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Completed

NCT Number: NCT02500095

Substrate Metabolism, Growth Hormone Signaling, and Insulin Sensitivity During Fasting

Background: Calorie restriction increases longevity in many species and attenuate the development of chronic disorders including type 2 diabetes, cardiovascular diseases and cancer. In mice reduced activity of insulin-like growth factor I (IGF-I) and/or insulin is associated with extended longevity. Growth hormone (GH) is the main regulator of IGF-I production, but the molecular mechanism whereby GH switches from IGF-I stimulation (protein anabolism) to fatty acid oxidation (fatty acid catabolism) as well as induction of insulin resistance during fasting remains enigmatic.

Hypotheses: The changes of the global set of metabolites, induction of insulin resistance, and the shift in metabolism from protein anabolism to lipolysis together with the potentially favorable effect of calorie restriction during fasting depend on preserved fasting-induced GH secretion.

Aim: The investigators wish to provide knowledge on changes in metabolites and shift in signaling pathways that take place at the transition to the fasting state among healthy overweight and obese subjects. Furthermore the investigators wish to determine the effect of GH on the adaption of the metabolism to a fasting state.

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Key information

Conditions

Healthy

Age range

20 year–60 year

Sex eligibility

Male

Study type

Interventional

Phase

Not applicable

Primary location

Aarhus University Hospital

Aarhus, 8000, Denmark

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • healthy men
  • written consent
  • body mass index (BMI) 25-40
  • age 20-60 years

Exclusion criteria

  • any kind of disease
  • regular medication

Treatment and study plan

Fasting

Other

72 hours of fasting

Saline

Drug

Concomitant saline during fasting

Pegvisomant

Drug

Concomitant Growth hormone receptor blockade with Pegvisomant during fasting

Primary outcomes

  1. Insulin and growth hormone signaling, expressed as CHANGE in phosphorylation of intracellular target proteins and CHANGE in messenger ribonucleic acid (mRNA) expression of target genes in muscle- and fat-tissue.

    Time frame: Muscle and fat biopsies obtained at t1= 9.00 am (60 min) and t2=12.30 am (270 min) on each study day after 0, 4 and 8 weeks (interval of 4 weeks between each of the three study days)

    Change in phosphorylation of target proteins and mRNA expression of target genes

Secondary outcomes

  1. Glucose metabolism

    Time frame: Change in glucose metabolism using glucose tracer from t=0 min - 360 min on each study day after 0, 4 and 8 weeks (interval of 4 weeks between each of the three study days)

    Change in glucose metabolism assessed by tracer kinetics on every study day and by indirect calorimetry.

  2. Magnetic resonance (MR) spectroscopy

    Time frame: During fasting: t= 12 hours and t= 48 hours of fasting

  3. Change in concentrations of metabolites in the insulin and growth hormone signaling pathways using metabolomics

    Time frame: Muscle-tissue obtained at t1= 9.00 am (60 min) and t2=12.30 am (270min) on each study day after 0, 4 and 8 weeks (interval of 4 weeks between each of the three study days)

    Method: Metabolomics

  4. Fat metabolism

    Time frame: Change in fat metabolism using palmitic acid tracer from t1=180 min - 240 min and t2=300 min - 360 min on each study day after 0, 4 and 8 weeks (interval of 4 weeks between each of the three study days)

    Change in fat metabolism assessed by tracer kinetics on every study day and by indirect calorimetry.

  5. Protein metabolism

    Time frame: Change in protein metabolism using urea tracer from t=0 min - 240 min on each study day after 0, 4 and 8 weeks (interval of 4 weeks between each of the three study days)

    Change in protein metabolism assessed by tracer kinetics on every study day and by indirect calorimetry.

Sponsors and collaborators

Lead sponsor

University of Aarhus

Other

Registry information

Official study title

Substrate Metabolism, Growth Hormone Signaling, and Insulin Sensitivity During Fasting in Overweight and Obese Human Subjects and the Impact of Growth Hormone Receptor Blockade

Important dates

Study start
2015
Primary completion
2016
Study completion
2016
First posted
Jul 16, 2015
Registry last updated
Nov 23, 2016

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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