Clinical trial NCT04831398: The Effects of Acute Melatonin Supplementation on Cardiovascular Responses to Sympathetic Activation
Official title: The Effects of Acute Melatonin Supplementation on Cardiovascular Responses to Sympathetic Activation
Study type: INTERVENTIONAL
Overall status: RECRUITING
Phase: PHASE4
Conditions: Healthy
Lead sponsor: University of Oklahoma
Sponsor class: OTHER
First posted: 2021-04-05
Enrollment: 100
Sex: ALL
Minimum age (years): 18
Maximum age (years): 35
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Intervention model description: This study is a single-blind crossover design.
Primary purpose: BASIC_SCIENCE

Brief summary: the purpose of this experiment is to determine if acute melatonin supplementation alters central and peripheral cardiovascular responses to a cold pressor test at rest and during dynamic exercise.

Detailed description: After IRB approval, experiments will take place in the Human Circulation Research Laboratory in the Department of Health and Exercise on the University of Oklahoma Norman campus. All subjects will complete a total of 3 visits. The first is a screening visit to provide informed consent and to ensure the potential participant meets all inclusion criteria and no exclusion criteria. Once consented and enrolled, participants will be familiarized with experimental protocols. On separate days (visits 2 and 3), participants will complete placebo (PLA) and melatonin (MEL) in a randomly ordered, single-blind, counter-balanced design. PLA or MEL treatment will precede testing by 30min to maximize absorption into the circulation (Bartoli, 2013).

All experiments (PLA/MEL) will begin with the subject lying supine for 5 min of quiet rest where baseline measurements are taken, followed by activation of the lower body negative pressure (LBNP) device causing suction at -20 mmHg. Following LBNP participants will be given 10 minutes of rest to recover all variables to pre-LBNP values. After which participants will be given a hand grip dynamometer to complete 7 minutes of exercise at an intensity of 20% MVC at a 1s contraction to 2s relaxation cycle paced by a metronome. During the final 2 minutes of the 7 minutes of exercise the LBNP device will be activated again to -20mmHg such that the participant will be completing LBNP during rhythmic grip exercise. After the completion of exercise, the subject will remain supine for 10min. Then the a Total Labile Signal (TLS) procedure will be conducted. Where the experimental limb is occluded using a blood pressure cuff for 5min. The cuff is then rapidly deflated. The lowest oxyhemoglobin measured during the occlusion is recorded. After the TLS procedure, the subject will be de-instrumented and will leave the laboratory.

Eligibility criteria: Inclusion Criteria:

* Healthy men and women
* Women must be premenopausal with a regular menstrual cycle (26-30 days)

Exclusion Criteria:

* History of autonomic dysfunction
* Cardiovascular diseases
* Diabetes
* Tobacco/nicotine use
* Systolic Pressure \>= 130 mmHg
* Diastolic Pressure \>= 85 mmHg
* Regular melatonin use \>= 1 use/week
* Allergy to melatonin
* Cardiometabolic medication use (e.g. anti-hypertensives, insulin-sensitizing, statins)
* Sex hormone replacement medical use (e.g. testosterone, estrogen, progesterone)
* Pregnancy

Primary outcomes:
measure: Muscle Tissue Oxygenation
timeFrame: 7 minutes of rest and 7 minutes of exercise
measure: Mean Arterial Pressure
timeFrame: 7 minutes of rest and 7 minutes of exercise
Secondary outcomes:
measure: Cerebral Oxygenation
timeFrame: 7 minutes of rest and 7 minutes of exercise
measure: Heart Rate
timeFrame: 7 minutes of rest and 7 minutes of exercise
measure: Respiratory Rate
timeFrame: 7 minutes of rest and 7 minutes of exercise
measure: Cardiac Output
timeFrame: 7 minutes of rest and 7 minutes of exercise
measure: Stroke Volume
timeFrame: 7 minutes of rest and 7 minutes of exercise
measure: Total peripheral resistance
timeFrame: 7 minutes of rest and 7 minutes of exercise
measure: Heart Rate Variability
timeFrame: 7 minutes of rest and 7 minutes of exercise
Other outcomes:
Locations:
city: Norman
country: United States
facility: Department of Health and Exercise Science
state: Oklahoma
Study officials:
affiliation: University of Oklahoma
name: Jeremy M Kellawan
role: PRINCIPAL_INVESTIGATOR
References: