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Fat Tissue Microperfusion to Measure Leptin Secretion and Its Relations With Fat Breakdown in Humans

This study has been completed.
Sponsor:
ClinicalTrials.gov Identifier:
NCT00001722
First Posted: November 4, 1999
Last Update Posted: March 4, 2008
The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
Information provided by:
National Institutes of Health Clinical Center (CC)
  Purpose

Leptin is a hormone that acts in the body as a chemical messenger. It is produced in fat cells and is believed to regulate body weight in humans. Leptin decreases appetite and influences the energy balance of the body.

This study will attempt to measure levels of leptin production in the fat pad of the body by using a process called microperfusion. Microperfusion works by inserting 2 to 3 probes (thin tubes) into the fat pad around the belly button. These probes can measure chemicals in an area known as the extracellular space. This is the small space between cells and blood vessels that hormones, medicines, nutrients, and salts travel through.

The study will investigate the effects of a meal, insulin, glucose (sugar), and the medication isoproterenol on leptin levels. Researchers believe that leptin levels are regulated along with the enzyme, hormone sensitive lipase (HSL). When hormone sensitive lipase is activated fat is broken down in a process called lipolysis. In addition, increased levels of HSL result in decreased levels of leptin, which in turn increases appetite and food intake.


Condition
Healthy Obesity

Study Type: Observational
Official Title: Adipose Tissue Microperfusion to Assess Leptin Secretion and Its Relations With Lipolysis in Humans

Further study details as provided by National Institutes of Health Clinical Center (CC):

Estimated Enrollment: 70
Study Start Date: April 1998
Estimated Study Completion Date: July 2003
Detailed Description:

The adipocyte hormone leptin serves as a humoral signal of energy stores, acting on central neuronal networks that regulate ingestive behavior and energy balance. The basis for the circadian rhythm and pulsatility of circulating leptin levels in the face of a relatively stable adipose mass is not known. We have already established the feasibility and validity of adipose tissue microperfusion in humans for measurements of leptin in adipose tissue interstitial fluid. The aim of this study now is to assess the specific aspects of the regulation of adipose tissue metabolism in situ.

The hormone sensitive lipase (HSL) catalyzes the final, rate limiting step of energy mobilization from adipose tissue. Its activation results in hydrolysis of triglycerides, a process referred to as lipolysis. Increased HSL activity during fasting and stress, is physiologically coupled with significant reductions in circulating leptin levels, which in turn, results in increased food intake, and thus, restoration of energy balance. We hypothesize that local neural signals from the sympathetic nervous system to adipocytes through beta-adrenergic receptors simultaneously regulate leptin secretion and lipolysis, the latter via the modulation of HSL activity. This hypothesis will be tested by measurements of interstitial levels of leptin and glycerol in adipose tissue in situ before and after local administration of a beta-adrenergic agonist. Food intake and beta-adrenergic stimulation are excellent potential stimuli in the study of the novel fat-derived hormones, resistin and adiponectin.

We hypothesize that insulin has regulatory effects on leptin secretion and lipolysis. This hypothesis will be tested by measurement of interstitial levels of leptin, TNF-alpha, and interleukin-6 in adipose tissue in situ and after local administration of insulin.

  Eligibility

Information from the National Library of Medicine

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Ages Eligible for Study:   Child, Adult, Senior
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Criteria

INCLUSION CRITERIA

Healthy subjects ages 18 to 50 years.

Healthy volunteers studied as outpatients.

EXCLUSION CRITERIA

Minors (less than 18 years of age)

Subjects taking any medication on a regular basis.

Individuals with hepatic, renal, HPA axis or thyroid dysfunction.

Very lean individuals (defined as a body mass index less than 19).

Smokers.

Pregnant or lactating woman.

Individuals with allergies to teflon, polyethylene or skin tape.

Individuals with known allergy to isoproterenol.

Individuals unable to abstain from alcohol, tobacco, tea, and coffee for 18 hours prior and during the study.

  Contacts and Locations
Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT00001722


Locations
United States, Maryland
National Institute of Child Health and Human Development (NICHD)
Bethesda, Maryland, United States, 20892
Sponsors and Collaborators
Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)
  More Information

Publications:
ClinicalTrials.gov Identifier: NCT00001722     History of Changes
Other Study ID Numbers: 980103
98-CH-0103
First Submitted: November 3, 1999
First Posted: November 4, 1999
Last Update Posted: March 4, 2008
Last Verified: July 2003

Keywords provided by National Institutes of Health Clinical Center (CC):
Obesity
Sympathetic Nervous System
Fat Tissue
Metabolism
Adipose Tissue
Microdialysis
Leptin
Lipolysis
Normal Volunteer