Nimodipine Reduces Microvasospasms After Experimental Subarachnoid Hemorrhage.

BACKGROUND: The only established pharmacological treatment option improving outcomes for patients suffering from subarachnoid hemorrhage (SAH) is the L-type-calcium channel inhibitor nimodipine. However, the exact mechanisms of action of nimodipine conferring neuroprotection after SAH have yet to be determined. More recently, spasms of the cerebral microcirculation were suggested to play an important role in reduced cerebral perfusion after SAH and, ultimately, outcome. It is unclear whether nimodipine may influence microvasospasms and, thus, microcirculatory dysfunction. The aim of the current study was, therefore, to assess the effect of nimodipine on microvasospasms after experimental SAH. METHODS: Male C57Bl/6 N mice (n=3-5/group) were subjected to SAH using the middle cerebral artery perforation model. Six hours after SAH induction, a cranial window was prepared, and the diameter of cortical microvessels was assessed in vivo by 2-photon-microscopy before, during, and after nimodipine application. RESULTS: Nimodipine significantly reduced the number of posthemorrhagic microvasospasms. The diameters of nonspastic vessels were not affected. CONCLUSIONS: Our results show that nimodipine reduces the formation of microvasospasms, thus, shedding new light on the mode of action of a drug routinely used for the treatment of SAH for >3 decades. Furthermore, L-type Ca2+ channels may be involved in the pathophysiology of microvasospasm formation.

Perivascular Macrophages Mediate Microvasospasms After Experimental Subarachnoid Hemorrhage.

BACKGROUND: Subarachnoid hemorrhage (SAH) is characterized by acute and delayed reductions of cerebral blood flow (CBF) caused, among others, by spasms of cerebral arteries and arterioles. Recently, the inactivation of perivascular macrophages (PVM) has been demonstrated to improve neurological outcomes after experimental SAH, but the underlying mechanisms of protection remain unclear. The aim of our exploratory study was, therefore, to investigate the role of PVM in the formation of acute microvasospasms after experimental SAH. METHODS: PVMs were depleted in 8- to 10-week-old male C57BL/6 mice (n=8/group) by intracerebroventricular application of clodronate-loaded liposomes and compared with mice with vehicle liposome injections. Seven days later, SAH was induced by filament perforation under continuous monitoring of CBF and intracranial pressure. Results were compared with sham-operated animals and animals who underwent SAH induction but no liposome injection (n=4/group each). Six hours after SAH induction or sham surgery, numbers of microvasospasms per volume of interest and % of affected pial and penetrating arterioles were examined in 9 standardized regions of interest per animal by in vivo 2-photon microscopy. Depletion of PVMs was proven by quantification of PVMs/mm3 identified by immunohistochemical staining for CD206 and Collagen IV. Statistical significance was tested with t tests for parametric data and Mann-Whitney U test for nonparametric data. RESULTS: PVMs were located around pial and intraparenchymal arterioles and were effectively depleted by clodronate from 671±28 to 46±14 PVMs/mm3 (P<0.001). After SAH, microvasospasms was observed in pial arteries and penetrating and precapillary arterioles and were accompanied by an increase to 1405±142 PVMs/mm3. PVM depletion significantly reduced the number of microvasospasms from 9 IQR 5 to 3 IQR 3 (P<0.001). CONCLUSIONS: Our results suggest that PVMs contribute to the formation of microvasospasms after experimental SAH.

Acid-Ion Sensing Channel 1a Deletion Reduces Chronic Brain Damage and Neurological Deficits after Experimental Traumatic Brain Injury.

