"If bingeing on sugar is really a form of addiction, there should be long-lasting effects in the brains of sugar addicts," Hoebel said. "Craving and relapse are critical components of addiction, and we have been able to demonstrate these behaviors in sugar-bingeing rats in a number of ways."
At the annual meeting of the American College of Neuropsychopharmacology in Scottsdale, Ariz., Hoebel will report on profound behavioral changes in rats that, through experimental conditions, have been trained to become dependent on high doses of sugar.
"We have the first set of comprehensive studies showing the strong suggestion of sugar addiction in rats and a mechanism that might underlie it," Hoebel said. The findings eventually could have implications for the treatment of humans with eating disorders, he said.
Lab animals, in Hoebel's experiments, that were denied sugar for a prolonged period after learning to binge worked harder to get it when it was reintroduced to them. They consumed more sugar than they ever had before, suggesting craving and relapse behavior. Their motivation for sugar had grown. "In this case, abstinence makes the heart grow fonder," Hoebel said.
The rats drank more alcohol than normal after their sugar supply was cut off, showing that the bingeing behavior had forged changes in brain function. These functions served as "gateways" to other paths of destructive behavior, such as increased alcohol intake. And, after receiving a dose of amphetamine normally so minimal it has no effect, they became significantly hyperactive.