[11C]Fallypride

Background:
Dopamine is a natural chemical in the brain that may influence eating behavior and physical activity. Researchers want to measure the brain s dopamine activity and understand how it differs in people with obesity.
Objective:
To better understand how brain function, particularly dopamine activity, relates to body weight and eating behavior.
Individuals may be able to participate if they:
Have a BMI of at least 18.5 kg/m2
Are weight-stable and generally healthy
Are between ages 18-45 years
Have normal blood pressure
Are not using illegal drugs (based on urine drug screen)
Are not following a special diet
Do not have metal implants
Design:
Participants will be screened with:
Medical history
Physical exam
Questionnaires and an interview to see if it is safe to have a PET/MRI scan
Fasting blood and urine tests
Participants will eat a special diet given to them for the 5 days before their inpatient visit.
Participants will have a 5-day inpatient visit. Some days include blood and urine tests. Each day includes surveys and tests to measure habits and likes/dis-likes. A sample schedule may be:
Day 1: Participants will wear a monitor that uses a needle below the skin to measure glucose. Their body fat will be measured with low-dose x-rays
Day 2: Participants will have a PET scan. They will lie on a table that slides in and out of a donut-shaped scanner. They will be injected with a small amount of a radioactive substance and wear a cap on their head.
Day 3: Participants will have an MRI. They will lie on a table that slides in and out of a scanner.
Day 4: Participants will have another PET scan. This time, they will drink a milk shake during a break from the scanner. Then, they will go back inside the scanner for the end of their scan.
Day 5: Participants will wear a hood for up to 40 minutes to measure their breathing. They will also drink special water and collect samples of their urine to measure the rate they burn energy.
For 12 months after the visit, participants will track their weight and physical activity daily using a special scale and activity monitor. A few times over the year, the study team will send participants special activity monitors to use for 7 days at a time.
Participants will have an in-person 1-day follow-up visit. This includes most tests except for PET scanning....