Voluntary Exercise Promotes Beneficial Anti-aging Mechanismsin SAMP8 Female Brain

Sergi Bayod & Carolina Guzmán-Brambila & Sandra Sanchez-Roige &

Jaume F. Lalanza & Perla Kaliman & Daniel Ortuño-Sahagun &

Rosa M. Escorihuela & Mercè Pallàs

Received: 25 April 2014 /Accepted: 2 July 2014# Springer Science+Business Media New York 2014

Abstract Regular physical exercise mediates health and lon-gevity promotion involving Sirtuin 1 (SIRT1)-regulated path-ways. The anti-aging activity of SIRT1 is achieved, at least inpart, by means of fine-tuning the adenosine monophosphate(AMP)-activated protein kinase (AMPK) pathway bypreventing the transition of an originally pro-survival programinto a pro-aging mechanism. Additionally, SIRT1 promotesmitochondrial function and reduces the production of reactive

oxygen species (ROS) through regulating peroxisomeproliferator-activated receptor γ coactivator 1α (PGC-1α),the master controller of mitochondrial biogenesis. Here, byusing senescence-accelerated mice prone 8 (SAMP8) as amodel for aging, we determined the effect of wheel-runningas a paradigm for long-term voluntary exercise on SIRT1-AMPK pathway and mitochondrial functionality measured byoxidative phosphorylation (OXPHOS) complex content in thehippocampus and cortex. We found differential activation ofSIRT1 in both tissues and hippocampal-specific activation ofAMPK. These findings correlated well with significant chang-es in OXPHOS in the hippocampal, but not in the cerebralcortex, area. Collectively, the results revealed greater benefitsof the exercise in the wheel-running intervention in a murinemodel of senescence, which was directly related with mito-chondrial function and which was mediated through the mod-ulation of SIRT1 and AMPK pathways.

Keywords Voluntary exercise . Aging . Senescence . Sirtuin1 . AMPK .Mitochondria . SAMP8

Introduction

Current demographic data clearly indicate that worldwide, theaged population increased in an exponential manner over thelast decades. Aging could be defined as a gradual functionaldecline and deterioration of physiological function over time,including lower metabolic rate, declines in exercise perfor-mance, multiple endocrine changes, and a decrease in cogni-tive and memory task performance (World HealthOrganization, WHO 2011). Therefore, the intrinsic and irre-versible senescence-related process is particularly devastatingin neurodegenerative illnesses such Alzheimer’s disease (AD)(Imtiaz et al. 2014).

Sergi Bayod and Carolina Guzmán-Brambila contributed equally to thiswork.

S. Bayod :M. Pallàs (*)Unitat de Farmacologia i Farmacognòsia. Facultat de Farmàcia,Institut de Biomedicina (IBUB), Universitat de Barcelona, NucliUniversitari de Pedralbes, 08028 Barcelona, Spaine-mail: pallas@ub.edu

S. Bayod :M. PallàsCentros de Investigación Biomédica en Red de EnfermedadesNeurodegenerativas (CIBERNED), Barcelona, Spain

J. F. Lalanza : R. M. EscorihuelaInstitut de Neurociències, Departamento. de Psiquiatria i MedicinaLegal, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain

C. Guzmán-BrambilaDivisión de Biotecnología y Salud, Escuela de Medicina, InstitutoTecnológico y de Estudios Superiores de Monterrey, CampusGuadalajara, Guadalajara 45201, Jalisco, Mexico

D. Ortuño-SahagunInstituto de Investigación en Ciencias Biomédicas (IICB), CUCS,Universidad de Guadalajara, Sierra Mojada No. 950, Col.Independencia, Guadalajara 44340, Jalisco, Mexico

S. Sanchez-RoigeSchool of Psychology, University of Sussex, Falmer, Brighton BN19QG, UK

P. KalimanInstituto de Investigaciones Biomédicas de Barcelona IIBB-CSIC,c/Rosselló 161, 6th floor, 08036 Barcelona, Spain

J Mol NeurosciDOI 10.1007/s12031-014-0376-6

It is widely assumed that continued physical activity willincrease the lifespan (Navarro et al. 2004), and it is claimed asan excellent strategy to help older persons in maintainingindependence, recovering from illness, and reducing their riskof disease (Kaliman et al. 2011). The benefit of exercise isrelated with its participation in several cellular processes thatprevents cell senescence (Bamidis et al. 2014). In this way,vasoactive intestinal peptide (VIP) was transiently expressedin the hippocampus after wheel-running activity and accom-panied by typical markers of active neuronal networks as c-Fos, whereas other neuronal activity markers are not modifiedby exercise (Eilam et al. 1999). These, among others, indicatethat exercise activates specific cellular processes that can bebeneficial for the brain.

