OPRM1 and Hypothermia: 2014). In the same studies, 7-OH decreased operant responding for food in a naltrexone-reversible manner without α2-adrenergic involvement, again consistent with MOR agonism (Matsumoto et al. 2014). Hypothermia patterns further differentiate targets: reference α2-agonists produce yohimbine-reversible hypothermia, whereas 7-OH does not display α2-mediated thermoregulation; mitragynine, by contrast, shows α2-linked hypothermia (Matsumoto et al. 2014). These antagonist-defined pharmacological fingerprints reinforce 7-OH’s MOR selectivity in vivo.