Bullying Victimization and Psychiatric Symptoms Among Syrian Adolescent Refugees in Southeast Turkey: A Structural Equation Modeling Study.

ObjectiveThe purpose of this study was to compare the peer bullying of refugee and non-refugee adolescents, and to explore the association between bullying victimization and psychiatric symptoms among Syrian adolescent refugees in the Southeast Anatolia region of Turkey. Methods: The sample of the study consists of 217 adolescents in the 13-17 age group who are school-going, 102 refugee adolescents, and 115 non-refugee adolescents. The study data was obtained using the Sociodemographic Characteristics Questionnaire developed by the researchers, Olweus Bully/Victim Questionnaire (OBVQ) and Depression Anxiety Stress Scale 42 (DASS-42). A structural equation model was used to assess the association between bullying victimization and depressive symptoms, while also considering mediation by stress and anxiety. Results: In this study, 44.1% of refugee adolescents reported experiencing at least one bullying victimization, while this rate was 27.8% in the non-refugee group, and this difference was found statistically significant. The logistic regression analysis revealed that poor school performance was a risk factor for bullying victimization in refugee adolescent. Moreover, the structural equation model analysis revealed that bullying victimization significantly increased the stress level in refugee adolescents, and depressive symptoms were significantly affected by stress and anxiety levels. Conclusion: Taking into consideration that bullying victimization is a significant problem among Syrian refugee adolescents; anti-bullying programmes should be implemented as this may improve the mental health of Syrian refugee adolescents.

Vesicular HMGB1 release from neurons stressed with spreading depolarization enables confined inflammatory signaling to astrocytes.

The role of high mobility group box 1 (HMGB1) in inflammation is well characterized in the immune system and in response to tissue injury. More recently, HMGB1 was also shown to initiate an "inflammatory signaling cascade" in the brain parenchyma after a mild and brief disturbance, such as cortical spreading depolarization (CSD), leading to headache. Despite substantial evidence implying a role for inflammatory signaling in prevalent neuropsychiatric disorders such as migraine and depression, how HMGB1 is released from healthy neurons and how inflammatory signaling is initiated in the absence of apparent cell injury are not well characterized. We triggered a single cortical spreading depolarization by optogenetic stimulation or pinprick in naïve Swiss albino or transgenic Thy1-ChR2-YFP and hGFAP-GFP adult mice. We evaluated HMGB1 release in brain tissue sections prepared from these mice by immunofluorescent labeling and immunoelectron microscopy. EzColocalization and Costes thresholding algorithms were used to assess the colocalization of small extracellular vesicles (sEVs) carrying HMGB1 with astrocyte or microglia processes. sEVs were also isolated from the brain after CSD, and neuron-derived sEVs were captured by CD171 (L1CAM). sEVs were characterized with flow cytometry, scanning electron microscopy, nanoparticle tracking analysis, and Western blotting. We found that HMGB1 is released mainly within sEVs from the soma of stressed neurons, which are taken up by surrounding astrocyte processes. This creates conditions for selective communication between neurons and astrocytes bypassing microglia, as evidenced by activation of the proinflammatory transcription factor NF-ĸB p65 in astrocytes but not in microglia. Transmission immunoelectron microscopy data illustrated that HMGB1 was incorporated into sEVs through endosomal mechanisms. In conclusion, proinflammatory mediators released within sEVs can induce cell-specific inflammatory signaling in the brain without activating transmembrane receptors on other cells and causing overt inflammation.

12/15-lipoxygenase inhibition attenuates neuroinflammation by suppressing inflammasomes.

