Lapchak Paul A, Araujo Dalia M, Weir Christopher J, Wei Jiandong, Zivin Justin A
University of California San Diego, Department of Neuroscience, La Jolla, CA 92093-0624, USA.
Brain Res. 2003 Jan 10;959(2):183-90. doi: 10.1016/s0006-8993(02)03739-3.
Caspase inhibition has been proposed as a target to attenuate ischemia-induced neurodegeneration and behavioral dysfunction. The present study evaluated the pharmacological effects of a single dose of an irreversible cell permeant general (nonselective) caspase inhibitor, Boc-D-fluoromethylketone (BDFMK) administered intrathecally (i.t.) in a reversible spinal cord ischemia model (RSCIM). Quantal analysis indicated that the P(50) (represents the duration of ischemia that produces permanent paraplegia in 50% of the animals in a group) of the control group was 25.08+/-4.71 min. Using the RSCIM, neuroprotection is observed if a drug significantly prolongs the P(50) compared to the control group. The P(50) values for the BDFMK-treated groups were 27.21+/-2.62, 27.28+/-3.29 and 28.98+/-2.32 min, for the three dose groups studied. There were no statistically significant changes when measured 18 or 48 h following ischemia. Biochemical analysis of cell extracts from the caudal lumbar spinal cord indicated that there was increased production of the 120-kDa fragment of fodrin suggesting enhanced caspase-3 activity, an increase that was reduced by i.t. BDFMK administration. Moreover, in caudal lumbar spinal cord extracts from a set of paraplegic rabbits (25-50 min occlusion), we measured a 32-42% decrease of caspase-3 activity in BDFMK-treated rabbits. The present study shows that i.t. administration of BDFMK reduced caspase-3 activity, but the inhibition did not translate into a significant behavioral improvement. Our results suggest that administration of a single dose of the caspase inhibitor BDFMK is insufficient to attenuate ischemia-induced behavioral deficits following aortic occlusion.
半胱天冬酶抑制已被提议作为减轻缺血性神经退行性变和行为功能障碍的一个靶点。本研究评估了在可逆性脊髓缺血模型（RSCIM）中鞘内注射（i.t.）单剂量不可逆的细胞渗透性通用（非选择性）半胱天冬酶抑制剂Boc-D-氟甲基酮（BDFMK）的药理作用。定量分析表明，对照组的P(50)（代表使一组动物中50%出现永久性截瘫的缺血持续时间）为25.08±4.71分钟。使用RSCIM，如果一种药物与对照组相比能显著延长P(50)，则可观察到神经保护作用。在所研究的三个剂量组中，BDFMK处理组的P(50)值分别为27.21±2.62、27.28±3.29和28.98±2.32分钟。缺血后18小时或48小时测量时，无统计学显著变化。对尾侧腰段脊髓细胞提取物的生化分析表明，血影蛋白120 kDa片段的产生增加，提示半胱天冬酶-3活性增强，而鞘内注射BDFMK可减少这种增加。此外，在一组截瘫兔（闭塞25 - 50分钟）的尾侧腰段脊髓提取物中，我们测量到BDFMK处理兔的半胱天冬酶-3活性降低了32 - 42%。本研究表明，鞘内注射BDFMK可降低半胱天冬酶-3活性，但这种抑制并未转化为显著的行为改善。我们的结果表明，单剂量给予半胱天冬酶抑制剂BDFMK不足以减轻主动脉闭塞后缺血诱导的行为缺陷。
