Effects of IM Oxytocin on Pupil Diameter and HRV

Overview

The goal of this study is to test the effects of oxytocin on heart rate variability and pupil diameter, both of which have subtle effects on the activity rate of the autonomic nervous system.

Full Title of Study: “Effects of Intramuscular Oxytocin on Pupil Diameter and Heart Rate Variability”

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Crossover Assignment
    • Primary Purpose: Basic Science
    • Masking: Triple (Participant, Investigator, Outcomes Assessor)
  • Study Primary Completion Date: December 2019

Detailed Description

This protocol focuses on two measures of autonomic control to quantify central actions of oxytocin. First, the study team proposes to examine the influence of oxytocin on heart rate variability with focus on its effect on high frequency variability, most commonly ascribed to parasympathetic nervous system activity acting to brake sympathetic tone. Intranasal oxytocin has been demonstrated to have a large effect size on this measure which can be repeated at frequent intervals. As a secondary assessment of parasympathetic activity, the study team will measure high frequency fluctuation in pupil diameter, termed hippus, which also reflects parasympathetic nervous system activity. This outcome measure can be assessed in 3 seconds using equipment currently being used under Institutional Review Board (IRB) approved protocols.

Interventions

  • Drug: Oxytocin
    • Oxytocin 10 IU
  • Drug: Placebo
    • Placebo

Arms, Groups and Cohorts

  • Experimental: Oxytocin First, then Placebo
    • Subjects in this arm will receive Intramuscular injection of Oxytocin (PitocinĀ®), 10 International Units (IU) at the first visit. Then at the next visit, they will receive Intramuscular injection of (1 milliliter) saline.
  • Experimental: Placebo, Then Oxytocin
    • Subjects in this arm will receive intramuscular injection of (1 milliliter) saline at the first visit. Then at the next visit, they will receive Intramuscular injection of Oxytocin (PitocinĀ®), 10 International Units (IU).

Clinical Trial Outcome Measures

Primary Measures

  • Fluctuation in Pupil Diameter (Hippus) -Pre drug administration
    • Time Frame: Baseline
    • Magnitude of power at the dominant frequency in the Fourier transform of pupil diameter in the .1-2 Hz range, termed hippus. Pupil measurements will be made for 20 seconds every 5 minutes for 20 minutes
  • Fluctuation in Pupil Diameter (Hippus) -Post drug administration
    • Time Frame: up to 90 minutes after study drug administration
    • Magnitude of power at the dominant frequency in the Fourier transform of pupil diameter in the .1-2 Hz range, termed hippus. Pupil measurements will be made for 20 seconds every 5 minutes until 90 minutes after study drug administration.
  • Heart rate variability in the high frequency range (HF-HRV) as a reflection of level of parasympathetic nervous system tone
    • Time Frame: baseline
    • Variability in heart rate in the 0.12-0.40 Hz frequency
  • Heart rate variability in the high frequency range (HF-HRV) as a reflection of level of parasympathetic nervous system tone
    • Time Frame: up to 90 minutes after study drug administration
    • Variability in heart rate in the 0.12-0.40 Hz frequency

Participating in This Clinical Trial

Inclusion Criteria

  • Male or female > 18 and < 66 years of age,
  • Body Mass Index (BMI) <40
  • Generally in good health as determined by the Principal Investigator based on prior medical history
  • Normal blood pressure and resting heart rate without medication

Exclusion Criteria

  • Hypersensitivity, allergy, or significant reaction to any ingredient of PitocinĀ®
  • Any disease, diagnosis, or condition (medical or surgical) that, in the opinion of the Principal Investigator, would place the subject at increased risk
  • Women who are pregnant (positive result for serum pregnancy test at screening visit),
  • Women who are currently nursing or lactating, women that have been pregnant within 2 years.
  • Neuropathy, chronic pain, diabetes mellitus, or taking benzodiazepines or pain medications on a daily basis.
  • Previous eye surgery, eye medications, cataracts

Gender Eligibility: All

Minimum Age: 18 Years

Maximum Age: 66 Years

Are Healthy Volunteers Accepted: Accepts Healthy Volunteers

Investigator Details

  • Lead Sponsor
    • Wake Forest University Health Sciences
  • Provider of Information About this Clinical Study
    • Sponsor
  • Overall Official(s)
    • James C Eisenach, MD, Principal Investigator, Wake Forest University Health Sciences
  • Overall Contact(s)
    • Regina Curry, 336-716-4294, RECURRY@WAKEHEALTH.EDU

References

Norman GJ, Cacioppo JT, Morris JS, Malarkey WB, Berntson GG, Devries AC. Oxytocin increases autonomic cardiac control: moderation by loneliness. Biol Psychol. 2011 Mar;86(3):174-80. doi: 10.1016/j.biopsycho.2010.11.006. Epub 2010 Nov 30.

Turnbull PR, Irani N, Lim N, Phillips JR. Origins of Pupillary Hippus in the Autonomic Nervous System. Invest Ophthalmol Vis Sci. 2017 Jan 1;58(1):197-203. doi: 10.1167/iovs.16-20785.

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