L-arginine and Brown Adipose Tissue

Glucose Intolerance Clinical Trial

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Official title:

The Effect of L-arginine on Brown Adipose Tissue Metabolism in South Asian and White Caucasian Subjects

Clinical Trial Details — Status: Recruiting

Administrative data

• NCT number: NCT02291458
• Other study ID #: NL2014-001733-86
• Status: Recruiting
• Phase: Phase 3
• First received: November 11, 2014
• Last updated: November 13, 2014
• Start date: November 2014
• Est. completion date: December 2015

Study information

• Verified date: November 2014
• Source: Maastricht University Medical Center
• Contact: n/a
• Is FDA regulated: No
• Health authority: Netherlands: The Central Committee on Research Involving Human Subjects (CCMO)
• Study type: Interventional

Clinical Trial Summary

The South Asian population is facing an epidemic of type 2 diabetes, of which the underlying cause is still unknown. It is currently hypothesized that an ethnic susceptibility towards a disturbed energy metabolism may underlie this disadvantageous metabolic phenotype. In line with this, the investigators recently discovered that Dutch South Asian subjects have 32% lower resting energy expenditure (REE) and 34% lower energy-combusting brown adipose tissue (BAT) compared to matched white Caucasians. Nitric oxide (NO) was recently shown to be crucial for BAT development and, interestingly, South Asians have diminished NO bioavailability. Thus, the disadvantageous metabolic phenotype in South Asians may be caused by diminished NO bioavailability resulting in lower BAT volume. Therefore, the investigators hypothesize that increasing NO generation in the body by administration of L-arginine, the precursor of NO, will improve their metabolic phenotype by increasing BAT volume, thereby increasing REE and clearance of triglycerides and glucose by BAT. To investigate this, the investigators will perform a randomized placebo-controlled multicenter cross-over study in moderately obese Dutch South Asians and matched white Caucasians. Subjects will receive L-arginine (9 gram/day) or placebo for 6 weeks, followed by a wash-out period of 4 weeks and then again 6 weeks of one of either treatments. At the end of both treatment periods, a cold-induced PET-CT scan will be performed. Furthermore, muscle and fat biopsies will be obtained and thermoregulation will be assessed.

Description:

Rationale: The South Asian population originally descends from the Indian subcontinent and represents approximately 20% of the total world population. This population is facing an epidemic of type 2 diabetes, of which the underlying cause is still unknown. A high prevalence of a disadvantageous metabolic phenotype, consisting of obesity, insulin resistance and dyslipidemia, may at least in part contribute to this excess risk. It is currently hypothesized that an ethnic susceptibility towards a disturbed energy metabolism may underlie this disadvantageous metabolic phenotype. In line with this, the investigators recently discovered that Dutch South Asian subjects have 32% lower resting energy expenditure (REE) and 34% lower energy-combusting brown adipose tissue (BAT) compared to matched white Caucasians. Nitric oxide (NO) was recently shown to be crucial for BAT development and, interestingly, South Asians have diminished NO bioavailability. Thus, the disadvantageous metabolic phenotype in South Asians may be caused by diminished NO bioavailability resulting in lower BAT volume. Therefore, the investigators hypothesize that increasing NO generation in the body by administration of L-arginine, the precursor of NO, will improve their metabolic phenotype by increasing BAT volume, thereby increasing REE and clearance of triglycerides and glucose by BAT.

Objectives: The primary objectives are: 1) to determine the effect of L-arginine on glucose uptake by brown adipose tissue and to assess whether the effect differs between South Asian and white Caucasian subjects; 2) to determine the effect of L-arginine on whole body energy expenditure and to assess whether the effect differs between South Asian and white Caucasian subjects; 3) to determine the effect of L-arginine on fat mass and to assess whether the effect differs between South Asian and white Caucasian subjects.

Study design: A randomized placebo-controlled multicenter cross-over study will be performed in moderately obese Dutch South Asians and matched white Caucasians. Subjects will receive L-arginine (9 gram/day) or placebo for 6 weeks, followed by a wash-out period of 4 weeks and then again 6 weeks of one of either treatments. At the end of both treatment periods, a cold-induced PET-CT scan will be performed. Furthermore, muscle and fat biopsies will be obtained, thermoregulation will be assessed, an oral glucose tolerance will be performed and the investigators will assess NO-dependent and independent vasodilation by means of iontophoresis.

