枸橼酸咖啡因对新生大鼠缺氧缺血性脑损伤后髓鞘碱性蛋白的影响

Effects of caffeine citrate on myelin basic protein in neonatal rats with hypoxicischemic brain damage

摘要:

目的 研究枸橼酸咖啡因对新生大鼠缺氧缺血性脑损伤(HIBD)后脑白质髓鞘碱性蛋白(MBP)表达的影响及其相关机制。方法 将48 只7 日龄Sprague-Dawley 新生大鼠随机分为假手术组、HIBD 组和枸橼酸咖啡因干预组,每组16只。左侧颈总动脉结扎并缺氧(80 mL/L 氧气和920 mL/L 氮气)2h 制作HIBD 模型;假手术组仅分离左侧颈总动脉,不行结扎及缺氧处理;干预组在缺氧缺血前、缺氧缺血后0、24、48、72 h 给予枸橼酸咖啡因(20 mg/kg)腹腔注射,HIBD 组分别在同一时间点以等量生理盐水行替代腹腔注射。各组大鼠于12 日龄处死,采用免疫组织化学法检测左侧脑皮层下白质MBP 的表达;实时荧光定量逆转录聚合酶链式反应技术(Real-time PCR)检测各组大鼠左侧脑组织腺苷A1 受体(A1R)和A2a 受体(A2aR)mRNA 的含量。结果 HIBD 组左侧脑皮质下白质MBP 表达较假手术组明显减少(P<0.05),干预组较HIBD 组MBP 表达增多,但仍低于假手术组(P<0.05);HIBD 组A1R mRNA 较假手术组显著上调(P<0.05),干预组A1R mRNA 较HIBD 组显著下降(P<0.05)。结论 枸橼酸咖啡因能减轻缺氧缺血后新生大鼠脑白质损伤,这种保护作用可能与下调腺苷A1R 表达有关。

Abstract:

Objective To study the effects of caffeine citrate on myelin basic protein (MBP) expression in the cerebral white matter of neonatal rats with hypoxic-ischemic brain damage (HIBD) and the related mechanism.Methods Forty-eight seven-day-old Sprague-Dawley neonatal rats were randomly assigned to 3 groups:sham operation (n=16), HIBD (n=16) and HIBD+caffeine citrate (n=16). The rats in the HIBD and HIBD+caffeine citrate groups were subjected to left common carotid artery ligation, and then were exposed to 80 mL/L oxygen and 920 mL/L nitrogen for 2 hours to induce HIBD. The rats in the sham operation group were only subjected to a sham operation, without the left common carotid artery ligation or hypoxia exposure. Caffeine citrate (20 mg/kg) was injected intraperitoneally before hypoxia ischemia (HI) and immediately, 24 hours, 48 hours and 72 hours after HI. The other two groups were injected intraperitoneally with an equal volume of normal saline at the corresponding time points. On postnatal day 12, the expression of MBP in the left subcortical white matter was detected by immunohistochemistry, and the levels of adenosine A1 receptor mRNA and A2a receptor mRNA in the left brain were detected by real-time PCR.Results The expression of MBP in the left subcortical white matter in the HIBD group was lower than in the sham operation group (P<0.05). The MBP expression in the HIBD+caffeine citrate group was significantly higher than in the HIBD group, but was still lower than the sham operation group (P<0.05). Real-time PCR showed that the adenosine A1 receptor mRNA expression was significantly higher in the HIBD group than in the sham operation group, and it was significantly lower in the HIBD+caffeine citrate group than in the HIBD group (P<0.05).Conclusions Caffeine citrate can improve brain white matter damage following HIBD in neonatal rats and the protection mechanism might be related with the down-regulation of adenosine A1 receptor expression.