Synaptic Plasticity

Question 1

Evidence of depression following enhancement

Answer 1

PSP generation at high, medium and low calcium concentrations

Question 2

Where are Munc13 and synaptotagmin involved

Answer 2

Synaptotagmin: prepares vesicular release- involved in Facilitation

Munc13-1: depression
Munc13-2: augmentation/potentiation

Question 3

Munc13-1 role evidence

Answer 3

Munc13-1 KO evidence
Reduced depression after EPSCs/ IPSCs generated

Knock in of Calmodulin-insensitive Munc13-1 in mice
Reduced vesicle recovery time (presynaptic membrane capacitance and AMPAr mediated EPSCs)
Slower recovery from depression
Is a similar response to CaM inhibition in KOs

Question 4

Munc13-2 role evidence

Answer 4

Munc13-2 KO
Reduced ability to induce augmentation
Rescue restored some augmentation

Mutant CaM insensitive 13-2 (W387R)
-Showed no augmentation

Question 5

Calcium-sensitive domains of P/Q channels: role

Answer 5

IM Domain: facilitation and potentiation

CBD Domain: Depression

Question 6

IM domain role evidence

Answer 6

Mutated IM domain shows reduced induction of facilitation and potentiation
-At low calcium levels, Ca2+ interacts with IM to induce P/Q channel activity

Question 7

CBD domain role evidence

Answer 7

Mutated CBD domain shows no induction of depression

• At high calcium levels, Ca2+ interacts with CBD to reduce P/Q channel activity
• Not limited by vesicle release upon HFS

Question 8

Theory of multiple mechanisms of Short term plasticity (Cheng 2008)

Answer 8

Deletion of both Calcium sensitive domains still leaves some enhancement and depression
There may be other factors which contribute to control

Question 9

Hippocampal model of plasticity

Answer 9

Prolonged stimulation of perforant path

• Elevated EPSP production in CA1 maintained for 3 hours
• NMDA antagonist APV blocked

Question 10

NMDA independent LTP in Hippocampal mossy fibres

Answer 10

Mossy fibres (Dentate gyrus granule cells project to CA3 pyramidal cells)
Lack NMDA receptors, glutamate acts upon mGluRs and Kainate receptors
Presynaptic calcium entry directly increases cAMP
R type channels may mediate this effect (blocking P/Q does nothing)

Question 11

Synaptic enlargement over time

Answer 11

Spines increase in size, produce increased EPSPs

Question 12

Changes in AMPA subunit expression

Answer 12

Induction: mGluR1 homomers
- Greater inward current- naturally blocked by polyamine

Over time: replaced by mGluR1/mGluR2 heteromers
- Greater outward current (mGluR2 prevents influx)

Question 13

LTP in inhibitory synapses

Answer 13

HFS IPSPs generated
Calcium and NMDA dependent
Not GABA dependent

Question 14

Nitric oxide as a second messenger and opioids

Answer 14

Inhibition of synthesis (L-NAME)
Stimulation of synthesis (SNAP)

Opioids prevent IPSC administration
Upstream of cGMP production (administration reduces this effect)

Question 15

Nitric oxide in alzheimers disease

Answer 15

Early AD
Increased vesicle release (EPSPSs)
L-NAME abolishes late LTP and reduces pre-pulse facilitation

Late AD
NO forms reactive oxygen species which are implicated in AD, depleting vesicular pools/reserves and accelerating disease progression

Question 16

mGluR dependent LTD

Answer 16

Presynaptic- mGluR2
Decreases cAMP, common in mossy fibres/cerebellum

Post-synaptic- mGluR2

Question 17

Endocannabinoid and downstream effects

Answer 17

Agonism (WIN) and Antagonism (AM251) of CB1 receptors

CB1: induces LTD by activating PKA/cAMP
Reduced mIPSCs when PKA antagonised
Targets RIM-alpha (synaptic release machinery)
RIM-A KO reduces inhibitory LTD production

Question 18

TRPV1 mediated LTD

Answer 18

Capsacin
Antagonism/ KOs reduced effect

Calcineurin dependent
-Blocked by Cyclosporin A

Question 19

12-S-HPETE role

Answer 19

Potential natural agonist of TRPV1

-KO/Antagonism

Question 20

Optogenetic fear pairing and memory

Answer 20

Shock paired with sound, also with optogenetic stimulation
Training reduces lever presses
Optogenetic LTD- increased lever presses (mice forget)
Optogenetic LTP- reduced lever presses (mice remember again)

Question 21

Anisomycin and Actinomycin

Answer 21

Asinomycin (protein synthesis inhibitor)
Prevents initial EPSP spike but is maintained

Actinomycin (mRNA synthesis inhibitor)
EPSP spike but not maintained

Question 22

Initiation factors role

Answer 22

Phosphorylation of eif21s1 by DHPG induces LTD

Mutation of phosphorylation site Ser-Ala prevents this

Question 23

Synaptic tagging theory

Answer 23

Staufen staining- colocalises mRNA with actin

Question 24

CREB action

Answer 24

Forskolin (cAMP agonist)
Western blot increased pCREB with KCl

Fear shock conditioning LaCZ (B-galactoside reporter)
Morris Water Maze KOs reduced performance

Question 25

BDNF and CREB

Answer 25

BDNF- growth of inhibitory synapses Mutation of CREB binding site - reduced CREB/RNA Pol II binding - reduced mRNA and glut - less staining of GABAergic synapses/ colocalisation of markers (GAD65, VGAT)

Question 26

NFAT role

Answer 26

CaN activated Dopamine agonist increases NFAT activity (Luciferase) Nifedipine decreases NFAT activity (Luciferase) Enhances GluR2 expression - Increased luciferase activity in constitutively active mutant - Increased AMPA current - mutant glur2 reduced activity

Question 27

Cocaine and NFAT | Other cocaine effects

Answer 27

Increased NFATc4 translocation in cocaine use (western blot) Due to increased dopaminergic activation in striatum Increases H3K9 methyltransferase expression- increased gene expression

Question 28

DNA methylation evidence

Answer 28

DNMT inhibitor (Zebularine)- reduced LTP ``` Fear conditioning- reduces PPI methylation Inhibiting methylation (Zebularine) reduces fear conditioning response ``` Reelin methylation reduced in response to fear conditioning Methylation in hippocampus reverts to baseline after 24h

Question 29

Histone acetylation evidence

Answer 29

Fear conditioned mice- increased acetylation (Western blot) HDAC2 O/E Morris Watermaze test performance reduced, less LTP HDAC2KO/ Inhibition (Trichostatin A)

Question 30

HDAC and alzheimers

Answer 30

APP overexpression model increased HDAC2 Sodium butyrate (inhibitor) restores function Improved memory in WTs P25 OE: HDAC2 KOs similar to WTs in Morris water maze/fear conditioning

Question 31

HDAC4

Answer 31

Class 2a HDAC Represses genes (neurotransmission, AMPA receptor trafficking) involved in synaptic transmission Mutation assc. with Bradydactyly Mental retardation; cerebellar and visual neurodegeneration

Question 32

Histone H2A.Z subunit exchange

Answer 32

Presence of H2A.Z subunit appears to negatively affect plasticity - Fear conditioning: reduced h2afz gene expression - Depletion of H2A.Z in rats using AAV improved fear conditioning - Restrictive effect on memory creation

Question 33

Histone methylation

Answer 33

H3K4 increases expression H3K9 decreases expression fear conditioning performance