Study population: Mildly obese (BMI 25-30 kg/m2) pre-diabetic male volunteers of South Asian and white Caucasian descent aged between 35-50 years.

Intervention: The intervention will consist of administration of 9 grams of L-arginine per day in three gifts (3dd 3 gram).

Recruitment information / eligibility

• Status: Recruiting
• Enrollment: 26
• Est. completion date: December 2015
• Est. primary completion date: October 2015
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: Male
• Age group: 35 Months to 50 Years

Eligibility

Inclusion Criteria:

• Caucasian or South Asian ethnicity

• Age: 35-50 years

• Gender: male

• BMI: 25-30 kg/m2

• Plasma glucose levels 2 h after OGTT between 7.8 and 11 mM (e.g. impaired glucose tolerance) or Fasting plasma glucose levels > 5.5 mM

• Good general health

Exclusion Criteria:

• Type 2 diabetes (determined on basis of oral glucose tolerance test (OGTT))

• BMI > 30 kg/m2

• Plasma glucose levels 2 h after OGTT < 7.8 mM

• Plasma L-arginine levels < 41 or > 114 uM

• Use of beta-blockers (these inhibit BAT activity) < 1 month before start of study or during study

• Systolic blood pressure < 90 mmHg

• Haematocrit < 0.41 or > 0.51 l/l

• Haemoglobin < 8.5 or > 11.0

• Creatinine (enzymatic method) < 45 or > 100 µmol/L

• ASAT > 45 U/L

• ALAT > 50 U/L

• Alkaline phosphatase > 125 U/L

• Gamma GT > 45 U/L

• Participation in an intensive weight-loss program or vigorous exercise program during the last year before the start of the study

• Abuse of drugs and/or alcohol

• Hyperthyroidism or hypothyroidism

• Participation in earlier research or medical examinations that included PET-CT scanning

• Psychologically unstable subjects (as judged by the treating medical specialist)

• Subjects with mental retardation (as judged by the treating medical specialist)

• Subjects with severe behaviour disorders (as judged by the treating medical specialist)

Study Design

Allocation: Randomized, Endpoint Classification: Efficacy Study, Intervention Model: Crossover Assignment, Masking: Double Blind (Subject, Caregiver, Investigator), Primary Purpose: Treatment

Related Conditions & MeSH terms

• Adipose Tissue, Brown
• Glucose Intolerance
• Nitric Oxide

Intervention

Drug:
• L-arginine
9 gram L-arginine / day for 6 weeks
• Placebo
9 gram placebo / day for 6 weeks

Locations

Country	Name	City	State
Netherlands	Maastricht University Medical Center +	Maastricht	Limburg

Sponsors (2)

Lead Sponsor	Collaborator
Maastricht University Medical Center	Leiden University Medical Center

Country where clinical trial is conducted

Netherlands, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Standard uptake value of Brown adipose tissue	Glucose uptake by brown adiopse tissue will be assessed by cold-induced 18F-FDG PET-CT scan	6 weeks	No
Primary	Energy expenditure	Energy expenditure will be determined by means of indirect calorimetrie	6 weeks	No
Primary	Fat mass	Fat mass will be determined by DEXA scan	6 weeks	No
Secondary	Body temperatures	Skin and core body temperatures as well as gradients will be assessed by means of iButtons and ingestion of a telemetric pill, respectively.	6 weeks	No
Secondary	Skin perfusion and endothelial-dependent and independent vasodilation	This will be measured by means of Laser Doppler Flowmetry (LDF) and iontophoresis	6 weeks	No
Secondary	Skeletal muscle mitochondrial respiration/uncoupling	This will be determined in muscle biopsies by using the Oroboros 2k Oxygraph instrument present in our laboratory .	6 weeks	No
Secondary	Brown adipocyte recruitment and inflammation in WAT	This will be measured in subcutaneous WAT biopsies by assessing mRNA expression via real time polymerase-chain reaction (RT-PCR) and protein content by immunohistochemical stainings.	6 weeks	No
Secondary	Blood parameters	Venous blood will be drawn by means of a catheter placed in the antecubital vein of the underarm. By using radioimmunoassay, high performance liquid chromotogaphy (HPLC) and enzyme-linked immunosorbent assay (ELISA), blood parameters (i.e. lipids, glucose, inflammatory markers and endothelial activation markers) will be analyzed. In addition, we will perform DNA analyses from blood.	6 weeks	No