Brain Blood Flow Responses to Stress: Sex Differences

Human Cerebral Blood Flow Regulation: Sex, Mechanism, and Stress Differences (Phase 2)

Twenty-six otherwise healthy adults between 18-40 years of age composed of 13 males and 13 females will be enrolled in this study to determine how sex and sex hormones influence cerebral blood flow (CBF) control in healthy young adults without confounds of age or disease. Participants can expect to be on study for approximately 16 days.

Study Overview

• Status: Completed
• Conditions: Cerebrovascular Disorders
• Intervention / Treatment: Drug: Placebo; Drug: Indomethacin; Drug: Orilissa; Drug: Estradiol; Drug: Testosterone gel; Drug: Anastrozole

Detailed Description

Objective: To determine cerebrovascular control mechanisms in humans and provide mechanistic knowledge to offer new sex-specific therapeutic options for cerebrovascular diseases. The current objective is to determine how sex and sex hormones influence CBF control in healthy young adults without confounds of age or disease.

The central hypothesis is men exhibit reduced cerebral vasodilator function due in part to differences in COX signaling compared to women. Comprehensive CBF data from multi-modal MRI indicate the magnitude of sex differences-as well as the vasodilator mechanisms-are regionally distinct.

The investigators will address 2 specific aims:

1. Are cerebral vasodilator responses greater in women across other physiologic stressors? Do all cerebral vessels respond equally, or are there regional differences-by sex?
2. What mechanisms regulate the increase in CBF to stress; do these differ by sex, or brain region?

This study will be conducted in compliance with federal investigational drug regulations (21 CFR 312) and Good Clinical Practice (GCP) guidelines, as well as state law and institutional policies.

Study Population: Phase 2 include 26 total participants 13 men and 13 women invited back from the Study 2020-0336 (NCT04265053) for Aim 3 who are ≥18 - ≤ 40 years old and considered healthy.

Approach: CBF testing will be performed in research-dedicated 3T magnets. Participants will experience one hypoxia and one hypercapnia trial during each visit. S, study design focuses on the use of Indomethacin to test COX as a potential mechanism explaining sex differences in CBF control. To do this, 4 MRI visits in a double-blind placebo controlled design will be conducted. One set of placebo-Indo visits occurs after the first 4-7 days of sex hormone suppression (with Orilissa) and the second set of MRI visits occurs after 12-16 days of Orilissa while supplementing a single sex hormone by sex.

On day 0 participants will start hormone suppression using Orilissa (male subjects will also start an Anastrozole). After day 2, MRI Visit 1 will be scheduled to occur. Prior to the first study visit the order of drug supplementation will be randomized. Options are: placebo for the first MRI visit, then Indomethacin for the second MRI visit or Indomethacin for the first MRI visit, then placebo for the second MRI visit. After MRI visits 1 and 2 are completed, participants will begin sex hormone add-back (males will receive testosterone and females will receive estradiol). Once participants have been on the hormone add-back protocol for 3-4 days MRI Visits 3 and 4 will be scheduled. Prior to MRI visit 3 the order of drug supplementation will be randomized again.

. Added to protocol on 07/01/2024 = Fecal samples will be collected: at baseline (before beginning Orilissa), 4-8 days after taking the first dose of Orilissa, and 12-16 days after taking the first estradiol or testosterone dose. Subjects will provide 3 fecal samples at home throughout the course of their participation and will take the samples to FedEx to be shipped.

