Tsuchiya Shunsuke, Buhr Ethan D, Higashide Tomomi, Sugiyama Kazuhisa, Van Gelder Russell N
Department of Ophthalmology, University of Washington School of Medicine, Seattle, Washington, United States of America.
Department of Ophthalmology, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan.
PLoS One. 2017 Sep 21;12(9):e0184790. doi: 10.1371/journal.pone.0184790. eCollection 2017.
Intraocular pressure (IOP) is known to have a strong circadian rhythm, yet how light/dark cycles entrain this rhythm is unknown. The purpose of this study was to assess whether, like the retina, the mammalian ciliary body and IOP clocks have an intrinsic ability to entrain to light/dark cycles.
Iris-ciliary body complexes were obtained from period2:luciferase (PER2::LUC) mice and cultured to measure bioluminescence rhythmicity. Pairs of the iris-ciliary body complex were exposed to antiphasic 9:15 h light/dark cycle in vitro. After 4 days of exposure to light/dark cycles, bioluminescence was recorded to establish their circadian phases. In addition, pairs of the iris-ciliary body complex co-cultured with the retinas or corneas of wild-type mice were also investigated. The IOP circadian changes of free-running Opn4-/-;rd1/rd1 mice whose behavior was antiphasic to wild-type were measured by a rebound tonometry, and compared with wild-type mice. Opn3, Opn4, and Opn5 mRNA expression in the iris-ciliary body were analyzed using RT-PCR.
The iris/ciliary body complex expressed Opn3, Opn4, and Opn5 mRNA; however, unlike in retina and cornea, neither the iris-CB complex nor the co-cultured complex was directly entrained by light-dark cycle in vitro. The diurnal IOP change of Opn4-/-;rd1/rd1 mice showed an antiphasic pattern to wild-type mice and their rhythms followed the whole-animal behavioral rhythm.
Despite expressing mRNA for several non-visual opsins, circadian rhythms of the iris-ciliary body complex of mice do not entrain directly to light-dark cycles ex vivo. Unlike retina, the iris/ciliary body clocks of blind mice remain synchronized to the organismal behavioral rhythm rather than local light-dark cycles. These results suggest that IOP rhythm entrainment is mediated by a systemic rather than local signal in mice.
已知眼压（IOP）具有强烈的昼夜节律，但光/暗周期如何调节这种节律尚不清楚。本研究的目的是评估哺乳动物睫状体和眼压时钟是否像视网膜一样具有内在的能力来适应光/暗周期。
从周期2：荧光素酶（PER2::LUC）小鼠中获取虹膜-睫状体复合体，并进行培养以测量生物发光节律。将成对的虹膜-睫状体复合体在体外暴露于反相的9:15小时光/暗周期。在暴露于光/暗周期4天后，记录生物发光以确定它们的昼夜节律相位。此外，还研究了与野生型小鼠的视网膜或角膜共培养的成对虹膜-睫状体复合体。通过回弹眼压计测量行为与野生型相反的自由活动的Opn4-/-;rd1/rd1小鼠的眼压昼夜变化，并与野生型小鼠进行比较。使用RT-PCR分析虹膜-睫状体中Opn3、Opn4和Opn5 mRNA的表达。
虹膜/睫状体复合体表达Opn3、Opn4和Opn5 mRNA；然而，与视网膜和角膜不同，虹膜-睫状体复合体或共培养复合体在体外均未直接被光暗周期调节。Opn4-/-;rdI/rd1小鼠的昼夜眼压变化与野生型小鼠呈反相模式，且它们的节律遵循整个动物的行为节律。
尽管小鼠虹膜-睫状体复合体表达了几种非视觉视蛋白的mRNA，但其昼夜节律在体外并未直接适应光暗周期。与视网膜不同，盲鼠的虹膜/睫状体时钟仍与机体行为节律同步，而非局部光暗周期。这些结果表明，小鼠眼压节律的调节是由全身信号而非局部信号介导的。
