Many behavioral effects of delta-9-tetrahydrocannabinol (THC), including its discriminative-stimulus effects, are modulated by endogenous opioid systems.
Behavioral Neuroscience Research Branch, National Institute on Drug Abuse, Division of Intramural Research, National Institute of Health, Room 318, 5500 Nathan Shock Drive, Baltimore, MD, 21224, USA. msolinas@intra.nida.nih.gov