Soluble epoxide hydrolase inhibition reverses cognitive dysfunction in a mouse model of metabolic syndrome by modulating inflammation.

Midlife metabolic syndrome (MetS) is associated with cognitive impairment in late life. The mechanism of delayed MetS-related cognitive dysfunction (MetSCD) is not clear, but it has been linked to systemic inflammation and chronic cerebral microangiopathy. Currently there is no treatment for late life MetSCD other than early risk factor modification. We investigated the effect of soluble epoxide hydrolase (sEH) inhibitor 4-[[trans-4-[[(tricyclo[3.3.1.13,7]dec-1-ylamino)carbonyl]amino]cyclohexyl]oxy]-benzoic acid (t-AUCB) on cognitive performance, cerebral blood flow (CBF), and central and peripheral inflammation in the high-fat diet (HFD) model of MetS in mice. At 6 weeks of age, male mice were randomly assigned to receive either HFD or standard chow (STD) for 6 months. Mice received either t-AUCB or vehicle for 4 weeks. Cognitive performance was evaluated, followed by CBF measurement using magnetic resonance imaging (MRI). At the end of the study, blood was collected for measurement of eicosanoids and inflammatory cytokines. The brains were then analyzed by immunohistochemistry for glial activation markers. The HFD caused a significant impairment in novel object recognition. Treatment with t-AUCB increased plasma levels of 14,15-EET, prevented this cognitive impairment and modified hippocampal glial activation and plasma cytokine levels, without affecting CBF in mice on HFD. In conclusion, sEH inhibition for four weeks prevents cognitive deficits in mice on chronic HFD by modulating inflammatory processes without affecting CBF.

Prenatal delta-9-tetrahydrocannabinol exposure alters fetal neurodevelopment in rhesus macaques.

Prenatal cannabis use is associated with adverse offspring neurodevelopmental outcomes, however the underlying mechanisms are relatively unknown. We sought to determine the impact of chronic delta-9-tetrahydrocannabinol (THC) exposure on fetal neurodevelopment in a rhesus macaque model using advanced imaging combined with molecular and tissue studies. Animals were divided into two groups, control (n = 5) and THC-exposed (n = 5), which received a daily THC edible pre-conception and throughout pregnancy. Fetal T2-weighted MRI was performed at gestational days 85 (G85), G110, G135 and G155 to assess volumetric brain development. At G155, animals underwent cesarean delivery with collection of fetal cerebrospinal fluid (CSF) for microRNA (miRNA) studies and fetal tissue for histologic analysis. THC exposure was associated with significant age by sex interactions in brain growth, and differences in fetal brain histology suggestive of brain dysregulation. Two extracellular vesicle associated-miRNAs were identified in THC-exposed fetal CSF; pathway analysis suggests that these miRNAs are associated with dysregulated axonal guidance and netrin signaling. This data is indicative of subtle molecular changes consistent with the observed histological data, suggesting a potential role for fetal miRNA regulation by THC. Further studies are needed to determine whether these adverse findings correlate with long-term offspring neurodevelopmental health.

Proteomic profiling of concurrently isolated primary microvascular endothelial cells, pericytes, and vascular smooth muscle cells from adult mouse heart.

The microcirculation serves crucial functions in adult heart, distinct from those carried out by epicardial vessels. Microvessels are governed by unique regulatory mechanisms, impairment of which leads to microvessel-specific pathology. There are few treatment options for patients with microvascular heart disease, primarily due to limited understanding of underlying pathology. High throughput mRNA sequencing and protein expression profiling in specific cells can improve our understanding of microvessel biology and disease at the molecular level. Understanding responses of individual microvascular cells to the same physiological or pathophysiological stimuli requires the ability to isolate the specific cell types that comprise the functional units of the microcirculation in the heart, preferably from the same heart, to ensure that different cells have been exposed to the same in-vivo conditions. We developed an integrated process for simultaneous isolation and culture of the main cell types comprising the microcirculation in adult mouse heart: endothelial cells, pericytes, and vascular smooth muscle cells. These cell types were characterized with isobaric labeling quantitative proteomics and mRNA sequencing. We defined microvascular cell proteomes, identified novel protein markers, and confirmed established cell-specific markers. Our results allow identification of unique markers and regulatory proteins that govern microvascular physiology and pathology.

