Espion erg equipment

At 4–6 weeks of age, mice were dark-adapted overnight, manipulations were conducted under dim red light illumination, and recordings were made using Espion ERG Diagnosys equipment (Diagnosys LLL, Littleton, MA), as previously described (Wert et al., 2013 (link), 2015 (link); Wert, Sancho-Pelluz, et al., 2014 (link); Wert, Skeie, et al., 2014 (link)). Mice were first anesthetized by IP injection of 0.1 ml/10 g body weight of anesthetic solution (1 ml of 100 mg/ml ketamine and 0.1 ml of 20 mg/ml xylazine in 8.9 ml of phosphate-buffered saline). Body temperature was maintained at 37°C using a heating pad. Mouse pupils were dilated by topical administration of 2.5% phenylephrine hydrochloride and 1% tropicamide. Electrodes were placed on the corneas, and gonioscopic prism solution (Alcon) applied to each eye. ERG responses were recorded simultaneously from both eyes using an Espion Visual Electrophysiological System (Diagnosys). Rod and mixed rod–cone responses were recorded from dark-adapted mice using pulses of 0.001 and 3 cd·s/m² (white 6,500K), respectively. Then, mice were light-adapted for photopic responses for at least 10 min in the Ganzfeld dome. Recordings were carried out under rod-suppressing continuous background illumination of 30cd/m² (white 6,500K), Cone responses were recorded using pulses of 30 cd·s/m² (xenon).

Mice were dark-adapted overnight, manipulations were conducted under dim red light illumination and recordings were made using Espion ERG Diagnosys equipment (Diagnosys LLL, Littleton, MA, USA). Adult C57BL/6J control mice were tested at the beginning of each session to ensure equal readouts from the electrodes for both eyes before testing the transgenic experimental mice. Both eyes were recorded simultaneously. A total of 40–60 responses were averaged for each trial. All further detail on the electroretinogram (ERG) method has been described previously.^{19 (link),20 (link)} Unpaired t-tests between C57BL6/J controls and transgenic mice were used to determine statistical significance for the a- and b-wave maximal amplitudes at 1 and 2 months of age.