{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,27]],"date-time":"2026-09-27T06:58:11Z","timestamp":1790492291402,"version":"4.1.0"},"reference-count":63,"publisher":"SAGE Publications","license":[{"start":{"date-parts":[[2026,6,1]],"date-time":"2026-06-01T00:00:00Z","timestamp":1780272000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"},{"start":{"date-parts":[[2026,6,1]],"date-time":"2026-06-01T00:00:00Z","timestamp":1780272000000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.sagepub.com\/page\/policies\/text-and-data-mining-license"}],"funder":[{"DOI":"10.13039\/100000069","name":"National Institute of Arthritis and Musculoskeletal and Skin Diseases","doi-asserted-by":"publisher","award":["AR059397"],"award-info":[{"award-number":["AR059397"]}],"id":[{"id":"10.13039\/100000069","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["journals.sagepub.com"],"crossmark-restriction":true},"short-container-title":["Mol Pain"],"published-print":{"date-parts":[[2026,6]]},"abstract":"<jats:p>\n                    Small diameter unmyelinated (group IV) and myelinated (group III) muscle afferents transmit action potentials to signal muscle pain and the exercise pressor reflex (EPR). The EPR helps to drive the cardiovascular response to exercise. \u00b5- (\u00b5OR), \u03b4- (\u03b4OR), and\n                    <jats:italic toggle=\"yes\">\u03ba<\/jats:italic>\n                    - (\u03baOR) opioid receptors (OR) have been shown to be expressed by dorsal root ganglia (DRG) neurons, but only peripheral \u00b5OR activation has been shown to inhibit the EPR mediated by group IV afferents. To determine if this results from differential OR expression, we identified group IV neurons in DRG and axons in gastrocnemius muscles from both male and female rats, and used immunocytochemistry to compare the expression of \u00b5OR, \u03b4OR, and \u03baOR. We show that \u00b5OR labeling was more frequently observed in group IV somata and axons vs. \u03b4OR or \u03baOR. OR axonal labeling was lower than somata labeling, particularly for \u03b4OR &amp; \u03baOR. There were no significant differences in OR staining between male and female animals. The relatively high \u00b5OR axonal expression suggests that \u00b5OR are selectively transported to the peripheral group IV axons and can explain the selective effect of \u00b5OR agonists to inhibit group IV afferent activity that generates the EPR and muscle pain.\n                  <\/jats:p>","DOI":"10.1177\/17448069261492539","type":"journal-article","created":{"date-parts":[[2026,9,23]],"date-time":"2026-09-23T17:02:00Z","timestamp":1790182920000},"update-policy":"https:\/\/doi.org\/10.1177\/sage-journals-update-policy","source":"Crossref","is-referenced-by-count":0,"title":["Differential expression of \u00b5-, \u03b4-, and \u03ba-opioid receptors in muscle afferents from male and female rats"],"prefix":"10.1177","volume":"22","author":[{"given":"Jeong Sook","family":"Kim-Han","sequence":"first","affiliation":[{"name":"AT Still University of Health Sciences"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Megan","family":"Elmslie","sequence":"additional","affiliation":[{"name":"AT Still University of Health Sciences"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"John R.","family":"Miller","sequence":"additional","affiliation":[{"name":"AT Still University of Health Sciences"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lance","family":"Evans","sequence":"additional","affiliation":[{"name":"AT Still University of Health Sciences"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Farida","family":"Elkadi","sequence":"additional","affiliation":[{"name":"AT Still University of Health Sciences"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Joshua","family":"Moody","sequence":"additional","affiliation":[{"name":"AT Still University of Health Sciences"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jonathan","family":"Easterwood","sequence":"additional","affiliation":[{"name":"AT Still University of Health Sciences"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2988-4482","authenticated-orcid":false,"given":"Keith S.","family":"Elmslie","sequence":"additional","affiliation":[{"name":"AT Still University of Health Sciences"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"179","published-online":{"date-parts":[[2026,9,23]]},"reference":[{"key":"e_1_3_3_2_2","doi-asserted-by":"publisher","DOI":"10.1113\/expphysiol.2011.057539"},{"key":"e_1_3_3_3_2","doi-asserted-by":"publisher","DOI":"10.1007\/s10286-002-0059-1"},{"key":"e_1_3_3_4_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.autneu.2020.102698"},{"key":"e_1_3_3_5_2","doi-asserted-by":"publisher","DOI":"10.3389\/fncel.2017.00419"},{"key":"e_1_3_3_6_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.janh.2017.02.001"},{"key":"e_1_3_3_7_2","doi-asserted-by":"publisher","DOI":"10.1124\/pr.112.005942"},{"key":"e_1_3_3_8_2","doi-asserted-by":"publisher","DOI":"10.1097\/ACO.0b013e32834873e5"},{"key":"e_1_3_3_9_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.coph.2008.12.009"},{"key":"e_1_3_3_10_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41586-026-10299-9"},{"key":"e_1_3_3_11_2","doi-asserted-by":"publisher","DOI":"10.1152\/ajpheart.00116.2013"},{"key":"e_1_3_3_12_2","doi-asserted-by":"publisher","DOI":"10.1152\/ajpheart.00387.2010"},{"key":"e_1_3_3_13_2","doi-asserted-by":"publisher","DOI":"10.1152\/ajpregu.00156.2014"},{"key":"e_1_3_3_14_2","doi-asserted-by":"publisher","DOI":"10.1152\/jn.00034.2018"},{"key":"e_1_3_3_15_2","doi-asserted-by":"publisher","DOI":"10.1523\/JNEUROSCI.15-12-08156.1995"},{"key":"e_1_3_3_16_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.pain.2004.05.025"},{"key":"e_1_3_3_17_2","doi-asserted-by":"publisher","DOI":"10.1177\/1744806916660721"},{"key":"e_1_3_3_18_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.cell.2009.04.019"},{"key":"e_1_3_3_19_2","doi-asserted-by":"publisher","DOI":"10.1152\/jn.00219.2012"},{"key":"e_1_3_3_20_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.neuroscience.2008.02.080"},{"key":"e_1_3_3_21_2","doi-asserted-by":"publisher","DOI":"10.1152\/japplphysiol.00597.2003"},{"key":"e_1_3_3_22_2","first-page":"231","article-title":"Free nerve endings in skeletal muscle of the cat","volume":"105","author":"Stacey MJ","year":"1969","unstructured":"Stacey MJ. 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