Chapter 6: Neurotransmitter Systems

Question 1

3 criteria for deciding if a substance acts as a neurotransmitter

Answer 1

1. synthesis and storage in presynaptic neuron
2. released by presynaptic neuron axon terminal upon stimulation
3. elicits a cell response similar to that of known NTs (when applied to a postsynaptic terminal

Question 2

ways to localize transmitters and transmitter-synthesizing enzymes for study

Answer 2

1. immunocytochemistry
2. immunohistochemistry

Question 3

Antibodies detect special proteins/peptides via their ()

Answer 3

specific binding sites

Question 4

2 classes of antibodies

Answer 4

1. monoclonal
2. polyclonal

Question 5

the first step of immunostaining

Answer 5

fixation

Question 6

why is fixation important

Answer 6

1. prevent autolysis and bacterial attack
2. preserve volume and shape during tissue processing
3. allow clear staining of sections
4. prevent loss of small molecules during washing stages

Question 7

Most fixation reagents () -> inactivates most of the enzymes and fixes the structure of proteins inside cell

Answer 7

cross-link proteins

Question 8

3 types of tissue sectioning for fixation

Answer 8

1. paraffin-embedded
2. cryosection
3. vibratome

Question 9

this type of tissue sectioning is useful for live or thick tissues

Answer 9

vibratome

Question 10

localizes synthesis of protein or peptide to a cell by detecting mRNA

Answer 10

in situ hybridization

Question 11

a model to study CNS neurons to check for NT release upon stimulation

Answer 11

brain slice

Question 12

summary of how brain slice is used to study NT release

Answer 12

Brain slice is kept alive in vitro -> stimulate synapses, collect and measure released chemicals

Question 13

because using brain slice has its cons, new methods such as () have been widely used to probe specific transmitter release

Answer 13

optogenetics

Question 14

a method to assess postsynaptic actions by ejecting (small amt) candidate molecules from micropipette; postsynaptic response is measured by microelectrode

Answer 14

microiontophoresis

Question 15

3 ways to determine NTR subtypes

Answer 15

1. neuropharmacological analysis of synaptic transmission
2. ligand-binding methods
3. molecular analysis of receptor proteins

Question 16

in neuropharmacological analysis, () are used to define receptor subtypes

Answer 16

agonists and antagonists

Question 17

2 subtypes of ACh receptors

Answer 17

1. nicotinic
2. muscarinic

Question 18

antagonist of nicotinic ACh receptor

Answer 18

curare

Question 19

antagonist of muscarinic ACh receptor

Answer 19

atropine

Question 20

nicotinic ACh receptors are localized in the (1), while muscarinic ACh receptors are localized in the (2)

Answer 20

1. skeletal muscle
2. heart

Question 21

Glutamate receptors have 3 subtypes (based on agonists):

Answer 21

1. AMPA (alpha-amino-3-hydroxyl-5-methyl-4-isoxazolepropinate)
2. NMDA (N-methyl-D-aspartate)
3. Kainate

Question 22

in ligand-binding methods, Identify natural receptors using ()

Answer 22

radioactive ligands

Question 23

how were opiod receptors found

Answer 23

Radioactively labeled opiate compounds and applied them to neuronal membranes from brain tissues

Question 24

() are involved in pain relief, euphoria, depressed breathing and constipation

Answer 24

Opioid receptors

Question 25

types of receptor protein classes

Answer 25

1. transmitter-gated ion channels 2. G protein-coupled receptors

Question 26

what is Dale's principle

Answer 26

a neuron has only 1 neurotransmitter

Question 27

Two or more transmitters released from one nerve terminal

Answer 27

co-transmitters

Question 28

the usual case for co-transmitters is:

Answer 28

peptide + (amino acid/amine)

Question 29

Only () neurons have ChAT (choline acetyltransferease)!

Answer 29

cholinergic

Question 30

precursor for three amine neurotransmitters that contain catechol group

Answer 30

tyrosine

Question 31

the 3 amine NTs that arise from tyrosine

Answer 31

1. dopamine 2. norepinephrine 3. epinephrine

Question 32

enzyme that converts tyrosine into dopamine precursor; activity of this enzyme is the rate-limiting step for catecholamine synthesis

Answer 32

tyrosine hydroxylase

Question 33

there is no fast extracellular degenerative enzyme for catecholamines; instead, catecholamine levels are reduced by selective uptake of the neurotransmitters back into the axon terminal via ()

Answer 33

Na+-dependent transporters

Question 34

(1) and (2) block catecholamine uptake.

