Study Investigates Dark Side of Chocolate Temptation

A recent animal study has reportedly identified a new mechanism by which the brain increases the desire to overconsume sweet and fatty treats like chocolate. Alexandra DiFeliceantonio, et al., “Enkephalin Surges in Dosal Neostriatum as a Signal to Eat,” Current Biology, October 2012. Relying on advanced opioid microdialysis techniques to detect extracellular levels of a neurotransmitter called enkephalin, University of Michigan researchers injected a drug into the neostriatum of rats to stimulate the mu opioid receptors before the animals were permitted to eat M&M candies. The results evidently showed that mu opioid stimulation “potently enhanced consumption of palatable M&M chocolates,” with injected rats “more than doubling total M&M intake.” In addition, the authors’ microdialysis study of the same brain region, which has primarily been linked to movement, purportedly revealed that naturally occurring enkephalin levels “rose to 150% of baseline when the rats were suddenly allowed to eat chocolates.”

According to the study, these findings imply that “opioid signals in anteromedial dorsal neostriatum are able to code and cause motivation to consume sensory reward.” As the lead author further explained to the press, “This means that the brain has more extensive systems to make individuals want to overconsume rewards than previously thought. It may be one reason why overconsumption is a problem today. The same brain area we tested here is active when obese people see food and when drug addicts see drug scenes. It seems likely that our enkephalin findings in rats mean that this neurotransmitter may drive some forms of overconsumption and addiction in people.” See ScienceDaily, September 20, 2012.