1. A Primer on Opioids/Opiates
Richard L. Bell, Ph.D.
Associate Professor Department of Psychiatry
Indiana University School of Medicine
***Earlier in the literature “opiates” referred to exogenous ligands for opioid receptors, whereas “opioids” referred to
endogenous ligands for opioid receptors

3. Opioid Agonists Exogenous opioids Endogenous opioids
Mu agonist (Ag) morphine, fentanyl, methadone,
codeine, hydrocodone, oxycodone,
hydromorphone, levorphanol,
meperidine, oxymorphone, tramadol, propoxyphene, sufentanil, remifentanil
Mu pAg pentazocine, butorphanol, nalbuphine, buprenorphine
Delta receptor morphine, fentanyl
Kappa receptor morphine, fentanyl, pentazocine, butorphanol, nalbuphine
Naloxone mu, delta, and kappa antagonist
Naltrexone mu, delta, and kappa antagonist
Endogenous opioids
Mu receptor beta-endorphin, endomorphin
Delta receptor leu-encephalin, met-encephalin,
beta-endorphin
Kappa receptor dynorphin

5. Befort 2015 Front Pharmacol

6. Delta receptor location and emotional/cognitive/physiological function
Chung and Kieffer 2013 Pharmacol Ther

7. Mu- and delta-receptor co-expression and functional areas of the brain (red reflects only mu-receptor)
Erbs et al 2015 Brain Struct Funct

8. Lalanne et al 2014 Front Psychiatry

9. Yijun-Cui et al 2014 Nature Neuroscience

10. Navratilova and Porreca 2014 Nature Neuroscience

11. Opioid Treatments for Addiction

12. Transcranial Stimulation decreases mu-opioid receptor
binding.

13. National Institute on Drug Abuse; Center for Disease Control and Prevention