Agonists and Antagonists Flashcards

1
Q

What are AMPA receptor agonists?

A

Glutamate and AMPA (the latter causes fast desensitisation)

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2
Q

What are AMPA receptor antagonists?

A

NBQX (competitive) and Telampanel (non-competitive)

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3
Q

What are the positive allosteric modulators of AMPA receptors?

A

Cyclothiazide, ampakines and LY404187

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4
Q

What are kainate receptor agonists?

A

Kainate, glutamate and domoate

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5
Q

What are kainate receptor antagonists?

A

CNQX and ACET

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6
Q

Which kainate antagonist is selective for GluK1?

A

ACET

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7
Q

What is the glu site agonist that binds at the SIS2 domain of GluN2A?

A

NMDA

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8
Q

What are the competitive Glu site antagonists that bind to the S1S2 domain of GluN2A-D?

A

R-AP5 and (R)-CPPene

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9
Q

What are the glycine site agonists that bind at the S1S2 domain of GluN1?

A

Glycine and D-Serine (but affinity of glycine for GluN1 is dependent on GluN2 tetramer)

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10
Q

What are the Glycine binding site antagonists at S1S2 domain of GluN1?

A

Kyurenate (endogenous) and 5,7-DCKN (synthetic)

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11
Q

What is the antagonist at the N-terminal domain of GluN2B leading to inhibition of NMDA receptors?

A

Eliprodil - it binds to the dimer interface between GluN2B and GluN1 subunits

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12
Q

What are the uncompetitive antagonists/channel blockers of NMDA receptors?

A

Ketamine, Memantine - low affinity
Phencyclidine (PCP)
MK-801 - high affinity, withdrawn from trials

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13
Q

What can block the pore of a glycine receptor?

A

Picrotoxin

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14
Q

What potently inhibits glycine receptors?

A

Strychnine and RU5135

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15
Q

What are the agonists of GABA A receptors?

A

GABA, gaboxadol, muscimol the psychoactive constituent of Amanita muscaria

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16
Q

What are the orthosteric (competitive) antagonists of GABA A receptors?

A

Dicentra cucullaria (Dutchman’s breeches), bicuculline and GABAzine

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17
Q

What are the non-competitive antagonists of GABA A receptors?

A

Anamirta cocculus, picrotoxin and U93631

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18
Q

What are allosteric modulators of GABA A receptors?

A

Benzodiazepines, barbiturates, anaesthetics and alcohol

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19
Q

What effect do benzodiazepines has on GABA A receptors?

A

Positive allosteric modulators - increase frequency of bursts of channel opening

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20
Q

What are inverse agonists of the benzodiazepine binding site on GABA A receptors?

A

DMCM (which is seizure promoting and anxiogenic) and flumazenil (also promotes anxiety but used to treat overdose)

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21
Q

Barbiturates directly activate GABA A receptors at high doses, what do they do at low doses/concentration?

A

They are positive allosteric modulators at lower doses.

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22
Q

Barbiturates tend to increase the duration of bursts of channel opening of GABA A receptors which means…

A

there is not a large toxicology window

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23
Q

Which anaesthetics target GABA A receptors?

A

Etomidate, propofol and pentobarbitol (Group 1 - IV anaesthetics)

24
Q

Which receptors do the Group 2 anaesthetics (nitrous oxide, ketamine, xenon and cyclopropane) target?

A

NMDA receptors, AMPA receptors, neuronal acetylcholine receptors and 2 pore potassium channels

25
Q

Which receptors do the Group 3 anaesthetics (halogenated ethers e.g. isofluorane and alkanes e.g. halothane, chloroform) target?

A

GABA A receptors, glycine receptors, NMDA receptors, AMPA receptors, neuronal ACh receptors, 2 pore potassium channels.

26
Q

Parasympathomimetic drugs exert a similar action to which neurotransmitter?

A

Acetylcholine

27
Q

What are examples of parasympathomimetic drugs?

A

Metacholine, carbachol, muscarine - drugs that directly stimulate cholinergic receptors

28
Q

What are examples of drugs that inhibit the cholinesterase enzyme?

A

Phyostigmine (used in glaucoma eyedrops) and neostigmine (used in treatment of myasthenia gravis)

29
Q

What parasympathomimetic drugs have irreversible effects?

