Recalling traumatic memories enhances the rewarding effects of morphine in male rats, finds new research published in JNeurosci. These findings may help to explain the co-occurrence of post-traumatic stress disorder (PTSD) and addiction.
More than half of PTSD patients also struggle with substance abuse, yet the underlying neural mechanisms of their addiction are not clear. Dopamine receptors in the prefrontal cortex may play a role, as they are involved in the processing of both fear- and reward-related memories.
Steven Laviolette and colleagues examined the involvement of two dopamine receptors in the recall of a traumatic experience -- a footshock -- and subsequent preference for morphine. Rats that were reminded of the troubling experience by an associated scent showed a greater freezing fear response and spent more time in an environment where they previously received a dose of morphine that ordinarily does not produce a preference for a morphine-paired environment. This effect was blocked by activation of the dopamine receptor D1R. A different dopamine receptor, D4R, increased freezing behavior and reward sensitivity after the recall of a minor footshock that does not produce a traumatic memory under normal conditions. The results suggest that abnormal dopamine signals in the prefrontal cortex may underlie the ability of traumatic memories to predispose individuals to addiction by increasing their sensitivity to the rewarding effects of drugs such as opioids.
Article: Fear Memory Recall Potentiates Opiate Reward Sensitivity through Dissociable Dopamine D1 vs. D4 Receptor-Dependent Memory Mechanisms in the Prefrontal Cortex
Corresponding author: Steven Laviolette (University of Western Ontario, Canada), firstname.lastname@example.org
JNeurosci, the Society for Neuroscience's first journal, was launched in 1981 as a means to communicate the findings of the highest quality neuroscience research to the growing field. Today, the journal remains committed to publishing cutting-edge neuroscience that will have an immediate and lasting scientific impact, while responding to authors' changing publishing needs, representing breadth of the field and diversity in authorship.
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The Society for Neuroscience is the world's largest organization of scientists and physicians devoted to understanding the brain and nervous system. The nonprofit organization, founded in 1969, now has nearly 37,000 members in more than 90 countries and over 130 chapters worldwide.