Localization of NG2 immunoreactive neuroglia cells in the rat locus coeruleus and their plasticity in response to stress

The locus coeruleus (LC) nucleus modulates adaptive behavioural responses to stress and dysregulation of LC neuronal activity is implicated in stress-induced mental illnesses. The LC is composed primarily of noradrenergic neurons together with various glial populations. A neuroglia cell-type largely unexplored within the LC is the NG2 cell. NG2 cells serve primarily as oligodendrocyte precursor cells throughout the brain. However, some NG2 cells are in synaptic contact with neurons suggesting a role in information processing. The aim of this study was to neurochemically and anatomically characterise NG2 cells within the rat LC. Furthermore, since NG2 cells have been shown to proliferate in response to traumatic brain injury, we investigated whether such NG2 cells plasticity also occurs in response to emotive insults such as stress. Immunohistochemistry and confocal microscopy revealed that NG2 cells were enriched within the pontine region occupied by the LC. Close inspection revealed that a sub-population of NG2 cells were located within unique indentations of LC noradrenergic somata and were immunoreactive for the neuronal marker NeuN whilst NG2 cell processes formed close appositions with clusters immunoreactive for the inhibitory synaptic marker proteins gephyrin and the GABA-A receptor alpha3-subunit, on noradrenergic dendrites. In addition, LC NG2 cell processes were decorated with vesicular glutamate transporter 2 immunoreactive puncta. Finally, ten days of repeated restraint stress significantly increased the density of NG2 cells within the LC. The study demonstrates that NG2 IR cells are integral components of the LC cellular network and they exhibit plasticity as a result of emotive challenges

Spatiotemporal distribution of GABA_A receptor subunits within Layer II of mouse medial entorhinal cortex:implications for grid cell excitability

GABAergic parvalbumin-expressing (PV+) interneurons provide powerful inhibitory modulation of grid cells in layer II of the medial entorhinal cortex (MEC LII). However, the molecular machinery through which PV+ cells regulate grid cell activity is poorly defined. PV+ interneurons impart inhibitory modulation primarily via GABA-A receptors (GABAARs). GABAARs are pentameric ion channels assembled from a repertoire of 19 subunits. Multiple subunit combinations result in a variety of receptor subtypes mediating functionally diverse postsynaptic inhibitory currents. Whilst the broad expression patterns of GABAAR subunits within the EC have been reported, those expressed by individual MEC LII cell types, in particular grid cells candidates, stellate and pyramidal cells, are less well described. Stellate and pyramidal cells are distinguished by their selective expression of reelin (RE+) and calbindin (CB+) respectively. Thus, the overall aim of this study was to provide a high resolution analysis of the major (α and γ) GABAAR subunits expressed in proximity to somato-dendritic PV+ boutons, on RE+ and CB+ cells, using immunohistochemistry, confocal microscopy and quantitative RT-PCR (qPCR). Clusters immunoreactive for the α1 and γ2 subunits decorated the somatic membranes of both RE+ and CB+ cells and were predominantly located in apposition to clusters immunoreactive for PV and vesicular GABA transporter (VGAT), suggesting expression in GABAergic synapses innervated by PV interneurons. Although intense α2 subunit-immunopositive clusters were evident in hippocampal fields located in close proximity to the EC, no specific signal was detected in MEC LII RE+ and CB+ profiles. Immunoreactivity for the α3 subunit was detected in all RE+ somata. In contrast, only a sub-population of CB+ cells was α3 immunopositive. These included CB-α3 cells which were both PV+ and PV−. Furthermore, α3 subunit mRNA and immunofluorescence decreased significantly between P 15 and P 25, a period implicated in the functional maturation of grid cells. Finally, α5 subunit immunoreactivity was detectable only on CB+ cells, not on RE+ cells. The present data demonstrates that physiologically distinct GABAAR subtypes are selectively expressed by CB+ and RE+ cells. This suggests that PV+ interneurons could utilize distinct postsynaptic signaling mechanisms to regulate the excitability of these different, candidate grid cell sub-populations

GABAA Receptor Subunit α3 in Network Dynamics in the Medial Entorhinal Cortex

Layer II of the medial entorhinal cortex (MEC LII) contains the largest number of spatially modulated grid cells and is one of the first regions in the brain to express Alzheimer’s disease (AD)-related pathology. The most common principal cell type in MEC LII, reelin-expressing stellate cells, are grid cell candidates. Recently we found evidence that γ-aminobutyric acid (GABA)A receptor subunits show a specific distribution in MEC LII, in which GABAA α3 is selectively associated with reelin-positive neurons, with limited association with the other principal cell type, calbindin (CB)-positive pyramidal neurons. Furthermore, the expression of α3 subunit decreases in mice between P15 and P25, which coincides with the emergence of stable grid cell activity. It has been shown that the α3 subunit undergoes specific developmental changes and that it may exert pro-inflammatory actions if improperly regulated. In this review article, we evaluate the changing kinetics of α3-GABAA receptors (GABAARs). during development in relation to α3-subunit expression pattern in MEC LII and conclude that α3 could be closely related to the stabilization of grid cell activity and theta oscillations. We further conclude that dysregulated α3 may be a driving factor in early AD pathology

