Opiates (agonists): morphine-action-on-opioid-receptors Published March 2, 2016 at 720 × 486 in Opiates (agonists) Morphine action on opioid receptors. Why Opiates Are Addicting? Opioid action. Morphine action on opioid receptors. Why Opiates Are Addicting? Opioid action.