Chapter 2: Transporters, receptors, and enzymes Flashcards

1
Q

P450 inhibitors: STICKFACES.COM Group

A

S - Sodium valproate
T - Ticlodipine
I - Isoniazid
C - Cimetidine
K - Ketoconazole
F - Fluconazole
A - Acute alcohol/amiodarone
C - Ciprofloxacin
E - Erythromycin
S - Sulfonamides
C - Cranberry juice
O - Omeprazole
M - Metronidazole
Group = grapefruit juice

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2
Q

P450 Inducers: BS CRAP GPS

A

B - Barbiturates
S - St. John’s Wort
C - Carbamazepine
R - Rifampin
A - Alcohol (chronic)
P - Pheytoin
G - Griseofulvin
P - Phenobarbital
S - Sulfonylureas

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3
Q

6 most important P450 enzymes

A

1A2
2B6
2D6
2C9
2C19
3A4

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4
Q

Serotonin transporter and gene family

A

presynaptic monoamine SERT/SLC6

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5
Q

Norepinephrine transporter/gene family

A

presynaptic monoamine NET/SLC6

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6
Q

Dopamine transporter/gene family

A

presynaptic monoamine DAT/SLC6

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7
Q

glial and GABA transporters

A

GAT1-4
GlyT1-2
EAAT1-5

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8
Q

GAT1-4 gene family/substrate

A

SLC6/GABA

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9
Q

GlyT1-2 gene family/substrate

A

SLC6/Glycine

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10
Q

EAAT1-5 gene family/substrate

A

SLC1/glutamate and aspartate

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11
Q

vesicular neurotransmitter transporters VMAT1-2 gene family/substrate

A

SLC18/serotonin
dopamine
histamine
norepinephrine

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12
Q

VaChT vesicular transporter gene family/substrate

A

SLC18/acetylcholine

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13
Q

VIAAT vesicular transporter gene family/substrate

A

SLC32/GABA

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14
Q

vGluT1-3 vesicular transporter gene family/substrate

A

SLC17/glutamate

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15
Q

false substrate for SERT

A

MDMA

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16
Q

false substrate for NET

A

dopamine, epinephrine, amphetamine

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17
Q

false substrate for DAT

A

norepinephrine, epinephrine, amphetamine

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18
Q

how do transporters concentrate monoamines into presynaptic neurons (reuptake)

A

sodium-potassium ATPase continually pumps sodium out of the cell to create a downhill gradient that allows for the uphill transport of the neurotransmitter

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19
Q

how do vesicular transporters package neurotransmitters into synaptic vesicles

A

proton ATPase continually pumps positively charged protons out of the vesicles so that the neurotransmitter can be transported into the vesicle to keep the charge the same

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20
Q

what is a neurotransmitter transporter

A

a type of receptor that binds to neurotransmitter prior to transporting it across the membrane

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21
Q

2 major classes of plasma membrane transporters

A

sodium/chloride-coupled transporters (SLC6 gene family)
Glutamate transporters (SLC1)

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22
Q

plasma membrane transporters on presynaptic membranes

A

SERT
NET
DAT

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23
Q

plasma membrane transporters located on glia and neuronal cells

A

GAT1-4
BGT1
Gly T1-2
EEAT1-5

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24
Q

SLC6 sodium/chloride-coupled includes which plasma membrane transporters

A

includes transporters for serotonin, norepinephrine, and dopamine as well as the neurotransmitter GABA and amino acid glycine

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25
Q

presynaptic SLC6 transporters

A

SERT
NET
DAT

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26
Q

glial SLC6 transporters

A

GAT1-4
BGT1
GlyT1-2

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27
Q

SLC1 glial transporter

A

EAAT1-5 (glutamate)

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28
Q

3 subclasses of intracellular synaptic vesicle transporters

A

SLC18
SLC32
SLC17

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29
Q

what are the two types of molecular transporters

A

plasma membrane transporters
intracellular synaptic vesicle transporters

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30
Q

SLC18 intracellular synaptic vesicle transporters

A

VMAT1-2 (vesicular monoamine transporters)
VAChT (vesicular acetylcholine transporter)