• Study Type: Interventional
• Enrollment (Actual): 22
• Phase: Phase 4

Contacts and Locations

Study Locations

• United States
  • Wisconsin
    • Madison, Wisconsin, United States, 53705
      • University of Wisconsin

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Age between ≥18 - ≤40 years inclusive
• Completed Phase 1: Study 2020-0336

Exclusion Criteria:

• Hypertensive

  • > 125 mmHg systolic blood pressure; or
  • > 80 mmHg diastolic blood pressure
• BMI ≥25 kg/m2
• Fasting blood glucose ≥100 mg/dl
• LDL cholesterol ≥130 mg/dl
• Triglycerides ≥150 mg/dl

• Current diagnosis or history of:

  • peripheral vascular disease
  • hepatic disease
  • renal disease
  • lung disease
  • gastrointestinal disorders/bleeding
  • hematologic disease
  • stroke
  • myocardial infarction
  • coronary heart disease
  • congestive heart failure
  • heart surgery
  • prediabetes
  • diabetes mellitus (type 1, type 2, MODY, or others)
  • sleep apnea
  • hypertension
  • some autoimmune diseases, such as inflammatory bowel disease or systemic lupus erythematosus (exclusion at discretion of reviewing MD)
• Current smoking, defined as the use of tobacco or nicotine products >5 times in the past 30 days.
• Cardiovascular medication use
• NSAID sensitivity
• Magnesium-restricted diet

• Any contraindications of having an MRI

  • (e.g. the requirement of anxiolytics in order to complete an MRI scan)
• Irregular menstrual cycle (females only)
• Medical conditions that can affect the menstrual cycle, such as hyperprolactinemia, prolactinoma, hypercortisolemia, and congenital adrenal hyperplasia (females only)
• Pregnancy, breast feeding, or plans to conceive within the next 3 months (females only)
• Polycystic ovary syndrome (females only)
• Hirsutism defined as unwanted and/or excessive hair growth on the face, chest, or back (females only)
• Levonorgestrel intrauterine device (IUD) (females only)

• Hormonal birth control will not be allowed in women, in order to control for high variability between type, dose, and route of therapy. However, in discussion with Dr. Davis (Co-I) and Dr. Laura Cooney M.D., physician experts in medical and reproductive endocrinology and infertility, there are two broad exceptions to this birth control criteria:

  • Copper intrauterine devices (IUDs) will be allowed as they do not change systemic sex hormone levels).
  • Women currently taking hormonal birth control (i.e. contraceptive pills, patch, ring) for contraception only (not for a medical condition such as those listed in exclusion criteria above) may consider temporarily stopping to become eligible for enrollment. Hormonal birth control must be stopped at least one month prior to Study Visit 1 to provide time for menstruation to resume. Then stoppage continues through the last planned study visit. Screening information will be reviewed by endocrinology physicians to determine eligibility and timing on this issue.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Factorial Assignment
• Masking: Double

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Placebo First: Hormone Suppression; Participants drug (placebo vs Indo) are randomized prior to first set of MRI visits, while experiencing hormone suppression.	Drug: Placebo; Placebo; Drug: Indomethacin; to inhibit cyclooxygenase (COX); Other Names: Indo; Drug: Orilissa; to suppress hormones 200mg dose 2x per day (all participants); Drug: Estradiol; Women will receive oral estradiol 2mg/daily
Experimental: Indo First: Hormone Suppression; Participants drug (placebo vs Indo) are randomized prior to first set of MRI visits, while experiencing hormone suppression.	Drug: Placebo; Placebo; Drug: Indomethacin; to inhibit cyclooxygenase (COX); Other Names: Indo; Drug: Orilissa; to suppress hormones 200mg dose 2x per day (all participants)
Experimental: Placebo First: Hormone Add-Back; Participants drug (placebo vs Indo) are randomized prior to second set of MRI visits, while experiencing hormone add-back.	Drug: Placebo; Placebo; Drug: Indomethacin; to inhibit cyclooxygenase (COX); Other Names: Indo; Drug: Orilissa; to suppress hormones 200mg dose 2x per day (all participants); Drug: Estradiol; Women will receive oral estradiol 2mg/daily; Drug: Testosterone gel; 50 mg each morning for add back phase (male participants); Drug: Anastrozole; 1mg/day in men to prevent conversion of testosterone to estradiol
Experimental: Indo First: Hormone Add-Back; Participants drug (placebo vs Indo) are randomized prior to second set of MRI visits, while experiencing hormone add-back.	Drug: Placebo; Placebo; Drug: Indomethacin; to inhibit cyclooxygenase (COX); Other Names: Indo; Drug: Orilissa; to suppress hormones 200mg dose 2x per day (all participants); Drug: Estradiol; Women will receive oral estradiol 2mg/daily; Drug: Testosterone gel; 50 mg each morning for add back phase (male participants); Drug: Anastrozole; 1mg/day in men to prevent conversion of testosterone to estradiol