It is well known that regular physical exercise mediateshealth and longevity promotion involving Sirtuin 1 (SIRT1)-regulated pathways, including the antioxidant processes, mac-romolecular damage repair mechanism, energy and mitochon-drial functions, and neuronal plasticity (Bamidis et al. 2014).In experimental aging models, a decrease in SIRT1 has beendescribed (Hubbard and Sinclair 2014; Pallàs et al. 2008).Moreover, in aged rats, moderate, prolonged exercise trainingis able to induce an increase in SIRT1 activity (Corbi et al.2012; Radak et al. 2013), suggesting that this could counteractage-related dysfunctions.

The anti-aging activity of SIRT1 is achieved at least in partby fine-tuning the adenosine monophosphate (AMP)-activat-ed protein kinase (AMPK) pathway and preventing the tran-sition of an originally pro-survival program into a pro-agingmechanism (Wang et al. 2011). In the mitochondria, SIRT1promotes its functions and reduces the production of reactiveoxygen species (ROS) through regulating the master control-ler of mitochondrial biogenesis, peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α), and AMPKpathway (Fernández-Marcos and Auwerx 2011). AMPK isthe primary regulator of cellular responses for reducing ATPlevels, and it acts as a sensor to maintain the energy balancewithin a cell (Burkewitz et al. 2014). AMPK also activates theenzyme SIRT1, which provides a possible mechanism forindirect activation of SIRT1, controlling senescence (Hardie2011; Wang et al. 2011). Thus, it appears that there is aninterconnection between the energy sensor AMPK and theother potential targets that are involved in age regulation(Inoki et al. 2003; Corradetti et al. 2004; Shaw et al. 2004;Shaw 2009).

However, a pertinent experimental model for studying themost important physiological changes that occur with age andthe pathological consequences of these changes is necessaryfor understanding aging. Senescence-accelerated mouse prone8 (SAMP8) has been described as an animal model with age-related learning deficiencies (Nomura and Okuma 1999;Takeda 2009), jointly with alterations in synaptic plasticity(del Valle et al. 2012), neurotransmission, and some of the

histopathological AD hallmarks (Canudas et al. 2005; Gutiérrez-Cuesta et al. 2008) compared with those in senescence-accelerated mouse resistant 1 (SAMR1) as genetic control. Inaddition, this murine model has been used to test the preventiveeffects of pharmacological strategies acting on aging-involvedcellular pathways such as the SIRT1-AMPK-PGC-1α axis(Tajes et al. 2009; Porquet et al. 2013), reinforcing the usefulnessof SAMP8 as an animal model of age-related deficiencies.

The purpose of this work was to determine the effect oflong-term voluntary exercise on the SIRT1-AMPK pathwayand in mitochondrial functionality in the hippocampus andcerebral cortex of SAMP8, as key role cellular processesinvolved in the deleterious events related with the agingprocess.

Materials and Methods

Animals

Female R1/P8 (6 months old) mice were maintained understandard conditions (temperature 23±1 °C, humidity 50–60 %, 12-h:12-h light/dark cycle, lights on at 8 a.m.), withfood (A04, Harlan, Spain) and tap water available ad libitumthroughout the study. They were housed in groups of 2–6same-sex mice per cage (except during wheel-running ses-sions) in plastic Macrolon colony boxes (15 cm high×27 cmwide×27 cm deep) with a sawdust floor.

All experimental procedures were approved by the EthicsCommittee of the University Autonomous of Barcelona(Comissió Ètica d’Experimentació Animal i Humana,CEEAH, UAB), following the “Principles of LaboratoryAnimal Care” and were carried out in accordance with theEuropean Communities Council Directive (86/609/EEC).

Voluntary Wheel-Running Paradigm

We analyzed the effects of 8 weeks of voluntary wheel-running (WR) in 6-month-old SAMP8 and SAMR1 mice.At the end of the intervention, all mice were 8 months old.The running wheels (ENV-044 Mouse Low-Profile WirelessRunningWheel, Med Associates Inc.; 15.5 cm circumference;25° from horizontal plane) were located in the animal colonyroom inside cages measuring 19 cm in height×27 cm inwidth×40 cm in depth. WR activity was monitored througha wireless transmitter system using a Hub (13.70×15.25 cm2)located in the same animal colony room. The Hub was con-nected to a PC, and the number of rotations performed eachminute was recorded.

