L5 DREADDs

Question 1

What does DREADD stand for?

Answer 1

Designer receptor exclusively activated by designer drug

Question 2

What are DREADDs?

Answer 2

Engineered GPCRs that can be controlled remotely by the researcher using specific ligands i.e. can activate or inhibit the cell they are expressed in

Question 3

DREADDs are becoming widely used in __ research

Answer 3

neuroscience

Question 4

Why do we need DREADDs?

Answer 4

To look at the functionality of specific brain areas and the connections between multiple brain areas (circuits)

Question 5

How are DREADDs used?

Answer 5

1. Labelled with fluorescent tag (e.g. GFP)
2. Packaged in a viral construct (e.g. AAV)
3. Virus administered to target brain area via aseptic stereotaxis surgery
4. Designer ligand (e.g. CNO) can be administered via different routes
5. Researcher performs the necessary testing

Question 6

The first generation of DREADDs were based on…

Answer 6

the muscarinic ACh receptor

Question 7

Activation DREADD

Answer 7

hM3Dq

Question 8

Inhibition DREADD

Answer 8

hM4Di

Question 9

Do DREADDs respond to endogenous ligands?

Answer 9

No

Question 10

How can AAV tropism be further altered?

Answer 10

By creating recombinant versions of multiple AAV serotypes (pseudotyping)

Question 11

Which promoter drives transgene expression in neurons?

Answer 11

hSyn

Question 12

Which promoter drives general transgene expression?

Answer 12

CAG

Question 13

What is only expressed in tyrosine hydroxylase-containing cells?

Answer 13

Cre recombinase

Question 14

What designer ligand is the inactive metabolite of Clozapine?

Answer 14

Clozapine N-oxide (CNO)

Question 15

Clozapine is an agonist for…

Answer 15

endogenous mACh receptors

Question 16

Newer designer ligands in development

Answer 16

• Compound 21
• Perlapine (in vitro)
• Salvinorin B
• JHU37152 & JHU37160

Question 17

What did DREADD technology demonstrate in AgRP neurons?

Answer 17

That activation of AgRP neurons rapidly and dramatically induces feeding, reduces energy expenditure and ultimately increases fat stores. In contrast, inhibiting AgRP neurons in hungry mice reduced food intake.

Question 18

Ways to avoid important pitfalls with DREADDs

Answer 18

• Test the specificity of the experimental conditions
• Try to combine two DREADD ligands
• Conventional pharmacological controls must be used

Question 19

True or False: DREADDs are devoid of endogenous pharmacological activity.

Answer 19

False