Abstract. In order to determine the differential effects of flavonoids on cerebral ischemia, we investigated the effects of (−)-epigallocatechin gallate (EGCG), catechin, rutin, and quercetin on spatial memory impairment and neuronal death induced by repeated cerebral ischemia in rats. Both rutin and quercetin (50 mg / kg × 2) improved spatial memory impairment in the 8-arm radial maze task and neuronal death in the hippocampal CA1 area; however, catechin (200 mg / kg × 2) and EGCG (50 mg / kg × 1) did not. Administration of EGCG (50 mg / kg × 2) resulted in a high mortality rate. These results suggest that in this repeated cerebral ischemia model, the 4-oxo group and the 2,3-double bond in the C ring of rutin and quercetin are related to their neuroprotective action.

Reperfusion after brain ischemia causes thrombus formation and microcirculatory disturbances, which are dependent on the platelet glycoprotein Ib-von Willebrand factor (VWF) axis. Because ADAMTS13 cleaves VWF and limits platelet-dependent thrombus growth, ADAMTS13 may ameliorate ischemic brain damage in acute stroke. We investigated the effects of ADAMTS13 on ischemia-reperfusion injury using a 30-minute middle cerebral artery occlusion model in Adamts13 ؊/؊ and wild-type mice. After reperfusion for 0.5 hours, the regional cerebral blood flow in the ischemic cortex was decreased markedly in Adamts13 ؊/؊ mice compared with wild-type mice (P < .05), which also resulted in a larger infarct volume after 24 hours for Adamts13 ؊/؊ compared with wild-type mice (P < .01). Thus, Adamts13 gene deletion aggravated ischemic brain damage, suggesting that ADAMTS13 may protect the brain from ischemia by regulating VWF-platelet interactions after reperfusion. These results indicate that ADAMTS13 may be a useful therapeutic agent for stroke. (Blood. 2010; 115:1650-1653) Introductionvon Willebrand factor (VWF) is a large multimeric protein that plays a key role in thrombus formation by tethering platelets at sites of vascular injury. 1 Smaller VWF multimers are less active, and the potent thrombogenic activity of ultra-large VWF (ULVWF) secreted from endothelium is regulated in vivo through cleavage by ADAMTS13. 2,3 The importance of this mechanism for normal hemostasis is supported by evidence that patients with deficiency of ADAMTS13 function, diagnosed with thrombotic thrombocytopenic purpura, have ULVWF in circulating blood and VWFdependent microvascular thrombosis. 2 Recently, we demonstrated that ADAMTS13 cleaves VWF on the surface of platelet thrombi in a shear force-dependent manner, which limits thrombus growth in vitro. 4 These data suggest that ADAMTS13 is a key molecule that maintains a physiologic balance between hemostasis and thrombosis through regulation of VWF function in vivo.ADAMTS13 function is crucial for preventing thrombosis in the cerebral microvasculature, as indicated by the occurrence of neurologic deficits in thrombotic thrombocytopenic purpura, but the role of ADMTS13 in the pathogenesis of reperfusion injury after arterial thrombosis has not been established. To address this issue, we investigated the role of ADAMTS13 in a transient middle cerebral arterial occlusion (MCAO) model of ischemia-reperfusion injury in the mouse brain 5 using Adamts Ϫ/Ϫ mice. 6 Because brain ischemia-reperfusion injury is dependent on the platelet glycoprotein Ib-VWF axis 7 and platelet thrombosis adversely affects the postischemic cerebral microcirculation 8-11 leading to secondary brain damage, 10 ADAMTS13 may reduce platelet thrombus growth and thereby ameliorate ischemic brain injury by improving the postischemic no-reflow phenomenon. 12 Here we demonstrate that Adamts13 gene deletion aggravates postischemic cerebral blood reflow, resulting in larger infarct volume. This result suggests that ADAMTS13 may indeed supp...

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Glial scarring is traditionally thought to be detrimental after stroke. But emerging studies now suggest that reactive astrocytes may also contribute to neurovascular remodeling. Here, we assessed the effects and mechanisms of metabolic inhibition of reactive astrocytes in a mouse model of stroke recovery. Five days after stroke onset, astrocytes were metabolically inhibited with fluorocitrate (FC, 1 nmol). Markers of reactive astrocytes (glial fibrillary acidic protein (GFAP), HMGB1), markers of neurovascular remodeling (CD31, synaptophysin, PSD95), and behavioral outcomes (neuroscore, rotarod latency) were quantified from 1 to 14 days. As expected, focal cerebral ischemia induced significant neurological deficits in mice. But over the course of 14 days after stroke onset, a steady improvement in neuroscore and rotarod latencies were observed as the mice spontaneously recovered. Reactive astrocytes coexpressing GFAP and HMGB1 increased in peri-infarct cortex from 1 to 14 days after cerebral ischemia in parallel with an increase in the neurovascular remodeling markers CD31, synaptophysin, and PSD95. Compared with stroke-only controls, FC-treated mice demonstrated a significant decrease in HMGB1-positive reactive astrocytes and neurovascular remodeling, as well as a corresponding worsening of behavioral recovery. Our results suggest that reactive astrocytes in peri-infarct cortex may promote neurovascular remodeling, and these glial responses may aid functional recovery after stroke.

