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Neuropharmacology > Lecture 7 > Flashcards

Lecture 7 Flashcards

1
Q

What are the catecholamines?

A

dopamine, noradrenaline, adrenaline

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2
Q

What is one example of a tryptamine?

A

Serotonin

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3
Q

What is the first step of noradrenline synthesis

A

Tyrosine hydroxylase converts L-tyrosine to dihydroxyphenylalanine (DOPA)

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4
Q

Where is tyrosine hydroxylase found?

A
  • NA and DA neurones - adrenal chromaffin cells
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5
Q

What is the second step of noradrenline synthesis?

A

DOPA decarboxylase converts dihydroxyphenylalanine (DOPA) to dopamine

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6
Q

What is the final step of noradrenaline synthesis?

A

Dopamine-β-hydroxylase converts dopamine to noradrenaline

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7
Q

Where is dopamine-β-hydroxylase found?

A

NA vesicles

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8
Q

What is the role of phenylethanolamine N-methyl transferase?

A
  • converts noradrenaline to adrenaline in adrenal chromaffin cells of adrenal medulla
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9
Q

What drug inhibits tyrosine hydroxylase and what does this inhibit?

A
  • 𝛼-methylparatyrosine - inhibits DOPA production
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10
Q

What drug inhibits DOPA decarboxylase and what does this inhibit?

A
  • carbidopa and benserazide - inhibits dopamine production
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11
Q

What drug inhibits dopamine-β-hydroxylase and what does this inhibit?

A
  • disulfarim (antabuse) - inhibits noradrenaline production
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12
Q

Name examples of drugs inhibiting storage of noradrenaline

A
  • Reserpine - 𝛼-methyl DOPA
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13
Q

How does reserpine work?

A

1) inhibits NA uptake 2) depletes monoamines 3) decrease in sympathetic function - damages vesicles - decreases HR and BP

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14
Q

What are side effects of reserpine?

A
  • postural hypotension - hypothermia - sedation - depression (suicidal at high doses)
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15
Q

How does 𝛼-methyl DOPA work?

A

1) coverted to 𝛼-methyl NA 2) replaces/displaces NA 3) released instead of NA - less potent at 𝛼1 and activates 𝛼2= less NA release - decreases HR and BP

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16
Q

What does 𝛼-methyl DOPA treat?

A

Hypertension e.g. in pregancy

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17
Q

What is the role of 𝛼2 adrenoceptors in noradrenaline release?

A

Presynaptic inhibitory autoreceptors= inhibit Ca2+ release

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18
Q

Name a drug that inhibits noradrenaline release

A

Clonidine

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19
Q

How does clonidine work?

A
  • 𝛼2 agonist - decreases NA release
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20
Q

What is clonidine used to clinically treat?

A
  • hypertension - migraines - Tourette’s - menopausal flushing
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21
Q

What are the two uptake mechanisms of noradrenaline?

A
  • norepinephrine transporter (NET) - extraneuronal monoamine transporter (EMT)
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22
Q

What are the enzymes involved in noradrenaline/monoamine metabolism?

A
  • monoamine oxidase (MAO) - catechol-o-methyl transferase (COMT) - aldehyde dehydrogenase (ADH)
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23
Q

What are MAO inhibitors used for?

A

Depression

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24
Q

What are COMT inhibitors used for?

A

Parkinson’s disease

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25
Q

What are the subtypes of 𝛼 adrenoceptors?

A

𝛼1, 𝛼2

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26
Q

What are the subtypes of β adrenoceptors?

A

β1, β2, β3

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27
Q

Which is more effective at 𝛼 adrenoceptors- noradrenaline or isoprenaline?

A

Noradrenaline

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28
Q

Which is more effective at β adrenoceptors- noradrenaline or isoprenaline?

A

Isoprenaline

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29
Q

What is the physiological response of 𝛼1 activation?

A

Contraction

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30
Q

Where is the 𝛼1 receptor expressed?

A

Vascular and vas deferens smooth muscle

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31
Q

What is the physiological response of 𝛼2 activation?

A

Decreased noradrenaline release

32
Q

Where is the 𝛼2 receptor expressed?

A

Adrenergic nerve terminals

33
Q

What is the physiological response of β1 activation?

A

Increased heart rate and force of contraction

34
Q

Where is the β1 receptor expressed?

A

Cardiac muscle

35
Q

What is the physiological response of β2 activation?

A

Dilation and relaxtion

36
Q

Where is the β2 receptor expressed?

