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Transcript of Neurotransmitter Transporters and Flies: Tools to Study Behavior and Disease David Krantz MD, PhD...
![Page 1: Neurotransmitter Transporters and Flies: Tools to Study Behavior and Disease David Krantz MD, PhD Department of Psychiatry & Biobehavrioal Sciences David.](https://reader038.fdocuments.net/reader038/viewer/2022103015/5519d5a2550346443e8b4c0d/html5/thumbnails/1.jpg)
Neurotransmitter Transporters and Flies:Tools to Study Behavior and Disease
David Krantz MD, PhD
Department of Psychiatry & Biobehavrioal Sciences
David Geffen School of Medicine at UCLA
Gonda (Goldschmied) Center for Neuroscience and
Genetics Research
![Page 2: Neurotransmitter Transporters and Flies: Tools to Study Behavior and Disease David Krantz MD, PhD Department of Psychiatry & Biobehavrioal Sciences David.](https://reader038.fdocuments.net/reader038/viewer/2022103015/5519d5a2550346443e8b4c0d/html5/thumbnails/2.jpg)
Overview
• What are neurotransmitter transporters?
• How do changes in their function affect the nervous system?
• Why use flies to study them?
![Page 3: Neurotransmitter Transporters and Flies: Tools to Study Behavior and Disease David Krantz MD, PhD Department of Psychiatry & Biobehavrioal Sciences David.](https://reader038.fdocuments.net/reader038/viewer/2022103015/5519d5a2550346443e8b4c0d/html5/thumbnails/3.jpg)
Cell 2
Neurotransmitters are chemicals that allow cells to communicate
Cell 1
Receptors S y
n a
p s
e
Neurotransmitter
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Neurotransmitter types
• Monoamines– Dopamine, Serotonin, Norepinephrine,
Epineprine (Adrenalin)
• Actetylcholine• GABA• Glutamate
(Peptides, Gases- not today)
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Plasma membrane and vesicular transporters
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Why do neurotransmitters need transporters?
• Oil and water don’t mix• Transmitters like to be in
water• Cell and organelle
boundaries are oily• Transporters bridge the
water pools
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Plasma Membrane Neurotransmitter Transporters
Bröer S Br J Pharmacol. 2012 167, 256.
-Monoamine transporters are part of one gene family
-GABA and glutamate transporters are in other families
DopamineDAT
NoradrenalineNET
SerotoninSERT
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Mammalian Vesicular Transporters
VMAT2 in all aminergic brain cells
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Focus on Monoamine Neurotransmitters
NoradrenalinAttention
Blood pressure
HistamineGastric acid release
Immune response
DopamineReward
SerotoninAppetite,Mood
Gastrointestinal motility
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Dopamine transporterSerotonin “ “Norepi. “ “
Monoamine Transporters the Major Drug Targets for Stimulants and Antidepressants
Vesicular monoamine Transporter
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Dopamine transporterSerotonin “ “Norepi. “ “
Blockade of Plasma Membrane Amine Transporter Increases Extracellular Neurotransmitter
CocaineRitalin ProzacWellbutrinZoloft
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Dopamine transporterSerotonin “ “Norepi. “ “
Amphetamines Reverses the Flow(Mechanism is complex)
AmphetaminesMethamphetaminesAdderall- ADHD
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Vesicular monoamine Transporter (VMAT2)
Vesicular Transporters are Drug Targets
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Vesicular monoamine Transporter (VMAT)
Block VMAT with reserpine: Decreases monoamine storage and thus release-Antihypertensive effects-Depression
Reserpine
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What would happen if VMAT worked better? Or there was more of it?
Could that change behavior? Act as a stimulant? Antidepressant?
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Increases monoamine release
• Force cells to make more VMAT
• Record amine release• More amines comes out of
each vesicle• (Vesicles get a little bigger)
Sulzer labPothos et al, J. Neurosci. 2000
More VMAT in vitro:
“Normal cells”
Extra VMAT
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What about more VMAT in vivo?