As previously described (Álvarez-López et al. 2013;Cosín-Tomás et al. 2014), all mice in the WR condition wereindividually accommodated in cages (15 cm high×27 cmwide×27 cm deep) containing clean sawdust and running

J Mol Neurosci

wheel on three alternate days each week for 25 weeks. Weemployed and alternate procedure to avoid long-term isola-tion, which is known to produce detrimental behavioral effectsin rodents (Fone et al. 2008). WR sessions started between 1and 2 p.m. and lasted for 24 h. At the end of each session, themice were returned to their home cage with their companions.Sedentary (SED) control mice were handled the same as WRmice, but accommodated in large cages containing only cleansawdust. The animals were sacrificed by decapitation, andtheir brains were dissected on ice to obtain the hippocampusand cerebral cortex. Tissues were immediately frozen andstored at −80 °C for further analysis.

Inmunodetection by Western blot Analysis

Tissue samples were homogenized in lysis buffer contain-ing phosphatase and protease inhibitors (Cocktail II,Sigma), and cytosol and nuclear fractions were obtainedaccording to an established method (Giralt et al. 2013).The protein concentration was determined by theBradford method. Twenty micrograms of protein wasseparated by SDS-PAGE (5–15 %) and transferred ontoPVDF membranes (Millipore). The membranes wereblocked in 5 % non-fat milk in Tris-buffered saline con-taining 0.1 % Tween 20 (TBS-T) for 1 h at room temper-ature, followed by overnight incubation at 4 °C withprimary antibodies diluted in TBS-T and 5 % BSA:SIRT1 (1:1,000; Mill ipore) , p53 (1:1,000; CellSignaling) and acetylated p53 (1:500; Abcam), AMPKα(1:500; Cell Signaling), and p-AMPKα Thr172 (1:500;Cell Signaling), OXPHOS cocktail (1:500; MitoSciences),porin (1:500; MitoSciences), NeuN (1:1,000; Millipore),and GAPDH (1:2,000; Millipore). The membranes werethen washed and incubated with secondary antibodies for1 h at room temperature. Immunoreactive proteins werevisualized using a chemiluminescence-based detection kit(ECL kit; Millipore), and digital images were acquiredusing a ChemiDoc XRS+System (BioRad). Band intensi-ties were quantified by densitometric analysis usingImage Lab software (Biorad), and values were normalizedto GAPDH or porin for cytosol fraction and to NeuN fornuclear fraction.

Statistical Analysis

Data are expressed as mean±standard error of the mean(SEM). Statistical analysis was carried out usingGraphPad Prism software. Two-way analysis of variance(ANOVA) was conducted to assess the effects of strainand voluntary exercise. Comparisons between groupswere performed by two-tailed Student’s t test for indepen-dent samples. Statistical significance was set at p<0.05for all tests.

Results

SIRT1 activation is described as one of the keys to thecrossroad pathways linked with cellular mechanisms in-volved in aging and lifespan in mammals (Guarente2001). Moreover, exercise is a non-pharmacological strat-egy that could increase SIRT1 action directly or indirectlythrough the activation of several other mechanisms(Kaliman et al. 2011; Corbi et al. 2012). Therefore, todetermine the effect of long-term voluntary exercise inSAMP8 mice on the SIRT1-AMPK pathway and in mito-chondrial functionality, we first determined the SIRT1protein levels. SIRT1 was modified by the wheel-running intervention and influenced by strain both inSAMP8 hippocampus and cortex nuclear fractions (strainF(1.20)=193.9; p<0.0001 F(1.20)=109.1; p<0.001). Asignificant increase of deacetylase levels was found inthe cerebral nuclear fractions of exercised SAMP8(F(1.20) = 16.34; p = 0.00085 and F(1.20) = 94.06,p<0.001 for the hippocampus and cortex, respectively)(Figs. 1a and 2a). Additionally, cytoplasmic protein levelsin SIRT1 were found significantly increased in the hippo-campus of exercised mice (F(1.20)=5.881; p=0.0251)(Fig. 2c) but did not reach significance in the cortex(F(1.20)=3.011; p=0.0981) (Fig. 2c). Moreover, signifi-cant decreases in nuclear acetylated p53 were observed inboth tissues after the wheel-running protocol (F (1.20)=32.09, p<0.0001 for the hippocampus and F(1.20)=35.56,p<0.0001 for the cortex) (Figs. 1b and 2b).

