Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

D-amino acids in the healthy and diseased aging brain - Jean Marie Billard

57 views

Published on

Watching at the "D" side: D-amino acids and their significance in neurobiology
June 05 -June 09, 2016 – Lake Como School of Advanced Studies

Published in: Science
  • Be the first to comment

  • Be the first to like this

D-amino acids in the healthy and diseased aging brain - Jean Marie Billard

  1. 1. D-amino acids in the healthy and diseased aging brain Jean-Marie Billard Center of Psychiatry and Neurosciences 75014 Paris, France Team: Neurobiology of normal and pathological aging
  2. 2. from the U.S census Bureau’s International Data Base (IDB) (http://blogs.census.gov/2012/06/27/census-bureau-releases-demographic-estimates-and-projections-for-countries-of- the-world/) Age-related increase in life expectancy
  3. 3. Federal Interagency Forum on Aging related statistics (US, 2012) Age-related increase in cognitive impairment 5% 4% 10% 7% 16% 12% 23% 19% 37% 39% Percentage of persons age 65 or older with moderate or severe memory impairment by age group and sex 85 or older80 to 8470 to 74 75 to 7965 to 69 Men Women
  4. 4. In the US, the health care costs per patient with Alzheimer’s disease are roughly around $33,007 annually, as compared to $10,603 for an older person without the disease. Cognitive aging: a major challenge for the international community TODAY 2030 2050 47,5 75,6 135,5Current and projected numbers for people with Alzheimer’s or another dementia worldwide (in millions) From Changing the trajectory of Alzheimer’s Disease: A national imperative. Alzheimer’s study Group (may 2010)
  5. 5. - Are D-amino acids concerned in cognitive deficits linked to normal and pathological aging? - Is the characterization of changes in their metabolism of some help for the development of effective therapeutic strategies aimed at preventing age- related cognitive decline? TOPICS D-serine D-aspartate
  6. 6. Behavioural tasks to assess cognitive functions Morris Water Maze Object recognition Radial Arm Maze Barnes Maze Spontaneous alternation Olfactory discrimination Fear conditioning Elevated plus maze Morris Water Maze Radial Arm Maze Barnes Maze Object recognition Spontaneous alternation Olfactory discrimination Fear conditioning Elevated plus maze Spatial memory Non-spatial memory Anxiety state AGING AGING AGING
  7. 7. 1 23 4 Spatial memory: preferential target to characterize age-related deficits Testing day 0 500 1000 1500 2000 2500 3000 1 2 3 4 5 6 Young Distance(cm) Aged # # Probe trial Timespentineachquadrant(sec) 0 10 20 30 40 1 2 3 4 # Quadrant number (modified from Potier et al, Front Aging Neurosci. (2010) 2:1)
  8. 8. J. Physiol. (1973), 232, pp. 331-356 331 LONG-LASTING POTENTIATION OF SYNAPTIC TRANSMISSION IN THE DENTATE AREA OF THE ANAESTHETIZED RABBIT FOLLOWING STIMULATION OF THE PERFORANT PATH. T. V. P. BLISS AND T. L0MO From the National Institute for Medical Research, M ill Hill, London N W7 lAA and the lnstitute of Neurophysfology, University of Oslo, Norway T. Bliss, P. Anderson and T. Lomo Ex vivo slice preparation LTP: synaptic model of memory encoding The hippocampus: a precious tool for studying mechanisms of cognitive aging Reductions in" synapse number" Morphological changes in Aging
  9. 9. 60 80 100 120 140 160 180 200 220 -15 0 15 30 45 60 Young Aged Synapticefficacy(in%) Time(min) Long-term potentiation ** 20 40 60 80 100 120 -10 0 10 20 30 40 Young Aged Synapticefficacy(in%) Time (min) Long-term depression ** Memory deficits are correlated to impaired functional plasticity in aged rats (from Turpin et al, Neurobiol. Aging 32(2011)1495-1504; Billard & Rouaud, Europ. J. Neurosci. 25(2007)2260-2268)
