Drugs And Receptors 16.11.23

Question 1

Define receptor?

Answer 1

A component of a cell that interacts with a specific ligand* and initiates a change of biochemical events leading to the ligands observed effects

*Ligands can be exogenous (drugs) or endogenous (hormones, neurotransmitter, etc)

Question 2

What 3 types of chemicals can communicate through receptors?

Answer 2

Neurotransmitter —> acetylcholine, serotonin

Autacoids (local) —> cytokines, histamine

Hormones —> testosterone, hydrocortisone

Question 3

What are the 4 types of receptor?

Answer 3

Ligand-gated ion channels —>
nicotinic ACh receptor

G protein coupled receptors —> beta-adrenoceptors

Kinase-linked receptors —>
receptors for growth factors

Cytosolic/nuclear receptors —> steroid receptors

Question 4

What are ligand gated ion channels?

Answer 4

Ion channelsare pore-formingmembrane proteinsthat allowionsto pass through the channel pore so that the cell undergoes a shift inelectric chargedistribution
The change in charge can be mediated by an influx of any kind ofcation(+ve) or efflux of any kind ofanion (-ve).

Question 5

What are GCPRs?

Answer 5

GPCRs are the largest and most diverse group of membrane receptors in eukaryotes. (they have 7 membrane spanning regions)

Question 6

What is a G protein also known as?

Answer 6

Guanine nucleotide-binding proteins

Question 7

What do G proteins do?

Answer 7

G proteins are involved in transmitting signals from GPCRs

Question 8

How are G protein activity regulated?

Answer 8

Their activity is regulated by factors that control their ability to bind to and hydrolyzeguanosine triphosphate(GTP) toguanosine diphosphate(GDP)

Question 9

What are kinases?

Answer 9

Kinasesare enzyme that catalyze the transfer of phosphate groups between proteins - process is known as phosphorylation.

Question 10

How does kinase-linked receptors work?

Answer 10

The substrate gains a phosphate group ”donated” by ATP

Question 11

How do nuclear receptors work?

Answer 11

Work by modifying gene transcription, zinc fingers, bind DNA

Question 12

There are situations where an imbalance of chemicals/receptors can lead to pathology.

Allergy results in increased what levels?

Answer 12

Increased histamine

Question 13

There are situations where an imbalance of chemicals/receptors can lead to pathology.

Parkinson’s results in decreased what levels?

Answer 13

Decreased dopamine

Question 14

There are situations where an imbalance of chemicals/receptors can lead to pathology.

Myasthenia gravis results in a loss of what?

Answer 14

Loss of ACh receptors

Question 15

There are situations where an imbalance of chemicals/receptors can lead to pathology.

Mastocytosis results in increased what levels?

Answer 15

Increased c-kit receptor

Question 16

Define agonist (in terms of receptors)

Answer 16

A compound that binds to a receptor and activates it

Question 17

Define antagonist (in terms of receptors)

Answer 17

a compound that reduces the effect of an agonist

Question 18

Learn the two state model of receptor activation - it describes how drugs activate receptors by inducing or supporting a conformational change in the receptor from “off” to “on”.

Question 19

Define intrinsic activity

Answer 19

Intrinsic activity(IA) orefficacyrefers to the ability of a drug-receptor complex to produce a maximum functional response

Question 20

Learn what full agonist, partial agonist and intrinsic activity mean (see lecture)

Question 21

Define competitive antagonism

Answer 21

Binds to the same site

Question 22

Define non-competitive antagonism

Answer 22

Binds to an allosteric (non-agonist) site on the receptor to prevent activation of the receptor

Question 23

What are the 2 categories of cholinergic receptors?

Answer 23

Nicotinic and muscarinic

Question 24

What are the 4 factors governing drug action?

Answer 24

(Receptor-related —>)

affinity
efficacy

(Tissue-related —>)

receptor number
signal amplification

Question 25

Define affinity

Answer 25

Describes how well a ligand binds to the receptor

Question 26

Do agonists or antagonists have affinity and efficacy?

Answer 26

Agonists

Question 27

Do agonists or antagonists have affinity, but have zero efficacy?

Answer 27

Antagonists

Question 28

Learn about allosteric modulation

Question 29

Define inverse agonism

Answer 29

When a drug that binds to the same receptor as anagonistbut induces a pharmacological response opposite to that of theagonist.

Question 30

Isoprenaline is a ……-…………… ……………-………….. ………. And is used for …………………

Answer 30

Non-selective beta-adrenoreceptor agonist

Is used for bradycardia, heart block and rarely for asthma

Question 31

Salbutamol is a ……-…………… ………. And is used for …………………

Answer 31

beta2-adrenoceptor agonist

And is used to open up the medium and large airways in the lungs, used for COPD/asthma