George Abigail, Schmid Katrina L, Pow David V
Vision Touch and Hearing Research Centre, School of Biomedical Science, University of Queensland, Brisbane, Qld, Australia.
Exp Eye Res. 2005 Nov;81(5):616-25. doi: 10.1016/j.exer.2005.03.021. Epub 2005 Jun 9.
Myopia (short-sightedness) is a visual problem associated with excessive eye growth and vitreous chamber expansion. Within the eye serotonin (5-hydroxytryptamine, 5-HT) appears to have a variety of effects, it alters retinal amacrine cell processing, increases intraocular pressure, constricts ocular blood vessels, and is also mitogenic. This study sought to determine the role of the retinal serotonin system in eye growth regulation. Myopia was produced in 7-day-old chicks using -15 D spectacle lenses (LIM) and form deprivation (FDM). The effect on LIM and FDM of daily intravitreal injections of a combination of 5-HT receptor antagonists (1, 10, 50 microM), 5-HT(2) selective antagonist (Mianserin 0.5, 20 microM) or 5-HT (1, 10, 50 microM) were assessed. Counts were performed of serotonin and tyrosine hydroxylase positive neurons and the relative density used to account for areal changes due to eye growth. The effect of LIM and lens-induced hyperopia (LIH) on the numbers of 5-HT-containing amacrine cells in the retina were then determined. The combination of 5-HT receptor antagonists inhibited LIM by approximately half (1 microM RE: -7.12+/-1.0 D, AL: 0.38+/-0.06 mm vs. saline RE: -13.19+/-0.65 D, AL: 0.64+/-0.03 mm. RE: p<0.01, AL: p<0.01), whereas FDM was not affected (1 microM RE: -8.88+/-1.10 D vs. saline RE: -9.28+/-1.38 D). The selective antagonist was slightly less effective at inhibiting LIM (0.5 microM RE: -9.02+/-1.01 D). These data suggest that serotonin has a stimulatory role in LIM, although high doses of serotonin were inhibitory (1 microM RE: -9.30+/-1.34 D). 5-HT immunoreactivity was localised to a subset of amacrine cell bodies in the inner nuclear layer of the retina, and to two synaptic strata in the inner plexiform layer. LIM eyes had increased numbers of 5-HT-containing amacrine cells in the central retina (12.5%). Collectively, these results suggest that manipulations to the serotonin system can alter the eye growth process but the role of this transmitter system within this process remains unclear.
近视（近视眼）是一种与眼球过度生长和玻璃体腔扩张相关的视觉问题。在眼内，血清素（5-羟色胺，5-HT）似乎具有多种作用，它会改变视网膜无长突细胞的处理过程，升高眼压，收缩眼部血管，并且还具有促有丝分裂作用。本研究旨在确定视网膜血清素系统在眼球生长调节中的作用。使用-15 D的眼镜镜片（LIM）和形觉剥夺（FDM）在7日龄雏鸡中诱导产生近视。评估了每日玻璃体内注射5-HT受体拮抗剂组合（1、10、50微摩尔）、5-HT(2)选择性拮抗剂（米安色林0.5、20微摩尔）或5-HT（1、10、50微摩尔）对LIM和FDM的影响。对血清素和酪氨酸羟化酶阳性神经元进行计数，并使用相对密度来解释由于眼球生长引起的面积变化。然后确定LIM和晶状体诱导的远视（LIH）对视网膜中含5-HT的无长突细胞数量的影响。5-HT受体拮抗剂组合对LIM的抑制作用约为一半（1微摩尔：屈光不正（RE）：-7.12±1.0 D，眼轴长度（AL）：0.38±0.06毫米，而生理盐水组：RE：-13.19±0.65 D，AL：0.64±0.03毫米。RE：p<0.01，AL：p<0.01），而FDM不受影响（1微摩尔：RE：-8.88±1.10 D，生理盐水组：RE：-9.28±1.38 D）。选择性拮抗剂对LIM的抑制作用稍弱（0.5微摩尔：RE：-9.02±1.01 D）。这些数据表明血清素在LIM中具有刺激作用，尽管高剂量的血清素具有抑制作用（1微摩尔：RE：-9.30±1.34 D）。5-HT免疫反应性定位于视网膜内核层中无长突细胞体的一个亚群，以及内网状层中的两个突触层。LIM眼的中央视网膜中含5-HT的无长突细胞数量增加（12.5%）。总体而言，这些结果表明对血清素系统的操作可以改变眼球生长过程，但该递质系统在这一过程中的作用仍不清楚。
