PET Imaging of Brain mGluR5 Receptors Using [18F]SP203

July 3, 2018 updated by: National Institute of Mental Health (NIMH)

PET Imaging of Brain mGluR5 Receptors Using [18F]SP203 and [11C]SP203

The metabotropic glutamate subtype five (mGluR5) receptor is a protein found in the brain and is the target for the excitatory chemical messenger glutimate. The purpose of this protocol is to measure mGluR5 receptors in the brain using positron emission tomography (PET) and a research drug called [18F]SP203.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Metabotropic glutamate receptors are G-protein coupled receptors that respond to glutamate by activating proteins inside nerve cells that affect cell metabolism, thereby fine-tuning the signals sent between cells to maintain balance in neuronal activity. Metabotropic Glutamate receptors (mGluR5) are Group I receptors localized post-synaptically and found in several regions of the brain including the striatum, hippocampus, amygdala, and cortex. Activation of mGluR5 stimulates phospholipase C, resulting in phosphoinositide hydrolysis and increase of intracellular Ca2+ levels. Several potent antagonists for mGluR5 have been developed, including 6 methyl-2-(phenylethynyl)pyridine (MPEP) and 3-[(2-methyl-1,3-thiazol-4yl)ethynyl] pyridine (MTEP) however, no simple derivatives of MPEP or MTEP had proven to be useful for in vivo imaging.

In the present protocol, we will use a new PET ligand [(18)F]SP203 for two reasons: Part 1.) we will perform kinetic brain imaging to quantify mGluR5 binding parameters in brain and determine the reliability and reproducibility of these measures in 15 healthy controls Part 2.) if the tracer is proved successful in the part 1, we plan to estimate radiation-absorbed doses of [(18)F]SP203 in healthy human subjects by performing whole body imaging.

We will also use another new ligand, [11C]SP203, which has the same structure as [(18)F]SP203 but labeled with (11)C instead of (18)F. Part 3) the same purpose as part 1 but with [(11)C]SP203 instead of [(18)F]SP203. Part 4) if [(11)C]SP203 is proved successful in the part 3, we plan to estimate radiation absorbed doses of [(11)C]SP203 in healthy human subjects. At this moment, we do not plan to perform additional scans of [(18)F]SP203 under the current protocol. All future subjects will participate in scans of [(11)C]SP203.

Additionally, Part 5) we will measure the difference in [(18)F]SP203 concentration between the artery and the vein without PET scanning to assess whether the venous blood is a valid and less invasive substitute of arterial blood. In some of [(18)F]SP203 scans performed in the current protocol, we compared [(18)F]SP203 levels between radial artery and antecubital vein and observed 30% - 60% lower levels in vein. We plan to test whether sampling from a vein in the hand and / or warming up makes [(18)F]SP203 levels in vein similar to artery.

Successful development of a PET ligand to image mGluR5 will have a strong impact on clinical management of brain disorders with disruptions in glutamatergic transmission such as schizophrenia, anxiety, and neurodegenerative disorders including Alzheimer s and Parkinson s disease.

Study Type

Interventional

Enrollment (Actual)

50

Phase

  • Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Maryland
      • Bethesda, Maryland, United States, 20892
        • National Institutes of Health Clinical Center, 9000 Rockville Pike

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 65 years (ADULT, OLDER_ADULT)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Description

  • INCLUSION CRITERIA:

Healthy control subjects aged 18 65 years, with history/physical exam, ECG, and laboratory tests within one year of the PET scan within normal limits.

EXCLUSION CRITERIA:

  1. Current psychiatric illness, substance abuse or severe systemic disease based on history and physical exam.
  2. Laboratory tests with clinically significant abnormalities.
  3. Prior participation in other research protocols or clinical care in the last year such that radiation exposure would exceed the annual limits.
  4. Pregnancy and breast feeding.
  5. Claustrophobia. (part 1 and 3 only)
  6. Presence of ferromagnetic metal in the body or heart pacemaker. (part 1 and 3 only)
  7. Positive HIV test.
  8. Consumed alcohol within 48 hours before the PET scan.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: TREATMENT

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

National Institute of Mental Health (NIMH)

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

September 28, 2007

Study Completion (ACTUAL)

March 17, 2015

Study Registration Dates

First Submitted

October 2, 2007

First Submitted That Met QC Criteria

October 2, 2007

First Posted (ESTIMATE)

October 3, 2007

Study Record Updates

Last Update Posted (ACTUAL)

July 5, 2018

Last Update Submitted That Met QC Criteria

July 3, 2018

Last Verified

March 17, 2015

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • 070082
  • 07-M-0082

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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