Griffonia Simplicifolia Isolectin B4 Research Articles

Collagen matricryptin promotes cardiac function by mediating scar formation

AimsA peptide mimetic of a collagen-derived matricryptin (p1159) was shown to reduce left ventricular (LV) dilation and fibrosis after 7 days delivery in a mouse model of myocardial infarction (MI). This suggested p1159 long-term treatment post-MI could have beneficial effects and reduce/prevent adverse LV remodeling. This study aimed to test the potential of p1159 to reduce adverse cardiac remodeling in a chronic MI model and to elucidate p1159 mode-of-action. Materials and methodsUsing a permanent occlusion MI rodent model, animals received p1159 or vehicle solution up to 28 days. We assessed peptide treatment effects on scar composition and structure and on systolic function. To assess peptide effects on scar vascularization, a cohort of mice were injected with Griffonia simplicifolia isolectin-B4. To investigate p1159 mode-of-action, LV fibroblasts from naïve animals were treated with increasing doses of p1159. Key findingsMatricryptin p1159 significantly improved systolic function post-MI (2-fold greater EF compared to controls) by reducing left ventricular dilation and inducing the formation of a compliant and organized infarct scar, which promoted LV contractility and preserved the structural integrity of the heart. Specifically, infarcted scars from p1159-treated animals displayed collagen fibers aligned parallel to the epicardium, to resist circumferential stretching, with reduced levels of cross-linking, and improved tissue perfusion. In addition, we found that p1159 increases cardiac fibroblast migration by activating RhoA pathways via the membrane receptor integrin α4. SignificanceOur data indicate p1159 treatment reduced adverse LV remodeling post-MI by modulating the deposition, arrangement, and perfusion of the fibrotic scar.

Not All Lectins Are Equally Suitable for Labeling Rodent Vasculature.

The vascular system is vital for all tissues and the interest in its visualization spans many fields. A number of different plant-derived lectins are used for detection of vasculature; however, studies performing direct comparison of the labeling efficacy of different lectins and techniques are lacking. In this study, we compared the labeling efficacy of three lectins: Griffonia simplicifolia isolectin B4 (IB4); wheat germ agglutinin (WGA), and Lycopersicon esculentum agglutinin (LEA). The LEA lectin was identified as being far superior to the IB4 and WGA lectins in histological labeling of blood vessels in brain sections. A similar signal-to-noise ratio was achieved with high concentrations of the WGA lectin injected during intracardial perfusion. Lectins were also suitable for labeling vasculature in other tissues, including spinal cord, dura mater, heart, skeletal muscle, kidney, and liver tissues. In uninjured tissues, the LEA lectin was as accurate as the Tie2–eGFP reporter mice and GLUT-1 immunohistochemistry for labeling the cerebral vasculature, validating its specificity and sensitivity. However, in pathological situations, e.g., in stroke, the sensitivity of the LEA lectin decreases dramatically, limiting its applicability in such studies. This work can be used for selecting the type of lectin and labeling method for various tissues.

Hemovasculogenic origin of blood vessels in the developing mouse brain.

Vascular structures in the developing brain are thought to form via angiogenesis from preformed blood vessels in the cephalic mesenchyme. Immunohistochemical studies of developing mouse brain from E10.5 to E13.5 revealed the presence of avascular blood islands of primitive erythroid cells expressing hemangioblast markers (Flk1, Tal1/Scl1, platelet endothelial cell adhesion molecule 1, vascular endothelial-cadherin, and CD34) and an endothelial marker recognized by Griffonia simplicifolia isolectin B4 (IB4) in the cephalic mesenchyme. These cells formed a perineural vascular plexus from which angiogenic sprouts originated and penetrated the neuroepithelium. In addition, avascular isolated cells expressing primitive erythroid, hemangioblast and endothelial makers were visible in the neuroepithelium where they generated vasculogenic and hemogenic foci. From E10.5 to E13.5, these vasculogenic foci were a source of new blood vessel formation in the developing brain. In vitro, cultured E13.5 brain endothelial cells contained hemogenic endothelial cells capable of generating erythroid cells. Similar cells were present in primary cultures of dissociated cells from E10.5 embryonic head. Our results provide new evidence that the brain vasculature, like that of the yolk sac and the eye choriocapillaris and hyaloid vascular systems, develops at least in part via hemovasculogenesis, a process in which vasculogenesis and hematopoiesis occur simultaneously.