Control of coronary vascular resistance by eicosanoids via a novel GPCR.

Arachidonic acid metabolites epoxyeicosatrienoates (EETs) and hydroxyeicosatetraenoates (HETEs) are important regulators of myocardial blood flow and coronary vascular resistance (CVR), but their mechanisms of action are not fully understood. We applied a chemoproteomics strategy using a clickable photoaffinity probe to identify G protein-coupled receptor 39 (GPR39) as a microvascular smooth muscle cell (mVSMC) receptor selective for two endogenous eicosanoids, 15-HETE and 14,15-EET, which act on the receptor to oppose each other's activity. The former increases mVSMC intracellular calcium via GPR39 and augments coronary microvascular resistance, and the latter inhibits these actions. Furthermore, we find that the efficacy of both ligands is potentiated by zinc acting as an allosteric modulator. Measurements of coronary perfusion pressure (CPP) in GPR39-null hearts using the Langendorff preparation indicate the receptor senses these eicosanoids to regulate microvascular tone. These results implicate GPR39 as an eicosanoid receptor and key regulator of myocardial tissue perfusion. Our findings will have a major impact on understanding the roles of eicosanoids in cardiovascular physiology and disease and provide an opportunity for the development of novel GPR39-targeting therapies for cardiovascular disease.

Evaluation of neurotoxicity and long-term function and behavior following intrathecal 1 % 2-chloroprocaine in juvenile rats.

Spinally-administered local anesthetics provide effective perioperative anesthesia and/or analgesia for children of all ages. New preparations and drugs require preclinical safety testing in developmental models. We evaluated age-dependent efficacy and safety following 1 % preservative-free 2-chloroprocaine (2-CP) in juvenile Sprague-Dawley rats. Percutaneous lumbar intrathecal 2-CP was administered at postnatal day (P)7, 14 or 21. Mechanical withdrawal threshold pre- and post-injection evaluated the degree and duration of sensory block, compared to intrathecal saline and naive controls. Tissue analyses one- or seven-days following injection included histopathology of spinal cord, cauda equina and brain sections, and quantification of neuronal apoptosis and glial reactivity in lumbar spinal cord. Following intrathecal 2-CP or saline at P7, outcomes assessed between P30 and P72 included: spinal reflex sensitivity (hindlimb thermal latency, mechanical threshold); social approach (novel rat versus object); locomotor activity and anxiety (open field with brightly-lit center); exploratory behavior (rearings, holepoking); sensorimotor gating (acoustic startle, prepulse inhibition); and learning (Morris Water Maze). Maximum tolerated doses of intrathecal 2-CP varied with age (1.0 µL/g at P7, 0.75 µL/g at P14, 0.5 µL/g at P21) and produced motor and sensory block for 10-15 min. Tissue analyses found no significant differences across intrathecal 2-CP, saline or naïve groups. Adult behavioral measures showed expected sex-dependent differences, that did not differ between 2-CP and saline groups. Single maximum tolerated in vivo doses of intrathecal 2-CP produced reversible spinal anesthesia in juvenile rodents without detectable evidence of developmental neurotoxicity. Current results cannot be extrapolated to repeated dosing or prolonged infusion.

Regression of Multiple Meningiomas after Discontinuation of Chronic Hormone Therapy: A Case Report.

Introduction Meningiomas are more common in females and frequently express progesterone and estrogen receptors. Recent studies have revealed a high incidence of meningiomas in situations in which estrogen/progesterone levels are increased such as pregnancy, gender reassignment therapy, and fertility treatment. While the relationship remains unclear and controversial, these findings suggest exposure to high levels of endogenous or exogenous hormones may increase the risk of developing a meningioma. Patients and Methods A 40-year-old female with a history of endometriosis treated with chronic progesterone therapy presented with a visual deficit and was found to have multiple meningiomas, which regressed after cessation of exogenous progesterone. Conclusion A history of chronic hormone therapy should be included when evaluating patients diagnosed with meningiomas, particularly at a younger age and with multiple meningiomas. Cessation of exogenous progesterone resulting in regression of meningiomas suggests a direct action of progesterone on growth. Future studies are warranted to better elucidate this relationship.

