Neuropeptide Y (NPY) Regulation of Nociceptors

NCT ID: NCT00596193

Last Updated: 2012-03-08

Basic Information

• Recruitment Status: COMPLETED
• Total Enrollment: 11 participants
• Study Classification: OBSERVATIONAL
• Study Start Date: 2001-05-31
• Study Completion Date: 2008-05-31

Brief Summary

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.

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.

Conditions

Pain

Study Design

• Observational Model Type: CASE_CONTROL
• Study Time Perspective: PROSPECTIVE

Study Groups

Group I

patients with normal or irreversible pulpitis teeth with capsaicin administered at increasing volumes.

No interventions assigned to this group

Group II

Patients with normal teeth only with capsaicin added at a specific volume only

No interventions assigned to this group

Eligibility Criteria

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

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 50 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

The University of Texas Health Science Center at San Antonio

OTHER

Sponsor Role: lead

Responsible Party

Kenneth Hargreaves

Chair, Dept. of Endodontics

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Kenneth M Hargreaves, DDS,PhD

Role: PRINCIPAL_INVESTIGATOR

The University of Texas Health Science Center at San Antonio

Locations

University of Texas Health Science Center at San Antonio

San Antonio, Texas, United States

Countries

United States

Other Identifiers

HSC20010247H

Identifier Type: -

Identifier Source: org_study_id