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Cerebral Blow Flow (CBF): Hormone Suppression Hypoxia Condition	Hypoxia condition will be measured twice via MRI during the first set of study visits under hormone suppression. Reported here is the CBF under hypoxia for the placebo group as compared to the CBF under hypoxia for the Indo group.	first set of study visits (up to 2 hours) within the first 7 days on study
Cerebral Blow Flow: Hormone Suppression Hypercapnia Condition	Hypercapnia condition will be measured twice via MRI during the first set of study visits under hormone suppression. Reported here is the CBF under hypercapnia for the placebo group as compared to the CBF under hypercapnia for the Indo group.	first set of study visits (up to 2 hours) within the first 7 days on study
Cerebral Blow Flow: Hormone Add-Back Hypoxia Condition	Hypoxia condition will be measured twice via MRI during the second set of study visits under hormone add-back. Reported here is the CBF under hypoxia for the placebo group as compared to the CBF under hypoxia for the Indo group.	second set of study visits (up to 2 hours) within 12-16 days on study
Cerebral Blow Flow: Hormone Add-Back Hypercapnia Condition	Hypercapnia condition will be measured twice via MRI during the first set of study visits under hormone add-back. Reported here is the CBF under hypercapnia for the placebo group as compared to the CBF under hypercapnia for the Indo group.	second set of study visits (up to 2 hours) within 12-16 days on study

Collaborators and Investigators

• Sponsor: University of Wisconsin, Madison
• Collaborators: National Heart, Lung, and Blood Institute (NHLBI)
• Investigators: Principal Investigator: William G Schrage, PhD, University of Wisconsin, Madison

Study record dates

Study Major Dates

• Study Start (Actual): July 24, 2024
• Primary Completion (Actual): May 31, 2025
• Study Completion (Actual): May 31, 2025

Study Registration Dates

• First Submitted: February 2, 2024
• First Submitted That Met QC Criteria: February 2, 2024
• First Posted (Actual): February 12, 2024

Study Record Updates

• Last Update Posted (Actual): July 18, 2025
• Last Update Submitted That Met QC Criteria: July 17, 2025
• Last Verified: July 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Vascular Diseases; Cardiovascular Diseases; Cerebrovascular Disorders; Antineoplastic Agents; Physiological Effects of Drugs; Molecular Mechanisms of Pharmacological Action; Anti-Inflammatory Agents; Peripheral Nervous System Agents; Hormones; Hormones, Hormone Substitutes, and Hormone Antagonists; Antineoplastic Agents, Hormonal; Enzyme Inhibitors; Gout Suppressants; Antirheumatic Agents; Reproductive Control Agents; Sensory System Agents; Analgesics, Non-Narcotic; Analgesics; Anti-Inflammatory Agents, Non-Steroidal; Cyclooxygenase Inhibitors; Steroid Synthesis Inhibitors; Hormone Antagonists; Androgens; Tocolytic Agents; Estrogen Antagonists; Aromatase Inhibitors; Estrogens; Anastrozole; Testosterone; Estradiol; Indomethacin
• Other Study ID Numbers: 2023-0548; EDUC/KINESIOLOGY (Other Identifier: UW- Madison); 1R01HL150361-01 (U.S. NIH Grant/Contract); Protocol Version 07/01/2024 (Other Identifier: UW Madison)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No