Answer 34

1. Amphetamine 2. cocaine

Question 35

Serotonin, aka (1) is an amine neurotransmitter derived from (2)

Answer 35

1. 5-HT 2. tryptophan

Question 36

() are used as antidepressants becuase serotonin regulates mood, emotional behavior and sleep

Answer 36

Selective serotonin reuptake inhibitors (e.g. Prozac)

Question 37

Key enzyme in GABA synthesis; Good marker for GABAergic neurons

Answer 37

glutamin acid decarboxylase (GAD)

Question 38

GABAergic neurons are major source of () in the CNS.

Answer 38

synaptic inhibition

Question 39

ATP excites some neurons and binds to ()

Answer 39

purinergic receptors

Question 40

a small lipid molecule that serve as one of the retrograde messengers

Answer 40

endocannabinoids

Question 41

endocannabinoids bind to (), which blocks presynaptic calcium channel suppressing either the inhibitory and excitatory drive onto the neurons

Answer 41

CB1 receptor

Question 42

basic structure of transmitter-grated channels: ACh receptors

Answer 42

pentamer (5 protein subunits) form a pore

Question 43

subunits of nicotinic ACh receptor at NMJ

Answer 43

2alpha, beta, gamma, delta

Question 44

subunits of muscarinic ACh receptor in CNS neuron

Answer 44

3 alpha, 2 beta

Question 45

Each subunit of a transmitter-gated ion channel has (1) alpha-helical transmembrane domains (labeled 2)

Answer 45

1. 4 2. M1-4

Question 46

in contrast to pentamer ACh-gated channels, glutamate receptors are (1), and the (2) region in its subunits forms a hairpin that both enters and exits from the inside of the membrane

Answer 46

1. tetramers 2. M2

Question 47

among the glutamate-gated channels, (1) and (2) coexist in most postsynaptic membranes and mediate the bulk of fast excitatory synaptic transmission;

Answer 47

1. AMPA 2. NMDA

Question 48

AMPA and NMDA receptors contribute to EPSPs via presynaptic ()

Answer 48

glutamate release

Question 49

the () subtype of glutamate receptors are present in most pre- and postsynaptic membranes, but their functions are not clearly understood

Answer 49

Kainate

Question 50

the AMPA receptor is permeable to ()

Answer 50

Na and K

Question 51

the NMDA receptor is permeable to ()

Answer 51

Na, K, and Ca

Question 52

both (1) and (2) must coincide for voltage-dependent NMDA activation.

Answer 52

1. glutamate release 2. depolarization

Question 53

mediates non-GABA synaptic inhibition

Answer 53

glycine-gated channels

Question 54

GABA-gated and glycine-gated channels are mostly permeable to (1) ions, thus resulting in strong (2) to suppress neural activity

Answer 54

1. negative ions (Cl-) 2. IPSP

Question 55

3 steps in transmission of activation in G protein-coupled receptors

Answer 55

1. Binding of the neurotransmitter to the receptor protein 2. Activation of G-proteins 3. Activation of effector systems

Question 56

Basic structure of G-protein-coupled receptors (GPCRs)

Answer 56

Single polypeptide with 7 membrane-spanning alpha-helices

Question 57

G protein is short for ()-binding protein

Answer 57

guanosine triphosphate (GTP)

Question 58

the shortcut pathway of G protein-coupled effector systems

Answer 58

From receptor to G-protein to ion channel—fast and localized (no amplification)

Question 59

in (), the activation of GPCR couples neurotransmitter with downstream enzyme activation

Answer 59

second messenger cascades

Question 60

different G-proteins stimulate or inhibit adenylyl cyclase

Answer 60

push-pull method

Question 61

Stimulatory G proteins (Gs) bind to stimulatory () receptors

Answer 61

beta

Question 62

Inhibitory G proteins (Gi) bind to inhibitory () receptors

Answer 62

alpha

Question 63

GPCR activation of () is an example of where a signal cascade branches

Answer 63

phospholipase C (PLC)

Question 64

when activated by the G_alpha subunit, phospholipase C splits into 2 effectors ()

Answer 64

1. IP3 2. DAG

Question 65

() from PLC binds to Ca2+ channel on SR to release Ca2+ for activate calmodulin kinase

Answer 65

IP3

Question 66

() from PLC can activate protein kinase C (PKC)

Answer 66

DAG

Question 67

() activate proteins by phosphorylation

Answer 67

Protein kinases

Question 68

() inactivate proteins by dephosphorylation

Answer 68

Protein phosphatases

Question 69

the function of signal cascades allows for () by GPCRs

Answer 69

signal amplification

Question 70

One transmitter activates more than one receptor subtype -> greater postsynaptic response

Answer 70

divergence

Question 71

Different transmitters converge to affect same effector system; ensures more correct and precise signaling cascade thru multiple NTs

Answer 71

convergence