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      Squalenoyl Adenosine Nanoparticles provide Neuroprotection after Stroke and Spinal Cord Injury

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          Abstract

          There is an urgent need to develop new therapeutic approaches for the treatment of severe neurological trauma, such as stroke and spinal cord injuries. However, many drugs with potential neuropharmacological activity, like adenosine, are inefficient upon systemic administration because of their fast metabolisation and rapid clearance from the bloodstream. Here, we show that the conjugation of adenosine to the lipid squalene and the subsequent formation of nanoassemblies allow a prolonged circulation of this nucleoside, to provide neuroprotection in mouse stroke and rat spinal cord injury models. The animals receiving systemic administration of squalenoyl adenosine nanoassemblies showed a significant improvement of their neurologic deficit score in the case of cerebral ischaemia, and an early motor recovery of the hindlimbs in the case of spinal cord injury. Moreover, in vitro and in vivo studies demonstrated that the nanoassemblies were able to extend adenosine circulation and its interaction with the neurovascular unit. This paper shows, for the first time, that a hydrophilic and rapidly metabolised molecule like adenosine may become pharmacologically efficient owing to a single conjugation with the lipid squalene.

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          Most cited references36

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          Graded histological and locomotor outcomes after spinal cord contusion using the NYU weight-drop device versus transection.

          Injury reproducibility is an important characteristic of experimental models of spinal cord injuries (SCI) because it limits the variability in locomotor and anatomical outcome measures. Recently, a more sensitive locomotor rating scale, the Basso, Beattie, and Bresnahan scale (BBB), was developed but had not been tested on rats with severe SCI complete transection. Rats had a 10-g rod dropped from heights of 6.25, 12.5, 25, and 50 mm onto the exposed cord at Tl 0 using the NYU device. A subset of rats with 25 and 50 mm SCI had subsequent spinal cord transection (SCI + TX) and were compared to rats with transection only (TX) in order to ascertain the dependence of recovery on descending systems. After 7-9 weeks of locomotor testing, the percentage of white matter measured from myelin-stained cross sections through the lesion center was significantly different between all the groups with the exception of 12.5 vs 25 mm and 25 vs 50 mm groups. Locomotor recovery was greatest for the 6.25-mm group and least for the 50-mm group and was correlated positively to the amount of tissue sparing at the lesion center (p 0.05). Thus, spared descending systems appear to modify segmental systems which produce greater behavioral improvements than isolated cord systems.
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            Adenosine and brain function.

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              Adenosine and sleep-wake regulation.

              This review addresses three principal questions about adenosine and sleep-wake regulation: (1) Is adenosine an endogenous sleep factor? (2) Are there specific brain regions/neuroanatomical targets and receptor subtypes through which adenosine mediates sleepiness? (3) What are the molecular mechanisms by which adenosine may mediate the long-term effects of sleep loss? Data suggest that adenosine is indeed an important endogenous, homeostatic sleep factor, likely mediating the sleepiness that follows prolonged wakefulness. The cholinergic basal forebrain is reviewed in detail as an essential area for mediating the sleep-inducing effects of adenosine by inhibition of wake-promoting neurons via the A1 receptor. The A2A receptor in the subarachnoid space below the rostral forebrain may play a role in the prostaglandin D2-mediated somnogenic effects of adenosine. Recent evidence indicates that a cascade of signal transduction induced by basal forebrain adenosine A1 receptor activation in cholinergic neurons leads to increased transcription of the A1 receptor; this may play a role in mediating the longer-term effects of sleep deprivation, often called sleep debt.
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                Author and article information

                Journal
                101283273
                34218
                Nat Nanotechnol
                Nat Nanotechnol
                Nature nanotechnology
                1748-3387
                1748-3395
                3 November 2014
                24 November 2014
                2014
                18 May 2016
                : 9
                : 12
                : 1054-1062
                Affiliations
                [1 ]Institut Galien Paris-Sud UMR CNRS 8612, Faculty of Pharmacy, University of Paris-Sud XI, 92296 Châtenay-Malabry, France
                [2 ]Institute of Neurological Sciences and Psychiatry, Hacettepe University, Ankara 06100, Turkey
                [3 ]Department of Pharmaceutical Technology, Faculty of Pharmacy, Hacettepe University, Ankara 06100, Turkey
                [4 ]Department of Neurosurgery, Ankara Ataturk Research & Education Hospital, 06800 Bilkent Ankara, Turkey
                [5 ]Department of Anatomy, Faculty of Medicine, Hacettepe University, Ankara 06100, Turkey
                [6 ]CEA Saclay, iBiTecS-S/SCBM, Labex LERMIT, 91191 Gif-sur-Yvette, France
                [7 ]NanoBioPhotonics, Institut d’Electronique Fondamentale, University of Paris-Sud XI, 91405, Orsay Cedex, France
                [8 ]EA3544, Faculty of Pharmacy, University of Paris-Sud XI, 92296 Châtenay-Malabry, France
                [9 ]Institut d’Innovation Thérapeutique, IFR141 ITFM, Faculty of Pharmacy, University of Paris-Sud XI, 92296 Châtenay-Malabry, France
                Author notes

                Author contributions

                P.C. and T.D. conceived and designed the research. A.G. designed and performed the nanoparticles preparation, the side-effects and toxicity experiments, the stability and in vivo pharmacokinetic/biodistribution studies and the in vitro experiments. S.L. developed and performed the SQAd synthesis, D.D. helped analysing the chemical results. B.R., S.G.A., G.P. and O.L. developed and performed the radiolabelled compound synthesis. T.D. and M.Y. designed and performed the cerebral ischaemia experiments. B.D.-D. performed the histological stainings and countings for cerebral ischaemia experiments. S.C. and Y.C. were in charge of the nanoparticles preparation for the cerebral ischaemia experiments. H.E., O.F.T. and A.G. designed and performed the spinal cord injury experiments. M.F.Z. performed the ultrastructural evaluation of the spinal cord injury experiments. A.G., O.T. and N.H designed and performed the FRET NAs experiments. Y.L.D and A.G performed the sleep cycle experiments. J.M. performed the HPLC analysis. S.V. performed the complement activation experiments. H.C. helped analysing the radioactivity data and V.N. helped analysing the confocal data. P.C., T.D., K.A., A.G. and M.Y. co-wrote the paper. All authors discussed the results and commented on the manuscript.

                [* ]Correspondence and requests for materials should be adressed to P.C. and K.A. patrick.couvreur@ 123456u-psud.fr , karine.andrieux@ 123456parisdescartes.fr
                Article
                EMS60770
                10.1038/nnano.2014.274
                4351925
                25420034
                72b94664-f2b0-4c10-9d28-fc025e22b1c4

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                Nanotechnology
                Nanotechnology

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