Activated Retinal Microglia Secrete Exosomes Containing Galectin‐3

PurposeNumerous reports support a potential role for activated microglial cells in the mechanisms of degenerative retinal and brain diseases. Although the exact mechanism remains unknown, our study and those of others describe the transport and release of cytotoxic substances by activated microglia during the initial stages of neuronal cell death. Among these substances, galectin‐3 has emerged as an important player in inflammatory conditions and neurodegenerative diseases by mediating and/or modulating microglial activation. Galectin‐3, a member of an evolutionary conserved family of carbohydrate‐binding lectins, lacks a signal peptide and is most likely secreted via a non‐classical exocytic pathway involving extracellular vesicles (exosomes and microparticles).MethodsTo investigate the role of galectin‐3‐derived retinal microglia in degenerative retinal diseases, activated microglia were isolated from 4–5 week old mice retinas with a targeted mutation of the c‐mer proto‐oncogene tyrosine kinase gene (Mertk−/−) and characterized for expression of microglia specific markers. Extracellular vesicles were purified from 48h conditioned media of cultured microglia and characterized for expression of galectin‐3 and Alix, an exosome marker, using immunocytochemistry and Western blots.ResultsRetinal microglia from Mertk−/− mice displayed an activated phenotype characterized by expression of CX3Cr1, CD11b, and Griffonia simplicifolia isolectin B4 but not of the Müller glial marker glial fibrillary acidic protein (GFAP) nor the vascular endothelial cell marker PECAM‐1. Intense galectin‐3 immunofluorescence was observed throughout the cell body and processes of microglial cells; producing a ~30 kDa galectin‐3 reactive band in the cytosolic component in Western blots. Abundant amounts of extracellular vesicles (~100–200 nm in size) secreted by the cells in 48h conditioned medium displayed a ~30 kDa galectin‐3‐reactive band and an Alix‐reactive band, consistent with exosomes, in Western blots.ConclusionsOur study shows that activated microglia isolated from early Mertk−/− mice with retinal degeneration expressed high levels of galectin‐3. Moreover, galectin‐3 co‐localized with Alix‐expressing exosomes secreted by cultured microglia. The increased production and release of exosomal galectin‐3 by activated retinal microglia support a potential role for galectin‐3 and microglial cells in the mechanisms of degenerative retinal diseases.

Anti-angiogenic and anti-inflammatory effects of CD200-CD200R1 axis in oxygen-induced retinopathy mice model.

In this study, the expression changes and the potential effects of CD200 and its receptors during the process of retinal neovascularization (RNV) development had been detected, using a classic oxygen-induced retinopathy (OIR) mice model and CD200Fc (a CD200R1 agonist) intravitreal injection. 7 day postnatal (P7) C57BL/6J mice were raised in hyperoxia incubators with 75±2% oxygen for 5 days, and returned to room air at P12. All animals were subdivided into three groups: normoxia control, OIR, and OIR+CD200Fc group. The mice of OIR+CD200Fc group were intravitreal injected with CD200Fc (2μg/μL, 0.5μL) at P12. Retinas and vitreous samples were harvested at P17. The expression and localization of CD200 and its receptors were analyzed by Western blot, quantitative real-time polymerase chain reaction (qRT-PCR), enzyme-linked immunosorbent assay (ELISA), and retinal whole-mount immunofluorescence. To investigate the effects of CD200Fc treatment, vascular endothelial growth factor (VEGF)-A, platelet-derived growth factor (PDGF)-BB, pro-inflammatory cytokines, NV area, and microglial activation were detected respectively. In OIR group, both protein and RNA levels of CD200 and CD200R1 were significantly up-regulated. The increased CD200 and CD200R1 were co-localized with Alex594-labeled Griffonia simplicifolia isolectin B4 (IB4) on vascular endothelial cells in NV area of OIR samples, and CD200R1 was co-expressed with ionized calcium-bind adapter molecule 1 (iba1) on microglia in OIR samples at the same time. CD200Fc intravitreal injection could significantly reduce the release of VEGF-A, PDGF-BB, and pro-inflammatory cytokines; shrink the NV area; and inhibit the activation of microglia in OIR mice. These findings suggested that the up-regulation of CD200 and CD200R1 was closely related to RNV development, and the antiangiogenic effects of CD200Fc in OIR model might be realized by inhibition of inflammatory response and microglia activation. The results may provide a new therapeutic target for RNV diseases.

