L5 DREADDs Flashcards
What does DREADD stand for?
Designer receptor exclusively activated by designer drug
What are DREADDs?
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
DREADDs are becoming widely used in __ research
neuroscience
Why do we need DREADDs?
To look at the functionality of specific brain areas and the connections between multiple brain areas (circuits)
How are DREADDs used?
- Labelled with fluorescent tag (e.g. GFP)
- Packaged in a viral construct (e.g. AAV)
- Virus administered to target brain area via aseptic stereotaxis surgery
- Designer ligand (e.g. CNO) can be administered via different routes
- Researcher performs the necessary testing
The first generation of DREADDs were based on…
the muscarinic ACh receptor
Activation DREADD
hM3Dq
Inhibition DREADD
hM4Di
Do DREADDs respond to endogenous ligands?
No
How can AAV tropism be further altered?
By creating recombinant versions of multiple AAV serotypes (pseudotyping)
Which promoter drives transgene expression in neurons?
hSyn
Which promoter drives general transgene expression?
CAG
What is only expressed in tyrosine hydroxylase-containing cells?
Cre recombinase
What designer ligand is the inactive metabolite of Clozapine?
Clozapine N-oxide (CNO)
Clozapine is an agonist for…
endogenous mACh receptors
Newer designer ligands in development
- Compound 21
- Perlapine (in vitro)
- Salvinorin B
- JHU37152 & JHU37160
What did DREADD technology demonstrate in AgRP neurons?
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.
Ways to avoid important pitfalls with DREADDs
- Test the specificity of the experimental conditions
- Try to combine two DREADD ligands
- Conventional pharmacological controls must be used
True or False: DREADDs are devoid of endogenous pharmacological activity.
False
