The common degu (Octodon degus) is an emerging model in biomedical science research due to its longevity and propensity to develop human-like conditions. However, there is a lack of standardized techniques for this non-traditional laboratory animal. In an effort to characterize the model, we developed a chromatic pupillometry setup and analysis protocol to characterize the pupillary light reflex (PLR) in our animals. The PLR is a biomarker to detect early signs for central nervous system deterioration. Chromatic pupillometry is a non-invasive and anesthesia-free method that can evaluate different aspects of the PLR, including the response of intrinsically photosensitive retinal ganglion cells (ipRGCs), the disfunction of which has been linked to various disorders. We studied the PLR of 12 degus between 6 and 48 months of age to characterize responses to LEDs of 390, 450, 500, 525 and 605 nm, and used 5 with overall better responses to establish a benchmark for healthy PLR (PLR+) and deteriorated PLR (PLR-). Degu pupils contracted up to 65% of their horizontal resting size before reaching saturation. The highest sensitivity was found at 500 nm, with similar sensitivities at lower tested intensities for 390 nm, coinciding with the medium wavelength and short wavelength cones of the degu. We also tested the post-illumination pupillary response (PIPR), which is driven exclusively by ipRGCs. PIPR was largest in response to 450 nm light, with the pupil preserving 48% of its maximum constriction 9 s after the stimulus, in contrast with 24% preserved in response to 525 nm, response driven mainly by cones. PLR- animals showed maximum constriction between 40% and 50% smaller than PLR+, and their PIPR almost disappeared, pointing to a disfunction of the iPRGCs rather than the retinal photoreceptors. Our method thus allows us to non-invasively estimate the condition of experimental animals before attempting other procedures.

中文翻译：

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色度瞳孔测定法用于表征八爪鱼的瞳孔光反射。

普通degu（Octodon degus）是生物医学科学研究中的新兴模型，因为它具有长寿和发展类人疾病的倾向。但是，这种非传统的实验动物缺乏标准化的技术。为了表征该模型，我们开发了一种色度瞳孔测定设置和分析协议来表征动物中的瞳孔光反射（PLR）。PLR是用于检测中枢神经系统恶化的早期迹象的生物标志物。色度瞳孔测定法是一种无创且无麻醉的方法，可以评估PLR的不同方面，包括固有光敏性视网膜神经节细胞（ipRGC）的反应，该疾病的功能障碍与多种疾病有关。我们研究了6至48个月大的12个degus的PLR，以表征对390、450、500、525和605 nm LED的响应，并使用5个总体响应更好的LED建立了健康PLR（PLR +）和退化LED的基准PLR（PLR-）。德固族的学生在达到饱和状态之前收缩了其水平静息大小的65％。发现最高的灵敏度是在500 nm处，在390 nm的较低测试强度下具有相似的灵敏度，这与degu的中波长和短波长锥一致。我们还测试了仅由ipRGC驱动的照明后瞳孔反应（PIPR）。PIPR对450 nm的光响应最大，在刺激后9 s，瞳孔保留其最大收缩的48％，而对525 nm的响应保留24％，主要由视锥驱动。PLR-动物的最大收缩幅度比PLR +小40％至50％，并且其PIPR几乎消失，表明iPRGC而非视网膜感光器功能异常。因此，我们的方法使我们能够在尝试其他程序之前非侵入性地估计实验动物的状况。