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31
Q

which monoamines are transported VMAT1-2 intracellular synaptic vesicle transporters

A

serotonin
norepinephrine
dopamine
histamine

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32
Q

SLC32 gene family intracellular synaptic vesicle transporters

A

VIAATs (vesicular inhibitory amino acid transporters)

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33
Q

SLC17 gene family intracellular synaptic vesicle transporters

A

VGluT1-3 (vesicular glutamate transporters)

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34
Q

false substrate for SERT presynaptic transporter

A

MDMA (Ecstasy)

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35
Q

false substrates for presynaptic transporter NET

A

dopamine
epinephrine
amphetamine

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36
Q

false substrates for presynaptic transporter DAT

A

norepinephrine, epinephrine, amphetamine

37
Q

synaptic vesicle transporter for all 3 monoamines

A

VMAT2 (vesicular monoamine transporter 2)

38
Q

what are the 3 monoamines

A

sertraline
dopamine
norepinephrine

39
Q

does it take energy to concentrate monoamines into presynaptic neuron?

A

yes

40
Q

how is energy generated to concentrate monoamines into the presynaptic neuron

A

downhill transport of sodium coupled with uphill transport of the monoamine

41
Q

what does “the sodium pump” (adenosine triphosphatase) do to generate the energy to concentrate monoamines in the presynaptic neuron

A

continuously pumps sodium out of neuron creating a downhill gradient which creates an uphill gradient for the monoamine

42
Q

binding sites on SLC6 transporters

A

2 sodium ion binding sites
other binding sites for drugs (SSRIs)

43
Q

what happens when a drug binds to a receptor on an SLC6 transporter

A

prevents monoamine reuptake

44
Q

what binds to the SLC6 transporter in the absence of sodium

A

nothing; not sodium or monoamine

45
Q

how do you increase monoamine action

A

prevent it from binding to its transporter so it accumulates in the synapse

46
Q

which transporters are blocked by ADHD stimulants and cocaine

A

DAT
NET

47
Q

which tra
nsporters are blocked by most drugs for unipolar depression

A

SERT
NET
DAT

48
Q

what conditions are treated by blocking neurotransmitter transporters

A

anxiety, fibro neuropathic pain, postherpetic neuralgia, peripheral neuropathy and other pain conditions, eating disorders, impulsive-compulsive disorders, OCD, trauma/stress related disorders (PTSD)

49
Q

what condition are NOT treated by blocking monoamine binding to transporters

A

bipolar depression with mixed features

50
Q

what is the only medication that blocks GABA transporter GAT1 to increase synaptic GABA concentration

A

anticonvulsant tiababine

51
Q

what happens when glutamate is transported into glia

A

it is converted into glutamine to enter the presynaptic neuron for conversion back to glutamate

52
Q

differences of SLC1 to SLC6 transporters

A

glutamate is excitatory
exact location on pre/post synaptic neurons/glia is under investigation.
no drugs are known to block them
glutamate transport almost always has countertransport of potassium.
may work as timers rather than dimers

53
Q

transporters for neurotransmitter histamine

A

no presynaptic transporter
vesicular transporter is VMAT2 (same as monoamines)

54
Q

histamines inactivation

A

entirely enzymatic

55
Q

VMATs vesicular transporters are members of what gene family

A

SLC8

56
Q

VaChT

A

vesicular transporter for acetylcholine

57
Q

VIAAT is a vesicular transporter that is a member of what gene family

A

SLC32

58
Q

what gene family does vesicular transporter vGluT1-3 belong to

A

SLC17
vesicular transporter for glutamate

59
Q

SV2a transporter

A

novel vesicular transporter with 12 transmembrane regions that binds to anticonvulsant levetiracetam whic may reduce seizures by blocking neurotransmitter release

60
Q

how is energy generated to move neurotransmitters into synaptic vesicles

A

proton ATPase (proton pump) pumps positively charged protons out of synaptic vesicles continuously.
neurotransmitters are able to then concentrate against the gradient by substituting their own + charge in the vesicle for the + charge being pumped out
SO
neurotransmitters go in while protons go out, keeping the charge in the vesicle the same