The glutamate receptor delta 2 in relation to cerebellar development and plasticity

Understanding what are the mechanisms that strengthen, stabilize and restrict synaptic innervation is a relevant topic in glutamate receptor delta 2 (GluR delta 2)-related research. It also involves targeting and selection of afferent input during formation of the neuronal circuitry in the cerebellar cortex and its functioning. This review will focus oil the role of GluR delta 2, one of the main players in this field. Special emphasis will be placed on the processes that regulate the rapid translocation from climbing fibres to parallel fibres of GluR delta 2 and the role of GluR delta 2 in the reduction of supernumerary climbing fibre contacts on a single Purkinje cell. Furthermore, GluR delta 2 knockout mice show ataxia and impaired motor coordination, suggesting that the presence of GluR delta 2 plays an important role in controlling cerebellar functioning. (c) 2007 Elsevier Ltd. All rights reserved

Localization and functional roles of corticotropin-releasing factor receptor type 2 in the cerebellum

The corticotropin-releasing factor (CRF) type 2 receptor has three splice variants alpha, beta, and gamma. In the rodent brain only CRF-R2 alpha is present. In the cerebellum, CRF-R2 alpha has two different isoforms: a full-length form (fl) and truncated (tr). Both forms CRF-R2 have a unique cellular distribution. During postnatal cerebellar development, the expression patterns of tr and fl isoforms are changing. This suggests that, CRF and the related peptide urocortin (UCN) could play distinct roles in the immature and adult cerebellum, acting via different receptors subtypes. This review focuses on differences in the distribution of each isoform of CRF-R2 in view of their relationship to CRF and UCN release sites and their possible functional implications. Moreover, it includes novel findings of molecular pathways activating CRF-R2 isoforms through which CRF and UCN excert their specific actions

The dynamic developmental localization of the full-length corticotropin-releasing factor receptor type 2 in rat cerebellum

Corticotropin releasing factor receptor 2 (CRF-R2) is strongly expressed in the cerebellum and plays an important role in the development of the cerebellar circuitry, particularly in the development of the dendritic trees and afferent input to Purkinje cells. However, the mechanisms responsible for the distribution and stabilization of CRF-R2 in the cerebellum are not well understood. Here, we provide the first detailed analysis of the cellular localization of the full-length form of CRF-R2 in rat cerebellum during early postnatal development. We document unique and developmentally regulated subcellular distributions of CRF-R2 in cerebellar cell types, e.g. granule cells after postnatal day 15. The presence of one or both receptor isoforms in the same cell may provide a molecular basis for distinct developmental processes. The full-length form of CRF-R2 may be involved in the regulation of the first stage of dendritic growth and at later stages in the controlling of the structural arrangement of immature cerebellar circuits and in the autoregulatory pathway of the cerebellum

Erythroid progenitors from patients with low-risk myelodysplastic syndromes are dependent on the surrounding micro environment for their survival

To investigate whether the type of programmed cell death of myelodysplastic erythroid cells depends on their cellular context, we performed studies on cells from patients with low-risk myelodysplastic syndromes. We compared erythroid cells (and their precursor cells) from the mononuclear cell fraction with those from the hematon fraction, which are compacted complexes of hematopoietic cells surrounded by their own micro-environment. In directly fixed materials, erythroblasts exhibited signs of autophagy with limited apoptosis

Spumiform capillary basement membrane swelling:a new type of microvascular degeneration in senescent hamster

