The Effects of Acute Melatonin Supplementation on Cardiovascular Responses to Sympathetic Activation

University of Oklahoma (OU)

Status and phase: Enrolling; Phase 4

Conditions: Healthy

Treatments: Dietary Supplement: melatonin; Other: Placebo

Study type: Interventional

Funder types: Other

Identifiers

NCT04831398

13084

Details and patient eligibility

About

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.

Full 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.

Enrollment: 100 estimated patients

Sex: All

Ages: 18 to 35 years old

Volunteers: Accepts Healthy Volunteers

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

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Single Blind

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100 participants in 2 patient groups, including a placebo group

Placebo

Placebo Comparator group

Description:

Placebo (PLA) is 10 sublingual sprays of a diluted (1 microliter/29ml filtered water) mint extract.

Treatment:

Other: Placebo

Melatonin

Experimental group

Description:

5mg commercially available melatonin (MEL) spray will be given sublingually.

Treatment:

Dietary Supplement: melatonin