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Flashcards in Synaptic Transmission: Metabotropic Deck (32):
1

What are the three G proteins associated with the effector pathways using G coupled receptors? What effector protein does it act on and in what way?

Gs: (+) adenylyl cyclase
Gq: phospholipase C
Gi: (-) adenylyl cylase

2

Trace the following signal pathway from the effector protein adenylyl cyclase

adenylyl cylase (effector protein) --> cAMP (secondary messenger) --> Protein Kinase A (later effectors) -->phosphorylation (target action)

These can be all either increased or decreased depending on whether Gs or Gi

3

Neurotransmitter for Gs

Epinephrine

4

Neurotransmitter for Gi

Dopamine

5

Neurotransmitter for Gq

Glutamate

6

Trace the following signal pathway from the effector protein Phospholipase C (PLC)

PLC activates two secondary messengers:
Diacylglycerol --> Protein Kinase C (later effectors)
IP3 --> Ca2+ (later effectors

Both Protein Kinase C and Ca2+ increase protein phosphorylation and active calcium binding proteins

7

Activated beta/gamma subunits of G protein (can/cannot) act directly on channel

They can act directly on channels

8

4 important synaptic targets of GPCRs

1. Ligand gated channels
2. Cyclic nucleotide-gated channels
3. K+ channels in soma/dendrites
4. Modulate K+ and Ca2+ channels in presynaptic terminals

9

What effects does GPCR signaling have on K+ and Ca2+ channels in presynaptic terminals?

Alter transmitter release (calcium channels trigger neurotransmitter release)

10

Explain the effects of a K+ channel blockade

delayed repolarization (back to more negative) by potassium channel. Will give a broader action potential, cell stayed depolarized for longer period of time

11

In basal condition, an action potential (is/is not) maintained during glutamate. Why or why not?

AP is not maintained due to activation of slow, non activating K+ channel, causes hyperpolarization (K+ leaves cell, becomes more negative inside), and inhibits firing

12

With only a glutamate stimulus, AP firing is reduced over time due to ____

opening of the M-type K+ channels

13

What allows the cell to maintain AP firing rate during glutamate? How?

ACh- by reducing hyperpolarization caused by K+ channels?
excitatory effect by DECREASING the channel conductance (inhibits the M-type K+ channel)

14

Explain how ACh DECREASES the heart rate

Inhibitory effect of ACh muscarinic signaling. Activated a muscarinic receptor coupled to Gi, increases activity of K+ channel (channel open, K+ flow out, keep membrane potential close to negative K equilibrium)

15

Inhibitory effect of GPCR signaling mediated by (increasing/decreasing) channel conductances

increasing channel conductances of K+ channel

16

Backwards signaling across synapse (postsynaptic --> presynaptic)

Retrograde signaling

17

Activation of this linked receptor in presynaptic axon inhibits presyaptic calcium influx

CB1

18

Lipid molecules synthesized and released on-demand from plasma membrane. Chemically derived from?

Endocannabinoids- chemically derived from arachidonic acid

19

Neurotransmitters are amino acids or aa-based, while endocannabinoids are?

Lipids (gases can also be neurotransmitters!)

20

Transmitters are synthesized and stored in vesicles prior to release, meanwhile endocannabinoids are?

Synthesized on demand

21

What causes normal transmitter release? How is this different for endocannabinoids?

can be triggered independently of Ca2+

22

Indoleamine

serotonin

23

Monoamine transmitter systems 1(3), 2(1)

Catecholamines- DA, NE, Epi
Indoleamine-Serotonin

24

5 important features of monoamine transmitter systems

1. Relatively small # of neurons
2. Cell bodies in discrete brainstem nuclei
3. Widespread projections (single cell - 100,000 synapses)
4. Possible paracrine release of transmitter
5. Metabotropic (G protein coupled) receptors on post-synaptic

25

Dopamine:
-brain stem nuclei
-receptors
-target for

-substantia nigra, ventral tegmental
-D1- like and D2-like receptors
-target for antipsychotics, parkinson's, drug addiction

26

Norepinephrine:
-brain stem nuclei
-receptors
-target for

-locus coeruleus
-alpha, beta adrenergic receptors
-target for antidepressants, anti-anxiety drugs

27

Serotonin:
-brain stem nuclei
-receptors
-target for

-raphe nuclei
-5-HT receptor subtypes
-target for antidepressants, OCD, panic disorder drugs

28

In excitatory effect of ACh-muscarinic signaling, ACh activates ____ coupled to _____

muscarinic receptor coupled to Gq

29

In excitatory effect of ACh-muscarinic signaling, Gq activation leads to what?

IP3-mediated increase in intracellular Ca2+
(recall Gq-->phospholipase C --> IP3 ---> Ca2+)

30

Role for PIP2 depletion in ACh-muscarinic signaling pathway

Phospholipid precursor that phospholipase C acts on. depletion of precursor changes function of other proteins in membrane

31

In inhibitory effect of ACh-muscarinic signaling, ACh activates ____ coupled to _____

muscarinic reeptor coupled to Gi

32

In inhibitory effect of ACh-muscarinic signaling, what acts directly on K+ channel to increase activity?

Beta gamma subunits. (Activate K channel, inhibitory effect, decrease heart rate)