A close relationship between SIRT1 and AMPK is evi-denced in several tissues and animal models (Salminen andKaarniranta 2012). Following the increase in SIRT1, wesearched for AMPK activation through the levels of phos-phorylation in Thr 172. No changes were detected after wheel-running in the cortex (Fig. 2d, e), but a significant increase inphosphorylation of this kinase occurred in exercised SAMP8hippocampus (Fig. 1d, e) when compared with the SAMP8SED group (p<0.05).

SIRT1 plus AMPK acts effectively as an integratedsignaling network controlling mitochondrial function(Radak et al. 2013), which in turn plays a pivotal role inthe aging process (Navarro and Boveris 2007).Additionally, levels in the oxidative phosphorylation(OXPHOS) mitochondrial system were determined bothin the hippocampus and cortex. A significant increase inOXPHOS complex composition was determined in thehippocampus of wheel runner SAMP8 (complex I: F(1.20)=5.724, p=0.0267; complex II: F(1.20)=16.70, p=0.0006; complex III: F(1.20)=25.78, p<0,001; complexIV: F(1.20)=4.349, p<0.05; complex V: F(1.20)=6.211,p<0,0216) (Fig. 3), but no changes where observed in thecortex according to the unchanged activation of AMPK inthis tissue (data not shown).

J Mol Neurosci

Discussion

There is growing evidence that moderate exercise is not onlybeneficial for the physiology of the organism but also exerts apositive impact on aging (Loprinzi et al. 2013). However, themolecular bases of these favorable actions remain very farfrom being completely revealed. Under the experimental

conditions employed in this work, it has recently been dem-onstrated that 6 months of voluntary training on a runningwheel improved aging traits such as the skin color and bodytremor of SAMP8 mice (Álvarez-López et al. 2013).Additionally, long-term wheel running leads to increases inthe insulin-like growth factor-1 (IGF-1) plasma levels inexercised senescence-accelerated mice (SAM) mice in

Ac

p53

/to

talp

53N

ucl

ear

Sir

t1/N

euN

R

R1

Ac

p53

/to

talp

53(r

elat

ive

un

tis)

R1

Nu

clea

rS

irt1

/Neu

N(r

elat

ive

un

tis)

1 R1_W

A

C

R1_W

R

R1_W

R P8

WR P8

P8

P8_W

R

P8_W

R

P8_WR

Sirt 1

Ac-p53

total p53

NeuN

Cyt

op

lasm

ic S

irt1

/GA

PD

H(r

elat

ive

un

tis)

Sirt 1

pAMPK

totalAMPK

GADPH

R1

R

0.0

0.5

1.0

1.5

2.0

2.5

(rel

ativ

eu

nti

s)

R10

5

10

15 p

AM

PK

/AM

PK

(rel

ativ

e un

tis)

R1

E

R1_W

R P8

R1_W

R

R1_WR

8

P8_W

R

**##

P8

P8_W

R

*

#

P8 P88_WR

D

B

Fig. 1 Sirtuin1-adenosine monophosphate-activated protein kinase(SIRT1-AMPK) axis in hippocampus of senescence-accelerated(SAMR)1 and SAMP8, sedentary (SED) (R1 and P8), andwheel-running(R1_WR and P8_WR) mice. a Nuclear SIRT1, b cytoplasmic SIRT1, cacetylated p53, d, e phospho AMPK (pAMPK) levels and activation.

Protein levels were measured by Western blot analysis (n=6/group).Mean±standard error of the mean (SEM) are represented; two-wayanalysis of variance (ANOVA) results are indicated as *p<0.05;**p<0.01 vs. P8 and #p<0.05; ##p<0.01 vs. R1

J Mol Neurosci

reference to the sedentary ones, while no changes in the bodyweight (BW) were determined (Cosín-Tomás et al. 2014). TrkB, Bdnf, and neuritine gene upregulation was determined inwheel-running groups (Cosín-Tomás et al. 2014).

