Background:
Brown adipose tissue (BAT) is a type of fat in the body. It may prevent weight gain, improve insulin sensitivity, and reduce fatty liver. Researchers want to see if BAT helps the body burn energy.
Objective:
To learn more about how BAT works to burn energy.
Eligibility:
People ages 18-40 with a body mass index between 18 and 40
Design:
Participants will be screened with:
Medical history
Physical exam
Blood, urine, and heart tests
Dietitian interview
Participants will have an overnight baseline visit. This includes:
Repeats of screening tests
Exercise test
Scans. For one scan, a radioactive substance is injected into the arm.
FSIVGIT: An IV is inserted into veins in the right and left arms. Glucose and insulin are injected in one arm. Blood glucose and insulin levels are measured from the other.
Metabolic suite: Participants stay 18-19 hours in a room that measures their metabolic rate. Monitors on the body measure heart rate, movement, and temperature.
Optional fat biopsy: A small piece of tissue is removed with a needle.
Participants will take 2-4 pills daily for 4 weeks. All women will take the drug mirabegron. Men will be randomly get either the drug or a placebo.
All participants will have a visit after 2 weeks of the pills. They will repeat the screening tests.
Participants will have an overnight visit 2 weeks later. They will repeat the baseline tests.
Participants will keep food and medication diaries.
Participants will have a follow-up visit 2 weeks after stopping the pills. This includes heart tests.
Female
Age 18-40 years
BMI 18.00-40.0 kg/m²
Able to understand the research and willing to sign a written informed consent document
Hypersensitivity and associated allergic reactions to mirabegron (or similar drug substances or components)
Abnormal bladder function, diagnosis of bladder outlet obstruction, urinary incontinence, urgency, and urinary frequency or use of antimuscarinic medication to treat overactive bladder (OAB)
Type 1 or Type 2 Diabetes mellitus, fasting serum glucose >125 mg/dL, and/or an HbA1c test >6.5%
Hypertension, defined as blood pressure (Bullet)140/90 mmHg, based on WHO guidelines (https://www.who.int/news-room/fact-sheets/detail/hypertension)
Parallel
Mirabegron
DrugWomen will take 100mg daily for 4 weeks. Men will take 200mg daily for 4 weeks. The medication is available in 50 mg tablets.
B Complex Plus Vitamin C Tablets
Other interventionMales will be randomized to take placebo versus active drug (mirabegron). Those taking placebo will take 4 tablets each day to mirror to active group (taking 4 tablets of 50 mg each).
Cohorts 1 and 2: Change in BAT metabolic activity
Change in brown adipose tissue (BAT) metabolic activity as measured by 18FFDG PET/CT
Cohort 3: Change in insulin sensitivity
Change in glucose infusion rate, as measured by the hyperinsulinemic euglycemic clamp
Identify changes in metabolic health arising from BAT activation and/or prolonged treatment with mirabegron
Change in metabolic health parameters including body weight, fat mass, glucose tolerance, changes in levels of hormones, and improved liver function
Cohort 3: Changes in BAT metabolic activity
Change in brown adipose tissue (BAT) metabolic activity as measured by 18FFDG PET/CT
Cohorts 1 and 2: Changes in insulin sensitivity
Changes in glucose infusion rate, as measured by the hyperinsulinemic euglycemic clamp
Click on the lead sponsor to view all of their trials.
