Screening Approach for New Anti- Screening Approach for New Anti- Bipolar DrugsBipolar Drugs

By Jakob Avi ShimshoniBy Jakob Avi Shimshoni

IntroductionIntroduction

Bipolar Disorder (BD) is common, affecting approximately 1-2% Bipolar Disorder (BD) is common, affecting approximately 1-2% of the populationof the population

BD is characterized by unpredictable swings in mood from BD is characterized by unpredictable swings in mood from mania to depressionmania to depression

BD can be divided into bipolar manic-depression and unipolar BD can be divided into bipolar manic-depression and unipolar disorderdisorder

Manic episodes emerge gradually and last as long as several Manic episodes emerge gradually and last as long as several months to years when untreatedmonths to years when untreated

Frequent age of onset: 20-30 yearsFrequent age of onset: 20-30 years

Belmaker RH, N Engl J Med. 2004

Bipolar and abnormal myo-Inositol levels

In manic patients the findings suggest an increase in Inositol levels in the frontal cortexduring the manic phase and and a decrease during the depressive phase

Silverstone PH, et al., Bipolar Disorder, 2005

PIP2DAG

PLC

IP3Inositol

IP IP2

Inositol synthaseIno-1

Glucose-6-phosphate

IMPase

VPA

Li+

Drug-Therapy

First line mood-stabilizersFirst line mood-stabilizers Carbamazepine VPA LithiumCarbamazepine VPA Lithium

20-40% of bipolar patients are resistant to current drug-therapy

Severe adverse effects

N

C NH2O

Li+

Pressing need for developing better and safer mood stabilizer

Belmaker RH, N Engl J Med. 2004

Common Mechanism of Action

Increased growth cone spreading from rat dorsal root ganglia via Inositol depletion mechanism

Williams R, et al, Nature, 2002

All neurites elongate by growth at their distal end in a morphological distinct region called the growth cone

The growth cone integrates external signals acting on the growing neurite and translate them into changes in the rate and direction of growth

The Growth Cone

Harwood AJ, et al., 2004

Enlarged growth cones are often found at sites where the neurite is translocating slowly and making choices about which direction to take

Growth cones have a more narrowed, bullet-like appearance when they move more rapidly

Dorsal Root Ganglion (DRG)

DRG are composed of several thousand cell bodies of somatosensory neurons, involved in perception of pain and other stimuli

A whole rat DRG showing neuron outgrowth (x20)

Control conditions

Structure of VPA Isomers and Analogs Screened for Growth Cone Spreading Effect

COOH COOH COOH

COOH COOH

COOH CONH2

CONHCH3 CONHCONH2

COOH

CONH2

CONH2 CONH2

CONH2

VPA 4-ene-VPA 4-yne-VPA PIA

DIA VCA VPD

PID DID

VCD

TMCA TMCD

MTMCD TMCU

Structure of VPA Isomers and Analogs Screened for Growth Cone Spreading Effect

COOH COOH COOH

COOH COOH

COOH CONH2

CONHCH3 CONHCONH2

COOH

CONH2

CONH2 CONH2

CONH2

VPA 4-ene-VPA 4-yne-VPA PIA

DIA VCA VPD

PID DID

VCD

TMCA TMCD

MTMCD TMCU

Structure of VPA Isomers and Analogs Screened for Growth Cone Spreading Effect

COOH COOH COOH

COOH COOH

COOH CONH2

CONHCH3 CONHCONH2

COOH

CONH2

CONH2 CONH2

CONH2

VPA 4-ene-VPA 4-yne-VPA PIA

DIA VCA VPD

PID DID

VCD

TMCA TMCD

MTMCD TMCU

Effect of Aliphatic VPA Isomers on Growth Cone Spreading

c. 2mM LiCl

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b. 3mM VPA ***

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d.1mM PIA *

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f. 1mM DIA ***

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QuickTime and aªTIFF (LZW) decompressor

are needed to see this picture.