Neurochemical difference between somato- and viscero-projecting sensory neurons in the pig

The chemical coding of porcine somato (skin)- and viscero (urinary bladder)-projecting sensory neurons have been studied and compared using immunohistochemistry. Cell bodies of skin and bladder afferents were identified following Fast Blue injections into the skin of the hind leg as well as into wall of the urinary bladder, respectively. Immunohistochemistry revealed that small and medium-sized neurons projecting to both skin and bladder contained all of the studied substances i.e. substance P (SP), calcitonin gene-related pepide (CGRP), transient receptor potential vanilloid (TRPV1), lectin from Bandeiraea simplicifolia – Griffonia simplicifolia isolectin B4 (IB4) and galanin (GAL). Moreover, small-sized sensory neurons projecting to the bladder and skin of hind leg showed predominantly immunoreactivity to SP and TRPV1 and CGRP, as well as to CGRP and TRPV1 and IB4. It is worth stressing that the subset of sensory neurons innervating the skin exhibited these substances more often than bladder-projecting neurons. In addition, medium-sized skin-projecting neurons contained SP/GAL; SP/CGRP and CGRP/IB4 much more often than their bladder counterparts. On the other hand, small-sized perikarya that innervate the skin were less frequently expressed TRPV1, CGRP and GAL than the bladder-projecting neurons.In conclusion, the present report describes, for the first time, significant differences in the chemical coding between somato- and viscero-projecting sensory neurons in dorsal root ganglia. Moreover, these results provide morphological basis for further functional studies, which may explain the exact roles played by various subpopulations of somato- and viscero-projecting sensory neurons.

Distribution and neurochemistry of porcine urinary bladder-projecting sensory neurons in subdomains of the dorsal root ganglia: A quantitative analysis

The aim of the present study has been to verify the inter- and intraganglionic distribution pattern of porcine urinary bladder-projecting (UBP) neurons localized in the sacral dorsal root ganglia (DRGs). The morphology and chemical phenotype of these cells have also been investigated. These neurons were visualized using the fluorescent tracer Fast Blue (FB) which was injected bilaterally into the urinary bladder wall of five juvenile female pigs. The intraganglionic distribution showed that small- and medium-sized FB+ perikarya were mainly located in the central (S3–S4) and periphero-central (S2) region of the ganglia, while large cells were heterogeneously distributed. Immunohistochemistry revealed that the most frequently observed markers in small and medium-sized UBP perikarya were: neurofilament 200, lectin from Bandeiraea simplicifolia (Griffonia simplicifolia) isolectin B4, substance P, calcitonin gene-related peptide, pituitary adenylate cyclase-activating polypeptide and transient receptor potential vanilloid 1. Moreover, UBP neurons containing these substances were also mainly observed in the central and periphero-central region of the ganglion. Differences in the percentage of traced cells and their neuropeptide content were observed between the S2, S3 and S4 DRGs. In conclusion, the present study, for the first time, describes the arrangement of UBP DRGs neurons within particular subdomains of sacral ganglia, taking into account their size and chemical phenotype.

Comparison of Dextran Perfusion and GSI-B4 Isolectin Staining in a Mouse Model of Oxygen-induced Retinopathy.