<p>Brain microvasculature plays a critical role in the regulation of homeostasis of neural tissues. The present study focuses on characteristic microvascular basement membrane (bm) aberrations in the midbrain periaqueductal gray matter (PAG) and their relation to aging. The PAG can be considered a caudal extension of the limbic system and is a key structure in the regulation of a myriad of autonomic and motor control functions. In an ultrastructural study, morphologic changes in mesencephalic PAG capillaries were assessed in aged and young hamster and compared with those in caudal brainstem areas. Bm aberrations were studied in 1200 capillaries (n = 600 young hamsters; n = 600 aged hamsters). A new, never reported variant of bm degeneration was found that presented itself as foamy-like structures accumulating within the lamina densa of notably PAG capillaries. We classified these foamy structures as 'spumiform basement membrane degenerations' (sbmd) in which we could distinguish 4 stages depending on the size and intramembranous localization, ranging from split bm (stage I), intermediate stages II and III, to extensive stage IV, affecting almost the complete capillary bm outline. In the PAG of senescent animals various stages of sbmd were observed in 92 +/- 3% of all capillaries. Stage II was most prominently present (59%), followed by stage III (20%), and stage IV (13%). These bm aberrations were clearly age-dependent because in young animals, only 5% of the PAG capillaries showed characteristics of sbmd. For comparison, in the pontine reticular formation at the PAG-level, 41% of the capillaries showed a form of sbmd, but these defects were significantly less severe (stages I-II, 98%), and caudal brainstem structures displayed no sbmd at all. In addition to sbmd, diffuse endothelial changes, disrupted tight junctions, thickening of the bm, pericyte degeneration, and gliosis were observed in PAG capillaries. It is hypothesized that selective bm permeability of PAG capillaries results in a sequence of bm damage events that start with split bm, gradually changing into more and more extensive sbmd accumulations that eventually almost completely surround the capillary. Progressive sbmd in PAG capillaries might lead to a loss of blood-brain barrier function and consequently to impairment of autonomic and motor control functions exerted by the PAG. (C) 2013 Elsevier Inc. All rights reserved.</p>

Prognostic role of indoleamine 2,3-dioxygenase in endometrial carcinoma

Objective. Indoleamine-2,3-dioxygenase (IDO) suppresses the function of T-lymphocytes and is an important immune escape mechanism for cancer. Therefore, it is to be expected that IDO influences prognosis of cancer patients. This study aimed to investigate the prognostic role of IDO expression in a large cohort of endometrial carcinoma (EC) patients. Methods. A tissue microarray containing primary EC tissue of 355 patients treated in a single institution was used to evaluate IDO expression. Expression of IDO was associated with clinicopathological characteristics, survival and previously determined numbers of CD8(+) and Foxp3(+) T-lymphocytes. Results. IDOhigh expression was associated with lower numbers of intratumoral CD8(+) T-lymphocytes (p = 0.031). Next to well-known prognostic parameters, IDOhigh expression was independently associated with poor disease specific survival in the general cohort of EC patients (HR 2.62, 95% C.I. 1.48-4.66, p = 0.001) and among patients with early stage EC (HR 3.06, 95% C.I. 1.10-8.54, p = 0.032). Conclusion. Our results show that IDO expression is associated with poor survival. This provides evidence that further research into the use of IDO blocking agents in cancer treatment is valid where it might be a promising new therapeutic strategy. (c) 2012 Elsevier Inc. All rights reserved

Effects of different small HSPB members on contractile dysfunction and structural changes in a Drosophila melanogaster model for Atrial Fibrillation

The most common clinical tachycardia, Atrial Fibrillation (AF), is a progressive disease, caused by cardiomyocyte remodeling, which finally results in contractile dysfunction and AF persistence. Recently, we identified a protective role of heat shock proteins (HSPs), especially the small HSPB1 member, against tachycardia remodeling in experimental AF models. Our understanding of tachycardia remodeling and anti-remodeling drugs is currently hampered by the lack of suitable (genetic) manipulatable in vivo models for rapid screening of key targets in remodeling. We hypothesized that Drosophila melanogaster can be exploited to study tachycardia remodeling and protective effects of HSPs by drug treatments or by utilizing genetically manipulated small HSP-overexpressing strains. Tachypacing of Drosophila pupae resulted in gradual and significant cardiomyocyte remodeling, demonstrated by reduced contraction rate, increase in arrhythmic episodes and reduction in heart wall shortening, compared to normal paced pupae. Heat shock, or pretreatment with HSP-inducers GGA and BGP-15, resulted in endogenous HSP overexpression and protection against tachycardia remodeling. DmHSP23 overexpressing Drosophilas were protected against tachycardia remodeling, in contrast to overexpression of other small HSPs (DmHSP27, DmHSP67Bc, DmCG4461, DmCG7409, and DmCG14207). (Ultra)structural evaluation of the tachypaced heart wall revealed loss of sarcomeres and mitochondrial damage which were absent in tachypaced DmHSP23 overexpressing Drosophila. In addition. tachypacing induced a significant increase in calpain activity, which was prevented in tachypaced Drosophila overexpressing DmHSP23. Tachypacing of Drosophila resulted in cardiomyocyte remodeling, which was prevented by general HSP-inducing treatments and overexpression of a single small HSP, DmHSP23. Thus, tachypaced D. melanogaster can be used as an in vivo model system for rapid identification of novel targets to combat AF associated cardiomyocyte remodeling. (C) 2011 Elsevier Ltd. All rights reserved