Metabolism, Neural Activation and Plasticity after TBI:A Developmental Perspective

Christopher C. Giza, M.D.UCLA Brain Injury Research Center

Pediatric Neurology and NeurosurgeryMattel Children’s Hospital – UCLADavid Geffen School of Medicine

Traumatic Brain Injury in Youth

Basic ScientistsDavid Hovda, Ph.D.MeFernando Gomez-Pinilla, Ph.D.Grace Griesbach, Ph.D.Neil Harris, Ph.D.Andrey Mazarati, M.D., Ph.D.Mayumi Prins, Ph.D.Raman Sankar, M.D., Ph.D.

UCLA Brain Injury Research Center

Undergrads/PostbacFarbod Fazlollahi Phoebe HuaAditya Ponnaluri

Graduate StudentsDaya AlexanderGretchen MillerMaxine RegerNaomi Santa Maria

Lab Assistants Yan Cai, M.S.Sima GhavimDon Shin

Clinical Investigators Robert Asarnow, Ph.D.Talin Babikian, Ph.D.Fabienne Cazalis, Ph.D.Sarah DeBoard Marion, Ph.D.John DiFiori, M.D.Jason Lerner, M.D.Michelle Leung, ProgrammerAndy Madikians, M.D.Joyce Matsumoto, M.D.

www.birc.ucla.educgiza@mednet.ucla.edu

EEG Techs Andrea DuranConrad Szeliga

Naomi Santa MariaHannah Valino

Residents/FellowsGarni Barkoudarian, M.D.Meeryo Choe, M.D.Ivet Hartonian, M.D.Daniel Shrey, M.D.

NursesMaria EtchepareSue Yudovin

Joyce Matsumoto, M.D.David McArthur, Ph.D., M.P.H.

Medical Students Julia BreaultFloyd Buen

Post-docTiffany Greco

Summary

1. Introduction to Pediatric TBI

2. Metabolism and Metabolic Therapy

3. Neural Activation and Pro-plasticity Therapy

4. Effects of Repeated Injury in Development

5. Conclusions5. Conclusions

1000

1200

1400

Rat

e p

er 1

00,0

00Traumatic Brain Injury:

Epidemiology#1 cause of death and acquired disability in children and adolescents!!

0

200

400

600

800

0-4 5-9 10-14 15-19 20-24 25-34 35-44 45-54 55-64 65-74 75 +

Age Group (years)

Rat

e p

er 1

00,0

00

Male Female

CDC 2004 Report: TBI in the United States

Age of Injury and Mechanism

20

25

30

35

Nu

mb

er

of

Pa

tie

nts

Mechanism of Injury varies by Age

MVA

GSW

*ANOVA, p < 0.0001

0

5

10

15

20

0-1 y 1-4 y 4-8 y 8-12 y 12-16 y >16 y

Nu

mb

er

of

Pa

tie

nts

Age of Injury

GSW

Fall

Blunt

AHT

Valino H, Breault J, et.al. in preparation, 2012

Summary

1. Introduction to Pediatric TBI

2. Metabolism and Metabolic Therapy

a) Neurometabolic Cascade

b) Alternative Fuel Metabolic Therapy

3. Neural Activation and Pro-plasticity Therapy3. Neural Activation and Pro-plasticity Therapy

4. Effects of Repeated Injury in Development

5. Conclusions

Neurometabolic Cascade of mTBI:Basic Pathophysiology

Altered neurotrans-mission

Glu

tam

ate

K+

Cell DeathProtease activation

Ca2+Ionic flux

EnergyCrisis

Axonal injuryPump

Mito

K+

ADPATP

Glu

tam

ate

K+K+

K+

Ionic flux

activation

Treating for Neuroprotection: Ketones as Fuel

30

35

40

45

Standard DietKG Diet

Con

tusi

on V

olum

e (m

m3)

