OBJECTIVEAlthough cortical spreading depolarization (CSD) has been observed during the early phase of subarachnoid hemorrhage (SAH) in clinical settings, the pathogenicity of CSD is unclear. The aim of this study is to elucidate the effects of loss of membrane potential on neuronal damage during the acute phase of SAH.METHODSTwenty-four rats were subjected to SAH by the perforation method. The propagation of depolarization in the brain cortex was examined by using electrodes to monitor 2 direct-current (DC) potentials and obtaining NADH (reduced nicotinamide adenine dinucleotide) fluorescence images while exposing the parietal-temporal cortex to ultraviolet light. Cerebral blood flow (CBF) was monitored in the vicinity of the lateral electrode. Twenty-four hours after onset of SAH, histological damage was evaluated at the DC potential recording sites.RESULTSChanges in DC potentials (n = 48 in total) were sorted into 3 types according to the appearance of ischemic depolarization in the entire hemisphere following induction of SAH. In Type 1 changes (n = 21), ischemic depolarization was not observed during a 1-hour observation period. In Type 2 changes (n = 13), the DC potential demonstrated ischemic depolarization on initiation of SAH and recovered 80% from the maximal DC deflection during a 1-hour observation period (33.3 ± 15.8 minutes). In Type 3 changes (n = 14), the DC potential displayed ischemic depolarization and did not recover during a 1-hour observation period. Histological evaluations at DC potential recording sites showed intact tissue at all sites in the Type 1 group, whereas in the Type 2 and Type 3 groups neuronal damage of varying severity was observed depending on the duration of ischemic depolarization. The duration of depolarization that causes injury to 50% of neurons (P50) was estimated to be 22.4 minutes (95% confidence intervals 17.0–30.3 minutes). CSD was observed in 3 rats at 6 sites in the Type 1 group 5.1 ± 2.2 minutes after initiation of SAH. On NADH fluorescence images CSD was initially observed in the anterior cortex; it propagated through the entire hemisphere in the direction of the occipital cortex at a rate of 3 mm/minute, with repolarization in 2.3 ± 1.2 minutes. DC potential recording sites that had undergone CSD were found to have intact tissue 24 hours later. Compared with depolarization that caused 50% neuronal damage, the duration of CSD was too short to cause histological damage.CONCLUSIONSCSD was successfully visualized using NADH fluorescence. It propagated from the anterior to the posterior cortex along with an increase in CBF. The duration of depolarization in CSD (2.3 ± 1.2 minutes) was far shorter than that causing 50% neuronal damage (22.4 minutes) and was not associated with histological damage in the current experimental setting.
OBJECTIVEThe aim of this study was to evaluate whether combined gene therapy with vascular endothelial growth factor (VEGF) plus apelin during indirect vasoreconstructive surgery enhances brain angiogenesis in a chronic cerebral hypoperfusion model in rats.METHODSA chronic cerebral hypoperfusion model induced by the permanent ligation of bilateral common carotid arteries (CCAs; a procedure herein referred to as “CCA occlusion” [CCAO]) in rats was employed in this study. Seven days after the CCAO procedure, the authors performed encephalo-myo-synangiosis (EMS) and injected plasmid(s) into each rat's temporal muscle. Rats were divided into 4 groups based on which plasmid was received (i.e., LacZ group, VEGF group, apelin group, and VEGF+apelin group). Protein levels in the cortex and attached muscle were assessed with enzyme-linked immunosorbent assay (ELISA) on Day 7 after EMS, while immunofluorescent analysis of cortical vessels was performed on Day 14 after EMS.RESULTSThe total number of blood vessels in the cortex on Day 14 after EMS was significantly larger in the VEGF group and the VEGF+apelin group than in the LacZ group (p < 0.05, respectively). Larger vessels appeared in the VEGF+apelin group than in the other groups (p < 0.05, respectively). Apelin protein on Day 7 after EMS was not detected in the cortex for any of the groups. In the attached muscle, apelin protein was detected only in the apelin group and the VEGF+apelin group. Immunofluorescent analysis revealed that apelin and its receptor, APJ, were expressed on endothelial cells (ECs) 7 days after the CCAO.CONCLUSIONSCombined gene therapy (VEGF plus apelin) during EMS in a chronic cerebral hypoperfusion model can enhance angiogenesis in rats. This treatment has the potential to be a feasible option in a clinical setting for patients with moyamoya disease.
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