Howard Angela S, Fitzpatrick Richard, Pessah Isaac, Kostyniak Paul, Lein Pamela J
Department of Environmental Health Sciences, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD 21205, USA.
Toxicol Appl Pharmacol. 2003 Jul 1;190(1):72-86. doi: 10.1016/s0041-008x(03)00156-x.
Perinatal exposure to polychlorinated biphenyls (PCBs) is linked to cognitive deficits in humans and experimental animals; however, the mechanism(s) underlying this effect remain speculative. Apoptosis is essential to normal brain development, and perturbation of normal spatiotemporal patterns of apoptosis can cause persistent neural deficits. We tested the hypothesis that PCBs alter apoptosis in neuronal cell types critical to cognitive function. Primary cultures of rat cortical and hippocampal neurons were treated for 48 h with Aroclor 1254 or the congeners PCB 77 and 47, which represent coplanar and noncoplanar PCBs that bind the arylhydrocarbon receptor (AhR) with high and low affinity, respectively. Using Hoechst dye and an ELISA for DNA oligonucleosomes, we observed that Aroclor 1254 (10 microM) and PCB 47 (1 microM) significantly increased DNA fragmentation in hippocampal but not cortical neurons, and this effect was blocked by the caspase inhibitors, z-VAD-fmk and DEVD-CHO. In contrast, PCB 77 had no effect on apoptosis in either neuronal cell type, suggesting that PCB-induced apoptosis occurs independent of the AhR. The proapoptotic activity of PCBs was inhibited by the ryanodine receptor (RyR) antagonist FLA 365 and by the antioxidant alpha-tocopherol but not by antagonists of the IP(3) receptor (xestospongin C), L-type calcium channel (verapamil), or NMDA receptor (APV). These data indicate that noncoplanar PCBs induce apoptosis in hippocampal neurons subsequent to RyR activation and increased reactive oxygen species and suggest that altered regional profiles of apoptosis may be an important mechanism underlying the developmental neurotoxicity of PCBs.
围产期接触多氯联苯（PCBs）与人类和实验动物的认知缺陷有关；然而，这种效应背后的机制仍具有推测性。细胞凋亡对于正常的大脑发育至关重要，而正常细胞凋亡的时空模式受到干扰会导致持续性神经缺陷。我们检验了这样一个假设，即多氯联苯会改变对认知功能至关重要的神经元细胞类型中的细胞凋亡。用Aroclor 1254或同系物PCB 77和47对大鼠皮质和海马神经元的原代培养物进行48小时处理，它们分别代表以高亲和力和低亲和力与芳烃受体（AhR）结合的共平面和非共平面多氯联苯。使用Hoechst染料和DNA寡核苷酸小体酶联免疫吸附测定法，我们观察到Aroclor 1254（10微摩尔）和PCB 47（1微摩尔）显著增加了海马神经元而非皮质神经元中的DNA片段化，并且这种效应被半胱天冬酶抑制剂z-VAD-fmk和DEVD-CHO所阻断。相比之下，PCB 77对这两种神经元细胞类型中的细胞凋亡均无影响，这表明多氯联苯诱导的细胞凋亡独立于芳烃受体发生。多氯联苯的促凋亡活性被兰尼碱受体（RyR）拮抗剂FLA 365和抗氧化剂α-生育酚所抑制，但未被肌醇三磷酸受体（西司他汀C）、L型钙通道（维拉帕米）或N-甲基-D-天冬氨酸受体（APV）的拮抗剂所抑制。这些数据表明，非共平面多氯联苯在兰尼碱受体激活和活性氧增加后诱导海马神经元凋亡，并表明细胞凋亡区域分布的改变可能是多氯联苯发育神经毒性的重要潜在机制。