Here, our aim was to pinpoint some of the cellular andmolecular ways involved in the aging process that couldexplain the beneficial traits of the wheel-running exercise. Inthis manner, we determined a significant increase in nuclear

levels of SIRT1 in the hippocampus and cerebral cortex ac-cording to previous results in long-term moderate exercise inadult rats (Bayod et al. 2012; 2014). Pursuing SIRT1 protein-level increase, we identified some of the multiple cellulareffectors that turn on after SIRT1 activity, suggesting thisdeacetylase as a key contributor to wheel running-inducedbeneficial brain effects (Kaliman et al. 2011). In this respect,exercise induced an AMPK activation in the hippocampal

R1

R1_WR P8

P8_WR

0.0

0.2

0.4

0.6

0.8

1.0

*##

Cyt

opla

smic

Sirt

1/G

APD

H(r

elat

ive

untis

)

R1

R1_WR P8

P8_WR

0.0

0.1

0.2

0.3

0.4

**##

Nuc

lear

Sirt

1/N

euN

(rel

ativ

e un

tis)

R1

R1_WR P8

P8_WR

0

1

2

3

4

*#

Ac p

53/to

tal p

53(r

elat

ive

untis

)

R1

R1_WR P8

P8_WR

0.0

0.5

1.0

1.5

pAM

PK/G

APD

H(r

elat

ive

untis

)

R1

R1_WR P8

P8_WR

0.0

0.2

0.4

0.6

0.8 p

AMPK

/AM

PK(r

elat

ive

untis

)

Sirt 1

pAMPK

total AMPK

GADPH

R1 R1_WR P8 P8_WR

Sirt 1Ac-p53total p53NeuN

R1 R1_WR P8 P8_WR

A

C

B

D

E

Fig. 2 Sirtuin 1-adenosine monophosphate-activated protein kinase(SIRT1-AMPK) axis in cortex of senescence-accelerated (SAMR)1 andSAMP8 mice, sedentary (SED) (R1 and P8) mice, and wheel-running(R1_WR and P8_WR) mice. a Nuclear SIRT1, b cytoplasmic SIRT1, cacetylated p53, d, e phospho AMPK (pAMPK) levels and activation.

Protein levels were measured by Western blot analysis (n=6/group).Mean±standard error of the mean (SEM) are represented; two-wayanalysis of variance (ANOVA) results are indicated as *P<0.05;**p<0.01 vs. P8 sedentary (SED) and #p<0.05; ##p<0.01 vs. R1

J Mol Neurosci

area, but not in cortex, which corresponds to results recentlyobtained by Marosi et al. (2012), indicating a key role ofexercise specifically in the hippocampal area and mainly byreducing oxidative stress (OS).

To achieve an improved healthy and extended lifespan,efficient control of energy metabolic homeostasis is mandato-ry. The AMPK and SIRT1 axis shares a fine-tuning regulatingenergy metabolism that acts as a conserving energy sensor ofincreased levels of AMP and NAD+, respectively (Hardie2011). As mentioned, AMPK activation increases NAD+concentration that in turn leads to the functional activity ofSIRT1 (Canto and Auwerx 2009); additionally, SIRT1 is able

to deacetylate LKB1, which is an upstream activator ofAMPK (Lan et al. 2008; Zheng et al. 2012). Moreover, theAMPK pathway functions as an energy master regulator gatedto mitochondrial function, which is reported to be intrinsicallyrelated with the SIRT1 pathway (Zheng et al. 2012). A grow-ing body of evidence supports mitochondrial dysfunction as aprominent and early chronic OS-associated event that contrib-utes to synaptic abnormalities in aging (Quiroz-Baez et al.2013). Studies of the aging brain mitochondria have consis-tently reported reductions of complex I and IV activities andincreased ROS production (Navarro and Boveris 2007;Stefanatos and Sanz 2011). Other age-related mitochondrial

R1

R1_WR P8

P8_WR

0.0

0.5

1.0

1.5*#

Com

plex

I/po

rin(r

elat

ive

untis

)

R1

R1_WR P8

P8_WR

0.0

0.5

1.0

1.5 *##

Com

plex

II/p

orin

(rel

ativ

e un

tis)

R1

R1_WR P8

P8_WR

0.0

0.5

1.0

1.5 *#

Com

plex

III/p

orin

(rel

ativ

e un

tis)

R1

R1_WR P8

P8_WR

0.0

0.1

0.2

0.3

0.4

0.5 *#

Com

plex

IV/p

orin

(rel

ativ

e un

tis)

R1

R1_WR P8

P8_WR

0.0

0.5

1.0

1.5

2.0 *#

Com

plex

V/p

orin

(rel

ativ

e un

tis)