GPR39 localization in the aging human brain and correlation of expression and polymorphism with vascular cognitive impairment.

INTRODUCTION: The pathogenesis of vascular cognitive impairment (VCI) is not fully understood. GPR39, an orphan G-protein coupled receptor, is implicated in neurological disorders but its role in VCI is unknown. METHODS: We performed GPR39 immunohistochemical analysis in post mortem brain samples from mild cognitive impairment (MCI) and control subjects. DNA was analyzed for GPR39 single nucleotide polymorphisms (SNPs), and correlated with white matter hyperintensity (WMH) burden on pre mortem magnetic resonance imaging. RESULTS: GPR39 is expressed in aged human dorsolateral prefrontal cortex, localized to microglia and peri-capillary cells resembling pericytes. GPR39-capillary colocalization, and density of GPR39-expressing microglia was increased in aged brains compared to young. SNP distribution was equivalent between groups; however, homozygous SNP carriers were present only in the MCI group, and had higher WMH volume than wild-type or heterozygous SNP carriers. DISCUSSION: GPR39 may play a role in aging-related VCI, and may serve as a therapeutic target and biomarker for the risk of developing VCI.

Effects of prolonged peri-neural bupivacaine infusion in rat sciatic nerves (axon and myelin).

BACKGROUND/OBJECTIVE: Peripheral-nerve blocks (PNBs) using continuous-infusion of local anesthetics are used to provide perioperative analgesia. Yet little research exists to characterize the histopathological effects of continuous long-duration PNBs. Herein we test the hypothesis that continuous peri-neural bupivacaine infusion (3-day vs. 7-day infusion) contributes to histologic injury in a duration-dependent manner using an in vivo model of rat sciatic nerves. METHODS: We placed indwelling catheters in 22 rats for infusion with low-dose (0.5mg/kg/hr) bupivacaine or normal saline proximal to the right sciatic nerves for 3 or 7 consecutive days. Hind-limb analgesia was measured using Von-Frey nociceptive testing. At infusion end, rats were sacrificed, bilateral nerves were sectioned and stained with hematoxylin and eosin and CD68 for evaluation of inflammatory response, and eriochrome to assess damage to myelin. RESULTS: Animals receiving continuous infusion of bupivacaine maintained analgesia as demonstrated by significant decrease (50% on average) in nociceptive response in bupivacaine-infused limbs across time points. Both 7-day saline and bupivacaine-infused sciatic nerves showed significantly-increased inflammation by H&E staining compared to untreated native nerve controls (P = 0.0001, P < 0.0001). Extent of inflammation did not vary significantly based on infusate (7-day saline vs. 7-day bupivacaine P > 0.99) or duration (3-day bupivacaine vs 7-day bupivacaine P > 0.99). No significant change in sciatic nerve myelin was found in bupivacaine-infused animals compared to saline-infused controls, regardless of duration. CONCLUSIONS: Long-duration (7-day) bupivacaine infusion provided durable post-operative analgesia, yet contributed to equivalent neural inflammation as short duration (3-day) infusion of bupivacaine or saline with no evidence of demyelination.

Astrogliosis in juvenile non-human primates 2 years after infant anaesthesia exposure.

