中文摘要：

目的 探讨不同剂量右美托咪定（Dex）对大鼠体外循环（CPB）脑损伤的脑保护作用。方法 采用随机数字表法将体重250~350g、健康成年SD大鼠40只分为4组（n=10）：假手术组（S组）、CPB组（C组）、DexⅠ组（DⅠ组）和DexⅡ组（DⅡ组）。S组仅行动静脉穿刺置管术,DⅠ组、DⅡ组和C组行CPB转流2h,S组和C组静脉泵注与DⅡ组相同容量的生理盐水。DⅠ组在CPB前10min静脉泵注Dex2.5μg/kg负荷剂量,随后以2.5μg/（kg·h）的速度静脉输注,CPB转流2h;DⅡ组Dex负荷剂量为5μg/kg,静脉输注速度为5μg/（kg·h）。于CPB前（T0）、CPB1h（T1）、CPB2h（T2）时采集静脉血,测定血浆中白细胞介素（IL）-6、IL-10、S100β和神经元特异性烯醇化酶（NSE）的浓度。结果 与S组比较,C组T1、T2时点血浆IL-6、IL-10、S100β和NSE升高（P〈0.05）;与C组比较,DⅠ组T2时点血浆IL-6、S100β降低（P〈0.05）,DⅡ组T1、T2时点血浆IL-6、S100β降低（P〈0.05）,DⅠ组和DⅡ组T1、T2时点血浆NSE降低（P〈0.05）;与DⅠ组比较,DⅡ组T1时点血浆S100β降低（P〈0.05）,DⅡ组T2时点血浆NSE降低（P〈0.05）。结论 Dex可以剂量依赖性地降低S100β和NSE水平,有脑保护作用,其机制可能与抑制炎性反应有关。

英文摘要：

Objective To evaluate the effects of dexmedetomidine （Dex） on inflammatory cytokines, S100β and NSE in rats undergoing cardiopulmonary bypass. Methods Forty Sprague - Dawley rats, weighing 250 - 350 g, were randomly divided into 4 groups （n = 10 each） using a random number table, sham operation group （Group S） , cardiopul- monary bypass group （ Group C） , Dex I group （ Group D I ） , and Dex II group （ Group D II ）. Rats in the Group G re- ceived no CPB procedure. CPB rat model was established in Group C, Group D I and Group D II. In Group D I , Dex was infused at a rate of 2. 5 μg/（kg ·h） for2 h during CPB after a loading dose of Dex by 2. 5 μg/kg. In group DII, Dex was infused at a rate of 5 μg/（ kg · h） for 2 h during CPB after a loading dose of Dex by 5 μg/kg. Before CPB （T0）, 1 h after CPB （T1） , and 2 h after CPB （T2） , venous blood samples were collected for detection of plasma con- centrations of interleukin 6 （IL -6）, interleukin 10 （IL - 10）, S100β and NSE in using ELISA. Results Compared with Group S, concentrations of IL- 6, IL- 10, S100β and NSE at T1 and T2 were significantly increased in Group C （ P 〈 0. 05 ）. Compared with Group C, the concentrations of IL - 6 and S100β at T2 were significantly reduced in Group D I （ P 〈 0. 05 ） , as the concentrations of IL - 6 and S100β at T1 and T2 were significantly decreased in Group D II （ P 〈 0. 05）. Meanwhile, the concentrations of NSE at T1 and T2 were significantly reduced in Group D I and Group D II （P 〈0. 05）. Compared with Group D I , the concentration of S100β at T1 was significantly reduced in Group D II （P 〈 0. 05 ） , and the concentration of NSE at T2 was significantly reduced in Group D 11 （ P 〈 0. 05）. Conclusion Dex can attenuate the cerebral injury followed by CPB through inhibiting the inflammatory responses. And there is a certain correla- tion between the effect of cerebral protection and the doses of Dex.