Wang Cheng Z, Johnson Kenneth M
Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555-1031, USA.
Neuropsychopharmacology. 2007 May;32(5):1178-94. doi: 10.1038/sj.npp.1301202. Epub 2006 Sep 20.
This study determined the role of caspase-3 in phencyclidine (PCP)-induced neurodegeneration in postnatal rats. PCP administration to postnatal day 7 rats induced a dose-dependent increase in caspase-3 enzymatic activity in frontal cortex, striatum, and hippocampus. Enzymatic activation was present at 4 h, peaked between 6 and 12 h, and disappeared by 24 h. Further, cleaved caspase-3-immunoreactive neurons were detected as early as 2 h in the cortex, and were found throughout the brain, including, in addition, the thalamus and striatum. Within the cingulate, frontal, parietal, and retrosplenial cortices, immunoreactivity was specific for layers II-IV (especially layer II). Neurons positive for both silver staining and terminal deoxynucleotidyl transferase biotin-d-UTP nick-end labeling (TUNEL) were found in the same brain regions and subregions. Double labeling experiments confirmed that cleaved caspase-3 and TUNEL were coexpressed in many neurons in all brain regions and subregions studied. Temporal studies revealed that procaspase-3 cleavage preceded TUNEL staining by about 3 h, with many neurons being positive for both caspase-3 and TUNEL 9 h after PCP treatment. In organotypic corticostriatal slices, PCP caused a concentration- and time-dependent cleavage of procaspase-3 that was also colocalized with TUNEL staining in layers II-IV of the parietal cortex. Caspase-3 activation again preceded PCP-induced DNA damage assessed by TUNEL. PCP-induced neuronal death in vitro as measured by TUNEL staining was blocked 85% by Ac-AAVALLPAVLLALLAPDEVD-CHO, a cell-permeable selective caspase-3 inhibitor. These data demonstrate that caspase-3 activation plays a necessary role in the regionally selective neuronal death induced by PCP in the developing rat brain.
本研究确定了半胱天冬酶 - 3在苯环利定（PCP）诱导的新生大鼠神经退行性变中的作用。给出生后第7天的大鼠注射PCP，可导致额叶皮质、纹状体和海马体中半胱天冬酶 - 3酶活性呈剂量依赖性增加。酶活性在4小时时出现，6至12小时达到峰值，24小时时消失。此外，早在2小时就在皮质中检测到裂解的半胱天冬酶 - 3免疫反应性神经元，并且在整个大脑中都能发现，包括丘脑和纹状体。在扣带回、额叶、顶叶和压后皮质内，免疫反应性特异性存在于II - IV层（尤其是II层）。在相同的脑区和亚区中发现了银染和末端脱氧核苷酸转移酶生物素 - dUTP缺口末端标记（TUNEL）均呈阳性的神经元。双重标记实验证实，在所有研究的脑区和亚区中，许多神经元中裂解的半胱天冬酶 - 3和TUNEL共表达。时间研究表明，半胱天冬酶 - 3原酶的裂解比TUNEL染色早约3小时，在PCP处理后9小时，许多神经元的半胱天冬酶 - 3和TUNEL均呈阳性。在器官型皮质纹状体切片中，PCP导致半胱天冬酶 - 3原酶的浓度和时间依赖性裂解，其也与顶叶皮质II - IV层中的TUNEL染色共定位。半胱天冬酶 - 3激活再次先于通过TUNEL评估的PCP诱导的DNA损伤。通过TUNEL染色测量，PCP诱导的体外神经元死亡被细胞可渗透的选择性半胱天冬酶 - 3抑制剂Ac - AAVALLPAVLLALLAPDEVD - CHO阻断了85%。这些数据表明，半胱天冬酶 - 3激活在发育中的大鼠脑中由PCP诱导的区域选择性神经元死亡中起必要作用。