Introduction: Lipoxygenases (LOXs) have essential roles in stroke, atherosclerosis, diabetes, and hypertension. 12/15-LOX inhibition was shown to reduce infarct size and brain edema in the acute phase of experimental stroke. However, the significance of 12/15-LOX on neuroinflammation, which has an essential role in the pathophysiology of stroke, has not been clarified yet. Methods: In this study, ischemia/recanalization (I/R) was performed by occluding the proximal middle cerebral artery (pMCAo) in mice. Either the 12/15-LOX inhibitor (ML351, 50 mg/kg) or its solvent (DMSO) was injected i.p. at recanalization after 1 h of occlusion. Mice were sacrificed at 6, 24, and 72-h after ischemia induction. Infarct volumes were calculated on Nissl-stained sections. Neurological deficit scoring was used for functional analysis. Lipid peroxidation was determined by the MDA assay, and the inflammatory cytokines IL-6, TNF-alpha, IL-1beta, IL-10, and TGF-beta were quantified by ELISA. The inflammasome proteins NLRP1 and NLRP3, 12/15-LOX, and caspase-1 were detected with immunofluorescence staining. Results: Infarct volumes, neurological deficit scores, and lipid peroxidation were significantly attenuated in ML351-treated groups at 6, 24, and 72-h. ELISA results revealed that the pro-inflammatory cytokines IL-1beta, IL-6, and TNF-alpha were significantly decreased at 6-h and/or 24-h of I/R, while the anti-inflammatory cytokines IL-10 and TNF-alpha were increased at 24-h or 72-h of ML351 treatment. NLRP1 and NLRP3 immunosignaling were enhanced at three time points after I/R, which were significantly diminished by the ML351 application. Interestingly, NLRP3 immunoreactivity was more pronounced than NLRP1. Hence, we proceeded to study the co-localization of NLRP3 immunoreactivity with 12/15-LOX and caspase-1, which indicated that NLRP3 was co-localized with 12/15-LOX and caspase-1 signaling. Additionally, NLRP3 was found in neurons at all time points but in non-neuronal cells 72 h after I/R. Discussion: These results suggest that 12/15-LOX inhibition suppresses ischemia-induced inflammation in the acute and subacute phases of stroke via suppressing inflammasome activation. Understanding the mechanisms underlying lipid peroxidation and its associated pathways, like inflammasome activation, may have broader implications for the treatment of stroke and other neurological diseases characterized by neuroinflammation.

Optogenetic cortical spreading depolarization induces headache-related behaviour and neuroinflammatory responses some prolonged in familial hemiplegic migraine type 1 mice.

BACKGROUND: Cortical spreading depolarization (CSD), the neurophysiological correlate of the migraine aura, can activate trigeminal pain pathways, but the neurobiological mechanisms and behavioural consequences remain unclear. Here we investigated effects of optogenetically-induced CSDs on headache-related behaviour and neuroinflammatory responses in transgenic mice carrying a familial hemiplegic migraine type 1 (FHM1) mutation. METHODS: CSD events (3 in total) were evoked in a minimally invasive manner by optogenetic stimulation through the intact skull in freely behaving wildtype (WT) and FHM1 mutant mice. Related behaviours were analysed using mouse grimace scale (MGS) scoring, head grooming, and nest building behaviour. Neuroinflammatory changes were investigated by assessing HMGB1 release with immunohistochemistry and by pre-treating mice with a selective Pannexin-1 channel inhibitor. RESULTS: In both WT and FHM1 mutant mice, CSDs induced headache-related behaviour, as evidenced by increased MGS scores and the occurrence of oculotemporal strokes, at 30 min. Mice of both genotypes also showed decreased nest building behaviour after CSD. Whereas in WT mice MGS scores had normalized at 24 h after CSD, in FHM1 mutant mice scores were normalized only at 48 h. Of note, oculotemporal stroke behaviour already normalized 5 h after CSD, whereas nest building behaviour remained impaired at 72 h; no genotype differences were observed for either readout. Nuclear HMGB1 release in the cortex of FHM1 mutant mice, at 30 min after CSD, was increased bilaterally in both WT and FHM1 mutant mice, albeit that contralateral release was more pronounced in the mutant mice. Only in FHM1 mutant mice, contralateral release remained higher at 24 h after CSD, but at 48 h had returned to abnormal, elevated, baseline values, when compared to WT mice. Blocking Panx1 channels by TAT-Panx308 inhibited CSD-induced headache related behaviour and HMGB1 release. CONCLUSIONS: CSDs, induced in a minimally invasive manner by optogenetics, investigated in freely behaving mice, cause various migraine relevant behavioural and neuroinflammatory phenotypes that are more pronounced and longer-lasting in FHM1 mutant compared to WT mice. Prevention of CSD-related neuroinflammatory changes may have therapeutic potential in the treatment of migraine.

