Current Neurovascular Research - Volume 12, Issue 3, 2015

MicroRNAs have been discovered as regulators of gene expression and thus their potential in clinical disease diagnostics, prognosis and therapy is being actively pursued. MicroRNAs play an important role in atherosclerosis-related diseases, such as cerebrovascular and cardiovascular disease. However, the effect of miR-185 and miR-146a on patients with ischemic stroke (IS) in the different phases has not been reported. In this study, we investigated the amounts of three miRNAs, miR-185, miR-146a, and miR-145 in blood circulation of IS patients. We enrolled 60 patients with IS in the acute or sub-acute phase and 30 healthy controls. We divided the patients into two groups, patients with ischemic stroke in the acute phase (ISA) and patients with ischemic stroke in the subacute phase (ISS). We measured circulating miRNAs expression by miRNA microarray and real-time polymerase chain reaction (PCR) analysis. Testing by miRNA microarray and RT-PCR analyses showed that miR-145 levels in healthy subjects were similar to patients with IS, whereas miR-146a and miR-185 were present with quite low abundance in ISA compared with healthy individuals; moreover, we found that miR-146a levels were downregulated in ISA but upregulated in ISS which may help provide new insights into the diagnosis and therapy of IS.

Effect of combination of undifferentiated bone marrow stromal cells (BMSCs) and pulsed electromagnetic fields (PEMF) on transected sciatic nerve regeneration was assessed in rats. A 10 mm nerve segment was excised and a vein graft was used to bridge the gap. Twenty microliter undifferentiated BMSCs (2x 107 cells /mL) were administered into the graft inBMSC group with no exposure to PEMF. In BMSC/PEMF group the whole body was exposed to PEMF (0.3 mT, 2Hz) for 4h/day within 1-5 days. In PEMF group the transected nerve was bridged and phosphate buffered saline was administered into the graft. In authograft group (AUTO), the transected nervesegments were reimplanted reversely and the whole body was exposed to PEMF. The regenerated nerve fibers were studied within 12 weeks after surgery. Behavioral, functional, electrophysiological, biomechanical, gastrocnemius muscle mass findings, morphometric indices and immuonohistochemical reactions confirmed faster recovery of regenerated axons in BMSC/PEMF group compared to those in the other groups (P<0.05). The use of undifferentiated BMSCs with whole body exposure to PEMF improved functional recovery. Combination of local transplantation of in vitro bone-marrow stromal cells and pulsed electromagnetic fields could be considered as an effective, safe and tolerable treatment for peripheral nerve repair in clinical practice.

The accumulation of chronic stress is associated with cognitive dysfunction. Radix Angelica Sinensis (RAS) has been shown to have neuroprotective potential for treating Alzheimer's disease and vascular dementia. However, the impact of RAS on cognitive impairment induced by chronic stress has not been studied. In the present study, RAS significantly alleviated cognitive deficits in rats subjected to chronic restraint stress. This neuroprotective effect was associated with enhancement of synaptic efficacy by improving field excitatory postsynaptic potential amplitudes, alleviating adverse alterations in the structure of synapses and neurons in the hippocampus, and increasing the levels of brain-derived neurotrophic factor, microtubule-associated protein-2, and synaptophysin in the hippocampus. These findings provide initial evidence for the therapeutic potential of RAS for the treatment of neuronal deterioration caused by chronic stress.

Chronic cerebral hypoperfusion (CCH) has been considered as a critical cause for the development of cognitive decline and dementia of vascular origin. Melatonin receptors have been reported to be beneficial in improving memory deterioration. Phosphodiesterase-1 (PDE1) enzyme offers protection against cognitive impairments and cerebrovascular disorders. Aim of this study is to explore the role of agomelatine (a dual MT1 and MT2 melatonin receptor agonist) and vinpocetine (selective PDE1 inhibitor) in CCH induced vascular dementia (VaD). Two vessel occlusion (2VO) or bilateral common carotid arteries ligation method was performed to initiate a phase of chronic hypoperfusion in mice. 2VO animals have shown significant cognitive deficits (Morris water maze), cholinergic dysfunction (increased acetyl cholinesterase -AChE) activity alongwith increased brain oxidative stress (decreased brain catalase, glutathione, as well as superoxide dismutase with an increase in malondialdehyde levels), and significant increase in brain infarct size (2,3,5- triphenylterazolium chloride-TTC staining). Treatment of agomelatine and vinpocetine reduced CCH induced learning and memory deficits and limited cholinergic dysfunction, oxidative stress, and tissue damage, suggesting that agomelatine and vinpocetine may provide benefits in CCH induced VaD.