R1 R1_WR P8 P8_WRComplexVIIIIVII

I

Porin

GADPH

A

C

B

D

E

Fig. 3 Oxidative phosphorylation (OXPHOS) determination in the hip-pocampus of senescence-accelerated (SAMP)1 and SAMP8, sedentary(SED) (R1 and P8), and wheel-running (R1_WR and P8_WR) mice.Mitochondrial complexes were measured byWestern blot analysis (n=6/

group). Mean±standard error of the mean (SEM) are represented; two-way analysis of variance (ANOVA) results are indicated as *P<0.05 vs.SAMP8 SED and #p<0.05; ##p<0.01 vs. SAMR1 SED

J Mol Neurosci

changes include reduced membrane potential and increasedsize (Bertoni-Freddari et al. 2007). Defects in mitochondrialDNA (mtDNA) have been found in elderly persons and havebeen associated with decreased cytochrome oxidase activity inthe brain (Reddy and Beal, 2008). On the other hand, in theaging brain, mitochondrial biogenesis potentiation might rep-resent a compensatory response to progressive declines inbrain mitochondrial function (Onyango et al. 2010).

In the present study, the involvement of AMPK and SIRT1pathways in wheel-running effects is consistent with mito-chondrial functionality in senescent SAMP8 mice.According to AMPK activation in SAMP8 mice under thewheel-running exercise, we found an increase in OXPHOSmachinery, specifically in the hippocampus but not in thecortex. Enhancing aerobic glycolysis in the aging brain byincreasing OXPHOS would reduce the OS generated by dys-functional mitochondria and would prevent the brain fromutilizing alternative sources of metabolic energy, such as theketone body pathway that is a characteristic of Alzheimer’sdisease (Brinton 2008). Both mitochondrial dysfunction andincrease in OS have been directly correlated with neurode-generative pathologies; therefore, the positive effect of exer-cise during aging on mitochondrial activity by means of theSIRT1 and AMPK pathways would result in better metabolicperformance.

Overall, the results presented here in a murine model ofsenescence under a voluntary wheel-running paradigm reveala beneficial impact of exercise on signaling pathways thatregulate mitochondrial function specifically in the hippocam-pus of SAMP8, which are mediated by modulation of theSIRT1 and AMPK pathways.

Acknowledgments We thank Maggie Brunner, M.A., for revising thelanguage and style of the manuscript. This study was supported by grantsSAF2010-15050 (PK), PSI2008-06417-C03-03 (RME), and SAF-2012-39852 (MP) from the “Ministerio de Educación y Ciencia” and2009/SGR00893 from the “Generalitat de Catalunya.” S.B. was support-ed by a predoctoral fellowship (APIF) from the University of Barcelona.J.F.L. was supported by a predoctoral fellowship from the Generalitat deCatalunya (FI-DGR 2011).

References

Álvarez-López MJ, Castro-Freire M, Cosin-Tomas M, Sanchez-Roige S,Lalanza JF, Del Valle J, Párrizas M, Camins A, Pallás M,Escorihuela RM, Kaliman P (2013) Long-term exercise modulateshippocampal gene expression in senescent female mice. JAlzheimers Dis 33(4):1177–1190

Bamidis PD, Vivas AB, Styliadis C, Frantzidis C, Klados M, Schlee W,Siountas A, Papageorgiou SG. (2014) A review of physical andcognitive interventions in aging. Neurosci. Biobehav. Rev. S0149-7634(14)00075-X.

Bayod S, Del Valle J, Lalanza JF, Sanchez-Roige S, de Luxán-Delgado B,Coto-Montes A, Canudas AM, Camins A, Escorihuela RM, PallàsM (2012) Long-term physical exercise induces changes in Sirtuin 1

pathway and oxidative parameters in adult rat tissues. Exp Gerontol47(12):925–935

Bayod S, Menella I, Sanchez-Roige S, Lalanza JF, Escorihuela RM,Camins A, Pallàs M, Canudas AM (2014) Wnt pathway regulationby long-term moderate exercise in rat hippocampus. Brain Res16(1543):38–4

Bertoni-Freddari C, Fattoretti P, Giorgetti B, Grossi Y, Balietti M, CasoliT, Di Stefano G, Perretta G (2007) Synaptic and mitochondrialmorphometry provides structural correlates of successful brain ag-ing. Ann N YAcad Sci 1097:51–53

Brinton RD (2008) Estrogen regulation of glucose metabolism and mi-tochondrial function: therapeutic implications for prevention ofAlzheimer’s disease. Adv Drug Deliv Rev 60(13–14):1504–1511

Burkewitz K, Zhang Y, Mair WB. AMPK at the nexus of energetics andaging. (2014) Cell Metab. S1550-4131(14)00106-5.