BACKGROUND: Infant anaesthesia causes acute brain cell apoptosis, and later in life cognitive deficits and behavioural alterations, in non-human primates (NHPs). Various brain injuries and neurodegenerative conditions are characterised by chronic astrocyte activation (astrogliosis). Glial fibrillary acidic protein (GFAP), an astrocyte-specific protein, increases during astrogliosis and remains elevated after an injury. Whether infant anaesthesia is associated with a sustained increase in GFAP is unknown. We hypothesised that GFAP is increased in specific brain areas of NHPs 2 yr after infant anaesthesia, consistent with prior injury. METHODS: Eight 6-day-old NHPs per group were exposed to 5 h isoflurane once (1×) or three times (3×), or to room air as a control (Ctr). Two years after exposure, their brains were assessed for GFAP density changes in the primary visual cortex (V1), perirhinal cortex (PRC), hippocampal subiculum, amygdala, and orbitofrontal cortex (OFC). We also assessed concomitant microglia activation and hippocampal neurogenesis. RESULTS: Compared with controls, GFAP densities in V1 were increased in exposed groups (Ctr: 0.208 [0.085-0.427], 1×: 0.313 [0.108-0.533], 3×: 0.389 [0.262-0.652]), whereas the density of activated microglia was unchanged. In addition, GFAP densities were increased in the 3× group in the PRC and the subiculum, and in both exposure groups in the amygdala, but there was no increase in the OFC. There were no differences in hippocampal neurogenesis among groups. CONCLUSIONS: Two years after infant anaesthesia, NHPs show increased GFAP without concomitant microglia activation in specific brain areas. These long-lasting structural changes in the brain caused by infant anaesthesia exposure may be associated with functional alterations at this age.

Neurotoxicity of sub-anesthetic doses of sevoflurane and dexmedetomidine co-administration in neonatal rats.

BACKGROUND: Preclinical studies suggest that exposures of infant animals to general anesthetics cause acute neurotoxicity and affect their neurobehavioral development representing a potential risk to human infants undergoing anesthesia. Alternative or mitigating strategies to counteract such adverse effects are desirable. Dexmedetomidine (DEX) is a clinically established sedative with potential neuroprotective properties. DEX ameliorates experimental brain injury as well as neurotoxicity caused by anesthetic doses of sevoflurane (SEVO) or other general anesthetics in infant animals. However, it is unknown whether DEX also is beneficial when given together with lower doses of these drugs. Here we tested the hypothesis that DEX co-administration with a sub-anesthetic dose of SEVO reduces responsiveness to external stimuli while also protecting against SEVO-induced brain cell apoptosis. METHOD: Rats were exposed on postnatal day 7 for 6 h to SEVO 1.1, 1.8, or 2.5% and were given intraperitoneal injections of saline or DEX at different doses (1-25 µg/kg) three times during the exposure. Responsiveness to external stimuli, respiratory rates, and blood gases were assessed. Apoptosis was determined in cortical and subcortical brain areas by activated caspase-3 immunohistochemistry. RESULTS: Rats exposed to SEVO 1.1% alone were sedated but still responsive to external stimuli whereas those exposed to SEVO 1.8% reached complete unresponsiveness. SEVO-induced brain cell apoptosis increased dose-dependently, with SEVO 1.1% causing a small increase in apoptosis above that in controls. Co-administration of DEX at 1 µg/kg did not alter the responsiveness to stimuli nor the apoptosis induced by SEVO 1.1%. In contrast, co-administration of DEX at 5 µg/kg or higher with SEVO 1.1% reduced responsiveness but potentiated apoptosis. CONCLUSIONS: In the neonatal rat model, co-administration of a clinically relevant dose of DEX (1 µg/kg) with a sub-anesthetic dose of SEVO (1.1%) does not affect the neurotoxicity of the anesthetic while co-administration of higher doses of DEX with SEVO 1.1% potentiates it.

A neonatal nonhuman primate model of gestational Zika virus infection with evidence of microencephaly, seizures and cardiomyopathy.

Zika virus infection during pregnancy is associated with miscarriage and with a broad spectrum of fetal and neonatal developmental abnormalities collectively known as congenital Zika syndrome (CZS). Symptomology of CZS includes malformations of the brain and skull, neurodevelopmental delay, seizures, joint contractures, hearing loss and visual impairment. Previous studies of Zika virus in pregnant rhesus macaques (Macaca mulatta) have described injury to the developing fetus and pregnancy loss, but neonatal outcomes following fetal Zika virus exposure have yet to be characterized in nonhuman primates. Herein we describe the presentation of rhesus macaque neonates with a spectrum of clinical outcomes, including one infant with CZS-like symptoms including cardiomyopathy, motor delay and seizure activity following maternal infection with Zika virus during the first trimester of pregnancy. Further characterization of this neonatal nonhuman primate model of gestational Zika virus infection will provide opportunities to evaluate the efficacy of pre- and postnatal therapeutics for gestational Zika virus infection and CZS.

