Patanow C M, Day J R, Billingsley M L
Department of Pharmacology, Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey 17033, USA.
Neuroscience. 1997 Jan;76(1):187-202. doi: 10.1016/s0306-4522(96)00335-1.
A set of well-defined antisera against neuronal and glial proteins were used to characterize patterns of protein expression in rat hippocampus following transection of the fimbira-fornix and perforant pathways or after administration of the selective neurotoxicant trimethyltin (8 mg/kg, i.p.). SNAP-25 (synaptosomal protein, mol. wt 25,000) is a neuron-specific, developmentally regulated presynaptic protein, stannin is a protein enriched in cells sensitive to trimethyltin, and GAP-43 (growth-associated protein, mol. wt 43,000) is associated with axonal growth and regeneration. Glial fibrillary acidic protein is an astrocyte-specific intermediate filament protein and a marker for reactive gliosis. SNAP-25 immunoreactivity was altered following both neurotoxicant and mechanical injury. Three days after fimbria-fornix/perforant path lesions, there was a loss of SNAP-25 immunoreactivity in hippocampal efferent pathways and in the lesioned entorhinal cortex. By day 12, there was evidence of reinnervation of hippocampal subfields by SNAP-25-immunopositive commissural afferent fibers. On day 3, immunoblots showed the appearance of SNAP-25a, a developmental isoform produced by alternative splicing of nine amino acids in exon 5, in lesioned tissues. This isoform declined by day 12 and was not found in contralateral control hippocampus or non-lesioned brain regions. Stannin immunoreactivity was unchanged, while GAP-43 was prominent on day 12 post-lesion. Glial fibrillary acidic protein immunoreactivity indicated gliosis near the site of pathway transection. In contrast, trimethyltin induced a marked loss of stannin immunoreactivity in hippocampal neurons seven days after injection. Trimethyltin increased glial fibrillary acidic protein staining in the hippocampus and other damaged regions. SNAP-25 immunoreactivity was markedly increased in mossy fibers and other hippocampal fields seven days following trimethyltin. Immunoblot analysis showed that only the adult SNAP-25b isoform was expressed after trimethyltin intoxication. These data suggest that SNAP-25 is a useful marker for presynaptic damage. Furthermore, reexpression of developmental isoforms of SNAP-25a may precede functional reinnervation when the postsynaptic target remains intact.
使用一组针对神经元和神经胶质蛋白的明确抗血清，来表征大鼠海马体在穹窿-海马伞和穿通通路横断后或给予选择性神经毒素三甲基锡（8毫克/千克，腹腔注射）后的蛋白质表达模式。SNAP-25（突触体蛋白，分子量25,000）是一种神经元特异性、受发育调控的突触前蛋白，锡宁是一种在对三甲基锡敏感的细胞中富集的蛋白质，而GAP-43（生长相关蛋白，分子量43,000）与轴突生长和再生相关。胶质纤维酸性蛋白是一种星形胶质细胞特异性中间丝蛋白，也是反应性胶质增生的标志物。神经毒素和机械损伤后，SNAP-25免疫反应性均发生改变。穹窿-海马伞/穿通通路损伤三天后，海马传出通路和损伤的内嗅皮质中SNAP-25免疫反应性丧失。到第12天，有证据表明SNAP-25免疫阳性的连合传入纤维重新支配了海马亚区。在第3天，免疫印迹显示损伤组织中出现了SNAP-25a，这是一种由外显子5中九个氨基酸的可变剪接产生的发育异构体。这种异构体在第12天下降，在对侧对照海马体或未损伤的脑区中未发现。锡宁免疫反应性未改变，而损伤后第12天GAP-43很突出。胶质纤维酸性蛋白免疫反应性表明通路横断部位附近有胶质增生。相比之下，注射三甲基锡七天后，海马神经元中锡宁免疫反应性明显丧失。三甲基锡增加了海马体和其他受损区域的胶质纤维酸性蛋白染色。注射三甲基锡七天后，苔藓纤维和其他海马区域的SNAP-25免疫反应性明显增加。免疫印迹分析表明，三甲基锡中毒后仅表达成年SNAP-25b异构体。这些数据表明，SNAP-25是突触前损伤的有用标志物。此外，当突触后靶点保持完整时，SNAP-25a发育异构体的重新表达可能先于功能性重新支配。
