Generate and Test the Reliability of a PD Model of OXT on Pupillary Hippus as a Measure of CNS Activity

  • participants needed
  • sponsor
    Wake Forest University Health Sciences
Updated on 29 January 2023
body mass index
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Accepts healthy volunteers


The purpose of this research is to evaluate the effects of oxytocin (naturally occurring hormone) given by an intramuscular (IM; into the muscle) injection, has on your parasympathetic nervous system. The parasympathetic nervous system is the part of the involuntary nervous system that is sometimes called the "rest and digest" system; the parasympathetic system conserves energy as it slightly slows the heart rate, increases intestinal and gland activity, and relaxes sphincter muscles in the gastrointestinal tract.


This is a single site study at Wake Forest School of Medicine. Healthy volunteers and patients with advanced knee arthritis being seen in the Orthopedic Clinic in consultation for potential total knee arthroplasty will be recruited after their doctor visit if the decision is made not to perform surgery at this time.

Study participants will come to the Pain Clinical Research Unit on 2 occasions. On these visits, they will receive an intramuscular (i.m.) injection of placebo or oxytocin, 25 micrograms (μg) (Pitocin®), obtained from the research pharmacy. The order in this cross-over study will be randomized and double blind, and the studies separated by at least 48 hours. Every 2.5 minutes beginning 20 minutes before injection and until 180 minutes after injection oscillation in pupil diameter at low frequency (hippus) will be obtained using an infrared pupilometer, in which they focus on a central point of gaze for 20 seconds. Hippus, a measure of parasympathetic output to the pupil and affected by central actions of oxytocin as described in preliminary data, will be calculated as the magnitude of power in the 0-0.25 Hertz (Hz) bin of the spectral analysis of pupil diameter, after removing blink and saccade artifacts. After 180 minutes the study participant will be discharged from the Pain Clinical Research Unit.

Condition Chronic Pain, Osteoarthritis, Knee
Treatment Placebo, Oxytocin
Clinical Study IdentifierNCT04427709
SponsorWake Forest University Health Sciences
Last Modified on29 January 2023

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