We examined the neuroprotective mechanism of cannabidiol, non-psychoactive component of marijuana, on the infarction in a 4 h mouse middle cerebral artery (MCA) occlusion model in comparison with D 9 -tetrahydrocannabinol (D 9 -THC). Release of glutamate in the cortex was measured at 2 h after MCA occlusion. Myeloperoxidase (MPO) and cerebral blood flow were measured at 1 h after reperfusion. In addition, infarct size and MPO were determined at 24 and 72 h after MCA occlusion. The neuroprotective effect of cannabidiol was not inhibited by either SR141716 or AM630. Both pre-and postischemic treatment with cannabidiol resulted in potent and long-lasting neuroprotection, whereas only pre-ischemic treatment with D 9 -THC reduced the infarction. Unlike D 9 -THC, cannabidiol did not affect the excess release of glutamate in the cortex after occlusion. Cannabidiol suppressed the decrease in cerebral blood flow by the failure of cerebral microcirculation after reperfusion and inhibited MPO activity in neutrophils. Furthermore, the number of MPO-immunopositive cells was reduced in the ipsilateral hemisphere in cannabidioltreated group. Cannbidiol provides potent and long-lasting neuroprotection through an anti-inflammatory CB 1 receptorindependent mechanism, suggesting that cannabidiol will have a palliative action and open new therapeutic possibilities for treating cerebrovascular disorders. Keywords: cannabidiol, cannabinoid, cerebral blood flow, cerebral ischemia, glutamate, myeloperoxidase. Cannabis contains about 60 different cannabinoids, including the psychoactive component D 9 -tetrahydrocannabinol (D 9 -THC) and other major non-psychoactive components such as cannabidiol, cannabinol, and cannabigerol. D 9 -THC has been demonstrated to produce hypothermia, neuroprotection, and tolerance (Hampson et al. 2000;Rubino et al. 2000;Wiley and Martin 2002;Braida et al. 2003;Leker et al. 2003;Hayakawa et al. 2004;Mishima et al. 2005). These effects are, at least in part, related to binding to the CB 1 receptor. On the other hand, cannabidiol has a very low affinity (in the micromolar range) for CB 1 and CB 2 receptors and has been found to act as an anticonvulsant in animal models of epilepsy and in humans with epilepsy. Moreover, cannabidiol has been shown to have antispasmodic, anxiolytic, anti-nausea, and anti-rheumatoid properties

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Mammalian hibernators exhibit remarkable resistance to low body temperature, whereas non-hibernating (NHB) mammals develop ventricular dysfunction and arrhythmias. To investigate this adaptive change, we compared contractile and electrophysiological properties of left ventricular myocytes isolated from hibernating (HB) woodchucks (Marmota monax) and control NHB woodchucks. The major findings of this study were the following: 1) the action potential duration in HB myocytes was significantly shorter than in NHB myocytes, but the amplitude of peak contraction was unchanged; 2) HB myocytes had a 33% decreased L-type Ca2+ current (I(Ca)) density and twofold faster I(Ca) inactivation but no change in the current-voltage relationship; 3) there were no changes in the density of inward rectifier K+ current, transient outward K+ current, or Na+/Ca2+ exchange current, but HB myocytes had increased sarcoplasmic reticulum Ca2+ content as estimated from caffeine-induced Na+/Ca2+ exchange current values; 4) expression of the L-type Ca2+ channel alpha(1C)-subunit was decreased by 30% in HB hearts; and 5) mRNA and protein levels of sarco(endo)plasmic reticulum Ca2+-ATPase 2a (SERCA2a), phospholamban, and the Na+/Ca2+ exchanger showed a pattern that is consistent with functional measurements: SERCA2a was increased and phospholamban was decreased in HB relative to NHB hearts with no change in the Na+/Ca2+ exchanger. Thus reduced Ca2+ channel density and faster I(Ca) inactivation coupled to enhanced sarcoplasmic reticulum Ca2+ release may underlie shorter action potentials with sustained contractility in HB hearts. These changes may account for natural resistance to Ca2+ overload-related ventricular dysfunction and point to an important cardioprotective mechanism during true hibernation.

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