-No in vivo mammalian models
-Make fly model
-Why use flies?
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Why use flies?
-Cheap! (good for teaching!)
-”Conservation” of genes e.g. VMAT, DAT
-Cool genetic tools e.g. to make more VMAT
-Short life span
Genetic experiments in a month!
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How can we tell if there are more extracellular monoamines in flies? -Look at their known functions
DopamineGrooming
Locomotion
Serotonin Aggression
OctopamineEgg layingLocomotion
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How can we tell if there are more extracellular monoamines in flies? -Look at their known functions
DopamineGrooming
Locomotion
Serotonin Aggression
OctopamineEgg layingLocomotion
Stimulants as positive control
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DVMAT overexpression in vivomimics the effects of stimulants
Locomotion GroomingChang et al 2006
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A New Way to Increase Extracellular Amines
WellbutrinProzacRitalin Adderall
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Could we find a drug the would make VMAT work better?
Or just increase exocytosis of monoamines?
Could this be used to treat ADHD? depression? Parkinson’s disease?
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Antidepressants and stimulantsSome mechanisms not exploited
Amine agonist
Activate VMAT Increase exocytotic release
Block reuptake.degradation
CurrentDrugs:
No CurrentDrugs:
VMAT
neuronAminergic
Receptor
Amphetamines cause efflux, not exocytotic release
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To find drugs that might make VMAT work better…First make it work worse! Use dVMAT mutant
“Sensitized genetic background” detects drug effects better than wild type
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Primary ScreenTest drugs in dVMAT mutant
1 2 3
4 5 6
1 2 4 5 6Drug: 3 ..1042
Mix into food, Allow larvae to feed, record movement
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Example of Primary Screen Data
Number of grids crossed by P/P; UAS-VMAT. Screen on Drugs 105-122 (2A5-2B7)
0
1
2
3
4
5
6
7
2A
5-H
2A
5-L
2B
5-H
2B
5-L
2C
5-H
2C
5-L
2D
5-H
2D
5-L
2E
5-H
2E
5-L
2F
5-H
2F
5-L
2G
5-H
2G
5-L
2H
5-H
2H
5-L
2A
6-H
2A
6-L
VE
H
2B
6-H
2B
6-L
2C
6-H
2C
6-L
2D
6-H
2D
6-L
2E
6-H
2E
6-L
2F
6-H
2F
6-L
2G
6-H
2G
6-L
2H
6-H
2H
6-L
2A
7-H
2A
7-L
2B
7-H
2B
7-L
VE
H
0 hr Ave
2 hr Ave
24 hr Ave
-Select drugs that cause 3-4 SDs above the mean-40 hits out of 1042 drugs-3 time points, 2 concentrations, 7 undergrads, 5 months
Lawal et al, 2012
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Dacarbazine was one of the “hits” in the screen
• Chemotherapeutic agent– Alkylating agent
• Induces emesis via serotonin release– Supports fly data
• Toxicity could be a problem– Limits use
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Parse toxic vs. active bitswith derivatives
Dacarbazine AICA
MethdiazoniumDNA alkylation
AICA: Amino-4-imidazole-carboxamide Removes the toxic bit
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AICA also stimulates larval locomotion
Dacarbazine AICA
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How does Dacarbazine/AICAIncrease Locomotion?
• Increase Storage? • Increase Release?• Other mechanisms?• Collaborate with Nigel Maidment’s lab
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Potential Clinical Relevance
AICA derivatives for ADHD? Depression? Parkinson’s disease?
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• What are neurotransmitter transporters?
• Why use flies to study them? • How do changes in their function affect
the nervous system?
![Page 34: Neurotransmitter Transporters and Flies: Tools to Study Behavior and Disease David Krantz MD, PhD Department of Psychiatry & Biobehavrioal Sciences David.](https://reader038.fdocuments.net/reader038/viewer/2022103015/5519d5a2550346443e8b4c0d/html5/thumbnails/34.jpg)
Questions?