Sameshima H, Ota A, Ikenoue T
Department of Obstetrics and Gynecology and the Perinatal Center, Miyazaki Medical College, Miyazaki, Japan.
Am J Obstet Gynecol. 1999 Mar;180(3 Pt 1):725-30. doi: 10.1016/s0002-9378(99)70279-6.
Our purpose was to study the neuroprotective effect of magnesium sulfate on hypoxicischemic brain damage and how the timing of magnesium administration changes its effect in the newborn rat.
Seven-day-old rats (n = 91) were exposed to unilateral carotid artery ligation followed by 2 hours of hypoxia (8% oxygen in 92% nitrogen). Magnesium sulfate (270 mg/kg) was intraperitoneally administered 30 minutes before (pretreatment) or 30 minutes after (posttreatment) the 2 hours of hypoxia. In each experiment equivalent amounts of saline solution were administered as controls. Seven days after the injury the rats were killed and the brains were removed for histologic study with hematoxylin and eosin staining. The severity of brain atrophy and neuronal damage was evaluated in the cerebral cortex and hippocampus and compared by chi2 test between the magnesium group and the controls.
Ionized magnesium concentrations were significantly increased from 0.52 +/- 0.02 mmol/L to 1.38 +/- 0.07 mmol/L at 0.5 hour after injection and thereafter gradually decreased to 0.73 +/- 0.07 mmol/L at 3.5 hours. Magnesium significantly reduced the incidence of weight loss (0% in magnesium vs 29% in controls) and protected the cerebral cortex from neuronal loss (the incidence of normal, mild, moderate, and severe neuronal loss was 48%, 29%, 5%, and 19% in magnesium and 30%, 5%, 25%, and 40% in controls, respectively) in the pretreatment group. In the posttreatment group magnesium caused increased neuronal damage compared with the controls.
Magnesium sulfate has neuroprotective effects against hypoxia-ischemia. This effect is restricted to the pretreatment group in which magnesium sulfate is administered before the insult.
我们的目的是研究硫酸镁对新生儿缺氧缺血性脑损伤的神经保护作用，以及镁给药时间如何改变其在新生大鼠中的作用。
将7日龄大鼠（n = 91）进行单侧颈动脉结扎，随后缺氧2小时（92%氮气中含8%氧气）。在缺氧2小时前30分钟（预处理）或缺氧2小时后30分钟（后处理）腹腔注射硫酸镁（270 mg/kg）。在每个实验中，给予等量的生理盐水作为对照。损伤7天后处死大鼠，取出大脑用苏木精和伊红染色进行组织学研究。评估大脑皮质和海马体中脑萎缩和神经元损伤的严重程度，并通过卡方检验比较镁组和对照组。
注射后0.5小时，离子镁浓度从0.52±0.02 mmol/L显著增加至1.38±0.07 mmol/L，此后逐渐下降，在3.5小时时降至0.73±0.07 mmol/L。硫酸镁显著降低了体重减轻的发生率（镁组为0%，对照组为29%），并保护大脑皮质免受神经元损失（预处理组中正常、轻度、中度和重度神经元损失的发生率在镁组分别为48%、29%、5%和19%，在对照组分别为30%、5%、25%和40%）。在后处理组中，与对照组相比，硫酸镁导致神经元损伤增加。
硫酸镁对缺氧缺血具有神经保护作用。这种作用仅限于在损伤前给予硫酸镁的预处理组。