Comparison of Optic Nerve Sheath Diameters Measured by Optic Ultrasonography Before and After Lumbar Puncture in Idiopathic Intracranial Hypertension Patients.

Introduction: Idiopathic intracranial hypertension (IIH) symptoms include headache, blurred vision, and papilledema which may lead to permanent vision loss unless diagnosed and treated. Definitive diagnosis of IIH usually requires the measurement of intracranial pressure (ICP) via lumbar puncture (LP) which is an invasive and unwanted technique for patients. In our study, optic nerve sheath diameters (ONSD) were measured before and after lumbar puncture in IIH patients and the relationship of these measurements with ICP changes was evaluated as well as the effect of decreasing cerebrospinal fluid (CSF) pressure after a lumbar puncture on ONSD. Thus, we want to investigate whether optic nerve ultrasonography (USG) is a useful tool instead of the invasive LP for the diagnosis of IIH. Methods: A total of 25 patients who applied to the neurology clinics of Ankara Numune Training and Research Hospital between May 2014 and December 2015 and were diagnosed with IIH were included in the study. The control group consisted of 22 individuals who applied with complaints other than headaches, visual impairment or tinnitus. Optic nerve sheath diameters were measured from both eyes before and after the LP. After pre-LP measurements were taken, opening and closing CSF pressure was measured. In the control group, ONSD was measured with optic USG. Results: Mean age of the IIH group and the control group was determined as 34.8±11.5 and 45.8±13.3 years, respectively. In the patient group, mean CSF opening pressure was 33.9±8.0 cm H2O and mean closing pressure was 18.1±4.7 cm H2O. Mean ONSD measured pre-LP was 7.1±1.0 mm in the right eye and 6.9±0.7 mm in the left eye, while mean post-LP ONSD was 6.7±0.9 mm in the right eye and 6.4±0.8 mm in the left eye. There was a statistically significant difference between ONSD values before and after the LP (p=0.006 for the right eye, p<0.001 for the left eye). In the control group, mean ONSD was 5.4±0.7 mm in the right eye and 5.5±0.6 mm in the left eye, and a statistically significant difference was found between ONSD values before and after the LP (p<0.001 for the right eye and left eye). A significant positive correlation was determined between left ONSD measurements before the LP and CSF opening pressure (r=0.501, p=0.011). Conclusions: In the present study, it was found that ONSD measurement by optic USG significantly displays increased ICP, and decreasing pressure via LP is rapidly reflecting ONSD measurement. Based on these findings, it is suggested that ONSD measurements by optic USG, a non-invasive method, can be used in the diagnosis and follow-up of IIH patients.

Cortical spreading depression can be triggered by sensory stimulation in primed wild type mouse brain: a mechanistic insight to migraine aura generation.

