Four subjects (3 male, 1 female; mean age: 12 years, range: 9–18 years) received daily morphine treatment for 5 months (see below); four additional subjects, matched for age, weight, and sex, served as experimental controls (3 male, 1 female; mean age: 14 years, range: 11–21 years). Control subjects had a history of nicotine or cocaine exposure but were drug free for ~1 year prior to tissue collection. The metadata for nonhuman primate subjects are listed in Supplemental Supplementary Data 1–S26.