Oxygen-induced retinopathy (OIR) is a robust and widely used animal model for the study of retinal neovascularization (NV). Dextran perfusion and Griffonia simplicifolia isolectin B4 (GSI-B4) staining are two common methods for examining the occurrence and extent of OIR. This study provides a quantitative comparison of the two for OIR detection. At postnatal day 7 (PN7), fifteen C57BL/6J mice were exposed to a 75% hyperoxic condition for 5 days and then returned to room air conditions. At PN17, the mice received intravitreal injection of GSI-B4 Alexa Fluor 568 conjugate. After 10 hours, they were infused with FITC-dextran conjugate via the left ventricle. Retinal flat mounts were photographed by confocal microscopy. Areas with fluorescent signals and the total retinal areas were quantified by Image J software. Both GSI-B4 and dextran detected the peripheral neovascular area. The mean hyper fluorescence area was 0.33 ± 0.14% of whole retinal area determined by GSI-B4 staining and 0.25 ± 0.28% determined by dextran perfusion. The difference between the two measures was 0.08% (95% CI:-0.59%, 0.43%). The Pearson correlation coefficient between the two methods was 0.386,P =0.035. The mean coincidence rates were 14.3 ± 13.4% and 24.9 ± 18.5% for GSI-B4 and dextran staining, respectively. Both methods can complement each other in demonstrating and quantitatively evaluating retinal NV. A poor agreement was found between the two methods; GSI-B4 isolectin was more effective than FITC-dextran perfusion in evaluating the extent of retinal NV in a mouse model of OIR.

S100A4 gene silencing in oxygen-induced ischemic retinopathy inhibits retinal neovascularization via down-regulation of CREB expression.

To investigate the possible role of S100A4 in retinal neovascularization (RNV), as well as the underlying mechanism, in a mouse model of oxygen-induced retinopathy (OIR). Retinas used in the experiments were obtained from a mouse model of OIR with and without treatment by intravitreal injection of adnoviral-S100A4-RNAi or adenoviral-green fluorescent protein at postnatal day 12 (P12). At P17, the efficacy of adenoviral gene transfer was assessed with fluorescence microscopy. RNV was evaluated by whole-mount immunofluorescent staining of the mouse retina with Griffonia simplicifolia isolectin B4 conjugated to Alexa Fluor 594 and quantified by counting the number of pre-retinal neovascular cells. Protein and mRNA expression levels of S100A4, cyclic AMP (cAMP) response element-binding protein (CREB), B-cell lymphoma 2 (Bcl-2), and caspase-3 were determined using Western blot analysis and real-time PCR. Retinal S100A4 levels were positively correlated with the progression of RNV. In the intravitreal Ad-S100A4-RNAi transfer mice, both S100A4 protein and mRNA expression levels in the retina were significantly decreased at P17. Ad-S100A4-RNAi transfer was clearly demonstrated by the green fluorescent protein (GFP) in many layers of the retina, including the ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), and outer nuclear layer (ONL), 3 days after intravitreal injection. Whole-mount immunofluorescent staining of the retina and quantification of the pre-retinal neovascular cells demonstrated that RNV was significantly ameliorated. At the same time, the expression of CREB and Bcl-2 were significantly decreased at the transcriptional and translational levels in the OIR-S100A4 group, whereas caspase-3 expression was increased. Our results indicated that RNV was ameliorated by Ad-S100A4-RNAi transfer in a mouse model of OIR through mediation of the anti-apoptotic effect of Bcl-2 by reducing the expression of CREB, and that S100A4 may be a novel therapeutic target for ocular neovascularization diseases.

Plasma anti-α-galactoside antibody binds to serine- and threonine-rich peptide sequence of apo(a) subunit in Lp(a).

