不同N-乙酰-5-羟色胺(NAS)给药途径对大鼠视网膜缺血-再灌注损伤的影响

目的探讨腹腔与尾静脉注射N-乙酰-5-羟色胺(N-acetylserotonin,NAS)两种给药途径对大鼠视网膜缺血-再灌注损伤(retinal ischemia-reperfusion injury,RIRI)组织病理学、活性半胱氨酸天冬氨酸蛋白酶-3(Caspase-3)蛋白表达及细胞凋亡的影响。方法健康无眼疾成年Sprague-Dawley雄性大鼠54只,采用随机数字表法分为正常对照组(n=6)、RIRI腹腔组(n=12)、RIRI静脉组(n=12)、NAS腹腔组(n=12)和NAS静脉组(n=12),后四组采用升高眼压法建立大鼠RIRI模型。NAS腹腔组、NAS静脉组于建模前30 min分别经腹腔、尾静脉注射NAS(10 mg·kg^-1),RIRI腹腔组、RIRI静脉组于造模前30 min分别经腹腔、尾静脉注射同等剂量的生理盐水。RIRI后24 h,采用免疫组织化学染色检测各组大鼠视网膜中活性Caspase-3的表达,TUNEL染色检测各组视网膜细胞凋亡情况;RIRI后7 d,HE染色观察各组视网膜组织病理学变化。结果HE染色结果示,正常对照组大鼠视网膜各层细胞排列整齐、规则;RIRI后7 d,RIRI腹腔组与RIRI静脉组大鼠视网膜细胞排列稀疏、紊乱,形态不规则,视网膜内层厚度变薄;NAS腹腔组视网膜细胞形态较规则,排列较规整;NAS静脉组视网膜各层形态及细胞排列均趋于正常。NAS静脉组视网膜内层厚度(91.67±1.43)μm显著高于NAS腹腔组(87.80±1.33)μm、RIRI腹腔组(82.37±1.09)μm和RIRI静脉组(82.81±0.90)μm,差异均具有统计学意义(均为P<0.05);且NAS静脉组视网膜神经节细胞数(616.90±79.51)个·mm^-2显著高于NAS腹腔组(529.25±92.05)个·mm^-2、RIRI静脉组(434.42±87.17)个·mm^-2、RIRI腹腔组(390.72±72.12)个·mm^-2,差异均具有统计学意义(均为P<0.05)。免疫组织化学染色结果发现,RIRI后24 h,NAS静脉组活性Caspase-3阳性细胞数(145.01±22.54)个·mm^-2少于NAS腹腔组(221.34±30.84)个·mm^-2,差异具有统计学意义(P<0.05),二者活性Caspase-3阳性细胞数均显著少于RIRI静脉组(380.54±41.25)个·mm^-2和RIRI腹腔组(387.79±26.72)个·mm^-2,差异均具有统计学意义(均为P<0.05)。TUNEL染色结果示,RIRI后24 h,NAS静脉组TUNEL染色阳性细胞数(1468.03±128.40)个·mm^-2少于NAS腹腔组(1968.96±254.98)个·mm^-2,差异具有统计学意义(P<0.05),二者TUNEL染色阳性细胞数均显著少于RIRI静脉组(2122.77±165.76)个·mm^-2和RIRI腹腔组(2140.53±177.96)个·mm^-2,差异均具有统计学意义(均为P<0.05)。结论腹腔及静脉注射NAS治疗均可减少视网膜细胞凋亡,从而减轻RIRI大鼠视网膜损伤,且静脉注射给药的疗效优于腹腔给药。

Effects of different administration routes of N-acetylserotonin on retinal ischemia-reperfusion injury in rats

Objective　To investigate the changes of histopathological features, expression of active Caspase-3 protein and cell apoptosis in rats with retina ischemia-reperfusion injury (RIRI) by two different administration routes of N-acetylserotonin (NAS), intraperitoneal injection and tail intravenous injection. Methods　Totally 54 healthy adult male Sprague-Dawley rats were divided into normal control group (n=6), RIRI intraperitoneal group (n=12), RIRI intravenous group (n=12), NAS intraperitoneal group (n=12) and NAS intravenous group (n=12) by random number table method. RIRI models were established by ocular hypertension method. Rats in NAS intraperitoneal group and NAS intravenous group respectively received intraperitoneal injection and tail intravenous injection of NAS (10 mg·kg^-1) 30 minutes before modeling, and rats in RIRI intraperitoneal group and RIRI intravenous group respectively received intraperitoneal injection and tail intravenous injection of same amount of normal saline 30 minutes before modeling. Twenty-four hours after RIRI, the expression of active Caspase-3 in retina was detected by immunohistochemical staining, and the apoptosis of retinal cells was detected by TUNEL staining.Seven days after RIRI, the histopathological changes of retina were observed by HE staining. Results　HE staining showed that the retinal cells at each layer were orderly and regularly arranged for rats in normal control group; 7 days after RIRI, the retinal cells for rats in RIRI intraperitoneal and intravenous groups were sparsely and disorderly arranged, irregular in shape, and thinner in the inner retinal layer; the retinal cells in the NAS intraperitoneal group were regularly and orderly arranged; NAS intravenous group had basically normal cell morphology and arrangement in each retinal layer. The thickness of retinal inner layer in the NAS intravenous group was (91.67±1.43) μm, which was significantly higher than (87.80±1.33) μm in NAS intraperitoneal group, (82.37±1.09) μm in RIRI intraperitoneal group and (82.81±0.90) μm in RIRI intravenous group, and statistical differences were found (all P<0.05). And the number of retinal ganglion cells in the NAS intravenous group was (616.90±79.51) mm^-2, which was significantly higher than (529.25±92.05) mm^-2 in the NAS intraperitoneal group, (434.42±87.17) mm^-2 in RIRI intravenous group and (390.72±72.12) mm^-2 in RIRI intraperitoneal group, and statistical differences were found (all P<0.05). Immunohistochemical staining results showed: 24 hours after RIRI, the number of active Caspase-3 positive cells in the NAS intravenous group was (145.01±22.54) mm^-2, lower than (221.34±30.84) mm^-2 in the NAS intraperitoneal group (P<0.05), and both of which was significantly lower than (380.54±41.25) mm^-2 in the RIRI intravenous group and (387.79±26.72) mm^-2 in RIRI intraperitoneal group (all P<0.05). TUNEL staining showed: 24 hours after RIRI, the number of apoptotic cells in the NAS intravenous group was (1468.03±128.40) mm^-2, lower than (1968.96±254.98) mm^-2 in the NAS intraperitoneal group (P<0.05), and both of which was obviously lower than (2122.77±165.76) mm^-2 in the RIRI intravenous group and (2140.53±177.96) mm^-2 in the RIRI intraperitoneal group (all P<0.05). Conclusion　Both intraperitoneal and intravenous injection of NAS can reduce retinal cell apoptosis thereby relieving retinal damage in RIRI rats. Intravenous administration is more effective than intraperitoneal administration.