  10. 10. D-serine is required for functional plasticity at hippocampal synapses 80 100 120 140 160 180 200 220 -15 0 15 30 45 60 Synapticefficacy(in%) Time (min) Ctrl RgDAAO 2 1 1 2 1 2 Ctrl RgDAAO Time (min) 80 90 100 110 120 130 140 150 160 170 -15 0 15 30 45 60Synapticefficacy(in%) 2 1 1 2 1 2 CA1 DG (modified from Le Bail et al, PNAS 112(2015)E204-E23) CA3-CA1 SYNAPSES mPP-DG1 SYNAPSES
  11. 11. Exogenous D-serine rescues age-related LTP impairment 60 100 140 180 220 -15 0 15 30 45 60 Time (min) fEPSPslope(%ofbaseline) Young Aged D-SERINE 100 µM (Mothet et al, Aging Cell 5(2006)267-274; Turpin et al, Neurobiol. Aging 32(2011)1495-1504; Haxaire et al, Aging Cell 11(2012)336-344) In aged mice and rats In SAMP8 mice, a model of accelerated aging (modified from Yang et al, Neurosci. Lett. 379(2005)7-12)
  12. 12. The NMDA Receptor: a main target for D-serine GluN1 GluN2A/ N2B/ N2C/ N2D NMDA receptor activation is required for LTP Control medium + D-APV (80 µM) Time (min) fEPSPslope(%ofbaseline) 60 100 140 180 220 260 -15 0 15 30 45 60 D-serine may contribute to age-related deficits of functional plasticity through impaired NMDA receptor activation
  13. 13. NMDA receptor activation is impaired in aged rats 20 ms 0.5mV Aged Young 0 0.02 0.04 0.06 0.08 0.1 0.12 100 200 300 400 500 Young adult Aged Stimulus intensity (µA) NMDA-R-dependentfEPSPslope(mV/ms) ** (Potier et al, Exp. Gerontol.35(2000)1185-1199; Billard and Rouaud Europ. J. Neurosci. 25(2007)2260-2268))
  14. 14. 0 0.02 0.04 0.06 0.08 0.1 0,.2 0.14 NMDA-RdependentfEPSPslope(mV/ms) 100 200 300 400 5000 Stimulus intensity (µA) Young Aged * 0 10 20 30 40 50 AgedYoung IncreaseinNMDA-R-dependentfEPSPslope(in%) + D-serine control + D-serine and D-APV 20 ms 0.5mV Exogenous D-serine rescues age-related decrease in NMDA receptor activation (Junjaud et al, J. Neurochem. 98(2006)1159-1166; Mothet et al, Aging Cell 5(2006)267-274; Turpin et al, Neurobiol. Aging 32(2011)1495-1504; Haxaire et al, Aging Cell 11(2012)336-344)
  15. 15. 10 µM D-serine Young Aged Total 1 µM D-serine The affinity of NMDA receptor glycine binding site is not modified by age In aged rats In SAMP8 mice, a model of accelerated aging (Mothet et al, Aging Cell 5(2006)267-274; Potier et al, Front Aging Neurosci. (2010) 2:1) SAMP8 SAMR1 (Nagata et al, Mech. Ageing Dev. 104(1998)115-124) 0 0.5 1 1.5 2 2.5 SAMR1 SAMP8 DissociationconstantKD(µM)
  16. 16. D-serine levels are significantly reduced in aged ats D-serine Pyruvate + NH3 2 H2O + N2(g) luminol H2O2 3-aminophtalate (excited state) 3-aminophtalate (normal state) DAAOx HRP Photon (hν) Chemiluminescent assay HPLC analysis 0 1 2 3 4 5 D-serine L-serine glycine Aminoacidlevels(ratioYoung/Aged) (Mothet et al, Aging Cell 5(2006)267-274 267-274; Turpin et al, Neurobiol. Aging 32(2011)1495-1504) (Potier et al, Front Aging Neurosci. (2010) 2:1) 0 10 20 30 D-serinelevels (nmol/mgofprotéins) Young Aged ***
  17. 17. L-serine D-serine Pyruvate + NH3 Serine racemase (SR) D-amino acid oxidase (DAAO) β-actin Serine racemase D-amino acid oxidase Serine racemase expression is specifically altered in aged rats mRNAs 0 0,1 0,2 0,3 0,4 0,5 ** Protein/βactinratio SR DAAO PROTEIN EXPRESSION 0 0,02 0,04 0,06 0,08 * mRNA/βactinratio SR DAAO Young Aged (Mothet et al, Aging Cell 5(2006)267-274 267-274; Turpin et al, Neurobiol. Aging 32(2011)1495-1504; Haxaire et al, Aging Cell 11(2012)336-344)
  18. 18. Synaptic turn-over of D-serine Age-related decrease in D-serine synaptic availability could be due to: - Impaired Asc-1 expression and/or activation - Impaired ASCT expression and/or activation - Impaired release from astrocytes (modified from Wolosker, Biochem.& Biophys. Acta 1814(2011)1558-1566) Pyruvate+NH3 DAAO DAAO SR SR D-serine D-serine D-serine
  19. 19. Asc-1-dependent D-serine release modulates functional plasticity Asc-1 blockade reduces LTP expression Asc-1 activation underlies the increase in LTP expression by neutral amino acids (Sason et al, Cereb. Cortex (2016) in press)