Traumatic brain injury (TBI) causes long-lasting neurodegeneration and cognitive impairments; however, the underlying mechanisms of these processes are not fully understood. Acid-sensing ion channels 1a (ASIC1a) are voltage-gated Na+- and Ca2+-channels shown to be involved in neuronal cell death; however, their role for chronic post-traumatic brain damage is largely unknown. To address this issue, we used ASIC1a-deficient mice and investigated their outcome up to 6 months after TBI. ASIC1a-deficient mice and their wild-type (WT) littermates were subjected to controlled cortical impact (CCI) or sham surgery. Brain water content was analyzed 24 h and behavioral outcome up to 6 months after CCI. Lesion volume was assessed longitudinally by magnetic resonance imaging and 6 months after injury by histology. Brain water content was significantly reduced in ASIC1a-/- animals compared to WT controls. Over time, ASIC1a-/- mice showed significantly reduced lesion volume and reduced hippocampal damage. This translated into improved cognitive function and reduced depression-like behavior. Microglial activation was significantly reduced in ASIC1a-/- mice. In conclusion, ASIC1a deficiency resulted in reduced edema formation acutely after TBI and less brain damage, functional impairments, and neuroinflammation up to 6 months after injury. Hence, ASIC1a seems to be involved in chronic neurodegeneration after TBI.

The Differentially Expressed Genes of Human Sporadic Cerebral Cavernous Malformations.

OBJECTIVES: To understand the development of sporadic cerebral cavernous malformations (SCCM) comprehensively, we analyzed gene expression profiles in SCCMs by gene microarray. METHODS: The total number of the specimens collected in our study was 14, 7 of which were SCCMs, and the others were controls that were obtained from normal brain vessels. The total RNA was extracted and hybridized with oligonucleotide array containing 21522 genes. The analysis of Gene Ontology (GO) items and molecular pathways was performed based on the GO and Kyoto Encyclopedia of Genes and Genomes databases. The gene coexpression networks were constructed to identify the core genes regulating the progression of SCCMs. RESULTS: A total of 785 probes, showing differentially expressed genes (DEGs) between the 2 groups, were found by the gene chips. According to the analysis based on GO and Kyoto Encyclopedia of Genes and Genomes, 286 GO terms and 53 pathways were identified to be significantly relevant with the DEGs. All differential gene interactions were analyzed and the core genes were selected in the coexpression networks. CONCLUSIONS: The gene expression profiles obtained from SCCMs were significantly distinct from those of control brain vascular specimens. These DEGs are related to multiple molecular signal pathways, such as the mitogen-activated protein kinase pathway, cytokine-cytokine receptor interaction, focal adhesion, and inflammatory response. According to the analysis of the core genes selected in the gene coexpression networks, we postulated that CSF1R, XCL1, KCNMB1, RHOG, and TJP1 might exert enormous functions in the pathogenesis of SCCMs. However, further studies are required to aid in the clinical diagnosis and prevention of SCCMs.

The relation between angioarchitectural factors of developmental venous anomaly and concomitant sporadic cavernous malformation.

BACKGROUND: Past studies found that cerebral developmental venous anomaly (DVA) is often concurrent with cavernous malformation (CM). But the reason of the concurrency remains unknown. The purpose of this study was to confirm whether angioarchitectural factors relate to the concurrence and which angioarchitectural factors can induce the concurrency. METHODS: DVA cases were selected from the records of the same 3.0 T MR. The DVA cases was divided into two group which are DVA group and DVA concurrent with CM group. 8 angioarchitectural factors of the DVAs were selected and measured. Statistical analysis was performed by the Pearson chi-square statistic,analysis of variance (ANOVA) and multi-factor logistic regression analysis. RESULTS: Five hundred three DVA lesions were found and 76 CM lesions coexisting with DVA. In the single factor analysis, all the 8 angioarchitectural factors of DVA were related to the concurrency. In the multivariate analysis, 6 angioarchitectural factors. Result of multi-factor logistic regression analysis is Logit(P) = -4.858-0.932(Location) + 1.616(Direction) + 1.757(Torsion) + 0.237(Number) + 2.119(Stenosis rate of medullary vein)-0.015(Angle), goodness of fit is 90.1 %. CONCLUSIONS: The angioarchitectural factors of DVA are related to the concurrency of DVA and CM. 6 angioarchitectural factors may induce the concurrency.