04a: NT and Neuromodulators

Question 1

List the three main types of signal transduction pathways in plasma membrane receptors.

Answer 1

1. Ligand-gated channel (ionotropic)
2. G-Protein with second messenger production
3. G-protein with control of ion channel

Question 2

G-Proteins can couple receptor to:

Answer 2

1. Ion channel

2. Effector protein

Question 3

G(s) is activated. What’s its immediate effect?

Answer 3

Activates adenylyl cyclase

Question 4

Adenylyl cyclase is activated by which specific G-protein? What’s AC’s function?

Answer 4

G(s);
Produces cAMP (second messenger) from ATP

Question 5

cAMP action is terminated by (X).

Answer 5

X = hydrolysis via PDE

Question 6

G(c) is activated. What’s its immediate effect?

Answer 6

Activates guanylyl cyclase

Question 7

Guanylyl cyclase is activated by which specific G-protein? What’s GC’s function?

Answer 7

G(c);

Produces cGMP

Question 8

G(i) is activated. What’s its immediate effect?

Answer 8

Inhibits adenylyl cyclase

Question 9

G(q) is activated. What’s its immediate effect?

Answer 9

Activates PLC

Question 10

PLC is activated by which specific G-protein? What’s PLC’s function?

Answer 10

G(q);

Produces second messengers (IP3 and DAG)

Question 11

Odorants activate (X), which causes (increase/decrease) in (Y), which causes (increase/decrease) in (Z). Hence, (de/re/hyper)-polarization of olfactory receptors.

Answer 11

X = G(olf) G-protein
Increase;
Y = cAMP concentration;
Increase;
Z = permeability to Na and Ca
Depolarization

Question 12

List mechanisms that cause cessation of activity caused by G-proteins.

Answer 12

1. 2nd messengers inactivated
2. Phosphorylation/altering of receptors (less affinity for ligand)
3. Receptor-NT complexes removed via endocytosis

Question 13

List the biogenic amines.

Answer 13

1. NE
2. Serotonin
3. DA
4. Histamine

Question 14

List two examples of catecholamines.

Answer 14

NE and DA

Question 15

Enkephalin falls into which NT category? Name another NT that belongs in this category,

Answer 15

Neuroactive (Opioid) peptides

Endorphins

Question 16

List some gases that act as NT.

Answer 16

NO and CO

Question 17

List purines that act as NT.

Answer 17

ATP and adenosine

Question 18

Somatic NS uses (X) NT receptor. Its activation causes

Answer 18

X = nicotinic ACh

Increase in gNa, gK, gCa (depolarization)

Question 19

Binding of (X) to D1 receptors causes (increase/decrease) in which ion/messenger?

Answer 19

X = DA;

Increase in cAMP through G(s)

Question 20

Binding of (X) to D2 receptors causes (increase/decrease) in which ion/messenger?

Answer 20

X = DA

Decrease in cAMP through G(i)

Question 21

Which NT is considered the messenger for pleasure and reward?

Answer 21

DA

Question 22

Cocaine (stimulates/inhibits) the reuptake of (X), thus reinforcing its action.

Answer 22

Inhibits;

X = DA

Question 23

Glutamate reacts with (metabotropic/ionotropic) receptors

Answer 23

Both

Question 24

List the receptor subtypes that act as ion channels activated by glutamate.

Answer 24

1. Kainate
2. AMPA
3. NMDA

Question 25

NMDA channel is (blocked/unblocked) at Vm and is (blocked/unblocked) at (X) mV. By what?

Answer 25

Blocked; Unblocked X = -60 (or more positive) Mg

Question 26

T/F: A signal that opens AMPA channel will always open NMDA channel.

Answer 26

False - NMDA also voltage-dependent

Question 27

GABA is formed from (X).

Answer 27

X = Glutamate

Question 28

List GABA receptors. Star the ones that are metabotropic

Answer 28

GABA(a) and GABA(b)*

Question 29

Activation of GABA(a) receptor causes (increase/decrease) in

Answer 29

Increase; | gCl (opposes depol)

Question 30

Activation of GABA(b) receptor causes (increase/decrease) in

Answer 30

Decreases gCa and increases gK (via Gi)

Question 31

Glycine primarily acts by (increasing/decreasing) (X) conductance in (brain/SC).

Answer 31

Increasing; X = Cl SC

Question 32

List examples of NTs in the class of neuroactive peptides.

Answer 32

1. ADH and oxytocin 2. CCK and VIP 3. Substance P 4. Opioid peptides

Question 33

T/F: Only neurons release NO.

Answer 33

False - endothelial cells too

Question 34

NO mechanism is to (increase/decrease) (extracellular/cytosolic) which ion/second messenger?

Answer 34

Increase; cytosolic; cGMP

Question 35

ATP and adenosine act as (stimulatory/inhibitory) transmitters in autonomic NS.

Answer 35

Inhibitory

Question 36

ATP and adenosine act on (G-protein/ligand-gated) receptors.

Answer 36

Both

Question 37

In G-proteins, the alpha subunit is bound to (receptor/beta-gamma/GDP/GTP) when interacting with effector proteins.

Answer 37

Bound to GTP

Question 38

In G-proteins, which component is a GTPase? What occurs when it hydrolyzes GTP?

Answer 38

alpha subunit; | converts it back to inactive state (GDP-bound)

Question 39

Which ACh receptors are found in abundance in CNS? They use the (X) messenger system - causing increase/decrease in conductance of which ion(s)?

Answer 39

M1 metabotropic receptors; X = IP3 Increase gCa and decrease gK

Question 40

Serotonin is produced from (X) and broken down by (Y).

Answer 40

``` X = tryptophan; Y = oxidization by MAO ```

Question 41

Hallucinogenic agents, such as (X), are (Y) (agonists/antagonists).

Answer 41

X = LSD; Y = serotonin; Agonists

Question 42

Serotonin binds to (X) receptors. All are (ionotropic/metabotropic).

Answer 42

X = 5-HT Most metabotropic (GPCRs) except one

Question 43

Histamine receptors are found in which location(s)?

Answer 43

Peripheral tissues and brain

Question 44

Glu and Asp serve as NT at vast majority of (inhibitory/excitatory) synapses in (CNS/PNS).

Answer 44

Excitatory; CNS

Question 45

Main excitatory NT in brain.

Answer 45

Glu

Question 46

Glu (metabotropic/ionotropic) receptors involved in synaptic plasticity.

Answer 46

Metabotropic

Question 47

Main inhibitory NT in brain.

Answer 47

GABA

Question 48

GABA is formed from:

Answer 48

Glutamate

Question 49

Barbiturates/benzos are meds for (X). What's the Mechanism?

Answer 49

X = reducing anxiety/relaxing muscles Enhance GABA(a) effect on gCl

Question 50

Blocking of Glycine receptors by (X) causes (Y).

Answer 50

``` X = strychnine Y = hyperactivity/convulsions ```