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The frequency and severity of heat waves has increased in the last decades. Older adults (over 65 years) have impaired responses to heat stress making them at increased risk for adverse events. Previous heat waves report that women over 65 experience worse health outcomes than any other age group and age matched men.
Aging and reproductive hormones, specifically estrogen, independently alter responses to heat stress. However, the combined effects of low estrogen following menopause and aging on the response to heat stress are unknown. In this study, the investigators will identify the role of estrogen in pre and post menopausal women on thermoregulatory responses to heat stress.
Premenopausal and postmenopausal women will be recruited and different interventions will be given to each group. To mimic a postmenopausal hormone profile, premenopausal women will be given a GnRH antagonist, which acutely reduces estrogen concentrations. This induces a temporary post-menopausal state without compounding aging effects. Postmenopausal women will be given a transdermal estradiol patch to acutely raise estrogen concentrations. Supplementing estrogen in postmenopausal women allows for the effect of menopausal low estrogen concentration to be removed from the physiological effects of aging.
Subjects sign an informed consent form and undergo a medical screening prior to participation. The screening includes a physical exam, anthropometry, chemical and lipid profiles.
Each subject will complete 6 (3 for each treatment) experimental trials. For each intervention, participants will complete one passive heating experiment first, followed by two active heating experiments.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Premenopausal estrogen suppression | Experimental | Participants take a cellulose placebo tablet for 4 days prior to baseline testing and continue until experimental visits are complete. Following completion of placebo testing, participants begin taking 400 mg/day Elagolix for 4 days prior to testing and continue until experimental visits are complete. |
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| Postmenopausal estrogen supplementation | Experimental | Participants wear a transdermal estradiol patch or placebo patch for 5 days prior to testing and continue until experimental visits are complete. After 48 hr washout, participants then wear the alternative treatment for 5 days prior to testing until experimental visits are complete. |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Elagolix Oral Tablet | Drug | 2 x 200 mg tablet |
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| Measure | Description | Time Frame |
|---|---|---|
| Skin Blood Flow | Skin blood flow response to whole body heating is continuously monitored | Monitored continuously during both 3 hour passive heating experiments (Visit 1 and Visit 3 approx 3 weeks) |
| Local Sweat Rate | A small sweat capsule is placed on the forearm for the duration of whole body heating. | Monitored continuously during both 3 hour passive heating experiments (Visit 1 and Visit 3 approx 3 weeks) |
| Core Temperature | Changes in body temperature are measured through a telemetry pill swallowed before each experiment. | Monitored continuously during all 3 hour experimental visits (6 total average of 3 weeks) |
| Measure | Description | Time Frame |
|---|---|---|
| Body Mass | Body mass is measured on a scale. | Baseline and following 3 hr experimental visit (6 total visits for study completion, an average of 3 weeks) |
| Skin Temperature | Mean skin temperature is calculated from a weighted average of skin temperature from 4 different sites. |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Role | Phone | Extension | |
|---|---|---|---|---|
| W. Larry Kenney, Ph.D. | Contact | 814-863-1672 | w7k@psu.edu | |
| Olivia K. Leach, MS | Contact | okl5046@psu.edu |
| Name | Affiliation | Role |
|---|---|---|
| W. Larry Kenney, Ph.D. | The Pennsylvania State University | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Noll Laboratory | Recruiting | University Park | Pennsylvania | 16802 | United States |
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| ID | Term |
|---|---|
| D018882 | Heat Stress Disorders |
| ID | Term |
|---|---|
| D014947 | Wounds and Injuries |
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| ID | Term |
|---|---|
| C539351 | elagolix |
| C511292 | Ortho Evra |
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Subjects participate in 6 experiments, 3 for each treatment (Elagolix OR Estradiol and placebo). The order of treatment is random.
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Double (participant, investigator)
| Estradiol patch | Drug | 0.05 mg/day patch |
|
| cellulose placebo | Other | placebo tablet |
|
| placebo patch | Other | placebo patch |
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| Calculated continuously for the duration of each 3 hr experimental visit (6 total visits for study completion, an average of 3 weeks) |