Kiagiadaki Foteini, Thermos Kyriaki
Laboratory of Pharmacology, Department of Basic Sciences, Faculty of Medicine, University of Crete, Heraklion, Crete, Greece.
Invest Ophthalmol Vis Sci. 2008 Jul;49(7):3080-9. doi: 10.1167/iovs.07-1644. Epub 2008 Apr 4.
The aim of the present study was to use an in vivo model of retinal excitotoxicity to investigate the neuroprotective effect of somatostatin (SRIF)-ergic agents.
Adult Sprague-Dawley rats (weight range, 250-300 g) intravitreally received (RS)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid hydrobromide (AMPA; 21, 42, 84 nmol/eye) or PBS (50 mM). Time-dependent responses were examined in animals that received AMPA (42 nmol/eye). Animals received AMPA (42 nmol) alone or in combination with SRIF (10(-5), 10(-4) M) or the sst-selective ligands lanreotide (sst(2),10(-5),10(-4) M), L-779976 (sst(2,)10(-6),10(-5), 10(-4) M), L-797591 (sst(1),10(-4) M), and L-803087 (sst(4),10(-4) M). Immunohistochemistry and TUNEL studies were used to examine retinal cell loss and protection. Immunochemistry, Western blot analysis, and radioimmunoassay assessed the viability of sst(2A) receptors and SRIF levels, respectively, in control and AMPA-treated tissue.
AMPA (42 nmol) treatment resulted in total and major loss of ChAT and bNOS immunoreactivity, respectively, 24 hours after its administration. This loss was sustained up to 30 days for ChAT- and 8 days for bNOS-expressing amacrine cells. SRIF and the sst(2) receptors were not affected by AMPA. SRIF and the sst(2) analogs protected the retina from the AMPA insult in a dose-dependent manner, whereas activation of the sst(1) and sst(4) subtypes had no effect. TUNEL staining confirmed AMPA-induced retinal ischemia and L-779976 neuroprotection.
These results demonstrate for the first time that SRIF and the sst(2) analogs, administered intravitreally, protect the retina from excitotoxicity. Further studies are essential to ascertain the therapeutic relevance of these results.
本研究旨在利用视网膜兴奋性毒性的体内模型来研究生长抑素（SRIF）能药物的神经保护作用。
成年Sprague-Dawley大鼠（体重范围250 - 300 g）经玻璃体内注射（RS）-α-氨基-3-羟基-5-甲基-4-异恶唑丙酸氢溴酸盐（AMPA；21、42、84 nmol/眼）或磷酸盐缓冲液（PBS，50 mM）。对接受AMPA（42 nmol/眼）的动物进行时间依赖性反应检测。动物单独接受AMPA（42 nmol）或与SRIF（10⁻⁵、10⁻⁴ M）或sst选择性配体兰瑞肽（sst₂，10⁻⁵、10⁻⁴ M）、L-779976（sst₂，10⁻⁶、10⁻⁵、10⁻⁴ M）、L-797591（sst₁，10⁻⁴ M）和L-803087（sst₄，10⁻⁴ M）联合使用。采用免疫组织化学和TUNEL研究来检测视网膜细胞丢失和保护情况。免疫化学、蛋白质印迹分析和放射免疫测定分别评估对照组织和AMPA处理组织中sst₂A受体的活力和SRIF水平。
AMPA（42 nmol）处理后24小时，分别导致ChAT和bNOS免疫反应性完全丧失和大量丧失。这种丧失在表达ChAT的无长突细胞中持续长达30天，在表达bNOS的无长突细胞中持续8天。SRIF和sst₂受体不受AMPA影响。SRIF和sst₂类似物以剂量依赖性方式保护视网膜免受AMPA损伤，而sst₁和sst₄亚型的激活则无作用。TUNEL染色证实了AMPA诱导的视网膜缺血和L-779976的神经保护作用。
这些结果首次证明玻璃体内注射SRIF和sst₂类似物可保护视网膜免受兴奋性毒性损伤。进一步研究对于确定这些结果的治疗相关性至关重要。
