Interleukin 1 beta and corticotropin-releasing factor inhibit pain by releasing opioids from immune cells in inflamed tissue.
Proc Natl Acad Sci U S A. 1994 May 10;91(10):4219-23. doi: 10.1073/pnas.91.10.4219.
Proc Natl Acad Sci U S A. 1994.
PMID: 7910403
Free PMC article.