Figure 6.

Early blockade of TH prevents the effects of EE on retinal acuity. A, Schematic protocol. B, Left, Examples of images from P10 whole-mount retinas taken from eyes of EE and non-EE rats or of EE rats intraocularly injected at P6 and P9 with TH-AS or TH-MS oligonucleotides. Right, The number of TH-positive cells is reduced by the treatment with antisense oligonucleotides with respect to the mismatch treatment. In retinas from EE rats injected with TH-AS (n = 4), the number of TH-positive cells is significantly lower (asterisks) than in retinas of EE animals treated with TH-MS (n = 4) (39 ± 2 vs 58 ± 3 cells/mm²) and in retinas from EE untreated animals (66 ± 3 cells/mm²; n = 5) but does not differ from that in non-EE retinas (46 ± 3 cell/mm²; n = 6) (one-way ANOVA, p = 0.001). Scale bar, 100 μm. Error bars represent SEM. C, In a group of six EE animals injected at P6 and P9 with TH-AS in one eye and with TH-MS as a control in the other eye, retinal acuity was assessed with P-ERG at P25. After EE, retinal acuity in TH-MS eyes did not differ from that of EE eyes [0.62 ± 0.02 vs 0.67 ± 0.03 cycles/degree (c/deg)], whereas retinal acuity after EE in TH-AS animals was significantly lower than in EE rats and did not differ from that of non-EE rats of the same age [0.53 ± 0.01 vs 0.51 ± 0.01 c/deg; one-way ANOVA, p = 0.001, post hoc Tukey's test; EE untreated eyes vs EE TH-AS-treated eyes, p < 0.001 (asterisk); EE untreated eyes vs EE TH-MS-treated eyes, p = 0.208; EE TH-AS-treated eyes vs non-EE untreated eyes, p = 0.879; EE TH-MS-treated eyes vs TH-AS-treated eyes, p = 0.010 (asterisk)]. Error bars represent SEM. In five animals, retinal acuity was determined for both eyes (data points joined by dotted lines); it is evident that for all of these animals the acuity of the TH-AS-treated eye is lower than that for the TH-MS-treated contralateral eye (paired t test, p = 0.026).