  20. 20. Asc-1 activation is not altered in aged rats 75 100 125 150 175 200 225 -15 0 15 30 45 60 control L-AA fEPSPslope(%ofbaseline) YOUNG Time (min) * fEPSPslope(%ofbaseline) AGED Time (min) * 75 100 125 150 175 200 225 -15 0 15 30 45 60 control L-AA 0 2 4 6 8 10 12 14 YOUNG AGED YOUNG AGED IncreaseinLTPmagnitude(in%) L-AA D-Ile (Billard JM, unpublished results)
  21. 21. 24 months old Wistar LOU/C %ofMortality" 55%" " " " " 50%" " " " " 45%" 20 24 28 32" Age (month)" W" W" Lou" Lou" The LOU/C rat: a model of healthy aging Lou" Bodyweight(g)! 0 6 12 18 24" 500" " 400" " 300" " 200" " 100" " 0" Age (month)" W! • No age-related severe pathologies (pituitary tumors, chronic nephropathy, arteriosceloris) Increased longevity Resistance to obesity (Modified from Alliot et all, J. Gerontol 57(2002)B312-320)
  22. 22. Learning and memory are preserved in aged LOU/C rats (Kollen et al, Neurobiol. Aging 31(2010)129-142; Menard et al, Front. Aging Neurosci; 6(2014)81) (see also Menard et al, Front. Aging Neurosci; 6(2014)81) Morris water maze Object recognition Testing day 200 400 600 800 1000 1200 1400 1 2 3 4 5 6 Distance(cm) Young Aged
  23. 23. Time (min) Young Aged 60 100 140 180 220 260 300 -15 0 15 30 45 60 fEEPSPslope(%ofbaseline) D-serine-dependent NMDA receptor activation and functional plasticity are not altered in aged LOU/C rats 0 5 10 15 20 25 30 35 40 45 IncreaseinfEPSPslopebyD-serine(in%) AgedYoung NMDA-R-dependentfEPSPslope(mV/ms) Stimulus intensity (µA) 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 100 200 300 400 500 Young Aged 20 ms 0.5mV Aged Young 0 (Kollen et al, Neurobiol. Aging 31(2010)129-142; Turpin et al, Neurobiol. Aging 32(2011)1495-1504)
  24. 24. D-serine availability is not modified in aged LOU/C rats Protein/ßactinratio 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 Young Aged YOUNG AGED SR DAAO mRNA/ßactinratio 0.005 0.010 0.015 0.020 0.025 0 0 0.001 0.002 0.003 Young Aged SR DAAO mRNAs Young Aged 0 5 10 15 20 25 30 D-serinelevels (nmol/mgofprotéins) (Turpin et al, Neurobiol. Aging 32(2011)1495-1504)
  25. 25. Free radical damage (Mustapha et al, PNAS 104(2007)2950-2955)(Wang & Barger, J. Neurosci. Res 90(2012)1218-1229) Serine racemase is sensitive to oxidative stress
  26. 26. ChangesinGSH/GSSGrationormalizedtoyoungaduls (in%) *** -25 -20 -15 -10 -5 0 5 10 15 20 Aged Wistar Aged LOU/C Oxidative stress is prevented in brains of aged LOU/C rats (Billard et al, unpublished results) (Moyse et al, Mech. Ageing Dev. 149(2015)19-30) Levels of endogenous antioxidants Levels of protein oxidative damage
  27. 27. Oxidative stress is reversed in the hippocampus of aged rats treated with L-NAC -100 -50 0 50 100 150 200 250 300 Carbonylated proteins Mean GSH/GSSG ratio ** ** Percentchangesnormalizedtoyoungadultrats Aged Aged + L-NAC (Haxaire et al, Aging Cell 11(2012)336-344)
  28. 28. The decrease in D-serine-dependent NMDA receptor activation is prevented in aged rats treated with L-NAC fEPSPslope(in%ofbaseline) 50 100 150 200 250 300 -15 0 15 30 45 60 Young adult Aged + L-NAC Time (min) 0 0.1 0.2 0.3 100 200 300 400 500 Young adult Aged+ L-NAC NMDA-R-dependentfEPSPslope(mV/ms) Stimulus intensity (µA) 0 10 20 30 40 50 60 IncreasebyexogenousD-serine(in%) YOUNG AGED+ L-NAC (Haxaire et al, Aging Cell 11(2012)336-344)
  29. 29. 0 2 0 4 0 6 0 8 0 1 0 0 1 2 0 D-serinelevels (%ofyoungadult) Young Aged + L-NAC D-SERINE LEVELS D-serine availability is preserved in aged rats treated with L-NAC Protecting redox status in aging could prevent injury of cellular mechanisms underlying cognitive aging, in part by maintaining potent NMDA-R activation by D- serine. (Haxaire et al, Aging Cell 11(2012)336-344)
  30. 30. Is D-serine a candidate in the search of relevent strategies to reduce cognitive deficits in healthy aging?
