

(E) Blockade of GABAA and GABAC receptors with 40 μM SR-95531 and 100 μM TPMPA (solid line, filled circles) significantly increased the amplitude of retinal PER2::LUC rhythms compared with vehicle-treated explants (dashed line, open circles). Mean peak-to-trough amplitudes (±SEM, n = 5; normalized to the amplitude of the second circadian cycle) of retinal PER2::LUC rhythms were plotted as a function of PER2::LUC cycle number in the LumiCycle. A single asterisk (*) indicates p < 0.007, post hoc t-test with Bonferroni-corrected α = 0.007.