Search

Alzheimer disease (AD) is a widespread neurodegenerative disease characterized by the accumulation of oligomeric toxic forms of β-amyloid (Aβ1-42) and dysfunction of the cholinergic system in the different brain regions. However, the exact mechanisms of AD pathogenesis and the role of the nicotinic acetylcholine receptors (nAChRs) in the disease progression remain unclear. Here, we revealed a decreased expression of a number of the Ly6/uPAR proteins targeting nAChRs in the cerebellum of 2xTg-AD mice (model of early AD) in comparison with non-transgenic mice both at mRNA and protein levels. We showed that co-localization of one of them, – neuromodulator Lynx1, with α7-nAChR was diminished in the vicinity of cerebellar astrocytes of 2xTg-AD mice, while Aβ1-42 co-localization with this receptor present was increased. Moreover, the expression of anti-inflammatory transcription factor KLF4 regulating transcription of the Ly6/uPAR genes was decreased in the cerebellum of 2xTg-AD mice, while expression of inflammatory cytokine TNF-α was increased. Based on these data together with observed astrocyte degeneration in the cerebellum of 2xTg-AD mice, we suggest the mechanism by which expression of the Ly6/uPAR proteins upon Aβ pathology results in dysregulation of the cholinergic system and particularly of α7-nAChR function in the cerebellum. This leads to enhanced neuroinflammation and cerebellar astrocyte degeneration. [ABSTRACT FROM AUTHOR]

Kagocel is a synthetic carboxymethylcellulose derivative copolymerized with gossypol. Clinical data evidence its safety and efficiency for the treatment of flu and other viral infections via enhancement of interferon production. The gut-associated lymphoid tissue seems a likely site of kagocel action. The study was aimed to investigate the molecular mechanisms of its action using murine Peyer's patches lymphocytes as a test system and the cytokines production and gene expression patterns as the primary outcomes. The Peyer's patches lymphocytes isolated from BALB/c mice were stimulated with concanavalin A, or, to mimic viral infection, with a combination of concanavalin A and TLR3 ligand poly I:C. After 24 h of stimulation the cells were treated with saline, 30, 100, or 300 μg/ml of kagocel, or, as positive controls, 300 μg/ml oats b-D-glucan or 300 μg/ml lentinan. After 24 and 72 h of incubation with these drugs cytokines production was analyzed with ELISA and gene expression pattern was investigated using nCounter Inflammation panel chips followed by bioinformatics analysis. Expression of genes involved in the inflammatory response, antiviral defense, lymphocytes survival and proliferation (C1qa, C2, C3, Ccl21a, Il11, Il1b, Il23a, Il5, Ltb4r2, Alox15, Pla2g4a, Ptger1, Mapkapk5, Hras, Ifna1, Tlr2, Mrc1, Mx2) was upregulated in kagocel-treated Peyer's patches lymphocytes. A list of plausible transcription factors (CEBPs, IRF, NFκB, RXR, Stat, Tead4, and ZSCAN) and master-regulators has been identified (cIAP, CIKS, dock9, MEKK1, FXR, IKK, IRAK, TRAF, dsRNA:TLR3:TRIF). The changes in gene expression pattern and the outcomes of bioinformatics analysis suggest that pattern recognition receptors, TLRs and dectin-1, are the key mediators of kagocel immunomodulatory action, with the possible involvement of interferon autocrine loop. The genes upregulated with kagocel include diverse components of the innate immune defense system. [ABSTRACT FROM AUTHOR]

Venoms are a rich source of highly specific toxins, which allow the identification of novel therapeutic targets. We have now applied high content screening (HCS) microscopy to identify toxins that modulate pain sensitization signaling in primary sensory neurons of rat and elucidated the underlying mechanism. A set of venoms and fractions thereof were analyzed for their ability to activate type II protein kinase A (PKA‐II) and extracellular signal‐regulated kinases (ERK1/2). We identified MeuNaTxα‐1, a sodium channel‐selective scorpion α‐toxin from Mesobuthus eupeus, which affected both PKA‐II and ERK1/2. Recombinant MeuNaTxα‐1 showed identical activity to the native toxin on mammalian voltage‐gated sodium channels expressed in Xenopus laevis oocytes and induced thermal hyperalgesia in adult mice. The effect of MeuNaTxα‐1 on sensory neurons was dose‐dependent and tetrodotoxin‐sensitive. Application of inhibitors and toxin mutants with altered sodium channel selectivity demonstrated that signaling activation in sensory neurons depends on NaV1.2 isoform. Accordingly, the toxin was more potent in neurons from newborn rats, where NaV1.2 is expressed at a higher level. Our results demonstrate that HCS microscopy‐based monitoring of intracellular signaling is a novel and powerful tool to identify and characterize venoms and their toxins affecting sensory neurons. [ABSTRACT FROM AUTHOR]