Pneumococcal meningitis is characterized by high rates of mortality and long-term cognitive impairment. In this study, we evaluated the effects of interleukin (IL)-1β receptor antagonist (IL-1Ra) on memory, cytokine, and brainderived neurotrophic factor (BDNF) levels in hippocampus after experimental pneumococcal meningitis. In a first experiment the animals were divided into four groups: control/saline, control treated with IL-1Ra, meningitis/saline, and meningitis treated with IL-1Ra. In the meningitis/saline group IL-1β and cytokine-induced neutrophil chemoattractant-1 (CINC-1) levels increased at 24 h post-infection; adjuvant treatment with IL-1Ra reversed the increased levels in the hippocampus. The levels of tumour necrosis factor-alpha (TNF-α), IL-4, IL-6, IL-10, and BDNF did not change in all groups at 24 h post-infection. In a second experiment, the animals were subjected to behavioural tasks (open field, step-down inhibitory avoidance task, and object recognition task), cytokine, and BDNF levels analysis 10 days after experimental meningitis induction. In the open-field task, the meningitis/saline group did not exhibit difference between the training and test sessions, in the motor and exploratory activity indicating memory injury. The meningitis/IL-1Ra group presented difference between training and test session indicating habituation memory. The meningitis/saline group showed impairment in long-term memory for novel object recognition and in aversive memory. The adjuvant treatment with IL-1Ra prevented memory impairment. After behavioural tasks the hippocampus was evaluated. The levels of IL-4, IL-6, IL-10, and BDNF were maintained elevated 10 days post-infection. CINC-1 levels were elevated only in meningitis/saline group and IL-1β decreased in meningitis/IL-Ra group. The levels of TNF-α did not change at 10 days post-infection. These findings illustrate the anti-inflammatory activity of IL-1Ra inhibitor in the first hours after meningitis induction. Adjuvant treatment with IL-1β receptor antagonist could be a new avenue as therapeutic target during bacterial meningitis.

Rufinamide is a structurally novel, antiepileptic drug approved for the treatment of Lennox-Gastaut syndrome. Its mechanism of action involves inhibition of voltage-gated Na+ channels (VGSCs) with possible membrane-stabilizing effects. VGSCs play a significant role in the pathogenesis of neuropathic pain. Therefore, we investigated the effects of rufinamide on tetrodotoxin-resistant sodium current (TTX-R INa) in acutely dissociated rat dorsal root ganglion (DRG) neurons isolated from streptozotocin-induced diabetic rats by using whole-cell voltage-clamp configuration. In addition, the functional and behavioural nociceptive parameters were evaluated to assess its potential in diabetic neuropathy. Diabetic rats demonstrated the mechanical allodynia and thermal hyperalgesia with reduced nerve perfusion and conduction velocity as compared to control. Rufinamide treatments (3 and 10 mg/kg) significantly improved these functional and nociceptive deficits. Diabetic rat DRG neurons exhibited increased TTX-R INa density as compared to control. The voltagedependent activation and steady-state inactivation curves for TTX-R INa in DRG neurons from diabetic rats were shifted negatively as compared to control. Rufinamide treatments significantly blocked the TTX-R Na+ channel activity as evident from significant reduction in INa density and hyperpolarizing shift in activation and inactivation curves as compared to diabetic control. This suggests that rufinamide acts on TTX-R Na+ channels, reduces channel activity and attenuates nerve functional and behavioral parameters in diabetic rats. Altogether, these results indicate therapeutic potential of rufinamide in the treatment of diabetic neuropathy.

