Melatonin receptors in chick ocular tissues: Implications for a role of melatonin in ocular growth regulation
Melatonin receptors in chick ocular tissues: Implications for a role of melatonin in ocular growth regulation
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DOI：
10.1167/iovs.05-0195
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发表时间：
2006-01-01
影响因子：
4.4
通讯作者：
Wiechmann, AF
中科院分区：
文献类型：
--
作者：
Rada, JAS;Wiechmann, AF
目的.涉及各种眼部参数的昼夜节律的影响与近视的发展有关。本研究的目的是确定褪黑激素受体亚型蛋白在鸡眼组织中的表达，并研究昼夜信号分子褪黑激素在正常眼生长和与近视发展相关的过度眼生长中的作用。通过Western印迹分析、狭缝印迹分析和免疫细胞化学检测Mel（1a）、Mel（1b）和Mel（1c）褪黑素受体蛋白在眼组织中的表达。为了检查褪黑激素对眼睛生长的影响，将小鸡维持在12小时的光-暗循环中，并用半透明的遮光器剥夺一只眼睛的单眼形觉5天。在5天的处理期间，在早期黑暗期间用褪黑激素（0.6mg）或2%乙醇媒介物对照全身注射小鸡。正常和剥夺眼睛的眼睛尺寸进行了检查，高频A-扫描超声。鸡眼组织的免疫细胞化学分析揭示了Mel（1a）受体亚型在角膜、脉络膜、巩膜和视网膜中的细胞分布。Western印迹和狭缝印迹分析表明，所有三种受体都存在于这些组织中，并且它们在视网膜-RPE-脉络膜中表现出不同的蛋白表达昼夜节律，其中Mel（1a）和Mel（1b）的峰值水平出现在夜间，Mel（1c）的峰值水平出现在白天。全身给予褪黑素可导致形觉剥夺眼和/或对照眼的前房深度、玻璃体腔深度和脉络膜厚度发生显著变化。本研究的结果表明，所有三种褪黑激素受体亚型表达在视网膜和视网膜外眼组织的鸡眼。这一发现，褪黑激素的管理改变了控制和形式剥夺的眼睛中的几个眼组织的生长表明，褪黑激素，通过特定的褪黑激素受体在眼组织中发挥作用，在眼睛的生长和发育中发挥作用。这一结论表明，褪黑激素的作用，结合褪黑激素受体的表达，参与了眼生长的昼夜节律的调节。
PURPOSE. The influences of diurnal rhythms involving a variety of ocular parameters are implicated in the development of myopia. The purpose of this study was to determine the expression of the melatonin receptor subtype proteins in chick ocular tissues and to examine the role of the circadian signaling molecule melatonin in normal ocular growth and the exaggerated ocular growth associated with the development of myopia.METHODS. Expression of the Mel(1a), Mel(1b), and Mel(1c) melatonin receptor proteins in ocular tissues was examined by Western blot analyses, slot blot analyses, and immunocytochemistry. For examining the effect of melatonin on ocular growth, chicks were maintained on a 12-hour light-dark cycle and were monocularly form-vision deprived in one eye with a translucent occluder for 5 days. During the 5-day treatment period, chicks were injected systemically during the early dark period with melatonin (0.6 mg) or 2% ethanol vehicle control. Ocular dimensions of normal and deprived eyes were examined by high frequency A-scan ultrasound.RESULTS. Immunocytochemical analysis of chick ocular tissues revealed the cellular distribution of the Mel(1a) receptor subtype in the cornea, choroid, sclera, and retina. Western blot and slot blot analyses demonstrated that all three receptors were present in these tissues and they demonstrated distinct diurnal rhythms of protein expression in the retina-RPE-choroid, with peak levels of Mel(1a) and Mel(1b) occurring during the night and peak levels of Mel(1c) during the day. Systemic administration of melatonin resulted in significant changes in anterior chamber depth, vitreous chamber depth, and choroidal thickness of form-deprived and/or control eyes.CONCLUSIONS. Results of this study show that all three melatonin receptor subtypes are expressed in retinal and extraretinal ocular tissues of the chick eye. The finding that administration of melatonin alters the growth of several ocular tissues in both control and form-deprived eyes suggests that melatonin, acting through specific melatonin receptors in ocular tissues, plays a role in ocular growth and development. This conclusion suggests that the action of melatonin, combined with expression of melatonin receptors, is involved in the regulation of the diurnal rhythm of ocular growth.