A

Parathion (an insecticide) and DFP (a toxic nerve gas)

30
Q

What are examples of sympatholytic drugs?

A

Guanethidine, reserpine and methyldopa

31
Q

What are some examples of sympathomimetic drugs?

A

Ephedrine, amphetamine and tyramine

32
Q

Which drugs increase alpha adrenergic receptor activity?

A

Methoxamine and phenylepinephrine

33
Q

Which drugs decrease alpha adrenergic receptor activity?

A

Phenoxybenzamine, phentolamine, prazocin (alpha1) and yohimbine (alpha2)

34
Q

Which drugs increase beta adrenergic receptor activity?

A

isoproterenol and the beta2 stimulators salbutamol and terbutaline

35
Q

Which drugs decrease beta adrenergic receptor activity?

A

propranolol and metaprolol (both beta blockers) and atenolol (beta1) and butoxamine (beta2)

36
Q

How does cocaine increase spatial and temporal distribution of dopamine?

A

By antagonism of dopamine transporter (DAT), norepinephrine transporter (NET) and serotonin transporter (SERT) preventing reuptake of dopamine from the synaptic cleft.

37
Q

How does amphetamine increase dopamine signalling?

A

It provides an alternative substrate to amines which usually couple with the co-transporters DAT and NET so is therefore a competitive antagonist at this site. When it alters the vesicular monoamine pump VMAT-2 it leads to long-lasting rewiring.

38
Q

How do SSRIs increase availability of 5HT in the synaptic cleft?

A

By blocking SERT

39
Q

What are the 5HT receptor agonists triptans and ergot alkaloids used for?

A

Migraine treatment - they increase cerebral vasoconstriction to counteract cranial vasodilation by targeting 5HT1B/D/F. They are counter indicated in CVD as 5HT1B is also found in peripheral smooth muscle.

40
Q

What is the anti-hypertensive 5HT2 receptor antagonist?

A

Ketanserin

41
Q

What are the 5HT3 receptor antagonists tropisetron and ondansetron used for?

A

To prevent nausea and vomiting

42
Q

What is the 5HT2C receptor agonist locaserin used for and why?

A

Obesity therapy as activation of 5HT2C receptor suppresses appetite.

43
Q

LSD is an agonist of which receptor?

A

5HT2A receptor (but also full or partial agonist of 1A/B/D/E, 2C, 5A, 6 and 7)

44
Q

Psilobycin is an agonist of which receptor?

A

5HT2A receptor (but high affinity for 2B and 2C, lower affinity for 1A and 1B)

45
Q

How does MDMA act on neurons?

A

It enters neurons via monoamine transporters (SERT=NET>DAT) where it then inactivates VMAT2 and inactivates or reverses SERT, NET and DAT. It is also a weak agonist at 5HT1 and 5HT2 receptors.

46
Q

Is cannabidiol an agonist or antagonist of CB1 receptors?

A

Antagonist

47
Q

Is THC an agonist or an antagonist at CB1?

A

Partial agonist

48
Q

What are two endogenous CB1 receptor agonists?

A

Anandimide (AEA) and 2-achidonylglycerol (2-AG)

49
Q

Which endocannabinioid is more abundant in the human brain and has higher efficacy?

A

2-arachidonylglycerol (2-AG)

50
Q

What are some examples of opiates (naturally occurring compounds that are usually derived from the resin of the opium poppy)?

A

Morphine, codeine and thebaine

51
Q

What is an example of a morphine ester?

A

Prodrugs such as diacetylmorphine (heroin)

52
Q

What are two examples of semi-synthetic opioids (derived from opium or morphine esters)?

A

Buprenorphine and oxycodone

53
Q

What are some examples of synthetic opioids?

A

Fentanyl, pethidine, methadone and tramadol

54
Q

What are some examples of endogenous opioids?

A

Enkephalins and endorphins

55
Q

What is diacetylmorphine (heroin) rapidly metabolised into?

A

6-monoacetylmorphine and then morphine through rapid removal of acetyl groups.

56
Q

Caffeine is an agonist or antagonist of adenosine receptors?

A

Competitive antagonist