Therapeutic Ultrasound Improves Myocardial Blood Flow and Reduces Infarct Size in a Canine Model of Coronary Microthromboembolism.

BACKGROUND: Therapeutic ultrasound (TUS) has been used to lyse infarct-related coronary artery thrombus. There has been no study examining the effect of TUS specifically on myocardial microthromboemboli seen in acute myocardial infarction and acute coronary syndromes. The aim of this study was to test the hypothesis that TUS improves myocardial blood flow (MBF) and reduces infarct size (IS) in this situation by dissolving myocardial microthrombi. METHODS: An open-chest canine model of myocardial microthromboembolism was created by disrupting a thrombus in the left anterior descending coronary artery, and 1.05- and 0.25-MHz TUS (n = 7 each) delivered epicardially for 30 min was compared with control (n = 6). MBF and IS (as a percentage of left anterior descending coronary artery perfusion bed size) were measured 60 min after treatment. In addition, immunohistochemistry was performed to assess microthrombi, and histopathology was performed to define inflammation. RESULTS: Transmural, epicardial, and endocardial myocardial blood volume and MBF (measured using myocardial contrast echocardiography) and percentage wall thickening were significantly higher 60 min after receiving TUS compared with control. The ratio of IS to left anterior descending coronary artery perfusion bed size was significantly smaller (P = .03) in the 1.05-MHz TUS group (0.14 ± 0.04) compared with the control (0.31 ± 0.06, P = .04) and 0.25-MHz (0.36 ± 0.08) groups. MBF versus percentage wall thickening exhibited a linear relation (r = 0.65) in the control and 1.05-MHz TUS groups but not in the 0.25-MHz TUS group (r = 0.29). The presence of myocardial microemboli in vessels >10 µm in diameter was significantly reduced in the 1.05-MHz TUS group compared with the other two groups. The distribution and intensity of inflammation was higher in the 0.25-MHz TUS group compared with the other groups. CONCLUSIONS: TUS at 1.05 MHz is effective in restoring myocardial blood volume and MBF, thus reducing IS by clearing the microcirculation of microthrombi. IS reduction is not seen at 0.25 MHz, despite improvement in MBF, which may be related to the increased inflammation noted at this frequency. Because both acute myocardial infarction and acute coronary syndromes are associated with microthromboembolism, these results suggest that TUS could have a potential adjunctive role in the treatment of both conditions.

Seeding of Abdomen with Primary Intracranial Hemangiopericytoma by Ventriculoperitoneal Shunt: Case Report.

BACKGROUND: Ventriculoperitoneal shunt (VPS) placement has been implicated in extraneural metastasis of many primary central nervous system tumors. Reported cases include, but are not limited to, medulloblastoma, germ cell tumor, astrocytoma, oligodendroglioma, lymphoma, ependymoma, melanoma, and choroid plexus tumors. However, a literature review reveals no reported cases of extraneural metastasis of solitary fibrous tumor/hemangiopericytoma (SFT/HPC). CASE DESCRIPTION: Here we report the case of a 34-year-old man with recurrent intracranial malignant SFT/HPC who had undergone surgical tumor resection and subsequent placement of a VPS for obstructive hydrocephalus in 2004. Subsequently, the patient presented in 2011 and again in 2013 with abdominal SFT/HPC metastasis likely caused by the presence of the VPS. CONCLUSION: The case raises concern regarding placement of a VPS in patients with obstructive hydrocephalus caused by SFT/HPC. To avoid spread of SFT/HPC to the abdomen, we propose that patients with intracranial SFT/HPC and obstructive hydrocephalus be treated primarily by endoscopic third ventriculostomy.

Association of Perivascular Localization of Aquaporin-4 With Cognition and Alzheimer Disease in Aging Brains.

