Figure 6: Dual inhibition of GABAA and GABAA-ρ receptors enhances proliferation. Tg(1016tuba1a:gfp) zebrafish were intravitreally injected with either 1× PBS (A), 6.25 nmol of the GABAA antagonist gabazine (B), 12.5 nmol of the GABAA-ρ receptor inhibitor TPMPA (C), or both (D). Fish were allowed to recover for 48 hours before sectioning and immunostaining with antibodies against PCNA or GFP to monitor DNA replication or dedifferentiation of Müller glia, respectively. GCL: Ganglion cell layer; INL: inner nuclear layer; ONL: outer nuclear layer. Scale bars: 50 μm. Green: tuba1a:GFP; red: PCNA; blue: TO-PRO-3 (A–D). Number of optical slices: 37 (A), 49 (B), 48 (C), and 61 (D). (E) Quantification of PCNA+ cells. Each data point is a separate eye and is an average of two sections, counting all PCNA+ cells in the inner nuclear layer. One-way analysis of variance with Tukey's multiple comparison tests were used to test for significance. Error bars are the mean ± SEM. n = 10 PBS, n = 10 Gabazine, n = 9 TPMPA, and n = 10 TPMPA/Gabazine. ****P = 1.2 × 10–5 (PBS vs. Gabazine/TPMPA), **P = 0.0016 (Gabazine vs. Gabazine/TPMPA); ***P = 0.0006 (TPMPA vs. Gabazine/TPMPA). GABAA: Gamma aminobutyric acid A; GFAP: glial fibrillary acid protein; GFP: green fluorescent protein; PCNA: proliferating cell nuclear antigen; TPMPA: (1,2,5,6-tetrahydropyridin-4-yl)methylphosphinic acid.