Delta Opioid Receptor (IMAGE) University of North Carolina Health Care Caption This is a digital crystal structure of the delta opioid receptor with sodium ion in blue at the center. Credit UNC / Scripps Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.