IMPORTANCE: Cognitive impairment and dementia, including Alzheimer disease (AD), are common within the aging population, yet the factors that render the aging brain vulnerable to these processes are unknown. Perivascular localization of aquaporin-4 (AQP4) facilitates the clearance of interstitial solutes, including amyloid-ß, through the brainwide network of perivascular pathways termed the glymphatic system, which may be compromised in the aging brain. OBJECTIVES: To determine whether alterations in AQP4 expression or loss of perivascular AQP4 localization are features of the aging human brain and to define their association with AD pathology. DESIGN, SETTING, AND PARTICIPANTS: Expression of AQP4 was analyzed in postmortem frontal cortex of cognitively healthy and histopathologically confirmed individuals with AD by Western blot or immunofluorescence for AQP4, amyloid-ß 1-42, and glial fibrillary acidic protein. Postmortem tissue and clinical data were provided by the Oregon Health and Science University Layton Aging and Alzheimer Disease Center and Oregon Brain Bank. Postmortem tissue from 79 individuals was evaluated, including cognitively intact "young" individuals aged younger than 60 years (range, 33-57 years), cognitively intact "aged" individuals aged older than 60 years (range, 61-96 years) with no known neurological disease, and individuals older than 60 years (range, 61-105 years) of age with a clinical history of AD confirmed by histopathological evaluation. Forty-eight patient samples (10 young, 20 aged, and 18 with AD) underwent histological analysis. Sixty patient samples underwent Western blot analysis (15 young, 24 aged, and 21 with AD). MAIN OUTCOMES AND MEASURES: Expression of AQP4 protein, AQP4 immunoreactivity, and perivascular AQP4 localization in the frontal cortex were evaluated. RESULTS: Expression of AQP4 was associated with advancing age among all individuals (R2 = 0.17; P = .003). Perivascular AQP4 localization was significantly associated with AD status independent of age (OR, 11.7 per 10% increase in localization; z = -2.89; P = .004) and was preserved among eldest individuals older than 85 years of age who remained cognitively intact. When controlling for age, loss of perivascular AQP4 localization was associated with increased amyloid-ß burden (R2 = 0.15; P = .003) and increasing Braak stage (R2 = 0.14; P = .006). CONCLUSIONS AND RELEVANCE: In this study, altered AQP4 expression was associated with aging brains. Loss of perivascular AQP4 localization may be a factor that renders the aging brain vulnerable to the misaggregation of proteins, such as amyloid-ß, in neurodegenerative conditions such as AD.

Intrathecal Catheterization and Drug Delivery in Guinea Pigs: A Small-animal Model for Morphine-evoked Granuloma Formation.

BACKGROUND: Intrathecal infusion of opioids in dogs, sheep, and humans produces local space-occupying masses. To develop a small-animal model, the authors examined effects of intrathecal catheterization and morphine infusion in guinea pigs. METHODS: Under isoflurane, polyethylene or polyurethane catheters were advanced from the cisterna magna to the lumbar enlargement. Drugs were delivered as a bolus through the externalized catheter or continuously by subcutaneous minipumps. Hind paw withdrawal to a thermal stimulus was assessed. Spinal histopathology was systematically assessed in a blinded fashion. To assist in determining catheter placement, ex vivo images were obtained using magnetic resonance imaging in several animals. Canine spinal tissue from previous intrathecal morphine studies was analyzed in parallel. RESULTS: (1) Polyethylene (n = 30) and polyurethane (n = 25) catheters were implanted in the lumbar intrathecal space. (2) Bolus intrathecal morphine produced a dose-dependent (20 to 40 µg/10 µl) increase in thermal escape latencies. (3) Absent infusion, a catheter-associated distortion of the spinal cord and a fibrotic investment were noted along the catheter tract (polyethylene > polyurethane). (4) Intrathecal morphine infusion (25 mg/ml/0.5 µl/h for 14 days) resulted in intrathecal masses (fibroblasts, interspersed collagen, lymphocytes, and macrophages) arising from meninges proximal to the catheter tip in both polyethylene- and polyurethane-catheterized animals. This closely resembles mass histopathology from intrathecal morphine canine studies. CONCLUSIONS: Continuous intrathecal infusion of morphine leads to pericatheter masses that morphologically resemble those observed in dogs and humans. This small-animal model may be useful for studying spinal drug toxicology in general and the biology of intrathecal granuloma formation in particular.

High fat diet-induced diabetes in mice exacerbates cognitive deficit due to chronic hypoperfusion.

