CNS Synases And Neurotransmitters

Question 1

NT across a synaptic cleft

Apposition of axon terminal to a postsynaptic structure

Answer 1

Chemical synapses

Question 2

Gap junctions

Direct passage of current

Answer 2

Electrical synapses

Question 3

Presynaptic and post synaptic membranes contain theses which are critical to synapse formation and activity-induced structural plasticity

Answer 3

Cell adhesion molecules (transmembrane proteins) that bridge the synapse

Question 4

Do all dendrites have spines

Answer 4

No

Question 5

What is critical to synapse formation and plasticity?

Answer 5

Cell adhesion molecules span the synapse

Question 6

Through these protein-protein interactions, synaptic NT can lead to structural and functional changes to the synapses

Answer 6

Postsynaptic receptors are coupled to scaffolding proteins which then link to cytoskeletal proteins

Question 7

Overview of the path of NT

Answer 7

-neurotransmitter synthesis (precursor entering the cell)
-vesicular transport (NT packed into synaptic vesicles and made outside and brough into vesicle)
-postsynaptic receptor
-NT binds to specific receptor and has excitatory or inhibitory response
-release-modulating autoreceptor (regulate terminal that have inhibitory effect on release of NT)
-NT can leak out of cleft
-clearance by astrocytes transporter
(Cleans up left over NT)

Question 8

Enzymatic synthesis of NT

Answer 8

Enzymes (and empty synaptic vesicles) must be axonally transported from soma to terminal

Question 9

Local synthesis of NT in axon terminals by enzyme located either…..

Answer 9

In cytoplasm or inside synaptic vesicles

Question 10

If NT synthesized in cytoplasm, needs tranlocated unto synaptic vesicle by what

Answer 10

Selective transporter protein in vesicular membrane

Question 11

Where are neuropeptides transcribes and translated?

Answer 11

In soma and modified in the Golgi

Question 12

Axonal transport of neuropeptides

Answer 12

Transport of neuropeptide-containing vesicle to terminals

Question 13

NT synthesis Is followed by sequestration into vesicles how?

Answer 13

Protein pump: ATP-dependent

Flow down EC gradient
The H+ going down the gradient supplies the energy

Question 14

Exceptions to NT sequestration into vesicles

Answer 14

• some NT synthesized by enzymes located inside synaptic vesicles from precursor molecules that must be sequestered by the vesicular membrane transporter
• neuropeptides transmitters are synthesized and sequestered in the soma, then vesicles undergo anterograde axonal transport to terminal

Question 15

Vesicles at rest

Answer 15

Few are already docked at active zone, most vesicles are tethered by actin and not yet docked

Question 16

Vesicles after AP and Ca++ influx

Answer 16

• Ca influx allows NT release by pre-docked vesicles
• Ca influx causes actin filament to de-polymerize, dis-associate from vesicles dock, fuse, and release, vesicles are recycled

Question 17

Ionotropic post synaptic receptor

Answer 17

Ion channel

Question 18

Metabotropic post synaptic receptor

Answer 18

Coupled to 2nd messengers, usually G protein

Question 19

Classical small molecule NT

Answer 19

• Ach
• amino acid NT
• biogenic amines
• indolamines

Question 20

Examples of amino acid NTs

Answer 20

• glutamate
• GABA
• histamine

Question 21

Major excitatory NT in CNS

Answer 21

Glutamate

Question 22

Y-aminobutryic acid, major inhibitory NT in CNS

Answer 22

GABA

Question 23

Some neurons in hypothalamus, involved in wakefulness

Answer 23

Histamine

Question 24

What are some biogenic amines

Answer 24

Cathecholamines

• dopamine
• norepi
• epi

Question 25

Example of indolamine

Answer 25

Serotonin

Question 26

What are monoamines?

