Corticotrophin-releasing factor (CRF) is a stress hormone released in the brain in response to stress, fear and anxiety. CRF may also be released in the nucleus accumbens brain area, in response to incentive motivation and a pursuit of rewards. Now research reports that following stressful situations, CRF release may elicit binge behavior such as binge eating and drug addiction relapse.
The study, published in BMC Biology, examined the effect of CRF injections on reward-seeking behavior in rats. Researchers at the University of Michigan in Ann Arbor, first trained young male rats to press one of two levers to obtain sugar pellets (the reward). The rats were then conditioned to press a lever to get three sugar pellets when Pavlovian cued with a 30-second tone. The investigators then injected either a placebo (salt water), CRF low or high doses, or amphetamines (known to increase reward seeking behavior) into the rats' nucleus accumbens brain area. They measured how often the rats pressed the sugar pellets lever after each injection treatment.
The researchers found that the rats pressed the sugar pellets lever more often for over a minute after the amphetamine or the CRF high dose injections. The rats' reward-seeking behavior was more pronounced after the CRF injections. The rats did not press the lever more often when injected with the placebo or without the Pavlovian cue. This shows that the binge-like behavior was due to the CRF injections and not a result of stress, frustration or anxiety.
"We conclude that CRF in nucleus accumbens shell amplifies positive motivation for cued rewards, in particular by magnifying incentive salience that is attributed to Pavlovian cues previously associated with those rewards," the study authors write. "CRF-induced magnification of incentive salience provides a novel explanation as to why stress may produce cue-triggered bursts of binge eating, drug addiction relapse, or other excessive pursuits of rewards."
REFERENCES:
1. Pecina S et al. Nucleus accumbens corticotropin-releasing factor increases cue-triggered motivation for sucrose reward: paradoxical positive incentive effects in stress? BMC Biol 2006 Apr 13;4:8.
Posted by Elaine Gavalas on August 7, 2006 01:21 PM
