Temple M D, Delahunty T M, Hamm R J, Phillips L L, Lyeth B G, Povlishock J T
Department of Psychology, Medical College of Virginia/Virginia Commonwealth University, Richmond, USA.
J Neurotrauma. 2001 Jan;18(1):47-55. doi: 10.1089/089771501750055767.
This study examined whether NMDA-stimulated cyclic GMP levels were altered at two different time points following lateral fluid percussion injury. At 60 min and 15 days postinjury, the left and right hippocampi were dissected and chopped into mini-prisms. Each hippocampus was divided into five equal parts and incubated with either the phosphodiesterase inhibitor IBMX (3-isobutyl-1-methylxanthine, 500 microM) alone, IBMX and N-methyl-D-aspartic acid (NMDA) OR IBMX, NMDA, and glycine (10 MM). Two concentrations of NMDA were used: 500 or 1,000 microM. Tissues were then assayed for levels of cyclic GMP. Results indicated that there were no changes in basal levels of cyclic GMP at either postinjury time point. At 60 min postinjury, there were no significant main effects for injury or drug concentration. There was a significant injury x side interaction effect with increased levels of NMDA-stimulated cyclic GMP in the hippocampus ipsilateral to the injury impact and decreased cyclic GMP levels in the contralateral hippocampus. There were no significant alterations in NMDA-stimulated cyclic GMP levels at 15 days postinjury. The data from this study indicated that NMDA-stimulated cyclic GMP accumulation is differentially altered in the hippocampus ipsilateral and contralateral to the site of the injury at 1 h after injury, but is normalized by 15 days postinjury. These findings implicate NMDA-mediated intracellular signaling processes in the acute excitotoxic response to injury.
本研究检测了在侧脑室液压冲击伤后的两个不同时间点，N-甲基-D-天冬氨酸（NMDA）刺激的环磷酸鸟苷（cGMP）水平是否发生改变。在伤后60分钟和15天，将左右海马体分离并切成小棱柱体。每个海马体被等分为五份，并分别与磷酸二酯酶抑制剂异丁基甲基黄嘌呤（IBMX，500微摩尔）单独孵育、与IBMX和N-甲基-D-天冬氨酸（NMDA）共同孵育或与IBMX、NMDA和甘氨酸（10毫摩尔）共同孵育。使用了两种浓度的NMDA：500或1000微摩尔。然后检测组织中的环磷酸鸟苷水平。结果表明，在任何一个伤后时间点，环磷酸鸟苷的基础水平均无变化。在伤后60分钟，损伤或药物浓度均无显著主效应。存在显著的损伤×侧别交互效应，损伤侧海马体中NMDA刺激的环磷酸鸟苷水平升高，而对侧海马体中环磷酸鸟苷水平降低。在伤后15天，NMDA刺激的环磷酸鸟苷水平无显著改变。本研究数据表明，伤后1小时，损伤部位同侧和对侧海马体中NMDA刺激的环磷酸鸟苷积累存在差异改变，但在伤后15天时恢复正常。这些发现提示NMDA介导的细胞内信号转导过程参与了对损伤的急性兴奋性毒性反应。
