"Fat bingeing behaviors developed in the rats with access to dietary fat on Mondays, Wednesdays, and Fridays -- the group with the most restricted access to the optional fat," Grigson said.
This group tended to take more cocaine late in training, continued to try to get cocaine when signaled it was not available, and worked harder for cocaine as work requirements increased.
"While the underlying mechanisms are not known, one point is clear from behavioral data: A history of bingeing on fat changed the brain, physiology, or both in a manner that made these rats more likely to seek and take a drug when tested more than a month later," Grigson said. "We must identify these predisposing neurophysiological changes."
While the consumption of fat in and of itself did not increase the likelihood of subsequent addiction-like behavior for cocaine, the irregular binge-type manner in which the fat was eaten proved critical. Rats that had continuous access to fat consumed more fat than any other group, but were three times less likely to exhibit addiction-like behavior for cocaine than the group with access only on Mondays, Wednesdays and Fridays.
"Indeed, while about 20 percent of those rats and humans exposed to cocaine will develop addiction-like behavior for the drug under normal circumstances, in our study, the probability of addiction to cocaine increased to approximately 50 (percent) for subjects with a history of having binged on fat," Grigson said.
Future studies will look more closely at how bingeing can lead to addiction-like behaviors -- whether bingeing on sugar or a mixture of sugar and fat also promotes cocaine or heroin addiction, for example, and whether bingeing on a drug, in turn, increases the likelihood of bingeing on fat.
|Contact: Matthew Solovey|