Human opiorphin is a naturally occurring antidepressant acting selectively on enkephalin-dependent delta-opioid pathways
Human opiorphin protects enkephalins from degradation by human neutral endopeptidase and aminopeptidase-N and inhibits pain perception in various behavioral rodent models of pain via endogenous enkephalin-related activation of opioidergic pathways. In addition to pain control, endogenous opioid pathways are also implicated in the modulation of emotion-related behaviors. Thus, we explored the dose-dependent motivational responses induced by opiorphin using the forced swim test, the standard rat model of depression. In addition, to further understand the endogenous events triggered by opiorphin, we