摘要目的:观察N-乙酰-5-羟色胺（NAS）对大鼠视网膜缺血再灌注损伤（RIRI）后视网膜小胶质细胞极化的影响，并基于核苷酸结合的寡聚结构域1 （NOD1）/受体相互作用蛋白2 （Rip2）通路初步探讨其机制。方法:采用随机数字表法将60只雄性Sprague Dawley大鼠分为假手术组（Sham组）、RIRI组、NAS组，分别为21、21、18只，以右眼为实验眼。RIRI组、NAS组大鼠采用前房高眼压法建立RIRI模型。NAS组大鼠分别于建模前及建模后30 min腹腔注射10 mg/kg NAS。建模后24 h，苏木素-伊红、免疫组织化学染色观察各组大鼠视网膜形态学变化，计数视网膜神经节细胞（RGC）；免疫荧光染色观察NAS干预对大鼠视网膜小胶质细胞极化的影响。转录组测序筛选Sham组、RIRI组间差异基因，蛋白质免疫印迹法（Western blot）、实时定量聚合酶链反应（RT-PCR）进行验证。免疫组织化学染色、Western blot、RT-PCR观察NAS对大鼠视网膜组织及小胶质细胞中NOD1、Rip2蛋白、mRNA表达的影响。一般线性回归分析NAS组、RIRI组大鼠视网膜组织中NOD1 +细胞数差值与M1、M2型小胶质细胞数差值的相关性。 结果:Sham组大鼠视网膜可见大量RGC；建模后24 h，与Sham组比较，RIRI组大鼠视网膜内层厚度显著增加、RGC数量显著减少；NAS组大鼠视网膜内层厚度显著变薄，RGC数量显著增多。与Sham组比较，RIRI组大鼠视网膜M1、M2型小胶质细胞数显著增多；与RIRI组比较，NAS组大鼠视网膜M1型小胶质细胞数显著减少，M2型小胶质细胞显著增多。三组大鼠视网膜M1、M2型小胶质细胞数比较，差异均有统计学意义（ P<0.05）。转录组测序结果显示，建模后24 h，视网膜 NOD1、 Rip2为重要差异基因；RIRI组视网膜中NOD1、Rip2 mRNA、蛋白相对表达量显著高于Sham组，差异均有统计学意义（ P<0.05）。RIRI组视网膜小胶质细胞中NOD1 +、Rip2 +细胞数及mRNA、蛋白相对表达量显著高于Sham组，NAS组亦较Sham组显著升高，但低于RIRI组，差异均有统计学意义（ P<0.05）。RIRI组视网膜小胶质细胞中离子钙接头蛋白1 （Iba-1） +/NOD1 +及Iba-1 +/Rip2 +细胞数较Sham组显著增多，NAS组较RIRI组显著减少，但仍显著多于Sham组，差异均有统计学意义（ P<0.05）。相关性分析结果显示，NAS组、RIRI组视网膜NOD1 +、Rip2 +细胞数差值与M1型小胶质细胞数差值呈正相关（ r=0.851、0.895），与M2型小胶质细胞数差值呈负相关（ r=-0.797、-0.819），差异均有统计学意义（ P<0.05）。 结论:NAS可促进RIRI大鼠视网膜小胶质细胞M2型极化，抑制M1型极化，其机制与NOD1/Rip2通路有关。

abstractsObjective:To investigate the effect of N-acetylserotonin (NAS) on the retinal microglia polarization in retinal ischemia-reperfusion injury (RIRI) rats and explore its mechanism via nucleotide-bound oligomeric domain 1 (NOD1)/receptor interacting protein 2 (Rip2) pathway.Methods:Healthy male Sprague Dawley rats were randomly divided into Sham ( n=21), RIRI ( n=21) and NAS (injected intraperitoneally 30 min before and after modeling with NAS, 10 mg/kg, n=18) groups, using random number table. And the right eye was used experimental eye. The RIRI model of rats in RIRI group and NAS group was established by anterior chamber high intraocular pressure method. Rats in NAS group were intraperitoneally injected with 10 mg/kg NAS before and 30 min after modeling, respectively. The retinal morphology and the number of retinal ganglion cell (RGC) in each group were detected by hematoxylin-eosin staining and immunohistochemical staining. The effect of NAS on polarization of retinal microglia was detected by immunofluorescence staining. Transcriptome sequencing technology was used to screen out the differentially expressed genes between Sham and RIRI groups. Western blot and real-time quantitative polymerase chain reaction (RT-PCR) were used to examine the differentially expressed genes. Immunohistochemical staining, Western blot and RT-PCR were used to investigate the effect of NAS on the expression of NOD1 and Rip2 protein and mRNA in retinal tissue and microglia of rats. General linear regression analysis was performed to determine the correlation between the number difference of NOD1 + cells and the number difference of M1 and M2 microglia in retinal tissues of rats in NAS group and RIRI group. Results:A large number of RGC were observed in the retina of rats in Sham group. 24 h after modeling, compared with Sham group, the inner retinal thickness of rats in RIRI group was significantly increased and the number of RGC was significantly decreased. The thickness of inner retina in NAS group was significantly thinner and the number of RGC was significantly increased. Compared with Sham group, the number of retinal microglia of M1 and M2 in RIRI group was significantly increased. Compared with RIRI group, the number of M1 microglia decreased significantly and the number of M2 microglia increased significantly in NAS group. There was statistical significance in the number of M1 and M2 microglia in the retina of the three groups ( P<0.05). Transcriptome sequencing results showed that retinal NOD1 and Rip2 were important differential genes 24 h after modeling. The mRNA and protein relative expressions of NOD1 and Rip2 in retina of RIRI group were significantly higher than those of Sham group, with statistical significance ( P<0.05). The number of NOD1 + and Rip2 + cells and the relative expression of mRNA and protein in retinal microglia in RIRI group were significantly higher than those in Sham group, and NAS group was also significantly higher than that in Sham group, but lower than that in RIRI group, with statistical significance ( P<0.05). The number of Iba-1 +/NOD1 + and Iba-1 +/Rip2 + cells in retinal microglia in RIRI group was significantly increased compared with that in Sham group, and the number of Iba-1 +/Rip2 + cells in NAS group was significantly decreased compared with that in RIRI group, but still significantly higher than that in Sham group, with statistical significance ( P<0.05). Correlation analysis results showed that the difference of retinal NOD1 + and Rip2 + cells in NAS group and RIRI group was positively correlated with that of M1 microglia ( r=0.851, 0.895), and negatively correlated with that of M2 microglia ( r=-0.797, -0.819). The differences were statistically significant ( P<0.05). Conclusion:NAS can regulate the microglial polarization from M1 to M2 phenotype, the mechanism is correlated with the NOD1/Rip2 pathway.