†

Standard Diet Ketogenic Diet

PND17

PND17 PND30 PND45 PND900

5

10

15

20

25

Age Groups

Con

tusi

on V

olum

e (m

m3)

**

†PND35

PND45

PND65

PND65

Prins, et al., J Neurosci Res, 2005

Post-TBI ketogenic diet reduces lesion volume in immature rats

Post-TBI transporter upregulation

Sham TBI

P35

Adu

lt

0.1mm

Prins & Giza, Dev Nsci 2006

TBI induces vascular endothelial expression of monocarboxylatetransporter 2 (MCT2)

Summary

1. Introduction to Pediatric TBI

2. Metabolism and Metabolic Therapy

3. Neural Activation and Pro-plasticity Therapy

1. Impaired glutamatergic neurotransmission and experience-dependent plasticity

2. Restoration of plasticity using glutamate agonist

4. Effects of Repeated Injury in Development

5. Conclusions

Traumatic Brain Injury:Fluid Percussion

Fluid percussion injury effects

• Diffuse concussive injury

• Dura intact

• Followed by apnea

Transducer

Saline filled cylinder

Piston

InjuryCap

• Followed by apnea and unresponsive-ness to toe pinch

• Normal open-field behavior as early as 1 day post-injury

• Little, if any overt cell death in developing animals

Developmental TBI: NMDARs

PID1Sham FPI FPI

PID2Sham FPI

PID4Sham FPI

PID7Sham

Hippocampus: Ipsilateral NR2A

20

40

% o

f Sha

m

*

20

30

40

50

60

eEP

SC

(pA

)

Sham

FPI*

*

Hippocampus: Ipsilateral CA1

ANOVA, Overall effect of injury, p<0.05

*

-60

-40

-20

0

20

1 2 3 4 5 6 7Post-injury day

% o

f Sha

m

Giza, Santa Maria & Hovda, J. Neurotrauma 2006

Protein levels of the NR2A subunit are selectively reduced after developmental TBI. NR1 & NR2B show little change.

0

10

20

Total NMDAR EPSC NR2A EPSC

eEP

SC

(pA

)

Li, et. al., National Neurotrauma Society abstract 2005

NR2A mediated postsynaptic currents are selectively reducedafter developmental TBI.

* p<0.05

**

Post-TBI Impaired Activation: Functional MRI

Condition 1 vs 3

Controls TBI

During a spatial working memory task, children post-acutely following moderate-severe TBI show much less network activation

Cazalis F, et al., Society for Neuroscience, abstract, 2007

Imaging Post-TBI NMDAR Activation with phMRI: RatControl PID3-4

20

40

60

80

DC

S-in

duce

d %

rCB

V

Control (n=5)LFP PID3-4 (n=5)

*

100%

75

50

25

0

LFP PID3-4

Santa Maria N.S., et al., J Neurotrauma abstr 2009

DCS administration selectively increases hippocampal rCBV. This activation is abolished 3-4 days after developmental TBI.

-20

0

Hipp Thal Cortex

DC

S-in

duce

d %

rCB

V

Experimental Design:

Enriched environment rearing for 17 days

SHAMSURGERY

STANDARD ENVIRONMENT

SHAMSURGERY

days

STANDARD ENVIRONMENT

Enriched environment rearing for 17 days

TBI Early in Life Results in a Loss of Developmental Potential

Control/STD

Sham/EEFP/EE

FP/STD

# tr

ials

to

cri

teri

on

30

40

50

*

Morris water maze Average after trauma

Average after trauma and EE

Average

Giza, Griesbach and Hovda, Behav Brain Res 2005

Morris water maze performance improves after enrichment, but does NOT improve with enrichment after developmental TBI.