Lipoprotein(a) immune complexes [Lp(a) IC] of varying particle density obtained by ultracentrifugation of plasma from normal healthy donors were markedly dominated by IgG. Lp(a) and immunoglobulins were liberated from plasma Lp(a) IC by treatment with melibiose, a sugar specific for circulating anti-α-galactoside antibody (anti-Gal). Upon incubation with plasma lipoprotein fraction anti-Gal but not the α-glucoside-specific antibody from human plasma formed de novo IC with Lp(a). Binding of Lp(a) sugar-reversibly enhanced the fluorescence of FITC-labeled anti-Gal as did binding of α-galactoside-containing glycoproteins. This effect apparently due to conformational shift in the Fc region of the antibody was also produced by apo(a) subunit separated from Lp(a) and de-O-glycosylated apo(a) but not by any other plasma lipoproteins or by Lp(a) pre-incubated with the O-glycan-specific lectin jacalin. O-Glycans and their terminal sialic acid moieties in apo(a) of circulating Lp(a)-anti-Gal IC, in contrast to those in pure Lp(a), were inaccessible to jacalin and anion exchange resin, respectively. Unlike other plasma lipoproteins, Lp(a) inhibited Griffonia simplicifolia isolectin B4 which also accommodates serine- and threonine-rich peptide sequence (STPS) as surrogate ligand to α-galactosides at its binding site. Results suggest that anti-Gal recognizes STPS in the O-glycan-rich regions of apo(a) subunit in Lp(a) which contains no α-linked galactose.

Rapid onset of perfused blood vessels after implantation of ECFCs and MPCs in collagen, PuraMatrix and fibrin provisional matrices

We developed an in vivo vascularization model in which human endothelial colony-forming cells (ECFCs) and human mesenchymal progenitor cells (MPCs) form blood vessel networks when co-injected (ECFC + MPC) into nude mice in rat tail type I collagen, bovine fibrin or synthetic peptide PuraMatrix matrices. We used three approaches to determine the onset of functional vascularization when ECFC + MPC suspended in these matrices were implanted in vivo. The first was immunohistochemistry to detect vessels lined by human endothelial cells and filled with red blood cells. The second was in vivo vascular staining by tail vein injection of a mixture of Ulex europaeus agglutinin I (UEA-I), a lectin specific for human endothelium, and Griffonia simplicifolia isolectin B4 (GS-IB4 ), a lectin specific for rodent endothelium. The third approach employed contrast-enhanced ultrasound to measure the perfusion volumes of implants in individual animals over time. Human endothelial-lined tubular structures were detected in vivo on days 1 and 2 after implantation, with perfused human vessels detected on days 3 and 4. Contrast-enhanced ultrasound revealed significant perfusion of ECFC + MPC/collagen implants on days 1-4, at up to 14% perfused vascular volume. ECFC + MPC implanted in fibrin and PuraMatrix matrices also supported perfusion at day 1, as assessed by ultrasound (at 12% and 23% perfused vascular volume, respectively). This model demonstrates that ECFC + MPC suspended in any of the three matrices initiated a rapid onset of vascularization. We propose that ECFC + MPC delivered in vivo provide a means to achieve rapid perfusion of tissue-engineered organs or for in situ tissue repair.

Hyaluronic acid-based hydrogel enhances neuronal survival in spinal cord slice cultures from postnatal mice

Numerous biomaterials based on extracellular matrix-components have been developed. It was our aim to investigate whether a hyaluronic acid-based hydrogel improves neuronal survival and tissue preservation in organotypic spinal cord slice cultures. Organotypic spinal cord slice cultures were cultured for 4 days invitro (div), either on hyaluronic acid-based hydrogel (hyaluronic acid-gel group), collagen gel (collagen group), directly on polyethylene terephthalate membrane inserts (control group), or in the presence of soluble hyaluronic acid (soluble hyaluronic acid group). Cultures were immunohistochemically stained against neuronal antigen NeuN and analyzed by confocal laser scanning microscopy. Histochemistry for choline acetyltransferance, glial fibrillary acidic protein, and Griffonia simplicifolia isolectin B4 followed by quantitative analysis was performed to assess motorneurons and different glial populations. Confocal microscopic analysis showed a 4-fold increase in the number of NeuN-positive neurons in the hyaluronic acid-gel group compared to both collagen (p < 0.001) and control groups (p < 0.001). Compared to controls, organotypic spinal cord slice cultures maintained on hyaluronic acid-based hydrogel showed 5.9-fold increased survival of choline acetyltransferance-positive motorneurons (p = 0.008), 2-fold more numerous resting microglial cells in the white matter (p = 0.031), and a 61.4% reduction in the number of activated microglial cells within the grey matter (p = 0.05). Hyaluronic acid-based hydrogel had a shear modulus (G') of ≈1200 Pascals (Pa), which was considerably higher than the ≈25 Pa measured for collagen gel. Soluble hyaluronic acid failed to improve tissue preservation. In conclusion, hyaluronic acid-based hydrogel improves neuronal and - most notably - motorneuron survival in organotypic spinal cord slice cultures and microglial activation is limited. The positive effects of hyaluronic acid-based hydrogel may at least in part be due to its mechanical properties.

