Toolkit/multi-tracer positron emission tomography imaging

multi-tracer positron emission tomography imaging

Assay Method·Research·Since 2021

Also known as: multi-tracer PET imaging, PET imaging

Taxonomy: Technique Branch / Method. Workflows sit above the mechanism and technique branches rather than replacing them.

Summary

Using multi-tracer positron emission tomography imaging, we detected DREADD expression in vivo, which was confirmed in nigrostriatal dopamine neurons by immunohistochemistry, as well as by assessed activation of the SN following agonist administration.

Usefulness & Problems

Why this is useful

Multi-tracer PET imaging was used to detect DREADD expression in vivo and to assess substantia nigra activation after agonist administration. It serves as a noninvasive imaging readout in the study.; in vivo detection of DREADD expression; assessment of substantia nigra activation following agonist administration

Source:

Multi-tracer PET imaging was used to detect DREADD expression in vivo and to assess substantia nigra activation after agonist administration. It serves as a noninvasive imaging readout in the study.

Source:

in vivo detection of DREADD expression

Source:

assessment of substantia nigra activation following agonist administration

Problem solved

It allows in vivo confirmation that the chemogenetic construct is expressed and that the targeted region shows activation after agonist exposure. This reduces reliance on endpoint-only histology.; provides noninvasive in vivo readout of chemogenetic construct expression and activation

Source:

It allows in vivo confirmation that the chemogenetic construct is expressed and that the targeted region shows activation after agonist exposure. This reduces reliance on endpoint-only histology.

Source:

provides noninvasive in vivo readout of chemogenetic construct expression and activation

Problem links

provides noninvasive in vivo readout of chemogenetic construct expression and activation

Literature

It allows in vivo confirmation that the chemogenetic construct is expressed and that the targeted region shows activation after agonist exposure. This reduces reliance on endpoint-only histology.

Source:

It allows in vivo confirmation that the chemogenetic construct is expressed and that the targeted region shows activation after agonist exposure. This reduces reliance on endpoint-only histology.

Published Workflows

Chemogenetic activation of nigrostriatal dopamine neurons in freely moving common marmosets.

2021

Objective: Establish and verify chemogenetic activation of nigrostriatal dopamine neurons in freely moving common marmosets and link that activation to natural behavior under stress-free conditions.

Why it works: The workflow first establishes hM3Dq expression in the substantia nigra, then verifies expression in vivo and histologically, and finally tests whether agonist administration produces regional activation and a predicted behavioral output in freely moving marmosets.

chemogenetic activation of nigrostriatal dopamine neuronsagonist-triggered activation of hM3Dq-expressing substantia nigra neuronsAAV-mediated gene deliveryPET imagingimmunohistochemistryoral agonist administrationbehavioral observation

Stages

  1. 1.
    Targeted DREADD delivery to substantia nigra(library_build)

    This stage creates the engineered primate model by introducing hM3Dq into the target brain region.

    Selection: Establish hM3Dq expression in the unilateral substantia nigra of marmosets.

  2. 2.
    In vivo imaging-based expression detection(confirmatory_validation)

    This stage noninvasively verifies that the chemogenetic receptor is expressed in vivo before downstream activation and behavioral interpretation.

    Selection: Detect DREADD expression in vivo by multi-tracer PET imaging.

  3. 3.
    Histological confirmation in nigrostriatal dopamine neurons(confirmatory_validation)

    This stage adds cellular confirmation beyond in vivo imaging.

    Selection: Confirm DREADD expression in nigrostriatal dopamine neurons by immunohistochemistry.

  4. 4.
    Agonist-triggered activation assessment(functional_characterization)

    This stage tests whether expressed DREADDs are functionally activatable by agonist administration.

    Selection: Assess activation of the substantia nigra following agonist administration.

  5. 5.
    Behavioral validation after oral DCZ(confirmatory_validation)

    This stage links chemogenetic activation to an observable behavioral output in freely moving marmosets.

    Selection: Observe contralateral rotation after consuming food containing DCZ and compare with following days without DCZ.

Steps

  1. 1.
    Inject AAV vectors expressing hM3Dq into unilateral substantia nigraengineered receptor and delivery harness

    Establish chemogenetic receptor expression in the target brain region.

    Expression must be established before in vivo detection, agonist activation, or behavioral testing can occur.

  2. 2.
    Detect DREADD expression in vivo using multi-tracer PET imagingassay method and imaged construct

    Verify in vivo expression of the chemogenetic receptor.

    In vivo expression evidence supports proceeding to functional and behavioral interpretation with greater confidence.

  3. 3.
    Confirm expression in nigrostriatal dopamine neurons by immunohistochemistryvalidated construct

    Confirm cellular localization of DREADD expression.

