Periocular injection of in situ hydrogels containing Leu-Ile, an inducer for neurotrophic factors, promotes retinal ganglion cell survival after optic nerve injury
Periocular injection of in situ hydrogels containing Leu-Ile, an inducer for neurotrophic factors, promotes retinal ganglion cell survival after optic nerve injury
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DOI：
10.1016/j.exer.2011.09.024
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发表时间：
2011-12-01
影响因子：
3.4
通讯作者：
Nitta, Atsumi
中科院分区：
文献类型：
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作者：
Nakatani, Masayoshi;Shinohara, Yuko;Nitta, Atsumi
眼内给药神经营养因子已被证明可以延缓视网膜神经节细胞（RGCs）的不可逆变性。如果这些神经营养因子能够以较低的侵入性方式输送，将有利于视神经损伤的治疗。二肽亮氨酸-异亮氨酸（Leu-Ile）似乎可以诱导大脑中神经营养因子的产生，包括脑源性神经营养因子（BDNF）和胶质细胞系源性神经营养因子（GDNF）。因此，我们在大鼠眼周库注射Leu-Ile，并在ON损伤模型中研究了该二肽诱导视网膜BDNF和GDNF的能力，以及延缓RGC丢失的能力。将含Leu-Ile的波洛莫-海藻酸盐水凝胶注入完整或损伤大鼠的结膜下间隙。采用酶免疫法测定视网膜BDNF和GDNF水平。在视网膜平板支架中评估RGCs的存活。Western blotting检测视网膜细胞外信号调节激酶（ERR）和cAMP反应元件结合蛋白（CREB）的激活情况。注射异硫氰酸荧光素共轭亮氨酸2 h后，视网膜荧光强度比生理盐水对照组高4.3倍。注射Leu-Ile后6 h视网膜BDNF水平和6-72 h GDNF水平均显著升高。Leu-Ile显著提高了ON损伤后14天的RGC存活率，并增强了注射后72小时ERK和48小时CREB在ON损伤视网膜中的激活。这些结果表明，眼周注入Leu-Ile可诱导视网膜生成BDNF和GDNF，最终可能提高ON损伤后RGC的存活率。(C) 2011 Elsevier Ltd.版权所有。
Intraocular administration of neurotrophic factors has been shown to delay irreversible degeneration of retinal ganglion cells (RGCs). It would be beneficial for the treatment of optic nerve (ON) injury if such neurotrophic factors could be delivered in a less-invasive manner. The dipeptide leucine-isoleucine (Leu-Ile) appears to induce the production of neurotrophic factors, including brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF), in the brain. We therefore administered Leu-Ile via periocular depot injection in rats and investigated the dipeptide's ability to induce BDNF and GDNF in the retina and to delay RGC loss in an ON injury model. Poloxamer-alginate hydrogels containing Leu-Ile were injected into the subconjunctival space of intact or ON-injured rats. BDNF and GDNF levels in the retina were determined by an enzyme immunoassay. Survival of RGCs was assessed in retinal flatmounts. Activation of extracellular signal-regulated kinases (ERR) and cAMP response element binding protein (CREB) in the retina was examined by Western blotting. At 2 h after injection of fluorescein isothiocyanate-conjugated Leu-Ile, the fluorescence intensities in the retina were 4.3-fold higher than those in the saline control. Treatment with Leu-Ile significantly increased the retinal levels of BDNF at 6 h and GDNF at 6-72 h after injection. Treatment with Leu-Ile significantly increased RGC survival to 14 days after ON injury and enhanced the activation of ERK at 72 h and CREB at 48 h after injection in the ON-injured retina. These results suggest that periocular delivery of Leu-Ile induces BDNF and GDNF production in the retina, which may eventually enhance RGC survival after ON injury. (C) 2011 Elsevier Ltd. All rights reserved.