Abstract 2709: Functional Role of FKBP51 in malignant progression of melanoma.

Abstract FKBP51 is a high molecular weight FK506-binding protein involved in the regulation of diverse biological processes. Its aberrant expression and pathological implications has been reported in some cancer types; however, its role in malignant melanoma has remained underexplored. In this study, we investigated the functional role of FKBP51 in melanoma pathogenesis by performing in vitro and in vivo studies. FKBP51 expression was observed in majority of primary and derivative melanoma cell lines. Interestingly, a greater expression of FKBP51 was detected in metastatic derivative lines (A375SM and FEMX-I) as compared to their respective parental cells (A375P and FEMX-V). Next, we stably repressed the expression of FKBP51 in A375SM and FEMX-I cells through short-hairpin RNA (shRNA)-mediated silencing. FKBP51 repression led to a decrease in growth and clonogenicity, in part, through suppression of cell cycle progression and induction of apoptosis. A reduced motility and invasion was also observed in both the FKBP51-silenced melanoma cell lines. Immunoblot analyses demonstrated loss of mesenchymal markers and elevated expression of epithelial markers in FKBP51-silenced cells, indicating a role of FKBP51 in epithelial to mesenchymal transition of melanoma cells. When injected subcutaneously into nude mice, FKBP51-silenced A375SM cells displayed significant inhibition of tumor growth as compared to the control cells. Immunohistochemical analysis of tumor tissues demonstrated a decrease in the proliferating (Ki67 positive) cells and increased numbers of apoptotic (TUNEL positive) cells in FKBP51-silenced A375SM as compared with control tumors. Furthermore, low vessel density and infiltration of myeloid derived suppressor cells (MDSC) was observed in tumors formed by FKBP51-silenced cells as examined by isolectin lectin B4 (Griffonia simplicifolia isolectin B4) and Gr-1 staining, respectively. Notably, tail vein injection of FKBP51- silenced cells produced no metastatic lesions in lungs, while significant metastases was observed in lungs of mice injected with control cells. Estimation of interleukin-8 (IL-8/CXCL-8), a chemokine previously associated with melanoma growth, metastasis and angiogenesis, demonstrated its decreased production in FKBP51-silenced cells and derived tumors. In conclusion, our study provides experimental evidence to support the functional significance of FKBP51 in malignant progression of human melanoma. Citation Format: Gurpreet Kaur, Sanjeev K. Srivastava, Sumit Arora, Arun Bhardwaj, Steven McClellan, Jonathan G. Scammell, William E. Grizzle, Laurie B. Owen, Oystein Fodstad, Ajay P. Singh, Seema Singh. Functional Role of FKBP51 in malignant progression of melanoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2709. doi:10.1158/1538-7445.AM2013-2709

Resveratrol suppresses calcium-mediated microglial activation and rescues hippocampal neurons of adult rats following acute bacterial meningitis

Acute bacterial meningitis (ABM) is a serious disease with severe neurological sequelae. The intense calcium-mediated microglial activation and subsequently pro-inflammatory cytokine release plays an important role in eliciting ABM-related oxidative damage. Considering resveratrol possesses significant anti-inflammatory and anti-oxidative properties, the present study aims to determine whether resveratrol would exert beneficial effects on hippocampal neurons following ABM. ABM was induced by inoculating Klebsiella pneumoniae into adult rats intraventricularly. The time-of-flight secondary ion mass spectrometry (TOF-SIMS), Griffonia simplicifolia isolectin-B4 (GSA-IB4) and ionized calcium binding adaptor molecule 1 (Iba1) immunohistochemistry, enzyme-linked immunosorbent assay as well as malondialdehyde (MDA) measurement were used to examine the calcium expression, microglial activation, pro-inflammatory cytokine level, and extent of oxidative stress, respectively. In ABM rats, strong calcium signaling associated with enhanced microglial activation was observed in hippocampus. Increased microglial expression was coincided with intense production of pro-inflammatory cytokines and oxidative damage. However, in rats receiving resveratrol after ABM, the calcium intensity, microglial activation, pro-inflammatory cytokine and MDA levels were all significantly decreased. Quantitative data showed that much more hippocampal neurons were survived in resveratrol-treated rats following ABM. As resveratrol successfully rescues hippocampal neurons from ABM by suppressing the calcium-mediated microglial activation, therapeutic use of resveratrol may act as a promising strategy to counteract the ABM-induced neurological damage.