Answer 26

All biogenic amines and indolamines - dopamine - norepi - epi - serotonin

Question 27

Neuropeptidess in CNS

Answer 27

-substance P (peripheral nerves, spinal cord, pain related) -endogenous opiates (enkephalins, dynorphins, B-endorphin) -orexin aka hypocretin (hypothalamus, regulates hunger and sleep) Hypothalamic peptide hormones (function elsewhere in CNS as NT

Question 28

Neuropeptides of the CNS distribution

Answer 28

Have limited neuroanatomical distributions and specific functions (sleep/wake cycle, hunger, stress response, emotional/cognitive role, social behavior)

Question 29

Released from postsynaptic neuron and acts on PREsynaptic neuron to regulate NT release

Answer 29

Retrograde messengers

Question 30

Some neuro chemicals mediate retrograde transmission this way

Answer 30

- synthesized and released by post neuron (non vesicular) - bind specific receptors or other targets in PRE neuron - regulate NT release, usually SUPPRESS release

Question 31

Examples of retrograde messengers

Answer 31

- endocannabinoids (brains own marijuana) - NO - CO

Question 32

What are the two precursor molecules for Ach?

Answer 32

Choline | Acetyl Co-A

Question 33

Where do you get choline

Answer 33

Both dietary and recycled

Question 34

Where do you get acetyl Co-A

Answer 34

Mitochondria

Question 35

What breaks down Ach

Answer 35

Acetylcholinesterase

Question 36

ChAT

Answer 36

Choline acetyltransferase

Question 37

Choline deficiency

Answer 37

If poor nutrition, critical to brain development especially for mother and fetus

Question 38

What all pathways in the brain use Ach?

Answer 38

A LOT | -Cranial motor nuclei III and X

Question 39

In CNS, neurons located in

Answer 39

Forebrain and midbrain regions

Question 40

Functional significant of neurons located in forebrain and midbrain regions

Answer 40

- regulates cognitive functions - reward seeking behavior - arousal/alertness/consciousness - sleep cycle

Question 41

Major excitatory NT in the CNS, especially in projection neurons. Ubiquitous (potent)

Answer 41

L-glutamate

Question 42

Functional significance of L-glutamate

Answer 42

- involved in virtually all functions - neuronal plasticity - learning/memory

Question 43

Glutamate excitotoxcicity

Answer 43

Mechanism implicated in a range of neurodegenerative disorders, stroke, traumatic brain injury

Question 44

What are the primary sources of glutamate

Answer 44

2 from mitochondria | 1 from astrocytes

Question 45

What kind of receptors does L-glutamate use

Answer 45

Ionotropic - AMPA or kainate - NMDA

Question 46

What kind of receptors are AMPA, kainate, and NMD?

Answer 46

Ionotropic

Question 47

AMPA

Answer 47

- ionotropic - ligand gated - Na+, K+ - L glutamate

Question 48

Kainate

Answer 48

- ionotropic receptor - ligand gated - Na+ K+ - L-glutamate

Question 49

NMDA

Answer 49

- ionotropic - ligand gates - Na+, K+, Ca2+ - L glutamate

Question 50

Key role in regulating neuronal excitability, morphological plasticity, and learning/memory

Answer 50

AMPA glutamate receptors

Question 51

Key mechanism for regulating neuronal excitability and synaptic plasticity-critical for learning and memory

Answer 51

Receptor trafficking to and from post synaptic membrane

Question 52

________ influx promote insertion of MORE AMPA receptors

Answer 52

EPSPs and Ca++

Question 53

_______ can induce removal AMPA receptors, creating silent synapses

Answer 53

Lack of stimulation or IPSPs

Question 54

Changes to neuronal excitability

Answer 54

Tend to be long lasting and slow to reverse

Question 55

Role of NMDA receptor

Answer 55

Amplifier of excitation

Question 56

Roles of NMDA as Ca++ channel

Answer 56

Amplifies depolarization | Key for synaptic plasticity

Question 57

Receptor mechanism of NMDA receptor

Answer 57

- voltage gated and ligand gated - at resting potential: Mg++ block - depolarization releases Mg++ block and allows Ca++ influx as well as Na+/K+

Question 58

Abused drugs that are NMDA antagonists

Answer 58

PCP | Ketamine

Question 59

Over activation of NMDA receptor

Answer 59

Can be toxic! | Too much intracellular Ca++

Question 60

Overactive glutamate and calcium can lead to what

Answer 60

Deficient synaptic clearance, necrosis, apoptosis