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J Pain. 2017 Sep;18(9):1078-1086. doi: 10.1016/j.jpain.2017.04.006. Epub 2017 Apr 29.

Age Differences in the Time Course and Magnitude of Changes in Circulating Neuropeptides After Pain Evocation in Humans.

Author information

1
Department of Community Dentistry and Behavioral Science, College of Dentistry, University of Florida, Gainesville, Florida; Pain Research and Intervention Center of Excellence, University of Florida, Gainesville, Florida. Electronic address: JRILEY@dental.ufl.edu.
2
Pain Research and Intervention Center of Excellence, University of Florida, Gainesville, Florida; Institute of Aging, College of Medicine, University of Florida, Gainesville, Florida.
3
Pain Research and Intervention Center of Excellence, University of Florida, Gainesville, Florida; Department of Restorative Dentistry, College of Dentistry, University of Florida, Gainesville, Florida.
4
Department of Orthopaedic Surgery, Duke University, Durham, North Carolina.
5
Department of Kinesiology, University of Indianapolis, Indianapolis, Indiana.
6
Department of Community Dentistry and Behavioral Science, College of Dentistry, University of Florida, Gainesville, Florida; Pain Research and Intervention Center of Excellence, University of Florida, Gainesville, Florida.
7
Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, Florida.
8
Pain Research and Intervention Center of Excellence, University of Florida, Gainesville, Florida; Department of Anesthesiology, College of Medicine, University of Florida, Gainesville, Florida.
9
Department of Anesthesiology, Harvard Medical School, Brigham and Women's Hospital, Chestnut Hill, Massachusetts.

Abstract

This study tested the hypothesis that older adults would have a stronger response for substance P (facilitatory) but weaker response to β-endorphin (inhibitory), in magnitude as well as time course. Eight younger and 9 older adults underwent 3 experimental sessions using well validated laboratory pain models: cold pressor task, contact heat pain, and a nonpainful control. Blood was collected through an indwelling catheter at baseline and 3, 15, 30, 45, and 60 minutes after stimuli administration. Older adults had higher baseline levels of both neuropeptides suggesting increased peripheral activity compared with younger adults. After the cold pressor task, older adults demonstrated a quick and strong release of substance P with dramatic recovery, whereas young adults maintained a constant low-grade response. Unlike substance P, β-endorphin increased between 3 and 15 minutes for both groups with the upsurge substantially higher for older adults. After heat pain, younger adults had an immediate surge in circulating substance P and β-endorphin that was more pronounced than among older adults. However, levels of substance P for younger adults slowly tapered whereas they continued to climb for the older adults through 30 minutes. β-endorphin peaked at 30 minutes for both groups and returned to baseline. No changes were observed during the nonpainful control session.

PERSPECTIVE:

Older adults had higher baseline levels of substance P and β-endorphin suggesting increased peripheral activity compared with younger adults. After pain evocation, older adults demonstrated a more intense early response for both neuropeptides suggesting peripheral mechanisms involved in the response to pain may change with age.

KEYWORDS:

Aging; biomarkers; neuropeptides; pain; substance P; β-endorphin

PMID:
28461253
PMCID:
PMC5581306
DOI:
10.1016/j.jpain.2017.04.006
[Indexed for MEDLINE]
Free PMC Article

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