BACKGROUND: Unlike the spontaneously appearing aura in migraineurs, experimentally, cortical spreading depression (CSD), the neurophysiological correlate of aura is induced by non-physiological stimuli. Consequently, neural mechanisms involved in spontaneous CSD generation, which may provide insight into how migraine starts in an otherwise healthy brain, remain largely unclear. We hypothesized that CSD can be physiologically induced by sensory stimulation in primed mouse brain. METHODS: Cortex was made susceptible to CSD with partial inhibition of Na+/K+-ATPase by epidural application of a low concentration of Na+/K+-ATPase blocker ouabain, allowing longer than 30-min intervals between CSDs or by knocking-down α2 subunit of Na+/K+-ATPase, which is crucial for K+ and glutamate re-uptake, with shRNA. Stimulation-triggered CSDs and extracellular K+ changes were monitored in vivo electrophysiologically and a K+-sensitive fluoroprobe (IPG-4), respectively. RESULTS: After priming with ouabain, photic stimulation significantly increased the CSD incidence compared with non-stimulated animals (44.0 vs. 4.9%, p < 0.001). Whisker stimulation also significantly increased the CSD incidence, albeit less effectively (14.9 vs. 2.4%, p = 0.02). Knocking-down Na+/K+-ATPase (50% decrease in mRNA) lowered the CSD threshold in all mice tested with KCl but triggered CSDs in 14.3% and 16.7% of mice with photic and whisker stimulation, respectively. Confirming Na+/K+-ATPase hypofunction, extracellular K+ significantly rose during sensory stimulation after ouabain or shRNA treatment unlike controls. In line with the higher CSD susceptibility observed, K+ rise was more prominent after ouabain. To gain insight to preventive mechanisms reducing the probability of stimulus-evoked CSDs, we applied an A1-receptor antagonist (DPCPX) to the occipital cortex, because adenosine formed during stimulation from ATP can reduce CSD susceptibility. DPCPX induced spontaneous CSDs but only small-DC shifts along with suppression of EEG spikes during photic stimulation, suggesting that the inhibition co-activated with sensory stimulation could limit CSD ignition when K+ uptake was not sufficiently suppressed as with ouabain. CONCLUSIONS: Normal brain is well protected against CSD generation. For CSD to be ignited under physiological conditions, priming and predisposing factors are required as seen in migraine patients. Intense sensory stimulation has potential to trigger CSD when co-existing conditions bring extracellular K+ and glutamate concentrations over CSD-ignition threshold and stimulation-evoked inhibitory mechanisms are overcome.

Anxiety in Paediatric Patients Diagnosed with COVID-19 and the Affecting Factors.

OBJECTIVE: Children may be greatly affected by events that increase stress in individuals in general and are reported as the vulnerable groups during the coronavirus disease-19 (COVID-19) pandemic. But most of the studies in the literature investigating the mental effects of the pandemic on children were conducted with healthy children and limited study has evaluated the effect on children diagnosed with COVID-19. The aim of this study is to determine the anxiety level in paediatric patients diagnosed with COVID-19 and the affecting factors. METHODS: This descriptive study was conducted with 292 children aged 8-18 years who were diagnosed with COVID-19. Data were collected using the Descriptive Characteristics Questionnaire and the Screen for Child Anxiety Related Emotional Disorders (SCARED). Interviews were held by phone. RESULTS: Males were 51.4% of participants, the mean age was 16.04 ± 1.93. 84.1% of them had a chronic disease; the transmission source was family/relatives/friends for 41.1%. By social isolation, 49.3% were affected and 33.2% were affected by disease symptoms the most in this process. The most common symptoms were headache (61.6%), and asthenia (59.9%). Mean anxiety scale score was 25.5 ± 14.37. The effect of gender, number of symptoms and transmission source on anxiety score was significant (p < 0.05). CONCLUSION: Paediatric patients diagnosed with COVID-19 were found to have high anxiety levels. It is recommended to re-evaluate the duration of children's social participation and support the management of COVID-19 symptoms that affect their anxiety level.

Arachidonic Acid Metabolites in Neurologic Disorders.