Lynx1 is a GPI‐tethered protein colocalized with nicotinic acetylcholine receptors (nAChRs) in the brain areas important for learning and memory. Previously, we demonstrated that at low micromolar concentrations the water‐soluble Lynx1 variant lacking GPI‐anchor (ws‐Lynx1) acts on α7‐nAChRs as a positive allosteric modulator. We hypothesized that ws‐Lynx1 could be used for improvement of cognitive processes dependent on nAChRs. Here we showed that 2 µM ws‐Lynx1 increased the acetylcholine‐evoked current at α7‐nAChRs in the rat primary visual cortex L1 interneurons. At higher concentrations ws‐Lynx1 inhibits α7‐nAChRs expressed in Xenopus laevis oocytes with IC50 ~ 50 µM. In mice, ws‐Lynx1 penetrated the blood‐brain barrier upon intranasal administration and accumulated in the cortex, hippocampus, and cerebellum. Chronic ws‐Lynx1 treatment prevented the olfactory memory and motor learning impairment induced by the α7‐nAChRs inhibitor methyllycaconitine (MLA). Enhanced long‐term potentiation and increased paired‐pulse facilitation ratio were observed in the hippocampal slices incubated with ws‐Lynx1 and in the slices from ws‐Lynx1‐treated mice. Long‐term potentiation blockade observed in MLA‐treated mice was abolished by ws‐Lynx1 co‐administration. To understand the mechanism of ws‐Lynx1 action, we studied the interaction of ws‐Lynx1 and MLA at α7‐nAChRs, measured the basal concentrations of endogenous Lynx1 and the α7 nAChR subunit and their association in the mouse brain. Our findings suggest that endogenous Lynx1 limits α7‐nAChRs activation in the adult brain. Ws‐Lynx1 partially displaces Lynx1 causing positive modulation of α7‐nAChRs and enhancement of synaptic plasticity. Ws‐Lynx1 and similar compounds may constitute useful hits for treatment of cognitive deficits associated with the cholinergic system dysfunction. [ABSTRACT FROM AUTHOR]

After a 16-year hiatus, Russia has resumed its program of biomedical research in space, with the successful 30-day flight of the Bion-M 1 biosatellite (April 19–May 19, 2013). The principal species for biomedical research in this project was the mouse. This paper presents an overview of the scientific goals, the experimental design and the mouse training/selection program. The aim of mice experiments in the Bion-M 1 project was to elucidate cellular and molecular mechanisms, underlying the adaptation of key physiological systems to long-term exposure in microgravity. The studies with mice combined in vivo measurements, both in flight and post-flight (including continuous blood pressure measurement), with extensive in vitro studies carried out shortly after return of the mice and in the end of recovery study. Male C57/BL6 mice group housed in space habitats were flown aboard the Bion-M 1 biosatellite, or remained on ground in the control experiment that replicated environmental and housing conditions in the spacecraft. Vivarium control groups were used to account for housing effects and possible seasonal differences. Mice training included the co-adaptation in housing groups and mice adaptation to paste food diet. The measures taken to co-adapt aggressive male mice in housing groups and the peculiarities of “space” paste food are described. The training program for mice designated for in vivo studies was broader and included behavioral/functional test battery and continuous behavioral measurements in the home-cage. The results of the preliminary tests were used for the selection of homogenous groups. After the flight, mice were in good condition for biomedical studies and displayed signs of pronounced disadaptation to Earth's gravity. The outcomes of the training program for the mice welfare are discussed. We conclude that our training program was effective and that male mice can be successfully employed in space biomedical research. [ABSTRACT FROM AUTHOR]

Here we evaluated the efficacy of bone repair using various native bovine biomaterials (refined hydroxyapatite (HA), demineralised bone matrix (DBM), and purified bone collagen (COLL)) as compared with commercially available bone mineral and bone autografts. We employed a conventional critical-sized (8 mm diameter) rat calvarial defect model (6-month-old male Sprague–Dawley rats, n = 72 in total). The artificial defect was repaired using HA, DBM, COLL, commercially available bone mineral powder, bone calvarial autograft, or remained unfilled (n = 12 animals per group). Rats were euthanised 4 or 12 weeks postimplantation (n = 6 per time point) with the subsequent examination to assess the extent, volume, area, and mineral density of the repaired tissue by means of microcomputed tomography and hematoxylin and eosin staining. Bovine HA and DBM powder exhibited excellent repair capability similar to the autografts and commercially available bone mineral powder while COLL showed higher bone repair rate. We suggest that HA and DBM powder obtained from bovine bone tissue can be equally applied for the repair of bone defects and demonstrate sufficient potential to be implemented into clinical studies. [ABSTRACT FROM AUTHOR]

The cardiovascular system is adapted to gravity, and reactions to the loss of gravity in space are presumably dependent on body size. The dependence of hematological parameters and body fluid volume on simulated microgravity have never been studied as an allometric function before. Thus, we estimated red blood cell (RBC), blood and extracellular fluid volume in hindlimb-unloaded (HLU) or control (attached) mice, rats and rabbits. RBC decrease was found to be size independent, and the allometric dependency for RBC loss in HLU and control animals shared a common power (-0.054±0.008) but a different Y 0 coefficient (8.66±0.40 and 10.73±0.49, respectively, P <0.05). Blood volume in HLU animals was unchanged compared with that of controls, disregarding body size. The allometric dependency of interstitial fluid volume in HLU and control mice shared Y 0 (1.02±0.09) but had different powers N (0.708±0.017 and 0.648±0.016, respectively, P <0.05), indicating that the interstitial fluid volume increase during hindlimb unloading is more pronounced in larger animals. Our data underscore the importance of size-independent mechanisms of cardiovascular adaptation to weightlessness. Despite the fact that the use of mice hampers application of a straightforward translational approach, this species is useful for gravitational biology as a tool to investigate size-independent mechanisms of mammalian adaptation to microgravity., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2018. Published by The Company of Biologists Ltd.)