  31. 31. Re-activation of the NMDA receptor co-agonist binding site rescues age-related deficits: Of learning and memoryOf functional plasticity (Billard & Rouaud, Europ. J. Neurosci. 25(2007)2260-2268) (Burgdorf et al, Neurobiol. Aging 32(2011)698-706) With D-cycloserine With Rapastinel (GLYX-13)
  32. 32. (Yamazaki et al, Neuron 84(2014)753-763) D-serine rescues memory impairment in aged Drosophila Age-related decrease in D-serine levels Age-related effects of D-serine
  33. 33. D-serine treatment induces oxidative stress in the brain In vivo Intrastriatal injection (Leipnitz et al, Int. J. Neurosci. 28(2010)297-301) Intraperitoneal injection (Armagan et al, Drug Chem. Toxicol. 34(2011)129-138) Long term administration of D-serine have nephro- (Carone et al 1985; Silbernagl et al, 1997) and hepatotoxic (Gonzalez-Hernandez et al, 2003) effects.
  34. 34. Young Aged mRNA/ßactinratio 0 0,02 0,04 0,06 0,08 0 0,02 0,04 0,06 0,08 mRNA/ßactinratio Decrease in serine racemase expression is limited in the brain of aged rats Protein/ßactinratio 0 0,4 0,8 1,2 0 0,4 0,8 1,2 Protein/ßactinratio (modified from: Turpin et al, Neurobiol. Aging 32(2011)1495-1504) CEREBRAL CORTEX CEREBELLAR CORTEX
  35. 35. D-serine does not rescue age-related LTP impairment in the dentate gyrus fEPSPslope(%ofbaeline) Adult + D-ser Aged + D-ser Time (min) 60 80 100 120 140 160 180 -15 0 15 30 45 60 ** Adult + D-ser Aged + D-ser fEPSPslope(%ofbaseline) Adult Aged ** 60 80 100 120 140 160 180 -15 0 15 30 45 60 Time (min) Adult Aged In contrast to CA1 area, D-serine is not critical for deficits in NMDA-R-dependent LTP in the aging dentate gyrus that rather involve altered glutamate availability. (Labarriere et al, AGE 36(2014):9698)
  36. 36. D-serine administration improves cognition in the elderly (Avellar et al, Oncotarget. (2016) doi: 10.18632/oncotarget.7691) Effects of one D-serine oral administration on Groton maze learning tested 1.5 hour later (mean age: 75 years-old, n=50) Groton maze learning test
  37. 37. D-serine and Alzheimer’s disease A neglected but finally promising story….
  38. 38. Senile plaque Neurofibrillary tangle Oligomers Amyloid deposits Synaptic loss & Neuronal death Dementia Alzheimer’s disease and the amyloid hypothesis Fibrils APP processing soluble Aβ monomer β sheet
  39. 39. Multiple targets for the Aβ peptide Intracellular effects of Aβ oligomers Synaptic effects of Aβ oligomers
  40. 40. Effects of Aβ oligomers on glutamate synapses: a role for D-serine? (from Tu et al, Mol. Neurodegener. 9(2014):48) Synaptic dysfunction & death AMPAR & NMDAR endocytosis
  41. 41. Aβ-induced neurotoxicity is limited in SRR-/- mice (Inoue et al, J. Neurosci. 28(2008)14486-14491) (Shleper et al, J. Neurosci. 25(2005)9413-9417) NMDA-induced neurotoxicity is reduced in the absence of D-serine On the road for a role of D-serine in Alzheimer’s disease: Part one
  42. 42. On the road for a role of D-serine in Alzheimer’s disease: Part two Aβ induces increase in D-serine levels in: (Brito-Moreira et al, Curr. Alz. Res.. 8(2011)552-562) In hippocampal cultures In microglia cultures (Wu et al, J. Neuroinflam. 1(2004):2) Aβ induces increase in serine racemase expression: At mRNA levels At protein levels dimer monomer (Wu et al, J. Neuroinflam. 1(2004):2; Madeira et al, Transl. Psychiatry 5(2015 ):e561 In hippocampal cultures In microglia cultures In hippocampal cultures In microglia cultures
  43. 43. On the road for a role of D-serine in Alzheimer’s disease: Part three Aβ treatment induces increase in D-serine levels in vivo (Madeira et al, Transl. Psychiatry 5(2015 ):e561 D-serine levels and SR expression are enhanced in animal models of Alzheimer’s disease
  44. 44. On the road for a role of D-serine in Alzheimer’s disease: Part four D-serine levels are regionally increased in the brain of AD patients (Madeira et al, Transl. Psychiatry 5(2015 ):e561) Serine racemase expression is increased in the Hippocampus of AD patients (Wu et al, J. Neuroinflam. 1(2004):2)