    Histological confirmation follows in vivo detection to strengthen mechanistic interpretation at the cell-type level.

  4. 4.
    Assess substantia nigra activation following agonist administrationchemogenetic receptor and agonist

    Test whether agonist administration functionally activates the targeted substantia nigra.

    Functional activation testing is needed after expression confirmation and before attributing behavioral effects to chemogenetic activation.

  5. 5.
    Administer DCZ in food and observe contralateral rotation behavioragonist delivery to activate expressed DREADD

    Elicit and measure behavioral consequences of unilateral nigrostriatal activation in freely moving marmosets.

    Behavioral testing is performed after expression and activation evidence to link the engineered perturbation to natural behavior.

Taxonomy & Function

Primary hierarchy

Technique Branch

Method: A concrete measurement method used to characterize an engineered system.

Target processes

No target processes tagged yet.

Implementation Constraints

cofactor dependency: cofactor requirement unknownencoding mode: genetically encodedimplementation constraint: context specific validationoperating role: sensor

The method requires PET imaging infrastructure and tracer-based imaging. The abstract does not specify the exact tracers or quantification method.; requires PET imaging capability; requires tracer-based imaging

The abstract does not show that PET alone resolves cellular identity, since immunohistochemistry was used for confirmation in dopamine neurons. It also does not provide detailed quantitative performance metrics.; the abstract does not specify tracer identities or quantitative PET metrics

Validation

Cell-freeBacteriaMammalianMouseHumanTherapeuticIndep. Replication

Supporting Sources

Ranked Claims

Claim 1activation readoutsupports2021Source 1needs review

Agonist administration was associated with assessed activation of the substantia nigra.

as well as by assessed activation of the SN following agonist administration
Claim 2behavioral effectsupports2021Source 1needs review

After consuming food containing deschloroclozapine, marmosets rotated contralaterally relative to the activated side 30-90 minutes later, and this effect was not observed on following days without DCZ.

The marmosets rotated in a contralateral direction relative to the activated side 30-90 min after consuming food containing the highly potent DREADD agonist deschloroclozapine (DCZ) but not on the following days without DCZ.
behavior onset window 30-90 min after consuming DCZ-containing food
Claim 3expression deliverysupports2021Source 1needs review

Adeno-associated virus vectors were used to express hM3Dq in the unilateral substantia nigra of four marmosets.

We injected adeno-associated virus vectors expressing the excitatory DREADD hM3Dq into the unilateral substantia nigra (SN) in four marmosets.
marmoset count 4 animals
Claim 4in vivo detectionsupports2021Source 1needs review

Multi-tracer PET imaging detected DREADD expression in vivo and immunohistochemistry confirmed expression in nigrostriatal dopamine neurons.

Using multi-tracer positron emission tomography imaging, we detected DREADD expression in vivo, which was confirmed in nigrostriatal dopamine neurons by immunohistochemistry

Approval Evidence

1 source2 linked approval claimsfirst-pass slug multi-tracer-positron-emission-tomography-imaging
Using multi-tracer positron emission tomography imaging, we detected DREADD expression in vivo, which was confirmed in nigrostriatal dopamine neurons by immunohistochemistry, as well as by assessed activation of the SN following agonist administration.

Source:

activation readoutsupports

Agonist administration was associated with assessed activation of the substantia nigra.

as well as by assessed activation of the SN following agonist administration

Source:

in vivo detectionsupports

Multi-tracer PET imaging detected DREADD expression in vivo and immunohistochemistry confirmed expression in nigrostriatal dopamine neurons.

Using multi-tracer positron emission tomography imaging, we detected DREADD expression in vivo, which was confirmed in nigrostriatal dopamine neurons by immunohistochemistry

Source:

Comparisons

Source-stated alternatives

Immunohistochemistry is presented as a confirmatory alternative or complement for verifying expression in dopamine neurons.

Source:

Immunohistochemistry is presented as a confirmatory alternative or complement for verifying expression in dopamine neurons.

Source-backed strengths

enabled in vivo detection of DREADD expression in this primate study

Source:

enabled in vivo detection of DREADD expression in this primate study

Compared with immunohistochemistry

Immunohistochemistry is presented as a confirmatory alternative or complement for verifying expression in dopamine neurons.

Shared frame: source-stated alternative in extracted literature

Strengths here: enabled in vivo detection of DREADD expression in this primate study.

Relative tradeoffs: the abstract does not specify tracer identities or quantitative PET metrics.

Source:

Immunohistochemistry is presented as a confirmatory alternative or complement for verifying expression in dopamine neurons.

Ranked Citations

  1. 1.
    StructuralSource 1MED2021Claim 1Claim 2Claim 3

    Extracted from this source document.