Canto C, Auwerx J (2009) Caloric restriction, SIRT1 and longevity.Trends Endocrinol Metab 20:325–331

Canudas AM, Gutierrez-Cuesta J, Rodríguez MI, Acuña-Castroviejo D,Sureda FX, Camins A, Pallàs M (2005) Hyperphosphorylation ofmicrotubule-associated protein tau in senescence-accelerated mouse(SAM). Mech Ageing Dev 126(12):1300–1304

Corbi G, Conti V, Scapagnini G, Filippelli A, Ferrara N (2012) Role ofSirtuins, calorie restriction and physical activity in aging. FrontBiosci (Elite Ed) 4:768–778

Corradetti MN, Inoki K, Bardeesy N, DePinho RA, Guan KL (2004)Regulation of the TSC pathway by LKB1: evidence of a molecularlink between tuberous sclerosis complex and Peutz-Jeghers syn-drome. Genes Dev 18(13):1533–1538

Cosín-Tomás M, Alvarez-López MJ, Sanchez-Roige S, Lalanza JF,Bayod S, Sanfeliu C, Pallàs M, Escorihuela RM, Kaliman P(2014) Epigenetic alterations in hippocampus of SAMP8 senescentmice and modulation by voluntary physical exercise. Front AgingNeurosci 20(6):51

del Valle J, Bayod S, Camins A, Beas-Zárate C, Velázquez-Zamora DA,González-Burgos I, Pallàs M (2012) Dendritic spine abnormalitiesin hippocampal CA1 pyramidal neurons underlyingmemory deficitsin the SAMP8 mouse model of Alzheimer’s disease. J AlzheimersDis 32(1):233–240

Eilam R, Davidson A, Gozes I, Segal M (1999) Locomotor activitycauses a rapid up-regulation of vasoactive intestinal peptide in therat hippocampus. Hippocampus 9(5):534–541

Fernández-Marcos PJ, Auwerx J (2011) Regulation of PGC-1α, a nodalregulator of mitochondrial biogenesis. Am J Clin Nutr 93(4):884S–890S

Fone KC, Porkess MV, Fone KC, Porkess MV (2008) Behavioural andneurochemical effects of post-weaning social isolation in rodents-relevance to developmental neuropsychiatric disorders. NeurosciBiobehav Rev 32(6):1087–1102

Giralt A, Saavedra A, Carretón O, Arumí H, Tyebji S, Alberch J, PérezNE (2013) PDE10 inhibition increases GluA1 and CREB phosphor-ylation and improves spatial and recognition memories in aHuntington’s disease mouse model. Hippocampus 23(8):684–695

Guarente L (2001) SIR2 and aging—the exception that proves the rule.Trends Genet 17(7):391–392

Gutierrez-Cuesta J, Tajes M, Jiménez A, Coto-Montes A, Camins A,Pallàs M (2008) Evaluation of potential pro-survival pathwaysregulated by melatonin in a murine senescence model. J PinealRes 45(4):497–505

Hardie DG (2011) AMP-activated protein kinase: an energy sensor thatregulates all aspects of cell function. Genes Dev 25(18):1895–1908

Hubbard BP, Sinclair DA (2014) Small molecule SIRT1 activators for thetreatment of aging and age-related diseases. Trends Pharmacol Sci35(3):146–154

Imtiaz B, Tolppanen AM, Kivipelto M, Soininen H (2014) Future direc-tions in Alzheimer’s disease from risk factors to prevention.Biochem Pharmacol 88(4):661–670

J Mol Neurosci

Inoki K, Zhu T, Guan KL (2003) TSC2mediates cellular energy responseto control cell growth and survival. Cell 26;115(5):577–590

Kaliman, P., Párrizas, M., Lalanza, J.F., Camins, A., Escorihuela, R.M.Pallàs, M. (2011) Neurophysiological and epigenetic effects ofphysical exercise on the aging process. Ageing Res Rev, 10: 475-786

Lan F, Cacicedo JM, RudermanN, Ido Y (2008) SIRT1modulation of theacetylation status, cytosolic localization, and activity of LKB1.Possible role in AMP-activated protein kinase activation. J BiolChem 283:27628–27635

Loprinzi PD, Herod SM, Cardinal BJ, Noakes TD (2013) Physicalactivity and the brain: a review of this dynamic, bi-directionalrelationship. Brain Res 1539:95–104