Chronic Opioid Potentiates Presynaptic but Impairs Postsynaptic N-Methyl-d-aspartic Acid Receptor Activity in Spinal Cords: IMPLICATIONS FOR OPIOID HYPERALGESIA AND TOLERANCE

Chronic Opioid Potentiates Presynaptic but Impairs Postsynaptic N-Methyl-d-aspartic Acid Receptor Activity in Spinal Cords: IMPLICATIONS FOR OPIOID HYPERALGESIA AND TOLERANCE

Propidium iodide staining: A new application in fluorescence microscopy for analysis of cytoarchitecture in adult and developing rodent brain

Immunohistochemical visualization of antigens in specimen has evolved to an indispensable technique in biomedical research for investigations of cell morphology and pathology both in bright field and fluorescence microscopy. While there are couple of staining methods that reveal entire cytoarchitecture in bright field microscopy such as Nissl or hemalaun-eosin, there are still limitations in visualizations of cytoarchitecture in fluorescence microscopy. The present study reports a simple staining method that provides the required illustration of cell allocations and cellular composition in fluorescence microscopy in adult and in developing rodent central nervous system using the fluorophore propidium iodide (PI, 5μg/mL). PI is a well-accepted marker for degenerating cells when applied prior to fixation (pre-fixation PI staining). Here, PI was added to the sections after the fixation (post-fixation PI staining). This revised labeling procedure led to similar cytoarchitectural staining patterns in fluorescence microscopy as observed with hemalaun in bright field microscopy. This finding was proven in organotypic hippocampal slice cultures (OHSC) and brain sections obtained from different postnatal developmental stages. Excitotoxically lesioned OHSC subjected to pre-fixation PI staining merely showed brightly labeled condensed nuclei of degenerating neurons. In contrast, post-fixation PI staining additionally revealed extensive labeling of neuronal cell bodies and glial cells within the OHSC, thus allowing visualization of stratification of neuronal layers and cell morphology. Furthermore, post-fixation PI staining was combined with NeuN, calbindin, calretinin, glial fibrillary acidic protein or Griffonia simplicifolia isolectin B4 (IB4) in post natal (p1 and p9) and adult rats. In early post-natal brain sections almost all mentioned cellular markers led to an incomplete staining of the native cell organization and resulted in an inaccurate estimation of cell morphology when compared to adult brains. In contrast, post-fixation PI staining allowed investigation of the whole cytoarchitecture independent of the developmental stage. Taken together, post-fixation PI staining provides a detailed insight in the morphology of both developing and adult brain tissues in fluorescence microscopy.

Nestin expressing progenitor cells during establishment of the neural retina and its vasculature

In order to test if nestin is a useful marker for various types of progenitor cells, we explored nestin expression in the retina during development. Nestin expression was co-evaluated with bromodeoxyuridine (BrdU) labeling and Griffonia simplicifolia isolectin B4 (GSIB4) histochemistry. Nestin immunoreactivity appears in cell soma of dividing neural progenitor cells and their leading processes in retinas from embryonic day (E) 13 to E20, in accordance with a BrdU-labeled pattern. At postnatal day (P) 5, it is restricted to the end feet of Müller cells. BrdU-labeled nuclei were mainly in the inner part of the inner nuclear layer in postnatal neonates. The retinal vessels demarcated with GSIB4-positive endothelial cells were first distributed in the nerve fiber layer from P3. Afterward the vascular branches sprouted and penetrated deeply into the retina. The endothelial cells positive for GSIB4 and the pericytes in the microvessels were additionally immunoreactive for nestin. Interestingly, the presumed migrating microglial cells showing only GSIB4 reactivity preceded the microvessels throughout the neuroblast layer during vascular sprouting and extension. These findings may suggest that nestin expression represents the proliferation and movement potential of the neural progenitor cells as well as the progenitor cells of the endothelial cell and the pericyte during retinal development. Thus, Müller glial cells might be potential neural progenitor cells of the retina, and the retinal microvasculature established by both the endothelial and the pericyte progenitor cells via vasculogenesis along microglia migrating routes sustains its angiogenic potential.

