Figure 1: Inhibition of the GABAA-ρ receptor in the absence of retina damage results in a Müller glia-derived proliferative response. Tg(1016tuba1a:gfp) zebrafish were intravitreally injected with either 1× PBS (A) or 25 nmol of the GABAA-ρ receptor inhibitor (1,2,5,6-tetrahydropyridin-4-yl)methylphosphinic acid (TPMPA; B), and then allowed to recover for 48 hours before sectioning. Immunostaining was performed with antibodies against PCNA or GFP to monitor DNA replication or dedifferentiation of Müller glia, respectively. Green: tuba1a:GFP; red: PCNA; blue: TO-PRO-3 in A and B. Scale bars: 50 μm. Number of optical slices: 53 (A) and 55 (B). GCL: Ganglion cell layer; INL: inner nuclear layer; ONL: outer nuclear layer. (C) Quantification of PCNA+ cells. Each data point is from a separate eye and is an average of two sections, counting all PCNA+ cells in the inner nuclear layer. Two-tailed Student's t-tests were used to test for significance. Error bars indicate the mean ± SEM. n = 29. ****P = 1.12 × 10–13, vs. PBS. GABA: Gamma aminobutyric acid; GFP: green fluorescent protein; PCNA: proliferating cell nuclear antigen.