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Neuropeptide Y (NPY) Regulation of Nociceptors

This study has been completed.
Information provided by (Responsible Party):
Kenneth Hargreaves, The University of Texas Health Science Center at San Antonio Identifier:
First received: January 7, 2008
Last updated: March 7, 2012
Last verified: March 2012
Neuropeptide Y (NPY) potently inhibits pain neurons in rats, but does this occur in human pain neurons? This hypothesis will be tested using microdialysis probes in patients who elect to have root canal treatment or extraction of thier tooth.


Study Type: Observational
Study Design: Observational Model: Case Control
Time Perspective: Prospective
Official Title: NPY Regulation of Nociceptors in Clinical Inflammation

Further study details as provided by The University of Texas Health Science Center at San Antonio:

Enrollment: 11
Study Start Date: May 2001
Study Completion Date: May 2008
Primary Completion Date: May 2008 (Final data collection date for primary outcome measure)
Group I
patients with normal or irreversible pulpitis teeth with capsaicin administered at increasing volumes.
Group II
Patients with normal teeth only with capsaicin added at a specific volume only

Detailed Description:

The ongoing studies in rats indicate that a sympathetically-derived neuropeptide, neuropeptide Y (NPY), potently inhibits the activity of the capsaicin-sensative class of nociceptors (i.e., "pain" neurons). It is not know whether these results, generated from rodent studies, occur in human tissues under normal or inflamed conditions. We plan to test the hypothesis that NPY inhibits the initiation of neurogenic inflammation, as measured by reduced release of substance P, from capsaicin-sensitive class of petidergic neurons innervating normal and inflamed dental pulp. Such actions would be physiologically and clinically significant, since inhibition of exocytosis from peripheral terminals of nociceptive primary afferent fibers would likely alter neurogenic inflammation, local vasodilation and , possibly pain. Our research strategy takes advantage of a uniquely innervated tissue: dental pulp. Application of any physiologic stimulus to human dental pulp, including thermal, osmotic, chemical or mechanical, produces only pain. Thus, virtually all sensory neurons that innervate pulp appear to be nociceptors. Accordingly, application of drugs to pulpal sensory neurons targets a population of sensory neurons consisting predominantly of nociceptors.

The research questions are as follows:

  1. Determine the capsaicin concentration-response curve from evoking the release of immunioreactive substance P (iSP) from normal and inflamed dental pulp.
  2. Determine the effect of NPY on altering basal and capsaisin-evoked release of iSP from normal and inflamed dental pulp.

We will evaluate the hypothesis that NPY inhibits capsaicin-sensitive neurons in humans using microdialysis probes implanted into anesthetized dental pulp, with release of immunoreactive substance P (iSP) as our dependent measure. This study will include patients who have elected to have a root canal procedure performed or to have a tooth extracted.


Ages Eligible for Study:   18 Years to 50 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Sampling Method:   Probability Sample
Study Population
Dental Patients

Inclusion Criteria:

  • teeth with diagnosis of normal pulp or irreversible pulpitis
  • mandibular teeth
  • indication for either root canal or extraction of tooth
  • age between 18-50

Exclusion Criteria:

  • history of taking steroids within the last month
  • history of hyperthyroidism, hypertension, asthma, uncontrolled or complicated Type-2 diabetes, drug abuse
  • age less than 18 or greater than 50
  • maxillary teeth
  Contacts and Locations
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Please refer to this study by its identifier: NCT00596193

United States, Texas
University of Texas Health Science Center at San Antonio
San Antonio, Texas, United States, 78229
Sponsors and Collaborators
The University of Texas Health Science Center at San Antonio
Principal Investigator: Kenneth M Hargreaves, DDS,PhD The University of Texas Health Science Center at San Antonio
  More Information

Responsible Party: Kenneth Hargreaves, Chair, Dept. of Endodontics, The University of Texas Health Science Center at San Antonio Identifier: NCT00596193     History of Changes
Other Study ID Numbers: HSC20010247H
Study First Received: January 7, 2008
Last Updated: March 7, 2012

Keywords provided by The University of Texas Health Science Center at San Antonio:
Neurons processed this record on April 27, 2017