QuickTimeª and aTIFF (LZW) decompressor

are needed to see this picture.

QuickTime and aªTIFF (LZW) decompressor

are needed to see this picture.

3mM VPA

1mM PIA 1mM DIA

myo-Inositol Reversal of Growth Cone Spreading

a. Control

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e. 1mM PIA+2mM Inositol

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d.1mM PIA *

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QuickTimeª and aTIFF (LZW) decompressor

are needed to see this picture.

1mM PIA

1mM PIA + 2mM Inositol

Effect of VPA Amide Derivatives on Growth Cone Spreading

a. Control

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b. 3mM VPA ***

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c. 3mM VPD

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d. 3mM DID

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e. 3mM PID

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QuickTimeª and aTIFF (LZW) decompressor

are needed to see this picture.

3mM VPA

QuickTime and aªTIFF (LZW) decompressor

are needed to see this picture.

3mM VPD

QuickTime and aªTIFF (LZW) decompressor

are needed to see this picture.

3mM DID

QuickTime and aªTIFF (LZW) decompressor

are needed to see this picture.

3mM PID

Effect of VPA Cyclopropyl Analogs on Growth Cone Spreading

a. Control

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b. 3mM VPA ***

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c. 3mM TMCA

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d. 3mM TMCD

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e. 1mM TMCU

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f. 1mM MTMCD *

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QuickTime and aªTIFF (LZW) decompressor

are needed to see this picture.

3mM VPA

QuickTime and aªTIFF (LZW) decompressor

are needed to see this picture.

3mM TMCA

QuickTime and aªTIFF (LZW) decompressor

are needed to see this picture.

3mM TMCD QuickTimeª and aTIFF (LZW) decompressor

are needed to see this picture. 3mM TMCU QuickTimeª and aTIFF (LZW) decompressor

are needed to see this picture.1mM MTMCD

The Cytoskeleton and Growth Cone Morphology

Neuronal morphology and growth cone motility are both dependent on the actin microfilaments and microtubules

acetylated-tubulin (green)

2 mM Lithium

cytoplasm (calcein blue)

Untreated

Li+ and VPA increase growth cone spreading

3 mM VPA

β-Catenin

HDACsVPA

GSK3Li+

Gene Expressionchanges which can

lead to Teratogenicity

Other Molecular Targets of VPA and Lithium

Phiel JC, J Biol Chemistry, 2001

Screening for Wnt Pathway Modulators

QuickTime and aªTIFF (LZW) decompressor

are needed to see this picture.

QuickTime and aªTIFF (LZW) decompressor

are needed to see this picture.

QuickTime and aªTIFF (LZW) decompressor

are needed to see this picture.

X

De repression by VPA

Testing VPA Derivatives and Analogues for TCF-Promotor Activity Stimulation

Conclusions

• Branching at C-2 of VPA and the derivatization by methylamine of the COOH group of TMCA intensified the growth cone spreading effect

• The potent VPA derivatives and analogs, PIA, DIA and MTMCD, do not stimulate TCF promoter activity, and therefore may regarded as non teratogenic

• The growth cone spreading effect of PIA, DIA and MTMCD is GSK3 independent

Present Research ProjectPresent Research Project

Elucidating the mechanisms underlying the growth cone Elucidating the mechanisms underlying the growth cone spreading effect of the mood stabilizersspreading effect of the mood stabilizers

GAP43 stained GC after VPA treatment

Actin and Microtubule stained GC after VPA treatment

Cardiff University

Prof. Adrian HarwoodProf. Adrian Harwood

Emma DaltonEmma Dalton

Prof. Trevor DaleProf. Trevor Dale

Dr. Ken EwanDr. Ken Ewan

Dr. Jonathan RyvesDr. Jonathan Ryves

Members of Harwood Members of Harwood and Dale Laband Dale Lab

Acknowledgements

Hebrew University of Jerusalem,

Israel

Prof. Meir Bialer

Prof. Boris Yagen