A single stress exposure facilitates memory formation through neuroplastic processes that reshape excitatory synapses in the hippocampus, probably requiring changes in extracellular matrix components. We tested the hypothesis that matrix metalloproteinase 9 (MMP-9), an enzyme that degrades components of extracellular matrix and synaptic proteins such as β-dystroglycan (β-DG₄₃), changes their activity and distribution in rat hippocampus during the acute stress response. After 2.5 h of restraint stress, we found (i) increased MMP-9 levels and potential activity in whole hippocampal extracts, accompanied by β-DG₄₃ cleavage, and (ii) a significant enhancement of MMP-9 immunoreactivity in dendritic fields such as stratum radiatum and the molecular layer of hippocampus. After 24 h of stress, we found that (i) MMP-9 net activity rises at somatic field, i.e., stratum pyramidale and granule cell layers, and also at synaptic field, mainly stratum radiatum and the molecular layer of hippocampus, and (ii) hippocampal synaptoneurosome fractions are enriched with MMP-9, without variation of its potential enzymatic activity, in accordance with the constant level of cleaved β-DG₄₃. These findings indicate that stress triggers a peculiar timing response in the MMP-9 levels, net activity, and subcellular distribution in the hippocampus, suggesting its involvement in the processing of substrates during the stress response.

中文翻译：

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基质金属蛋白酶9显示对急性应激的特定时间响应：大鼠海马中其水平和活性分布的变化

一次应力暴露通过重塑海马兴奋性突触的神经塑性过程促进记忆形成，可能需要改变细胞外基质成分。我们测试了基质金属蛋白酶的假说9（MMP-9），一种酶的细胞外基质和突触蛋白质如β-肌营养不良（β-DG的降解部件₄₃），改变了急性应激反应期间它们在大鼠海马活性和分布。束缚应激的2.5小时后，我们发现（i）增加的MMP-9水平和潜在活性在整个海马提取物，伴随着β-DG ₄₃切割，并且在树突状领域，如MMP-9免疫反应性的（ⅱ）显著增强放射状的地层和海马的分子层。应激24小时后，我们发现（i）MMP-9净活性在体细胞场，即锥体细胞层和颗粒细胞层，以及在突触场（主要是辐射层和海马分子层）均升高，和（ii ）海马synaptoneurosome馏分富含MMP-9，没有它的潜在酶活性的变体中，按照切割β-DG的恒定电平₄₃。这些发现表明，应激会触发海马中MMP-9水平，净活性和亚细胞分布的特殊时序反应，表明其在应激反应中参与了底物的加工。