BACKGROUND AND OBJECTIVE: Arachidonic acid (ARA) is essential for the fluidity, selective permeability, and flexibility of the cell membrane. It is an important factor for the function of all cells, particularly in the nervous system, immune system, and vascular endothelium. ARA is the second most common polyunsaturated fatty acid in the phospholipids of the nerve cell membrane after docosahexaenoic acid. ARA metabolites have many kinds of physiologic roles. The major action of ARA metabolites is the promotion of the acute inflammatory response, mediated by the production of pro-inflammatory mediators such as PGE2 and PGI2, followed by the formation of lipid mediators, which have pro-resolving effects. Another important action of ARA derivatives, especially COX, is the regulation of vascular reactivity through PGs and TXA2. There is significant involvement of ARA metabolites in neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and neuropsychiatric disorders. ARA derivatives also make an important contribution to acute stroke, global ischemia, subarachnoid hemorrhage, and anticoagulation-related hemorrhagic transformation. CONCLUSION: In this review, we have discussed experimental and human study results of neurologic disorders related to ARA and its metabolites in line with treatment options.

Investigation of the Effect of Human Milk Expression Techniques on Milk Content: A Systematic Review.

BACKGROUND: If the mother and infant cannot meet after birth, it is recommended to express milk and give it to the infant. There was evidence indicating that there might be decrease in essential nutrient values in human milk content depending on the expression technique in literature. The goal of this systematic review was to investigate the effect of human milk expression techniques on the macronutrient milk content and establish an evidence base for future studies. METHODS: Studies investigating the effect of human milk expression techniques on milk content were reviewed without year limitations. A literature review was conducted in six electronic databases (MEDLINE, Web of Science, PubMed, ScienceDirect, CINAHL and Cochrane) until 30 May 2021, using the keywords of breast milk expression techniques, milk content and breast milk pumping. RESULTS: From 258 articles initially screened, we included 6 articles in the systematic review. The fat, protein and lactose content of human milk was analyzed in the studies reviewed. It was concluded that there was no significant effect on the protein (9.7-9.8 g/dl and 2.1-2.1 g/dl, respectively) and lactose (6.50-6.53% and 6.1-6.1 g/dl, respectively) content of milk. However, the fat (58.30, 48.81g/l; 2.6-2.2 g/dl) content was affected. CONCLUSIONS: This study investigated the effect of milk expression techniques on the macronutrient content of human milk, and it was concluded that there was no significant effect on the protein and carbohydrate content of milk. However, the fat content was affected. Limitation of this study is that some factors that might affect the content of human milk were not standardized sufficiently in the included studies.

Updated review on the link between cortical spreading depression and headache disorders.

Introduction: Experimental animal studies have revealed mechanisms that link cortical spreading depression (CSD) to the trigeminal activation mediating lateralized headache. However, conventional CSD as seen in lissencephalic brain is insufficient to explain some clinical features of aura and migraine headache.Areas covered: The importance of CSD in headache development including dysfunction of the thalamocortical network, neuroinflammation, calcitonin gene-related peptide, transgenic models, and the role of CSD in migraine triggers, treatment options, neuromodulation, and future directions are reviewed.Expert opinion: The conventional understanding of CSD marching across the hemisphere is invalid in gyrencephalic brains. Thalamocortical dysfunction and interruption of functional cortical network systems by CSD may provide alternative explanations for clinical manifestations of migraine phases including aura. Not all drugs showing CSD blocking properties in lissencephalic brains have efficacy in migraine headache and monoclonal antibodies against CGRP ligand/receptors which are effective in migraine treatment, have no impact on aura in humans or CSD properties in rodents. Functional networks and molecular mechanisms mediating and amplifying the effects of limited CSD in migraine brain remain to be investigated to define new targets.

Migraine and neuroinflammation: the inflammasome perspective.