Marosi K, Bori Z, Hart N, Sárga L, Koltai E, Radák Z, Nyakas C (2012)Long-term exercise treatment reduces oxidative stress in the hippo-campus of aging rats. Neuroscience 13;226:21–28

Navarro A, Boveris A (2007) The mitochondrial energy transductionsystem and the aging process. Am J Physiol Cell Physiol 292(2):C670–C686

Navarro A, Gomez C, López-Cepero JM, Boveris A (2004) Beneficialeffects of moderate exercise on mice aging survival, behavior,oxidative stress, and mitochondrial electron transfer. Am J PhysiolRegul Integr Comp Physiol 286(3):R505–R511

Nomura Y, Okuma Y (1999) Age-related defects in lifespan and learningability in SAMP8 mice. Neurobiol Aging 20(2):111–115

Onyango IG, Lu J, Rodova M, Lezi E, Crafter AB, Swerdlow RH(2010) Regulation of neuron mitochondrial biogenesis andrelevance to brain health. Biochim Biophys Acta 1802(1):228–234

Pallàs M, Pizarro JG, Gutierrez-Cuesta J, Crespo-Biel N, Alvira D, TajesM, Yeste-Velasco M, Folch J, Canudas AM, Sureda FX, Ferrer I,Camins A (2008) Modulation of SIRT1 expression in differentneurodegenerative models and human pathologies. Neuroscience154(4):1388–1397

Porquet D, Casadesús G, Bayod S, Vicente A, Canudas AM, Vilaplana J,Pelegrí C, Sanfeliu C, Camins A, Pallàs M, del Valle J (2013)Dietary resveratrol prevents Alzheimer’s markers and increases lifespan in SAMP8. Age (Dordr) 35(5):1851–1865

Quiroz-Baez R, Flores-Domínguez D, Arias C (2013) Synaptic aging isassociated withmitochondrial dysfunction, reduced antioxidant con-tents and increased vulnerability to amyloid-β toxicity. CurrAlzheimer Res 10(3):324–331

Radak Z, Koltai E, Taylor AW, Higuchi M, Kumagai S, Ohno H, Goto S,Boldogh I (2013) Redox-regulating Sirtuins in aging, caloric restric-tion, and exercise. Free Radic Biol Med 58:87–97

Reddy PH, Beal MF (2008) Amyloid beta, mitochondrial dysfunctionand synaptic damage: implications for cognitive decline in aging andAlzheimer's disease. Trends Mol. Med 14(2):45–53

Salminen A, Kaarniranta K (2012) AMP-activated protein kinase(AMPK) controls the aging process via an integrated signalingnetwork. Ageing Res Rev 11(2):230–241

Shaw RJ (2009) LKB1 and AMP-activated protein kinase control ofmTOR signalling and growth. Acta Physiol 196(1):65–80

Shaw RJ, Kosmatka M, Bardeesy N, Hurley RL, Witters LA, DePinhoRA, Cantley LC (2004) The tumor suppressor LKB1 kinasedirectly activates AMP-activated kinase and regulates apoptosisin response to energy stress. Proc Natl Acad Sci U S A 101(10):3329–3335

Stefanatos R, Sanz A (2011) Mitochondrial complex I: a central regulatorof the aging process. Cell Cycle 10(10):1528–1532

Tajes M, Gutierrez-Cuesta J, Ortuño-Sahagun D, Camins A, Pallàs M(2009) Anti-aging properties of melatonin in an in vitro murinesenescence model: involvement of the Sirtuin 1 pathway. J PinealRes 47(3):228–237

Takeda T (2009) Senescence-accelerated mouse (SAM) with specialreferences to neurodegeneration models, SAMP8 and SAMP10mice. Neurochem Res 34(4):639–659

Wang Y, Liang Y, Vanhoutte PM (2011) SIRT1 and AMPK in regulatingmammalian senescence: a critical review and a working model.FEBS Lett 585(7):986–994

WHO, Global health and aging. (2011) Edited by: World HealthOrganization and US National Institute of Aging. 32 pp.

Zheng Z, Chen H, Li J, Li T, Zheng B, Zheng Y, Jin H, He Y, Gu Q, Xu X(2012) Sirtuin 1-mediated cellular metabolic memory of high glu-cose via the LKB1/AMPK/ROS pathway and therapeutic effects ofmetformin. Diabetes 61(1):217–228

J Mol Neurosci