Healthy
Conditions
Keywords
Healthy, Male
Brief summary
Aging in men reduces the amount of luteinizing hormone (LH) and testosterone (Te) secreted in each burst. Stress-associated mechanisms introduced by acute illness and chronic disease decrease LH and Te secretion further. A major unresolved issue is whether the aging process heightens the negative effects of a stressor (whether physical or metabolic) upon LH and Te secretion. This study will assess LH and Te secretion in response to a physical stressor (maximal exercise) and a common metabolic stressor (hyperglycemia) as a function of age in healthy men ages 18-80 yr.
Interventions
DRUGHyperglycemia
Hyperglycemia (rest controlled) will be induced by i.v. injection of 25 mL of dextrose 50% over 3 minutes with the subject supine.
DRUGSaline
Saline (rest controlled) will be induced by i.v. injection of 25 mL of saline over 3 minutes with the subject supine.
OTHERExercise
Monitored exercise of 7-minute biking, 2-minute arm weights and a blood draw at the 10-minute time point will be repeated 3 times,which takes 30 minutes. Bilateral arm curls begin at 20 pounds and decrease by 5 pounds as needed to sustain 2 minutes of exercise at a rate of 1 complete curl every 2 seconds.
PROCEDUREBlood Draws
Blood will be sampled every 10 min from 0700 to 1300 h. Each intervention will begin at 0800 h after 1 h of baseline sampling, and be completed by 0900 h. Intervention is followed by 4 additional h of sampling to capture recovery (total sampling 6 h). Ten-min samples are for Te, LH, ACTH, cortisol, and GH. Glucose will be checked every 30 min. At 07000 h an archival serum sample will be obtained for safety-monitoring purposes.
OTHERFasting procedure
Beginning at 1900 h on the evening prior to each study visit, subjects will remain fasting except for water, diet soda, and other non-caloric and non-caffeinated fluids, until 1300 h the next day.
Sponsors
Mayo Clinic
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
DOUBLE (Subject, Investigator)
Eligibility
Sex/Gender
MALE
Age
18 Years to 80 Years
Healthy volunteers
Yes
Inclusion criteria
* Community dwelling, healthy men age 18 to 80 * Body-Mass Index (BMI) 18-30 kg/m2 * Willingness to provide written informed consent * Physician acceptable screening ECG for participants 60 years and older
Exclusion criteria
* recent use of psychotropic or neuroactive drugs (within five biological half-live) * obesity (outside weight range above) * acute weight change (loss or gain of \>2 kg in 6 weeks * Laboratory test results not deemed physician acceptable * triglycerides \> 300 * BUN \>30 * creatinine \> 1.5 mg/dL * liver functions tests twice upper limit of normal * electrolyte abnormality * anemia; hemoglobin \< 12.0 gm/dL * drug or alcohol abuse * psychosis, depression, mania or severe anxiety * acute or chronic organ-system disease * endocrinopathy, other than primary thyroidal failure receiving replacement * untreated osteoporosis * nightshift work or recent transmeridian travel (exceeding 3 time zones within 7 days of admission) * PSA \> 4.0 ng/mL, History or suspicion of prostatic disease (elevated PSA,indeterminate nodule or mass, obstructive uropathy) * History of carcinoma (excluding localized basal cell carcinoma removed or surgically treated with no recurrence * History of thrombotic arterial disease (stroke, TIA, MI, angina) or deep vein thrombophlebitis * History of CHF, cardiac arrhythmias, congential QT prolongation, and medications used to treat cardiac arrhythmias * Gynecomastia \> 2 cm, untreated * Untreated gallbladder disease * History of smoking greater than one ppd.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in Testosterone concentration after 30 minutes of exercise | 30 minutes after initiating exercise | During the exercise visit subjects will perform an exercise test on a bike and lift weights with both arms for a total of 30 minutes. |
Countries
United States
Outcome results
None listed