BACKGROUND: Neuroinflammation has an important role in the pathophysiology of migraine, which is a complex neuro-glio-vascular disorder. The main aim of this review is to highlight findings of cortical spreading depolarization (CSD)-induced neuroinflammatory signaling in brain parenchyma from the inflammasome perspective. In addition, we discuss the limited data of the contribution of inflammasomes to other aspects of migraine pathophysiology, foremost the activation of the trigeminovascular system and thereby the generation of migraine pain. MAIN BODY: Inflammasomes are signaling multiprotein complexes and key components of the innate immune system. Their activation causes the production of inflammatory cytokines that can stimulate trigeminal neurons and are thus relevant to the generation of migraine pain. The contribution of inflammasome activation to pain signaling has attracted considerable attention in recent years. Nucleotide-binding domain (NOD)-like receptor family pyrin domain containing 3 (NLRP3) is the best characterized inflammasome and there is emerging evidence of its role in a variety of inflammatory pain conditions, including migraine. In this review, we discuss, from an inflammasome point of view, cortical spreading depolarization (CSD)-induced neuroinflammatory signaling in brain parenchyma, the connection with genetic factors that make the brain vulnerable to CSD, and the relation of the inflammasome with diseases that are co-morbid with migraine, including stroke, epilepsy, and the possible links with COVID-19 infection. CONCLUSION: Neuroinflammatory pathways, specifically those involving inflammasome proteins, seem promising candidates as treatment targets, and perhaps even biomarkers, in migraine.

Widespread brain parenchymal HMGB1 and NF-κB neuroinflammatory responses upon cortical spreading depolarization in familial hemiplegic migraine type 1 mice.

Neuroinflammatory changes involving neuronal HMGB1 release and astrocytic NF-κB nuclear translocation occur following cortical spreading depolarization (CSD) in wildtype (WT) mice but it is unknown to what extent this occurs in the migraine brain. We therefore investigated in familial hemiplegic migraine type 1 (FHM1) knock-in mice, which express an intrinsic hyperexcitability phenotype, the extent of neuroinflammation without and after CSD. CSD was evoked in one hemisphere by pinprick (single CSD) or topical KCl application (multiple CSDs). Neuroinflammatory (HMGB1, NF-κB) and neuronal activation (pERK) markers were investigated by immunohistochemistry in the brains of WT and FHM1 mutant mice without and after CSD. Effects of NMDA receptor antagonism on basal and CSD-induced neuroinflammatory changes were examined by, respectively, systemically administered MK801 and ifenprodil or topical MK801 application. In FHM1 mutant mice, CSD caused enhanced neuronal HMGB1 release and astrocytic NF-κB nuclear translocation in the cortex and subcortical areas that were equally high in both hemispheres. In WT mice such effects were only pronounced in the hemisphere in which CSD was induced. Neuroinflammatory responses were associated with pERK expression indicating neuronal activation. Upon CSD, contralateral cortical and striatal HMGB1 release was reduced by topical application of MK801 in the hemisphere contralateral to the one in which CSD was induced. This study reveals that neuroinflammatory activation after CSD is widespread and extends to the contralateral hemisphere, particularly in brains of FHM1 mutant mice. Effective blockade of CSD-induced neuroinflammatory responses in the contralateral hemisphere in FHM1 mice by local NMDA receptor antagonism suggests that neuronal hyperexcitability-related neuroinflammation is relevant in migraine pathophysiology, but possibly also other neurological disorders in which spreading depolarization is involved.

Depression, loneliness and factors influencing in Syrian refugee children.

AIMS: About 3.5 million Syrian refugees are living within the borders of Turkey. This study examined depression, loneliness and factors influencing refugee children who live outside the camps and attend school in Turkey. METHODS: This was a descriptive study in Sanliurfa, which has the second highest refugee population in Turkey. The sample consisted of 535 students attending 6-8 grades in five schools randomly selected of 18 schools located in the city centre where the Syrian children received their education. Data were collected using the Sociodemographic Characteristics Question Form, the Depression Scale for Children and the UCLA Loneliness Scale. Data were analysed by IBM spss v23. The percentage, average and standard deviation were determined. A linear regression analysis was used to examine the independent variables affecting loneliness and depression scores, and the Backward method was used to include independent variables in the model. Significance level was considered as P < .05. RESULTS: The average age of the children was 13.22 ± 1.33 years and 57.9% female. The average UCLA Loneliness Scale score was 42.95 ± 7.77. About 42% of the children received ≥19 on the depression scale, and 65% of them received ≥40 on the UCLA Loneliness Scale. Independent variables affecting depression score and UCLA loneliness score were analysed by a linear regression analysis. The linear regression model established for depression and UCLA loneliness score was obtained as statistically significant (P < .001). CONCLUSION: Depression and loneliness scores were relatively high in children, particularly those exposed to the devastating impacts of war. These results will make significant contributions to the planning of services to be provided for this group of children.

