异氟烷对大鼠海马切片的神经保护作用随衰老而降低：细胞内钙离子调节及 N-甲基-D-天冬氨酸受体介导的钙离子内流的变化

Isoflurane neuroprotection in rat hippocampal slices decreases with aging: changes in intracellular Ca2+ regulation and N-methyl-D-aspartate receptor-mediated Ca2+ influx.

作者信息

Zhan Xinhua, Fahlman Christian S, Bickler Philip E

机构信息

Severinghaus-Radiometer Research Laboratories, Department of Anesthesia and Perioperative Care, University of California at San Francisco, 94143-0542, USA.

出版信息

Anesthesiology. 2006 May;104(5):995-1003. doi: 10.1097/00000542-200605000-00016.

DOI:10.1097/00000542-200605000-00016

PMID:16645452

Abstract

BACKGROUND

Most in vitro neuroprotection studies with isoflurane have involved cells obtained during the embryonic or early postnatal period. However, in mature rodents, isoflurane neuroprotection does not persist. The authors determined whether neuroprotection of hippocampal slices with isoflurane decreases with aging and is due to decreased intracellular Ca regulation and survival protein phosphorylation.

METHODS

Hippocampal slices from 5-day-old, 1-month-old, and 19- to 23-month-old rats were deprived of oxygen and glucose for 5-30 min in media bubbled with 1% isoflurane. Cell death was assessed in the CA1, CA3, and dentate regions, and intracellular Ca concentration was measured in CA1 neurons. N-methyl-d-aspartate receptor (NMDAR)-dependent Ca influx was measured and the phosphorylation of NMDARs, and the survival proteins Akt and mitogen-activated protein kinase p42/44 were quantified.

RESULTS

Twenty minutes of oxygen and glucose deprivation killed approximately 40-60% of neurons in CA3 and dentate in all age groups. Isoflurane, 1%, reduced death of CA1, CA3, and dentate neurons in slices from 5-day-old rats but not those from 23-month-old rats. In 5-day slices, isoflurane attenuated NMDAR-mediated Ca influx, whereas in aging slices, Ca influx was increased protein kinase C. In aging slices, isoflurane did not increase the phosphorylation of Akt and p42/44.

CONCLUSIONS

Isoflurane neuroprotection of hippocampal slices during oxygen and glucose deprivation decreases with age. Isoflurane does not prevent large increases in intracellular Ca concentration during oxygen and glucose deprivation and does not induce the phosphorylation of the prosurvival proteins in aging slices. A protein kinase C-mediated increase in NMDAR activity may result in increased excitotoxicity and decreased neuroprotection by volatile anesthetics in the aging brain.

摘要

背景

大多数关于异氟烷的体外神经保护研究都使用了胚胎期或出生后早期获得的细胞。然而，在成年啮齿动物中，异氟烷的神经保护作用不会持续存在。作者确定了异氟烷对海马切片的神经保护作用是否会随着衰老而降低，以及是否由于细胞内钙调节和存活蛋白磷酸化的降低所致。

方法

将5日龄、1月龄以及19至23月龄大鼠的海马切片在含1%异氟烷的培养基中进行5至30分钟的缺氧和无糖处理。评估CA1、CA3和齿状区域的细胞死亡情况，并测量CA1神经元内的钙浓度。测量N-甲基-D-天冬氨酸受体（NMDAR）依赖性钙内流，并对NMDAR、存活蛋白Akt和丝裂原活化蛋白激酶p42/44的磷酸化进行定量分析。

结果

在所有年龄组中，20分钟的缺氧和无糖处理导致CA3和齿状区域约40%至60%的神经元死亡。1%的异氟烷可减少5日龄大鼠切片中CA1、CA3和齿状神经元的死亡，但对23月龄大鼠切片无效。在5日龄的切片中，异氟烷可减弱NMDAR介导的钙内流，而在衰老的切片中，蛋白激酶C使钙内流增加。在衰老的切片中，异氟烷不会增加Akt和p42/44的磷酸化。