Obesity
Conditions
Brief summary
Obesity and metabolic disease result when energy intake consistently exceeds energy expenditure. One appealing new target for treatment is the activation of brown adipose tissue (BAT), an organ recently found to be functional in adult humans. Brown adipocytes selectively express uncoupling protein 1 (UCP1), which renders the inner membrane of mitochondria leaky, thereby diverting chemical energy from ATP generation to heat production. Interest in BAT has been spurred by the recognition that in addition to classical BAT depots, other brown-fat-like cells are present in the subcutaneous white adipose tissue (WAT) in animals and also in humans.These cells have structural and functional properties that resemble brown adipocytes, and they are referred to as beige or 'brite' (brown-in-white) adipocytes. Interestingly, browning of WAT can be induced in animals and humans by physiological stimuli such as cold exposure, which increases adrenergic tone, and by exercise, which selectively drives WAT browning through irisin, an exercise-induced myokine. In addition b-adrenergic drugs and other pharmacological agents,such as prostaglandins, can induce browning of white adipose tissue. More recently, one study showed that treatment of C57BL/6 mice with phosphodiesterase inhibitor sildenafil (12 mg/kg/d) for 7 d caused 4.6-fold increase in uncoupling protein-1 expression and promoted establishment of a brown fat cell-like phenotype (browning) of WAT in vivo. Therefore, the investigators hypothesized that sildenafil can promote browning of white adipose tissue and improves insulin sensitivity in human adults.
Detailed description
The study subjects will be taken placebo (first stage) and sildenafil (second stage) intervention for 7 days, respectively afterward.Subcutaneous fat tissue and muscle samples will be obtained by biopsy from some individuals and measure the browning of white adipose tissue and insulin signaling.The insulin sensitivity will be tested by insulin clamp assay before and after each intervention, respectively. In addition,blood samples for biochemical analysis will be obtained before and after each intervention, respectively. The browning of white adipose tissue will be measured by the expressions of peroxisome proliferator-activated receptor-γ (PPARγ), PPARγcoactivator 1α (PGC-1α), uncoupling protein 1 (UCP-1), the second messenger cyclic guanosine-3', 5'-monophosphate (cGMP),PR domain containing 16 zinc finger transcription factor (Prdm16) and deiodinase, iodothyronine, type II (DIO2).The metabolic makers will be measured by blood pressure, heart rate, thyroid functions, resting metabolic rate, respiratory quotient, blood cGMP, blood insulin and blood glucose.
Interventions
DRUGsildenafil
sildenafil 100 mg per day for 7 days.
DRUGplacebo
an identical placebo per day for 7 days
Sponsors
Xiang Guang-da
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
DOUBLE (Subject, Investigator)
Eligibility
Sex/Gender
MALE
Age
20 Years to 30 Years
Healthy volunteers
Yes
Inclusion criteria
* overweight volunteers * 20-30 years old * body mass index \>=25 kg/m2 * normal glucose tolerance
Exclusion criteria
* normal body mass index * abnormal cardiovascular status * women * history of any local or systemic infectious disease with fever or requiring antibiotic within four weeks of drug administration * current addiction to alcohol or substances of abuse * children * current addiction to alcohol or substances of abuse * mental incapacity * the use of any medication within four weeks * subjects with hyperthyroidism or hypothyroidism, hypertension (even if controlled with medications)
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Browning of white adipose tissue | 7 days | The browning of white adipose tissue was measured by Western blot (including the expressions of peroxisome proliferator-activated receptor-γ (PPARγ), PPARγcoactivator 1α (PGC-1α), uncoupling protein 1 (UCP-1), the second messenger cyclic guanosine-3', 5'-monophosphate (cGMP),PR domain containing 16 zinc finger transcription factor (Prdm16) and deiodinase, iodothyronine, type II (DIO2)). |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Improvement of insulin sensitivity | 7days | The insulin sensitivity will be tested by insulin clamp before and after each intervention,respectively. |
Other
| Measure | Time frame | Description |
|---|---|---|
| Change of metabolic status | 3 months | The metabolic status including blood pressure, heart rate, thyroid functions, resting metabolic rate, respiratory quotient, blood cGMP, blood insulin and blood glucose will be measured before and after intervention in each group. |
Countries
China
Contacts
Primary ContactGuangda Xiang, MD
Outcome results
None listed