Ethnic disparities in pain processing among healthy adults: -opioid receptor binding potential as a putative mechanism

Janelle E. Letzen, Chung Jung Mun, Hiroto Kuwabara, Emily F. Burton, Brandon L. Boring, Taylor Walls, Traci J. Speed, Dean F. Wong, Claudia M. Campbell

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Although ethnic differences in pain perception are well documented, the underlying mechanism for these outcomes has not been established. µ-opioid receptor (MOR) function might contribute to this disparity, given that MORs play a key role in pain sensitivity and modulation. However, no study has characterized ethnic differences in MOR physiology. This study sought to address this knowledge gap by examining differences in µ-selective agonist binding potential (BPND; [11C]-Carfentanil) between 27 non-Hispanic black (NHB) and 27 demographically similar, non-Hispanic white participants. Participants completed questionnaires and two 90-minute high-resolution research tomograph positron emission tomography (PET) imaging sessions. During PET imaging, a capsaicin or control cream was applied to individuals' arms, and pain ratings were collected. Bonferroni-corrected PET volumes of interest analyses revealed significantly greater [11C]-Carfentanil BPNDamong NHB participants in bilateral ventral striatum ([left]: F1,52= 16.38, P < 0.001; [right]: F1,52= 21.76, P < 0.001), bilateral dorsolateral prefrontal cortex ([left] F1,52= 17.3, P < 0.001; [right]: F1,52= 14.17, P < 0.001), bilateral subgenual anterior cingulate cortex ([left]: F1,52= 10.4, P = 0.002; [right]: F1,52= 12.91, P = 0.001), and right insula (F1,52= 11.0, P = 0.002). However, there were no significant main effects of condition or ethnicity × condition interaction effects across models, likely attributable to individual variability in the direction of change within groups. BPNDvalues were significantly correlated with pain ratings collected during the capsaicin condition (r range = 0.34-0.46, P range = 0.01-0.001). Results suggest that NHB individuals might have generally greater unoccupied MOR density than non-Hispanic white peers. Findings have implications for physiological differences underlying ethnicity-related pain disparities. If replicated, these results further emphasize the need for tailored treatments in historically underserved populations.

Original languageEnglish
Pages (from-to)810-820
Number of pages11
Issue number4
StatePublished - Apr 1 2020


  • Endogenous pain modulation
  • Ethnic differences
  • Mu-opioid receptors
  • Neuroreceptor imaging
  • PET
  • [C]-Carfentanil


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