Diabetes causes endothelial dysfunction and increases the risk of vascular cognitive impairment. However, it is unknown whether diabetes causes cognitive impairment due to reductions in cerebral blood flow or through independent effects on neuronal function and cognition. We addressed this using right unilateral common carotid artery occlusion to model vascular cognitive impairment and long-term high-fat diet to model type 2 diabetes in mice. Cognition was assessed using novel object recognition task, Morris water maze, and contextual and cued fear conditioning. Cerebral blood flow was assessed using arterial spin labeling magnetic resonance imaging. Vascular cognitive impairment mice showed cognitive deficit in the novel object recognition task, decreased cerebral blood flow in the right hemisphere, and increased glial activation in white matter and hippocampus. Mice fed a high-fat diet displayed deficits in the novel object recognition task, Morris water maze and fear conditioning tasks and neuronal loss, but no impairments in cerebral blood flow. Compared to vascular cognitive impairment mice fed a low fat diet, vascular cognitive impairment mice fed a high-fat diet exhibited reduced cued fear memory, increased deficit in the Morris water maze, neuronal loss, glial activation, and global decrease in cerebral blood flow. We conclude that high-fat diet and chronic hypoperfusion impair cognitive function by different mechanisms, although they share commons features, and that high-fat diet exacerbates vascular cognitive impairment pathology.

Synergistic Antivascular and Antitumor Efficacy with Combined Cediranib and SC6889 in Intracranial Mouse Glioma.

Prognosis remains extremely poor for malignant glioma. Targeted therapeutic approaches, including single agent anti-angiogenic and proteasome inhibition strategies, have not resulted in sustained anti-glioma clinical efficacy. We tested the anti-glioma efficacy of the anti-angiogenic receptor tyrosine kinase inhibitor cediranib and the novel proteasome inhibitor SC68896, in combination and as single agents. To assess anti-angiogenic effects and evaluate efficacy we employed 4C8 intracranial mouse glioma and a dual-bolus perfusion MRI approach to measure Ktrans, relative cerebral blood flow and volume (rCBF, rCBV), and relative mean transit time (rMTT) in combination with anatomical MRI measurements of tumor growth. While single agent cediranib or SC68896 treatment did not alter tumor growth or survival, combined cediranib/SC68896 significantly delayed tumor growth and increased median survival by 2-fold, compared to untreated. This was accompanied by substantially increased tumor necrosis in the cediranib/SC68896 group (p<0.01), not observed with single agent treatments. Mean vessel density was significantly lower, and mean vessel lumen area was significantly higher, for the combined cediranib/SC68896 group versus untreated. Consistent with our previous findings, cediranib alone did not significantly alter mean tumor rCBF, rCBV, rMTT, or Ktrans. In contrast, SC68896 reduced rCBF in comparison to untreated, but without concomitant reductions in rCBV, rMTT, or Ktrans. Importantly, combined cediranib/SC68896 substantially reduced rCBF, rCBV. rMTT, and Ktrans. A novel analysis of Ktrans/rCBV suggests that changes in Ktrans with time and/or treatment are related to altered total vascular surface area. The data suggest that combined cediranib/SC68896 induced potent anti-angiogenic effects, resulting in increased vascular efficiency and reduced extravasation, consistent with a process of vascular normalization. The study represents the first demonstration that the combination of cediranib with a proteasome inhibitor substantially increases the anti-angiogenic efficacy produced from either agent alone, and synergistically slows glioma tumor growth and extends survival, suggesting a promising treatment which warrants further investigation.

Neurobehavioral and imaging correlates of hippocampal atrophy in a mouse model of vascular cognitive impairment.

