Using a combination of synthetic drugs and designer neural receptors, Dartmouth University scientists have discovered a way to suppress cravings in a region of the brain responsible for triggering those desires.
As postdoctoral fellow Stephen Chang and his colleagues explained in the latest edition of the European Journal of Neuroscience, they used a new technology known as DREADDs (designer receptors exclusively activated by designer drugs) to inactivate the parts of the brain which have been linked to food-related stimulation.
This marks the first time that scientists have been able to demonstrate how designer receptors and designer drugs can work together to alter these cues, and the team believes that the findings could ultimately help fight addictions, overeating, and other unhealthy habits.
“Although we have a sense of what brain circuits mediate reward, less is known about the neural circuitry underlying the transfer of value to cues associated with rewards,” Chang explained in a statement on Wednesday. “We were primarily interested in whether the ventral pallidum, a brain region implicated in processing reward, is also involved in sign-tracking.”
Altering ventral pallidum activity could curb cravings
Consumers are subjected to cues in the form of advertisements on a daily basis, and these ads can trigger our brains into purchasing specific goods or rewards—thus making the cues attractive to us on their own. This phenomenon can even make us crave fast food without feeling hungry or even seeing the products, the study authors explained.
Scientists used an experimental conditioning technique known as sign-tracking or autoshaping to study this phenomenon, but it had previously been impossible to inactivate the brain areas linked to this behavior. But now, Chang and his colleagues were able to inject the DREADDs into neurons through viruses, and use a designer drug to switch off those neurons.
Using this approach, they were able to temporarily inactivate the ventral pallidum repeatedly in a series of experiments involving rats. During the trials, a lever was inserted in a test chamber for a 10 second span. When the level was withdrawn, a food pellet reward was presented regardless of behavior, but the rats pressed and bit the lever as if it were the treat nonetheless.
The results indicated that activating DREADDs in the ventral pallidum prior to each of the test sessions successfully blocked that behavior. Furthermore, recordings of neurons in the ventral pallidum following activation of the designer receptor-drug system revealed that activity in this part of the brain could be sped up or slowed down to varying degrees.
“These results are the first to show that the ventral pallidum is necessary for the attribution of value to cues that are paired with rewards,” said Chang. “In terms of clinical applications, the results carry the potential for stripping away value from reward-paired cues in cases such as addiction. The ventral pallidum is a novel target for such work.”
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Feature Image: Thinkstock
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