MRS Measurement of Glutamate and GABA Metabolism in Brain

NCT ID: NCT00109174

Last Updated: 2025-12-08

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

RECRUITING

Clinical Phase

NA

Total Enrollment

200 participants

Study Classification

INTERVENTIONAL

Study Start Date

2006-09-06

Study Completion Date

2030-03-11

Brief Summary

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This study will use magnetic resonance spectroscopy (MRS) to measure in the brain the transfer of \[13\]C as it is naturally metabolized from glucose to specific chemical transmitters. From this method, we can measure the rate of production of an important excitatory neurotransmitter (glutamate) as well as an inhibitory neurotransmitter (GABA).

Detailed Description

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13C is a stable (i.e., non-radioactive) isotope of carbon with a natural abundance of \~1%. Following infusion of \[13C\]glucose and/or \[13C\]acetate, in vivo MRS (magnetic resonance spectroscopy) can monitor the rate of flux of the 13C atom from glucose and/or acetate to glutamate to glutamine. Thus, this procedure can provide measure of glutamate (GLU) and glutamine (GLN) turnover in brain. We have established parameters to obtain these measurements in nonhuman primate brain. The current protocol seeks approval to optimize MRS parameters and to develop new MRS techniques for human brain using the GE 3T, the Siemens 3T, and the Siemens 7T device.

Study population: All subjects will be aged 18 65 years, without serious medical illnesses and meet criteria listed in Section VI A.

Design: Subjects will receive either oral administration of \[13C\]glucose or an intravenous infusion of \[13C\]glucose and/or \[13C\]acetate to approximately double their plasma glucose levels. The plasma acetate level will remain within the physiological range observed in humans (Lebon et al, 2002). While lying in the 3T or 7T device, serial data acquisitions will be obtained over \~2 h to optimize the experimental conditions so as to measure the 13C signals from GLU, GLN and other metabolisms in brain.

Outcome measures: The primary goal of this study is to measure GLU/GLN turnover in brain. With no additional data acquisition, we can also obtain information on the synthesis of GABA, the major inhibitory neurotransmitter in brain. GLU is converted to GABA via the enzyme glutamic acid decarboxylase (GAD). While monitoring the transfer of 13C signal from GLU to GLN, we can simultaneously measure the transfer of 13C signal from GLU to GABA and thereby measure the activity of GAD (Li et al 2005). In addition to directly measure 13C signals, 13C labeling to brain metabolites can also be measured indirectly by detecting proton MRS during infusion of \[13C\]glucose and/or \[13C\]acetate.

Conditions

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Normal Physiology

Keywords

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Glutamate Excitatory Amino Acid Neurochemistry Brain Magnetic Resonance Spectroscopy

Study Design

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Allocation Method

NA

Intervention Model

SINGLE_GROUP

Primary Study Purpose

BASIC_SCIENCE

Blinding Strategy

NONE

Study Groups

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One arm

Subjects receive the same test

Group Type OTHER

3T and 7T device

Intervention Type DEVICE

3T and 7T device

Interventions

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3T and 7T device

3T and 7T device

Intervention Type DEVICE

Eligibility Criteria

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Inclusion Criteria

* 18-65 years of age
* Able to give written informed consent
* Healthy based on medical history and physical exam
* Enrolled in Protocol 01-M-0254 or Protocol 17-M-0181

Exclusion Criteria

* Any current Axis 1 diagnosis
* Clinically significant laboratory abnormalities
* Positive HIV test
* Metallic foreign bodies that would be affected by the magnetic resonance imaging (MRI) magnet, or fear of enclosed spaces likely to make the subject unable to undergo an MRI scan.
* History of neurological illness or injury with the potential to affect study data interpretation, such as multiple sclerosis, Parkinson s disease, seizure disorder or traumatic brain injury
* Prescription psychotropic medication; drug free less than 8 weeks (anticholinergics, benzodiazepine, fluoxetine, antipsychotics, and anticonvulsants)
* Serious medical illness as determined from H\&P or laboratory testing including Diabetes
* Inability to lie flat on camera bed for about two and a half hours
* Pregnant or breastfeeding
* Current substance use disorder based on DSM-5
* NIMH employees and staff and their immediate family members will be excluded from the study per NIMH policy.
Minimum Eligible Age

18 Years

Maximum Eligible Age

65 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

Yes

Sponsors

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National Institute of Mental Health (NIMH)

NIH

Sponsor Role lead

Responsible Party

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Responsibility Role SPONSOR

Principal Investigators

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Li An, Ph.D.

Role: PRINCIPAL_INVESTIGATOR

National Institute of Mental Health (NIMH)

Locations

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National Institutes of Health Clinical Center

Bethesda, Maryland, United States

Site Status RECRUITING

Countries

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United States

Central Contacts

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Christopher S Johnson

Role: CONTACT

Phone: (301) 402-6695

Email: [email protected]

Li An, Ph.D.

Role: CONTACT

Phone: (301) 896-2882

Email: [email protected]

Related Links

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Other Identifiers

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05-M-0144

Identifier Type: -

Identifier Source: secondary_id

050144

Identifier Type: -

Identifier Source: org_study_id