생쥐 Pilocarpine 모델에서 중첩경련으로 유발한 해마신경세포 사멸과 이끼섬유발아에 대한 MMP-9의 역할

Abstract

Purpose: Matrix metalloproteinases (MMPs) have been known to participate in various pathologic situations by modulating extracellular matrix. Although MMP-9 upregulation has been reported in some experimental seizure models, the exact role of MMP-9 in hippocampal cell death during epileptogenesis and subsequent mossy fiber sprouting (MFS) is not clear. Here, we investigated the role of MMP-9 on hippocampal cell death and MFS after pilocarpine-induced status epilepticus (SE) in mice, using highly specific hydroxamic MMP-9 inhibitor.

Methods: SE was induced by intraperitoneal pilocarpine administration in adult male C57BL/6 mice. MMP-9 specific inhibitor was administered intracerebroventrically 3 h after pilocarpine-induced SE. Expression and activation of MMP-9 were assessed by zymography and Western blot analysis. TdT-mediated UTP-biotin nick end labeling (TUNEL) and caspase-3 activity assay were also performed. MFS was investigated using Timm staining.

Results: Increased expression and activation of MMP-9 after pilocarpine-induced SE were observed in zymography and Western blot analysis. MMP-9 specific inhibitor decreased MMP-9 activity in in situ zymography and hippocampal cell death in cresyl violet staining. DNA fragmentation and caspase-3 activity were also attenuated by MMP-9 specific inhibitor. Four months after pilocarpine-induced SE, MFS was evident in vehicle-treated mice; in contrast, MFS was barely observed in MMP-9 specific inhibitor-treated mice.

Conclusions: This study suggests MMP-9 is associated with hippocampal cell death and MFS after pilocarpine-induced SE. Furthermore, the findings that MMP-9 specific inhibitor ameliorates cell death and MFS offers the possibility of MMP-9 specific hydroxamic inhibitor as novel therapeutic strategy to reduce hippocampal damage and epileptogenesis.