FIGURE 1.
Progressive alteration of electroretinographic responses in transgenic mice with increased intraocular IGF-I. A–F, evolution over time of ERG responses in TgIGF-I mice (pink lines) compared with healthy littermates (black lines). With age, TgIGF-I showed a progressive decline in the recorded amplitudes in response to all stimuli tested. A, scotopic threshold response, representing highly sensitive responses of rod photoreceptors; B, scotopic b-wave, representing rod responses; C, mixed scotopic, reflecting stimulation of both rod and cones under scotopic conditions; D, oscillatory potentials, which measure INL neuronal activity; E, photopic b-wave, depicting cone responses; F, flicker, repetitive photopic stimulations that analyze cone recovery. There were statistically significant reductions in the responses in animals aged more than 7.5 months. G, ERG responses were recorded 6 months after a single intravitreal administration of AAV2-hPEDF (left eye) and AAV2-null (right eye) vectors to TgIGF-I mice aged 1.5 months. Age-matched WT littermates were used as controls. Scotopic b-wave (Bscot), mixed a and b-waves, oscillatory potentials, and photopic b-wave (Bphot) were analyzed. Despite the counteraction of retinal neovascularization, the overexpression of PEDF was not able to ameliorate the electroretinographic responses of treated eyes, which presented reduced amplitudes in all tests performed, similar to those of null-injected, untreated eyes. Values are expressed as the mean ± S.E. of 5–9 animals/group. *, p <0.05; **, p <0.01; ***, p <0.001.