  45. 45. On the road for a role of D-serine in Alzheimer’s disease: Part five Determination of D-serine in CSF of patients with probable Alzheimer’s Disease Combining D-serine levels to the amyloid/Tau index remarkably increases the sensitivity and specificity of diagnosis of probable Alzheimer’s disease (modified from Madeira et al, Transl. Psychiatry 5(2015 ):e561) mild cognitive impairment clinical dementia rating IATI = Aβ42 / (240 + 1.18 x t – tau) Healthy controls Alzheimer’s disease
  46. 46. Role of the D-serine-related pathway in cognitive aging: conclusion Alzheimer’s disease NMDAr over-stimulation promoting cell and synapse loss Normal aging SR expression and D-serine levels Reduced NMDAr activation altering synaptic plasticity Cognitive decline + -
  47. 47. Changes in D-aspartate levels and hippocampal functions: short term effects after 3-months oral administration After genetic deletion of D-aspartate oxidase Increasing D-aspartate levels improves learning and memory after 3-months oral administration Increasing D-aspartate levels improves synaptic plasticity (iErrico et al, Neurobiol. Aging 32(2011)2229-2243) (in mice: Errico et al, Neurobiol. Aging 32(2011)2229-2243) (in rats: Topo et al, Amino acids 338(2010)1561-1569) (iErrico et al, Neurobiol. Aging 32(2011)2061-2074) After genetic deletion of D-aspartate oxidase (iErrico et al, Neurobiol. Aging 32(2011)2061-2074)
  48. 48. Changes in D-aspartate levels and hippocampal functions: long term effects After 12-months oral administration After genetic deletion of D-aspartate oxidase Increasing D-Aspartate levels rather impairs learning and memory After 12-months oral administration Increasing D-Aspartate levels impairs synaptic plasticity (iErrico et al, Neurobiol. Aging 32(2011)2229-2243) After genetic deletion of D-aspartate oxidase (iErrico et al, Neurobiol. Aging 32(2011)2061-2074) (iErrico et al, Neurobiol. Aging 32(2011)2229-2243) (iErrico et al, Neurobiol. Aging 32(2011)2061-2074)
  49. 49. Age-related effects of altered D-aspartate levels: intracellular pathways (Errico et al, Neurobiol. Aging 32(2011)2061-2074) Changes in calcium calmodulin kinase II activation Changes in extracellular signal-regulated kinase
  50. 50. D-aspartate delivery to rescue age-related deficits of hippocampal functions? (Errico et al, Neurobiol. Aging 32(2011)2061-2074) Effects on the expression of functional plasticity Effects on learning and memory
  51. 51. D-aspartate and cognitive aging: conclusion Two major lessons can be learned from the emerging knowledge interested in the role of D-aspartate in age- dependent cognitive functions: The activation of D-aspartate oxidase must be closely regulated since long lasting increase in D- aspartate appears to accelerate the rate of brain aging process. ¨Time-limited delivery of D-aspartate may be useful to reverse age-related cognitive aging. However much remains to be done and many questions, even for basic aspect, need to be answered: How do D-aspartate oxidase and D-aspartate levels behave in advancing ages? Is the D-aspartate-related pathway a putative target for Aβ oligomers in Alzheimer’s Disease?
  52. 52. D-amino acid and cognitive aging: a quest for the holy Grail In a few decades, a long road has been traveled since the first evidence of the presence of significant levels of D-amino acids in brain tissues to the current proposal of changes in D-amino acids levels as potential biomarkers of neurodegenetaive diseases. but Early 90’s Today detection NMDA activation synaptic plasticity learning & memory healthy aging pathological aging biomarker - The role of D-serine and D-aspartate remains to be refined. - Other routes involving D-alanine for example have to be considered. - The role of age-related changes in D-amino acid not only as free element but also in the structure of peptides has to be clarified. the ox is slow but the soil is patient (Nepali proverb)

×