61
Q

which vesicular transporters are NOT known to be targeted by drugs

A

ones for GABA (SLC32), acetylcholine (SLC18), and glutamate (SLC17)

62
Q

which vesicular transporters are targeted by many drugs

A

VMATs (SLC18 family)

63
Q

drugs that target VMAT vesicular transporters

A

amphetamine (both monoamine and vesicular transporters)
methylphenidate and cocaine (only monoamine transporters)
tetrabenzine and its derivatives as inhibitors

64
Q

structure of G-protein-linked receptors

A

7 transmembrane regions (spans membranes 7 tiems) that cluster around a central core that contains a neurotransmitter binding site

65
Q

how do drugs lead to modification of g-protein-linked-receptors

A

they mimick or block neurotransmitter function that normally happens at binding or allosteric sites on the receptor

66
Q

difference between neurotransmitters and drugs on g-protein-linked receptors

A

neurotransmitters interact with all receptor subtypes. Drugs interact only with a specific receptor subtype

67
Q

action of agonists on g-protein-linked receptors

A

turns on the synthesis of the second messenger to the greatest extent possible so downstream proteins are fully phosphorylated and genes are maximally expressed

68
Q

what are the 2 ways to stimulate G-protein-linked receptors with full agonist action

A

drugs bind directly to neurotransmitter sites
or indirectly boost levels of the neurotransmitters themselves

69
Q

2 ways drugs boost levels of neurotransmitters themselves

A

inhibition of monoamine transporters
blocking enzymatic destruction of neurotransmitters

70
Q

2 ways to block enzymatic destruction of neurotransmitters

A

inhibition of SERT, NET, DAT and GABA transporter GAT1

inhibition of enzyme acetylcholinesterase

71
Q

action of antagonist on g-protein-linked receptors

A

produces conformational change in receptor that causes signal transduction to remain at constitutive levels

72
Q

clinical purpose of antagonists on g-protein-linked receptors

A

block excessive neurotransmission
reverses agonists, partial agonists, and inverse agonists

73
Q

action of partial agonists on g-protein-linked receptors

A

produce signal transduction that is more than constitutive but less than agonist depending on how close the partial agonist is to the full agonist

74
Q

action of inverse agonist on g-protein linked receptors

A

causes conformational change to stabilize receptor in inactive form
essentially, turning action down below consitutive

75
Q

what happens when an enzyme is bound

A

it cannot bind with its substrate so it is inactivated
can be reversible or irreversible

76
Q

irreversible binding of an enzyme

A

cannot be displaced by the substrate (essentially killing it)

77
Q

reversible binding of an enzyme

A

when a substrate can compete for the receptor site and shove it off of the enzyme

78
Q

few drugs that bind enzymes used in clinical practice

A

MAOIs
acetylcholinesterase
glycogen synthase kinase (GSK)

79
Q

agents that target GSK enzymes that are used in clinical practice

A

lithium may target in this enzyme in the signal transduction pathway of neurotrophic factors

80
Q

what acts through phosphoprotein GSK-3 to promote cell death

A

neurotrophins, growth factors, and other signaling pathways
it is also possible that valproate and ECT act of GSK3

81
Q

consequences of inhibiting GSK3

A

may have neuroprotective actions, long term plasticity, and may contribute to mood stabilizing effects of lithium

82
Q

what are CYP enzymes

A

drug metabolizing enzymes that are mediated through the liver and gut that are responsible for a large amount of psychotropic drugs

83
Q

are pharmacokinetics or pharmacodynamics responsible for mechanism of action of psychotropic drugs

A

pharmacodynamics

84
Q

6 most important CYP450 enzymes

A

1A2
2B6
2D6
2C9
2C19
3A4

85
Q

extensive metabolizers

A

people who have “normal” rates of drug metabolism by CYP4550 enzymes

86
Q

what happens if there is reduced activity of CYP450 enzymes

A

risk for elevated drug levels as they are not metabolized fast enough
patients need less than standard doses

87
Q

ultra-rapid metabolizers

A

people who have elevated CYP450 enzyme activity

88
Q

consequences of being an ultra-rapid metabolizer

A

may require higher than standard doses due to resultant subtherapeutic drug levels