亚低温治疗蛛网膜下腔出血伴脑血管痉挛大鼠对脑代谢的影响

Effect of mild hypothermia treatment on cerebral metabolism in rats model of cerebral vasospasm after subarachnoid hemorrhage

目的探讨亚低温治疗蛛网膜下腔出血伴迟发性脑血管痉挛大鼠对脑代谢的影响。方法将40只成年SD大鼠随机分为对照组、常温组和亚低温治疗组，每组10只。另用4只观察蛛网膜下腔的血液分布，6只备用。采用两次枕大池注血制作模型。亚低温组用冰袋全身降温，维持体温在31～33℃；对照组和常温组维持体温在37～38℃。于第2次注血后第5天进行连续检测8h，检测指标包括脑微透析液中葡萄糖、乳酸、丙酮酸和乳酸／丙酮酸比值（L／P）。结果脑微透析液中葡萄糖水平：常温组（0．44±0．08）mmol／L〈亚低温治疗组（0．53±0．03）mmol／L〈对照组（0．74±0．06）mmol／L；丙酮酸水平：常温组（20．0±2．4）mmol／L〈亚低温治疗组（28．8±6．3）mmol／L〈对照组（35．9±7．6）mmol／L；乳酸水平：亚低温治疗组（0．66±0．05）gmol／L〈对照组（0．93±0．06）μmol／L〈常温组（1．91±0．32）μmol／L；L／P比值：亚低温治疗组（28±12）〈对照组（35±10）〈常温组（108±26）。在8h内重复测量的其他指标变化亦呈上述变化趋势。结论蛛网膜下腔出血伴迟发性脑血管痉挛后经亚低温治疗，可通过降低实验动物的脑氧耗量，维持细胞能量代谢以及减轻乳酸堆积等作用，对脑组织起到保护作用。

Objective To investigate the effect of mild hypothermia on cerebral metabolism in rats during the delayed cerebral vasospasm by using the microdialysis technique. Methods Forty adult SD rats were randomly divided into control, normal temperature and mild hypothermia groups （ n = 10 in each group） ; the other 4 rats were used for observing blood distribution of subarachnoid hemorrhage, and 6 were used as reserves. The model was made by injecting blood into cisterna magMa twice. Ice bags were used for total body hypothermia, and body temperatures were maintained between 31 to 33℃ in the mild hypothermia group; the body temperatures were maintained between 37 to 38℃ in the control and normal temperature groups. The 8-hour successive detection was performed at day 5 after the second injection. The detecting indexes included the values of glucose, lactic acid, pyruvic acid and lactic acid/pyruvic acid （L/P） in brain microdialysate. Results The levels of glucose in the brain microdialysate： （0. 44 ± 0. 08 ） mmol/L in the normal temperature group 〈 （0. 53 ± 0. 03 ） mmol/L in the mild hypothermia group 〈 （0.74±0. 06） mmol/L in the control group; the levels of pyruvic acid： （20. 0 ± 2.4） mmol/L in the normal temperature group 〈 （28.8 ± 6. 3 ） mmol/L in the mild hypothermia group 〈 （35.9 ± 7.6） mmol/L in the control group ： The levels of lactic acid ： （0. 66 ± 0. 05 ） mol/L in the mild hypothermia group 〈 （0. 93 ±0. 06） mol/L in the control group 〈 （1.91±0. 32） mol/L in the normal temperature group; L/P ratio： 28 ± 12 in the mild hypothermia group 〈35 ±10 in the control group 〈 108 ＋26 in the normal temperature group. The repeated measurements showed that the continuous monitoring the changes of the above indexes within 8 hours were also like the above changing trend. Conclusion Mild hypothermia treatment after delayed cerebral vasospasm may play a role in neuroprotection by reducing the oxygen consumption in experimental animals, maintaining cellular energy metabolism and lowering the accumulation of pyruvic acid.