实验动物分组的理想标准是什么,大概都有不同看法.不过应坚持一个原则:以说明问题为导向,根据不同的研究目的设计分组.并不是越多越好,有时候看似严格,其实是浪费,而且更容易出现漏洞,对真正说明问题并不一定有帮助.

来自武汉华中科技大学同济医院的工作。研究目的是探讨氢气饱和盐水对蓝光诱导的视网膜损伤的作用。研究方法：蓝光6小时暴露诱导大鼠视网膜损伤。在暴露后8小时、16小时和24小时分别检测效果。100只雄性SD大鼠随机分为4组。第一组包括30只动物只进行光照（损伤组）；第2组30只动物光照加生理盐水腹腔注射治疗（对照治疗组）。第三组30只动物光照加氢气生理盐水腹腔注射治疗。第4组10只动物未进行任何处理。（点评：动物分组存在重复的问题，当然严格意义上，采用损伤组和正常空白组作为对照更严格，但生理盐水治疗组和损伤组的比较并没有太大意义，而且会增加很多工作量，审稿人无法提出疑问，但也不必要浪费30只动物。合理的方法是先预实验证明两组无区别，然后不用单纯损伤对照的第一组就完全可以。）氢气饱和盐水的治疗剂量为1ml/100g体重。标本采集后进行HE染色、电子显微镜观察、生物化学检测。

形态学改变发现采用光镜和透射电子显微镜观察，视网膜外层核层厚度用IPP 6.0检测，氧化损伤指标MDA用比色法检测（532nm）。研究结果：第1组和第2组的视网膜结构损伤严重，氢气饱和盐水治疗的第三组明显减轻。第1组和2组无明显区别。而第3组和1、2组区别明显。外层细胞核厚度，第一组三个时间点分别为30.41± 4.04、26.11±2.8和20.63 ± 1.06；第2组分别为31.62 ±4.54, 25.08 ± 3.63 和 19.07 ± 3.86。第三组为29.75± 3.62, 28.83± 1.97和 27.61± 1.83，显然24小时区别最明显。要知道第一组和第2组也只有24小时出现显著的损伤改变。从这个意义上讲，观察的点应该放在24小时，而不是一味追求时间点，浪费动物和时间。那么多形态学可不是一点点工作量。MDA数据符合形态学结果，和正常组比较，模型组出现显著增加；和对照治疗组比较，治疗组出现显著下降（也许是动物数量太少，差别并不大，MDA测定比较粗，至少要8只以上动物，而且视网膜组织量比较少，更应注意）。结论是氢气可以保护蓝光诱导的视网膜损伤。

（点评只代表个人看法，并没有否定本研究的意思，研究结果仍是比较漂亮的，而且有一定新意，虽然氢气在眼睛损伤，包括视网膜损伤例如氧气的毒性损伤和糖尿病视网膜损伤都曾经有研究，但光损伤没有任何人研究过，仍有很大意义，说明氢气对视网膜光损伤具有潜在的治疗价值）

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Protective effect of saturated hydrogen saline against blue light-induced retinal damage in rats

AIM: To explore the effect of saturated hydrogen saline on blue light-induced retinal damage in rats.

·METHODS: The retinal damage of rats was induced by blue light exposure for 6 hours and examined 8 hours, 16 hours and 24 hours after the exposure. One hundred female Sprague-Dawley rats were randomly divided into four groups.

Group 1 included 30 rats received light exposure without any other treatment. Group 2 included 30 rats received light exposure with intraperitoneal injection of normal saline. Group 3 included 30 rats received light exposure with intraperitoneal injection of saturated hydrogen saline. And Group 4 included the other 10 rats which did not receive any treatment.

The amount of intraperitoneal injection of saturated hydrogen saline and normal saline was calculated in the ratio of 1ml/100g of rat weight. Specimens were collected and processed by H-E staining, ultrastructure observation, biochemical measurement. Morphological changes were observed by light microscope and transmission electron microscope (TEM) and the retinal outer nuclear layer (ONL) thickness was measured by IPP 6.0, while the malondialdehyde (MDA) was measured by colorimetric determination at 532nm.

RESULTS: Although the structure of retina in Group 1 and Group 2 was injured heavily, the injury in Group 3 was mild.The differences between Group 1 and Group 2 were not significant. Compared with the rats in Group 1 and Group 2, the ones in Group 3 had more clearly demarcated retina structure and more ordered cells by light microscope and TEM observation. The ONL thicknesses (400 times) of four groups at each time point except between Group 1 and Group 2 were significantly different ( <0.05). The thicknesses of the ONL in Group 1 at three time points were 30.41± 4.04, 26.11±2.82m and 20.63 ± 1.06, in Group 2 were 31.62 ± 4.54m, 25.08 ± 3.63 and 19.07 ± 3.86, in Group 3 were 29.75± 3.62, 28.83± 1.97and 27.61± 1.83滋m. In Group 4 the mean of the thickness was 37.35± 1.37滋m. As time went by, the damage grew more severely. At 24h point, the differences were most significant. Compared with Group 4, the thickness was 46.23% thinner in Group 1, 50.29% thinner in Group 2 and 28.04%thinner in Group 3. The stack structures of membranous disc in Group 3 were injured slightly, but in Group 1 and Group 2 the damage was more obvious by TEM. Compared with Group 4 at each time point, the content of MDA in Group 1 was higher ( <0.05). The content of MDA in Group 3 was significantly lower than those of Group 1 ( <0.05) and Group2 ( <0.05). Between the Group 1 and Group 2, the MDA concentration at each time point was no significant difference ( >0.05). ·CONCLUSION: Saturated hydrogen saline could protect the retina from light-induced damage by attenuating oxidative stress.