A stressed rat will seek a dose of cocaine that is too weak to motivate an unstressed rat. Researchers traced the physiological pathway that links stress and the stress hormone corticosterone to increased dopamine activity and heightened responsiveness to cocaine.
Dr. Paul E. M. Phillips spoke on “Phasic Dopamine Transmission During Substance Abuse,” describing investigations that he has led into the role of brief, seconds-long bursts of dopamine signaling in addictive processes. Dr. Rita Z. Goldstein spoke on “Targeting the Brain, Cognition, and Motivation for Intervention in Addiction.”
The Scientific Director of NIDA’s Intramural Research Program talks about switching off animals’ compulsive cocaine seeking by optogenetically activating the prefrontal cortex, and the implications of this work for people. In an accompanying podcast, Dr. Bonci walks viewers through experiments that showed that prefrontal cortex activity levels may constitute a simple switch controlling whether or not animals compulsively seek cocaine.
Two recent studies suggest that genotyping may enable clinicians to base therapies on individual patients’ potential responsiveness to opioid drugs’ therapeutic effects and vulnerability to their harmful effects.
A brain response occurs in the nucleus accumbens when rats encounter a cue that they associate with previous cocaine self-administration, but not a cue associated with a pleasurable non-drug experience. Moreover, the response correlates in time and intensity with the animals’ cue-induced relapse to cocaine-seeking.
Exposing rats to THC increases the likelihood that the animals will later self-administer nicotine. THC-exposed rats are also willing to work harder to obtain nicotine. When extrapolated to people, the findings suggest that THC’s pharmacological impact on the brain may make a person who uses marijuana more vulnerable to developing nicotine addiction, an underappreciated health consequence of marijuana use.
Almost one-third (32 percent) of the roughly 42,000 Monitoring the Future survey respondents reported having used marijuana during their lifetime. However, abuse of many other drugs—methamphetamine, heroin, cocaine, and some prescription medications—declined.
Teen mothers on three American Indian reservations improved on several measures of parenting after participating in Family Spirit, a home-visiting intervention developed with NIDA support. At 12 months postpartum, the women’s children exhibited reduced rates of emotional difficulties predicting later drug abuse and other behavioral problems. Infants at highest risk—those whose mothers had histories of drug abuse—benefited the most.
Researchers have shut down laboratory rats’ compulsive cocaine seeking by stimulating an area of the animals’ prefrontal cortex. The finding raises the possibility that stimulating neurons in this brain area may weaken or break cocaine’s grip on the behavior of people who are addicted to the drug.