Contrary to aneurysmal bleeding, non-aneurysmal non-traumatic subarachnoid hemorrhage (NASAH) is rarely associated with unfavorable clinical outcome, cerebral infarction and vasospasm. We aimed to identify independent predictors for a poor clinical course and outcome after NASAH. All patients with NASAH treated at our institution between January 2005 and December 2012 were retrospectively analyzed. Collected demographic, clinical and radiographic variables were divided into primary (admission) and secondary (follow-up) parameters. Independent predictors of unfavorable outcome (defined as modified Rankin scale=3-6), cerebral infarction and development of vasospasm were identified. In addition, a risk score for the estimation of clinical outcome was designed. Out of population with 157 NASAH patients, unfavorable outcome was documented in 57 cases (36.3%) at discharge and in 17 cases (10.8%) after 6 months. Cerebral infarction(s) were found in 7 patients (4.3%). In multivariate analyses, higher age (≥65 years), poorer initial clinical condition measured by Hunt & Hess grade and diffuse basal bleeding pattern were independent outcome predictors and therefore included in the risk score (1-8 points). The risk score correlated with outcome at discharge (p<0.0001) and clinical improvement after 6 months (p=0.0238). A diffuse basal bleeding pattern predicted the detection of vasospasm by transcranial Doppler (p=0.001). Poor initial clinical condition (p=0.028) and vasospasm (p=0.031) were associated with the occurrence of cerebral infarction. NASAH patients with higher age, bad clinical condition on admission and diffuse bleeding pattern are prone to unfavorable outcome. The proposed risk score helps to identify patients with poor prognosis after NASAH.

Perfusion-diffusion mismatch in magnetic resonance imaging (MRI) represents the non-core hypoperfused area in acute ischemic stroke. The mismatch has been used to predict clinical response after thrombolysis in acute ischemic stroke, but its role for predicting early neurological deterioration (END) in acute ischemic stroke without thrombolysis has not been clarified yet. In this study, we prospectively recruited 54 patients with acute non-lacunar ischemic stroke in anterior circulation without thrombolysis. All patients received the first perfusion MRI within 24 hours from stroke onset. Target mismatch profile was defined as a perfusion-diffusion mismatch ratio ≥ 1.2. END was defined as an increase of ≥ 4 points in the National Institute of Health Stroke Scale (NIHSS) score within 72 hours. There were 13 (24.1%) patients developing END, which was associated with larger infarct growth (p = 0.002), worse modified Rankin Scale (p = 0.001) and higher mortality rate at 3 months (p = 0.025). Target mismatch profiles measured by Tmax ≥ 4, 5 and 6 seconds were independent predictors for END after correcting initial NIHSS score. Among the 3 Tmax thresholds, target mismatch measured by Tmax ≥ 6 seconds had the highest odd’s ratio in predicting END (p < 0.01, odd’s ratio = 17), with an 80% sensitivity and a 79.5% specificity. In conclusion, perfusion-diffusion mismatch could identify the patients at high risk of early clinical worsening in acute ischemic stroke without thrombolysis.

Several studies have found that the molecular mechanisms of mitochondrial energy metabolism are impaired in major depressive disorder (MDD). Classic antidepressants and atypical antipsychotics can alter the function of enzymes involved in adenosine triphosphate (ATP) metabolism. Quetiapine is an atypical antipsychotic that, in addition to having a therapeutic benefit in treating MDD, appears to exert antioxidant and neuroprotective effects. Therefore, we aimed to evaluate the acute and chronic effects of quetiapine on the activity of enzyme complexes I to IV of the mitochondrial respiratory chain and creatine kinase (CK) in brain regions involved with MDD. After a single dose or serial injections over 14 days of quetiapine (20, 40, and 80 mg) were administered, isolates from the pre- frontal cortex, hippocampus, amygdala and nucleus accumbens were analyzed for enzyme activity levels. The enzyme activity varied according to the dose, brain region, and acute or chronic dosing protocols. In general, complexes I-III activity was increased, especially after acute administration. Acute administration also increased the activity of complex IV and CK in the amygdala while complex I was inhibited in the prefrontal cortex and nucleus accumbens. These results suggest that quetiapine produces an increase in respiratory chain complex activity, which may be underlying its efficacy against psychiatric disorders and neuronal damage.

Over the last decade, our understanding of the vascular endothelial growth factor (VEGF) has rapidly increased, becoming the focus of many investigations the world over. Besides its classical role in the vascular system, VEGF was also identified as a factor affecting the nervous system. One structure that responds to VEGF-signaling is the axonal growth cone, the correct behavior of which is essential for the development of a properly working neuronal network. It navigates growing axons to their final destination and helps to create proper synapses at predetermined locations. Recent data concerning the impact of VEGF on the actin cytoskeleton of neuronal growth cones are discussed and new findings of VEGF-signaling in regard to actin dynamics are specified. Overall, we describe the role of VEGF regulation of cofilin and the Arp2/3-complex in axonal growth cones.