A
  • cardiac blood vessels - skeletal muscle blood vessels - bronchial smooth muscle
37
Q

What is the physiological response of β3 receptor activation?

A

Lipolysis

38
Q

Where is the β3 receptor expressed?

A

Adipose tissue

39
Q

What G protein subtype does 𝛼1 receptors bind to?

A

G𝛼q

40
Q

What is the physiological response of G𝛼q activation?

A

Contraction of vascular smooth muscle

41
Q

What are the second messengers of G𝛼q?

A
  • protein kinase C (PKC) - Ca2+
42
Q

What G protein subtype does 𝛼2 receptors bind to?

A

G𝛼i

43
Q

What is the physiological response of G𝛼i activation?

A

Decreased insulin and noradrenaline release

44
Q

What are the second messengers of G𝛼i?

A
  • (Reduced activity of) cAMP and PKA - Gβ𝛾 inhibits voltage gated Ca2+ channels
45
Q

What G protein subtype does β1, 2 and 3 receptors bind to?

A

G𝛼s

46
Q

What is the physiological response of G𝛼s activation?

A
  • increased cardiac output - dilation/relaxation - lipolysis
47
Q

What are the second messengers of G𝛼s?

A

(Increased activity of) cAMP and PKA

48
Q

What are the mechanisms of G𝛼q activation?

A

1) stimulates phospholipase C β (PLCβ) 2) breaks down PIP2 to diacylglycerol (DAG) and IP3 - DAG activates PKC - IP3 causes influx of Ca2+

49
Q

What are the mechanisms of G𝛼i activation?

A

1) inhibits adenylate cyclase (AC) 2) reduction in cAMP, PKA activation and Ca2+ activity 3) Gβ𝛾 activates K+ channels leading to an efflux from the cell- hyperpolarisation and reduced excitability

50
Q

What are the mechanisms of G𝛼s activation?

A

1) stimulates adenylate cyclase 2) increased cAMP and activation of PKA

51
Q

List examples of directly-acting noradrenergic agonists

A
  • noradrenaline - adrenaline - salbutamol
52
Q

What is the physiological response of noradrenaline

A

Increased BP due to 𝛼1 vasoconstriction

53
Q

What is noradrenaline used to treat clinically?

A
  • shock - cardiac arrest
54
Q

What is the physiological response of adrenaline?

A
  • increased heart rate - increased force of contraction - bronchodilation
55
Q

What are the clinical uses of adrenaline?

A
  • treat cardiac arrest - treat anaphylactic shock - local anaesthetics
56
Q

What is the physiological response of salbutamol?

A

Smooth muscle relaxation e.g. bronchodilation

57
Q

What is salbutamol used to treat clincially?

A
  • asthma - inhibition of premature labour
58
Q

Name an example of an indirectly-acting noradrenergic agonist

A

Tyramine

59
Q

How does tyramine work?

A
  • stimulates NA release - competes with NA for NET - displaces NA from vesicle
60
Q

What is the cheese reaction?

A
  • Tyramine (cheese) - normally metabolised by MAO - With MAOIs amine levels increase - act as indirect sympathomimetics - provoke hypertensive crisis
61
Q

List examples of alpha adrenoceptor antagonists

A
  • prazosin - lebatolol
62
Q

What is the physiological respojnse of prazosin and labetolol?

A

Decreased blood pressure due to 𝛼1 block

63
Q

How does prazosin work?

A
  • treats hypertension - few side effects - no reflex increase HR
64
Q

How does labetolol block a reflex heart rate increase?

A

Blocks β1 receptors

65
Q

List examples of β adrenoceptor antagonists

A
  • propranolol - atenolol
66
Q

List an example of a β adrenoceptor partial agonist

A

Pindolol

67
Q

Is propranolol β selective or non-selective?

A

Non-selective

68
Q

Is atenolol β selective or non-selective?

A

β1 cardioselective

69
Q

What is the physiological response of propranolol?

A
  • decreased HR, BP and cardiac output
70
Q

What are the side effects of propranolol?

A
  • bronchoconstriction (β2) - sleep disturbance - hypoglycaemia - cardiac failure - cold extremities
71
Q

What is propranolol used for?

A
  • angina - dysrhythmias
72
Q

What is the physiological response of atenolol?

A

Decreased HR, BP and cardiac output via β1 block

73
Q

What is atenolol used for?

A

Hypertension

74
Q

What is the physiological response of pindolol?

A
  • partial agonists - don’t give max response - inhibit action of full agonists
75
Q

What is pindolol used for?

A

hypertension

Neuropharmacology (15 decks)

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