Neuronal activity-dependent increase of net matrix metalloproteinase activity is associated with MMP-9 neurotoxicity after kainate.
Matrix metalloproteinases (MMPs) and the tissue inhibitors of MMPs (TIMPs) are emerging as important modulators of brain physiopathology. Dramatic changes in the expression of MMPs and TIMPs occur during excitotoxic/neuroinflammatory processes. However, only the measurement of net protease activity is relevant physiologically, and the functional consequences of MMP/TIMP ratio modifications in the brain remain elusive. In order to assess MMP activity and effects in brain tissue, we combined in vivo and organotypic culture models of kainate (KA)-induced excitotoxicity to provoke selective neuronal death and neuroinflammation in the hippocampus. Using in situ zymography, we show that KA-induced excitotoxic seizures in rats increase net MMP activity in hippocampal neurons 8 h after seizures, before their death, and that this increase is neuronal activity-dependent. Three days after KA, proteolytic activity increases in blood vessels and reactive glial cells of vulnerable areas, in relation with neuroinflammation. At 7 and 15 days, proteolysis remains high in blood vessels whereas it is reduced in glia. In organotypic hippocampal cultures, which lack blood cell-mediated inflammation and extrinsic connections, a broad-spectrum inhibitor of MMPs (MMPI), but also a selective MMP-9 inhibitor, protect hippocampal neurons against KA-induced excitotoxicity. Moreover, recombinant MMP-9, but not MMP-2, induces selective pyramidal cell death in these cultures and KA-induced neuronal activity exacerbates the neuronal death promoting effects of MMP-9. These data strongly implicate MMPs, and MMP-9 in particular, in both excitotoxic neuronal damage and subsequent neuroinflammatory processes, and suggest that selective MMPIs could be therapeutically relevant in related neurological disorders.
D000818:Animals; D015703:Antigens, CD; D000951:Antigens, Neoplasm; D000954:Antigens, Surface; D030161:Avian Proteins; D051926:Basigin; D001798:Blood Proteins; D001808:Blood Vessels / Q000378:metabolism; D002452:Cell Count; D016923:Cell Death / Q000187:drug effects; D003975:Diazepam / Q000494:pharmacology; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004660:Encephalitis / Q000201:enzymology*; D018690:Excitatory Amino Acid Agonists / Q000633:toxicity*; D018757:GABA Modulators / Q000494:pharmacology; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D007150:Immunohistochemistry; D007608:Kainic Acid / Q000633:toxicity*; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D020782:Matrix Metalloproteinases / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000378:metabolism; D009457:Neuroglia / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000187:drug effects* / Q000201:enzymology; D009924:Organ Culture Techniques; D010618:Phenanthrolines / Q000494:pharmacology; D010663:Phenylmercury Compounds / Q000494:pharmacology; D011480:Protease Inhibitors / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012640:Seizures / Q000139:chemically induced / Q000201:enzymology / Q000378:metabolism*; D013997:Time Factors; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000494:pharmacology
D015703:Antigens, CD; D000951:Antigens, Neoplasm; D000954:Antigens, Surface; D030161:Avian Proteins; D001798:Blood Proteins; C102624:Bsg protein, Gallus gallus; C079432:Bsg protein, rat; D018690:Excitatory Amino Acid Agonists; D018757:GABA Modulators; D005904:Glial Fibrillary Acidic Protein; D008562:Membrane Glycoproteins; D010618:Phenanthrolines; D010663:Phenylmercury Compounds; D011480:Protease Inhibitors; D019715:Tissue Inhibitor of Metalloproteinase-1; D051926:Basigin; C067422:4-aminophenylmercury chloride; D020782:Matrix Metalloproteinases; D020780:Matrix Metalloproteinase 9; D003975:Diazepam; D007608:Kainic Acid