Vascular cognitive impairment (VCI) is the second most common cause of dementia. Reduced cerebral blood flow is thought to play a major role in the etiology of VCI. Therefore, chronic cerebral hypoperfusion has been used to model VCI in rodents. The goal of the current study was to determine the histopathological and neuroimaging substrates of neurocognitive impairments in a mouse model of chronic cerebral hypoperfusion induced by unilateral common carotid artery occlusion (UCCAO). Mice were subjected to sham or right UCCAO (VCI) surgeries. Three months later, neurocognitive function was evaluated using the novel object recognition task, Morris water maze, and contextual and cued fear-conditioning tests. Next, cerebral perfusion was evaluated with dynamic susceptibility contrast magnetic resonance imaging (MRI) using an ultra-high field (11.75 T) animal MRI system. Finally, brain pathology was evaluated using histology and T2-weighted MRI. VCI, but not sham, mice had significantly reduced cerebral blood flow in the right vs. left cerebral cortex. VCI mice showed deficits in object recognition. T2-weighted MRI of VCI brains revealed enlargement of lateral ventricles, which corresponded to areas of hippocampal atrophy upon histological analysis. In conclusion, our data demonstrate that the UCCAO model of chronic hypoperfusion induces hippocampal atrophy and ventricular enlargement, resulting in neurocognitive deficits characteristic of VCI.

Soluble Epoxide Hydrolase in Hydrocephalus, Cerebral Edema, and Vascular Inflammation After Subarachnoid Hemorrhage.

BACKGROUND AND PURPOSE: Acute communicating hydrocephalus and cerebral edema are common and serious complications of subarachnoid hemorrhage (SAH), whose causes are poorly understood. Using a mouse model of SAH, we determined whether soluble epoxide hydrolase (sEH) gene deletion protects against SAH-induced hydrocephalus and edema by increasing levels of vasoprotective eicosanoids and suppressing vascular inflammation. METHODS: SAH was induced via endovascular puncture in wild-type and sEH knockout mice. Hydrocephalus and tissue edema were assessed by T2-weighted magnetic resonance imaging. Endothelial activation was assessed in vivo using T2*-weighted magnetic resonance imaging after intravenous administration of iron oxide particles linked to anti-vascular cell adhesion molecule-1 antibody 24 hours after SAH. Behavioral outcome was assessed at 96 hours after SAH with the open field and accelerated rotarod tests. RESULTS: SAH induced an acute sustained communicating hydrocephalus within 6 hours of endovascular puncture in both wild-type and sEH knockout mice. This was followed by tissue edema, which peaked at 24 hours after SAH and was limited to white matter fiber tracts. sEH knockout mice had reduced edema, less vascular cell adhesion molecule-1 uptake, and improved outcome compared with wild-type mice. CONCLUSIONS: Genetic deletion of sEH reduces vascular inflammation and edema and improves outcome after SAH. sEH inhibition may serve as a novel therapy for SAH.

Role of recurrent hypoxia-ischemia in preterm white matter injury severity.

OBJECTIVE: Although the spectrum of white matter injury (WMI) in preterm infants is shifting from cystic necrotic lesions to milder forms, the factors that contribute to this changing spectrum are unclear. We hypothesized that recurrent hypoxia-ischemia (rHI) will exacerbate the spectrum of WMI defined by markers of inflammation and molecules related to the extracellular matrix (hyaluronan (HA) and the PH20 hyaluronidase) that regulate maturation of the oligodendrocyte (OL) lineage after WMI. METHODS: We employed a preterm fetal sheep model of in utero moderate hypoxemia and global severe but not complete cerebral ischemia that reproduces the spectrum of human WMI. The response to rHI was compared against corresponding early or later single episodes of HI. An ordinal rating scale of WMI was compared against an unbiased quantitative image analysis protocol that provided continuous histo-pathological outcome measures for astrogliosis and microglial activation. Late oligodendrocyte progenitors (preOLs) were quantified by stereology. Analysis of hyaluronan and the hyaluronidase PH20 defined the progressive response of the extracellular matrix to WMI. RESULTS: rHI resulted in a more severe spectrum of WMI with a greater burden of necrosis, but an expanded population of preOLs that displayed reduced susceptibility to cell death. WMI from single episodes of HI or rHI was accompanied by elevated HA levels and increased labeling for PH20. Expression of PH20 in fetal ovine WMI was confirmed by RT-PCR and RNA-sequencing. CONCLUSIONS: rHI is associated with an increased risk for more severe WMI with necrosis, but reduced risk for preOL degeneration compared to single episodes of HI. Expansion of the preOL pool may be linked to elevated hyaluronan and PH20.