亚低温和硫酸镁对缺氧缺血脑损伤保护作用的实验研究

Experimental study on protective effects of hypothermia and/or magnesium sulphate on hypoxic ischemic brain damage

目的探讨亚低温和硫酸镁对缺氧缺血脑损伤（ＨＩＢＤ）的保护作用。方法７日龄ＳＤ大鼠２８２只（体重：１４ｇ±２．３ｇ）右颈总动脉永久性结扎加８％氧气２小时。将此模型动物随机分为亚低温干预组（ｈｙ６０只）；硫酸镁（ＭｇＳＯ４）干预组（Ｍｇ６２只）；联合干预组（ＨＭ６０只）；室温恢复组（ＲｏＴ６０只）。５组动物于实验后２４小时、４８小时、７２小时测血浆Ｓ１００蛋白（Ｓ１００）和肌酸激酶脑型同功酶（ＣＫＢＢ）水平。实验２周后以脑组织病理切片的右侧脑损伤分数（ＢＩＳ）和右侧海马细胞死亡率（ＨＮＮＰ）判定疗效。结果ＲｏＴ、Ｍｇ、Ｈｙ和ＨＭ４组动物干预期间肛温（ＲＴ）平均为３６．６°Ｃ，３６．７°Ｃ，３２．５°Ｃ和３２．４°Ｃ，脑温（ＢＴ）低于ＲＴ０．３°Ｃ～０．６°Ｃ（γ＝０．９９，Ｐ＜０．０１）。ＲｏＴ组血浆Ｓ１００、ＣＫＢＢ于２４小时～４８小时达峰值（分别为１．２１μｇ／Ｌ～１．２４μｇ／Ｌ和５０．３ＩＵ／Ｌ～５７．２ＩＵ／Ｌ），是正常的２～３倍，３个干预组血浆Ｓ１００和ＣＫＢＢ水平明显低于ＲｏＴ组（Ｐ＜０．０１）。病理结果显示：ＲｏＴ、Ｍｇ、Ｈｙ和ＨＭ四组ＢＩＳ分别为３．２、１．８、０．３和１．２；Ｈ?

Objective To investigate the effects of moderate hypothermia and/or magnesium sulphate (MgSO 4) on cerebral hypoxic ischemic damage. Methods 7 d newborn SD rats (n=282,BW=14±2.3g), received right carotid arterial ligation and exposed to 8% oxygen for 2h after 3h～4h of recovery, and then allocated to 4 groups: Hypothermia (Hy n=60); MgSO 4(Mg n=62); Hy and Mg(HM n=60) and room temperature recovered group (RoT n=60). At 24h, 48h and 72h after the insult, the plasma levels of S 100 protein (S 100) and creatine phosphokinase BB isoenzyme(CK BB) were examined. Two weeks after HI, brain injury score (BIS) and percentages of necrotic neurons in hippocampus (HNNP) were determined under microscope.Results Brain temperature (BT) was about 0.3°C～0.6° lower than and closely correlated to rectal temperatue (RT γ=0.99, P <0.01), and RT of the animals in RoT, Mg, Hy and HM groups was kept at 36.6°C,36.7°C,32.5 °C and 32.4°C respectively during the intervention period. The peak level of S 100 and CK BB in RoT group (1.21μg/L～1.24μg/L and 50.3IU/L～57.2IU/L, respectively) were about 2 to 3 folds as high as normal levels at 24h to 48h after HI, while the plasma S 100 and CK BB levels in Mg, Hy and HM groups were significantly decreased ( P <0.01). BIS for RoT, Mg, Hy and HM groups were 3.2、1.8、0.3 and 1.2; HNNP were 71%, 31%, 11% and 17%, respectively. Conclusion All three therapies protect brain damage due to HI. The changes of plasma levels of S 100 and CK BB are well correlated with the protective effects.