Group

# tr

ials

to

cri

teri

on

0

10

20and EE

Smarter after EE

Measure P19 FPIMolecular NR2A (PID4)

Phos/total CAMKII(PID4)

Electro-physiological

Evoked EPSC (PID4)

What we have: FPI and NMDARSummary

Behavioral (subacute)

NOR (PID4)

Behavioral (chronic)

MWM Trials to Criterion (PID40)

phMRI(subcute)

∆∆∆∆rCBV (evoked)(PID3-5)

The concept of excitotoxicity led to the general idea that

Ikonomidou & Turski, Lancet Neurol, 2002

However, it is increasingly apparent that GLUTAMATE

CAN ALSO BE GOOD.

led to the general idea that GLUTAMATE WAS BAD post-injury and should be blocked.

D-Cycloserine (DCS) Treatment Reverses TBI Dysfunction

30

S-SalS-highDCS FP-Sal

FP-lowDCS

FP-highDCS

ANOVA,

Hippocampal NR2A

-30

-20

-10

0

10

20

30

%ch

ange

fro

m S

-Sal

ANOVA, Overall injury effect (p<.01)Overall drug effect (p<.05)

Santa Maria N.S., et al, J Neurotrauma abst 2007

Treatment with DCS restores normal NR2A levels in rats

D-cycloserine

• NMDAR co-agonist• Binds at glycine site• FDA approved agent (for TB)• Good bioavailability• Penetrates BBB

Experimental Design:

Enriched environment rearing for 17 days

SHAMSURGERY

STANDARD ENVIRONMENT

SHAMSURGERY

days

STANDARD ENVIRONMENT

Enriched environment rearing for 17 days

D-Cycloserine (DCS) Treatment Restores post-TBI Plasticity

EE34 DCS effect on Sham groups

40

50

60

70

80

TT

5sC

SStdSal

SStdDCS

NS

NS

EE34 DCS effect on LFP groups

40

50

60

70

80

TT

5sC

FStdSal

FStdDCS

*#

One-way ANOVA* p<0.05# p=0.19

Treatment with DCS has no effect in sham rats, but given after developmental TBI, DCS improves spatial memory in adulthood preferentially in EE reared animals

0

10

20

30

40

Group

TT

5sC SStdDCS

SEESal

SEEDCS

NS

0

10

20

30

40

GroupT

T5s

C FStdDCS

FEESal

FEEDCS

Santa Maria N.S., et al., J Neurotrauma abst 2008

Measure P19 FPI DCS Molecular NR2A (PID4)

Phos/total CAMKII(PID4)

Restored NR2A (PID4)Restored phos/total CAMKII (PID4)

Electro-physiological

Evoked EPSC (PID4) -

What we have: FPI and NMDARSummary

Behavioral (subacute)

NOR (PID4) Restored NOR (PID4)

Behavioral (chronic)

MWM Trials to Criterion (PID40)

Restored MWM Trials to CriterionRestored MWM Probe Trial (PID40-50)

phMRI(subcute)

∆∆∆∆rCBV (evoked)(PID3-5)

-

Future Clinical Directions

Can we use this..

…to turn this……into this… and will it then lead to…

….this?

Summary

1. Introduction to Pediatric TBI

2. Metabolism and Metabolic Therapy

3. Neural Activation and Pro-plasticity Therapy

4. Effects of Repeated Injury in Development

5. Conclusions5. Conclusions

Concussion in juvenile rat

Post-injury day 21 hr test interval

RTBISingle TBI

APP staining at Post-injury day 1

Prins ML, et al., Dev Nsci 2010

24 hr test interval

Axonal injury and working memory impairment after repeat TBI can be modeled in rats.

Conclusions1. The developing brain has both resiliencies and

vulnerabilities to TBI.

2. The neurometabolic cascade of TBI is distinct in the young brain, and metabolic therapy with alternative substrates may be an age-specific treatment.

3. The young brain is resilient to TBI but shows altered / 3. The young brain is resilient to TBI but shows altered / impaired neural activation and plasticity.

4. Judicious use of glutamate agonists coupled with behavioral interventions can restore experience-dependent plasticity after TBI.

5. Repeated injury in the young brain can result in worse sequelae, depending upon the timing of the injuries.

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