The deletion of Math5 disrupts retinal blood vessel and glial development in mice

Retinal vascular development is a complex process that is not yet fully understood. The majority of research in this area has focused on astrocytes and the template they form in the inner retina, which precedes endothelial cells in the mouse retina. In humans and dogs, however, astrocyte migration follows behind development of blood vessels, suggesting that other cell types may guide this process. One such cell type is the ganglion cell, which differentiates before blood vessel formation and lies adjacent to the primary retinal vascular plexus. The present study investigated the potential role played by ganglion cells in vascular development using Math5−/− mice. It has previously been reported that Math5 regulates the differentiation of ganglion cells and Math5−/− mice have a 95% reduction in these cells. The development of blood vessels and glia was investigated using Griffonia simplicifolia isolectin B4 labeling and GFAP immunohistochemistry, respectively. JB-4 analysis demonstrated that the hyaloid vessels arose from choriovitreal vessels adjacent to the optic nerve area. As previously reported, Math5−/− mice had a rudimentary optic nerve. The primary retinal vessels did not develop post-natally in the Math5−/− mice, however, branches of the hyaloid vasculature eventually dove into the retina and formed the inner retinal capillary networks. An astrocyte template only formed in some areas of the Math5−/− retina. In addition, GFAP+ Müller cells were seen throughout the retina that had long processes wrapped around the hyaloid vessels. Transmission electron microscopy confirmed Müller cell abnormalities and revealed disruptions in the inner limiting membrane. The present data demonstrates that the loss of ganglion cells in the Math5−/− mice is associated with a lack of retinal vascular development.

Neuronal Death Induced by Nanomolar Amyloid β Is Mediated by Primary Phagocytosis of Neurons by Microglia

Alzheimer disease is characterized by neuronal loss and brain plaques of extracellular amyloid β (Aβ), but the means by which Aβ may induce neuronal loss is not entirely clear. Although high concentrations of Aβ (μM) can induce direct toxicity to neurons, we find that low concentration (nM) induce neuronal loss through a microglia-mediated mechanism. In mixed neuronal-glial cultures from rat cerebellum, 250 nM Aβ1-42 (added as monomers, oligomers or fibers) induced about 30% loss of neurons between 2 and 3 days. This neuronal loss occurred without any increase in neuronal apoptosis or necrosis, and no neuronal loss occurred with Aβ42-1. Aβ greatly increased the phagocytic capacity of microglia and induced phosphatidylserine exposure (an "eat-me" signal) on neuronal processes. Blocking exposed phosphatidylserine by adding annexin V or an antibody to phosphatidylserine or inhibiting microglial phagocytosis by adding either cytochalasin D (to block actin polymerization) or cyclo(RGDfV) (to block vitronectin receptors) significantly prevented neuronal loss. Loss of neuronal synapses occurred in parallel with loss of cell bodies and was also prevented by blocking phagocytosis. Inhibition of phagocytosis prevented neuronal loss with no increase in neuronal death, even after 7 days, suggesting that microglial phagocytosis was the primary cause of neuronal death induced by nanomolar Aβ.

Isoliquiritigenin from licorice root suppressed neovascularisation in experimental ocular angiogenesis models

AimTo explore the antiangiogenic property of isoliquiritigenin (ISL) on in vivo and in vitro models.DesignLaboratory investigation.MethodsThe effect of ISL on angiogenesis development was investigated using ex ovo chick chorioallantoic membrane...