KCl-induced cortical spreading depression waves more heterogeneously propagate than optogenetically-induced waves in lissencephalic brain: an analysis with optical flow tools.

Although cortical spreading depolarizations (CSD) were originally assumed to be homogeneously and concentrically propagating waves, evidence obtained first in gyrencephalic brains and later in lissencephalic brains suggested a rather non-uniform propagation, shaped heterogeneously by factors like cortical region differences, vascular anatomy, wave recurrences and refractory periods. Understanding this heterogeneity is important to better evaluate the experimental models on the mechanistics of CSD and to make appropriate clinical estimations on neurological disorders like migraine, stroke, and traumatic brain injury. This study demonstrates the application of optical flow analysis tools for systematic and objective evaluation of spatiotemporal CSD propagation patterns in anesthetized mice and compares the propagation profile in different CSD induction models. Our findings confirm the asymmetric angular CSD propagation in lissencephalic brains and suggest a strong dependency on induction-method, such that continuous potassium chloride application leads to significantly higher angular propagation variability compared to optogenetically-induced CSDs.

F-actin polymerization contributes to pericyte contractility in retinal capillaries.

Although it has been documented that central nervous system pericytes are able to contract in response to physiological, pharmacological or pathological stimuli, the underlying mechanism of pericyte contractility is incompletely understood especially in downstream pericytes that express low amounts of alpha-smooth muscle actin (α-SMA). To study whether pericyte contraction involves F-actin polymerization as in vascular smooth muscle cells, we increased retinal microvascular pericyte tonus by intravitreal injection of a vasoconstrictive agent, noradrenaline (NA). The contralateral eye of each mouse was used for vehicle injection. The retinas were rapidly extracted and fixed within 2 min after injections. Polymeric/filamentous (F-actin) and monomeric/globular (G-actin) forms of actin were labeled by fluorescently-conjugated phalloidin and deoxyribonuclease-I, respectively. We studied 108 and 83 pericytes from 6 NA- and 6 vehicle-treated retinas and, found that F/G-actin ratio, a microscopy-based index of F-actin polymerization, significantly increased in NA-treated retinas [median (IQR): 4.2 (3.1) vs. 3.5 (2.1), p = .006], suggesting a role for F-actin polymerization in pericyte contractility. Shift from G-actin monomers to polymerized F-actin was more pronounced in 5th and 6th order contracted pericytes compared to non-contracted ones [7.6 (4.7) vs. 3.2 (1.2), p < .001], possibly due to their dependence on de novo F-actin polymerization for contractile force generation because they express α-SMA in low quantities. Capillaries showing F-actin polymerization had significantly reduced diameters compared to the ones that did not exhibit increased F/G-actin ratio in pericytes [near soma / branch origin diameter; 0.67 (0.14) vs. 0.81 (0.34), p = .005]. NA-responsive capillaries generally did not show nodal constrictions but a tide-like diameter decrease, reaching a maximum near pericyte soma. These findings suggest that pericytes on high order downstream capillaries have F-actin-mediated contractile capability, which may contribute to the vascular resistance and blood flow regulation in capillary bed.

Contributions of 12/15-Lipoxygenase to Bleeding in the Brain Following Ischemic Stroke.

Ischemic strokes are caused by one or more blood clots that typically obstruct one of the major arteries in the brain, but frequently also result in leakage of the blood-brain barrier and subsequent hemorrhage. While it has long been known that the enzyme 12/15-lipoxygenase (12/15-LOX) is up-regulated following ischemic strokes and contributes to neuronal cell death, recent research has shown an additional major role for 12/15-LOX in causing this hemorrhagic transformation. These findings have important implications for the use of 12/15-LOX inhibitors in the treatment of stroke.

