Yagihashi Tomoyuki, Wakabayashi Yoshihiro, Kezuka Jun, Usui Masahiko, Iwasaki Takuya
Department of Ophthalmology, Tokyo Medical University, Tokyo, Japan.
Acta Ophthalmol Scand. 2007 May;85(3):303-8. doi: 10.1111/j.1600-0420.2006.00829.x.
We previously reported marked elevation of glutamate, gamma-aminobutyric acid (GABA) and alanine in the vitreous after combined cataract surgery and vitrectomy for macular disorder. Photo-stimulation by the operating microscope and increased intraocular pressure (IOP) are possible causes of postoperative increases in amino acids. An animal model was used to verify this hypothesis.
Forty-five coloured rabbits were studied; stress was applied to simulate cataract surgery. Simultaneous photic and pressure stress, photic stress alone, or pressure stress alone were exerted for 20 mins. The vitreous was extracted at the end of the stress period, or 10 mins or 30 mins later. Levels of six amino acids (asparate, glutamate, glycine, taurine, alanine and GABA) in the vitreous were analysed quantitatively.
Significant increases in vitreous glutamate concentrations in treated eyes were observed following simultaneous photic and pressure stress, as well as after pressure stress alone, whereas no difference was found after photic stress alone. The mean glutamate concentrations in treated eyes and fellow eyes, respectively, were 5.59 +/- 2.03 microM and 4.36 +/- 2.09 microM (p < or = 0.05) 10 mins after simultaneous photic and pressure stress, and 4.32 +/- 0.97 microM and 2.29 +/- 0.51 microM (p < 0.05) 10 mins after pressure stress alone. Taurine concentration was elevated by pressure stress alone at 0 min and at 10 mins post-stress. Alanine concentration was reduced by photic stress alone at 10 mins post-stress. In all protocols, no significant differences between treated and fellow eyes were observed at 30 mins after stress. Time-dependent changes were observed not only in the treated eyes, but also in untreated fellow eyes.
Elevations of vitreous glutamate in cataract surgery may be caused by pressure stress due to irrigation. Photic stress caused by the operating microscope has little influence. Sympathetic response may be involved in amino acid changes due to stress in cataract surgery.
我们之前报道过，在白内障手术联合玻璃体切割术治疗黄斑疾病后，玻璃体中的谷氨酸、γ-氨基丁酸（GABA）和丙氨酸显著升高。手术显微镜的光刺激和眼内压（IOP）升高可能是术后氨基酸增加的原因。我们使用动物模型来验证这一假设。
对45只彩色兔子进行研究；施加应激以模拟白内障手术。同时施加光和压力应激、单独施加光应激或单独施加压力应激20分钟。在应激期结束时、或10分钟或30分钟后提取玻璃体。定量分析玻璃体中六种氨基酸（天冬氨酸、谷氨酸、甘氨酸、牛磺酸、丙氨酸和GABA）的水平。
在同时施加光和压力应激后以及仅施加压力应激后，观察到处理眼的玻璃体谷氨酸浓度显著增加，而仅施加光应激后未发现差异。同时施加光和压力应激10分钟后，处理眼和对侧眼的平均谷氨酸浓度分别为5.59±2.03微摩尔/升和4.36±2.09微摩尔/升（p≤0.05），仅施加压力应激10分钟后分别为4.32±0.97微摩尔/升和2.29±0.51微摩尔/升（p<0.05）。仅压力应激在应激后0分钟和10分钟时牛磺酸浓度升高。仅光应激在应激后10分钟时丙氨酸浓度降低。在所有方案中，应激后30分钟时处理眼和对侧眼之间未观察到显著差异。不仅在处理眼中观察到了时间依赖性变化，在未处理的对侧眼中也观察到了。
白内障手术中玻璃体谷氨酸升高可能是由于冲洗引起的压力应激所致。手术显微镜引起的光应激影响很小。交感反应可能参与了白内障手术应激引起的氨基酸变化。
