Abstract
Purpose :
Ophthalmic disorders are among the most prevalent comorbidities of Down syndrome (DS). Therefore, when studying mouse models of DS, ignoring how vision is affected in these animals can lead to misinterpretation of results from behavioral tests highly dependent on the integrity of the visual system. Here, we used optical imaging technologies and electroretinography (ERG) to study eye structure and function in two important mouse models of DS: Ts65Dn and Dp(16)1Yey/+.
Methods :
Cornea and anterior segment were examined by slit-lamp. Thickness of retinal layers was quantified by Optical Coherence Tomography (OCT). Retinal vasculature parameters were assessed in vivo by bright field and fluorescent imaging, and in vitro by retinal flat-mount preparations. A Ganzfeld ERG system was used to assess retinal function in adult mice by evaluating ERG responses to flash stimuli of various intensities.
Results :
Total retinal thickness is significantly increased in Ts65Dn and Dp(16)1Yey/+ compared with control mice; primarily due to increased thickness of the inner nuclear layer (INL). Additionally, increased retinal vessel caliber was found in chromosomally altered mice when compared with their respective controls. ERG responses in Ts65Dn and Dp(16)1Yey/+ mice showed subtle, but significant alterations compared to their controls. ERG properties were independent of the thickness of the INL, but dependent on the anesthetic agent used (ketamine, tribromoethanol, or urethane).
Conclusions :
We provide evidence of retinal alterations in Ts65Dn and Dp(16)1Yey/+ mice that are similar to those reported in persons with DS. Our ERG results should raise caution about the choice of anesthetic agents in ERG experiments.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.