Mouse Models of Familial Hemiplegic Migraine for Studying Migraine Pathophysiology.

Migraine, an extremely disabling neurological disorder, has a strong genetic component. Since monogenic migraines (resulting from mutations or changes in a single gene) may help researchers discover migraine pathophysiology, transgenic mice models harboring gene mutations identified in Familial Hemiplegic Migraine (FHM) patients have been generated. Studies in these FHM mutant mice models have shed light on the mechanisms of migraine and may aid in the identification of novel targets for treatment. More specifically, the studies shed light on how gene mutations, hormones, and other factors impact the pathophysiology of migraine. The models may also be of relevance to researchers outside the field of migraine as some of their aspects are relevant to pain in general. Additionally, because of the comorbidities associated with migraine, they share similarities with the mutant mouse models of epilepsy, stroke, and perhaps depression. Here, we review the experimental data obtained from these mutant mice and focus on how they can be used to investigate the pathophysiology of migraine, including synaptic plasticity, neuroinflammation, metabolite alterations, and molecular and behavioral mechanisms of pain.

12/15 Lipoxygenase as a Therapeutic Target in Brain Disorders.

Lipoxygenases are a family of lipid-oxidizing enzymes, which generate eicosanoids and related compounds from arachidonic acid and other polyunsaturated fatty acids. These metabolites play important roles in physiology and pathogenesis of host defense mechanisms, cardiovascular diseases, cancer, inflammatory, allergic and neurodegenerative diseases. The 12/15-lipoxygenase (LOX) is special in that it can directly oxidize lipid membranes containing polyunsaturated fatty acids, without the preceding action of a phospholipase, leading to the direct attack on membranous organelles, such as mitochondria. The cytotoxic activity of human 12/15-LOX is up-regulated in neurons and endothelial cells especially after a stroke and thought to contribute to both neuronal cell death and blood-brain barrier leakage. The discovery of inhibitors that selectively target recombinant 12/15-LOX in vitro, as well as possessing activity against the murine orthologous ex vivo, could potentially support a novel therapeutic strategy for the treatment of stroke and other brain disorders related to 12/15-LOX. Here we reviewed 12/15-LOX chemistry shortly, and the diseases in which 12/15-LOX has a role in their pathophysiology and recent advances of 12/15-LOX inhibitors as a treatment option for neurological diseases.

Brain Peptides for the Treatment of Neuropsychiatric Disorders.

The realization of the importance of growth factors in adult CNS led to several studies investigating their roles in neuropsychiatric disorders. Based on the observations that chronic stress decreases brain-derived neurotrophic factor (BDNF) and antidepressant treatments reverse BDNF to normal levels, "neurotrophic hypothesis of depression" was proposed. Subsequent studies found that several other growth factors, including fibroblast growth factor (FGF), vascular endothelial growth factor, nerve growth factor were also decreased by chronic stress. Growth factors promote stem cell survival, angiogenesis and neurogenesis in addition to having anti-apoptotic and anti-inflammatory effects, all of which make them potential drug candidates as neuroprotective or neurorestorative agents. Indeed, certain peptides have consistently been shown to improve stroke outcome in experimental models of cerebral ischemia. Recent developments in nanotechnology appear promising in overcoming the blood-brain barrier and in delivering sufficient amounts of these large peptides to the brain after systemic administration. In addition to the translational potential resulting from application of nanotechnical approaches for delivering these large peptide growth factors, recent success obtained with small molecule and peptide antagonists of calcitonin gene-related peptide has created renewed enthusiasm to elucidate the role of neuropeptides in migraine headache, one of the most common health problems in the world. In this review, we will first focus on the role of FGF2 in mood disorders as well as in ischemic stroke. We will also introduce the nanomedicines developed to efficiently deliver FGF2 to the brain. In the last section, we will explore roles of the neuropeptides in migraine and its acute and prophylactic treatment.