Neurochemical Pathway May Link Compulsive Eating, AddictionIn a recent study, the compound Ezlopitant — already known to suppress alcohol cravings in humans — was found to decrease the urge of rodents to drink sweetened water.  The research took place at the Ernest Gallo Clinic and Research Center which is affiliated with the University of California, San Francisco. 

“This finding suggests a possible link between the neurochemical pathways for addiction and compulsive eating,” says Selena Bartlett, principal investigator of the study and director of the Pre-Clinical Development Group at the Gallo Center.

Compulsive eating is characterized by bouts of uncontrollable eating and the resultant weight gain.  Typically, overeating becomes an addiction as the sufferer repeatedly uses food as a means of dealing with stress and other negative emotions.  Furthermore, science has long noted the similarities between chemical addiction and sugar addiction in the brain.

In the current study, rats that were given ezlopitant showed a significant decrease in motivation to drink water sweetened with sugar, water sweetened with saccharin, as well as an alcohol solution.

Ezlopitant is an NK1 receptor-antagonist, a group of drugs that inhibit the action of substance P, a neurotransmitter that is believed to play a role in the human ‘reward system,’ a network of structures in the brain that controls cravings and addictions to alcohol and other drugs.

“Substance P is released in your brain in response to certain stimuli, and needs to bind with receptors on neurons in order to have an effect,” explains Bartlett. “The NK1 receptor is where it binds, and ezlopitant prevents that binding.”

A possible reason for the rats’ lack of interest could be that the NK1 receptor is part of the same reward system that links compulsive craving for sweets with craving for drugs and alcohol, believes Bartlett.

In fact, the rats responded so well that NK1 may become a potential target in food addiction treatments.

“In other studies, NK1-receptor antagonists have been shown to decrease craving for alcohol in humans with alcohol-use disorder,” she says. “In our study, the decrease in the rats’ consumption of sweetened water was, in fact, even greater than their decrease in alcohol consumption. For the first time, we’ve shown that this receptor might be a target for compulsive eating. We’re looking at a potentially promising new approach to addressing pathological food addiction.”

Bartlett adds that her laboratory is focused on the development of medications for human use, so, “naturally,” she says, “we’d like to see this experiment replicated in humans as soon as possible.”

Co-authors of the study were Pia Steensland of the Karolinksa Institute, Stockholm, Sweden, and Jeffrey A. Simms, Carsten K. Nielsen, Joan Holgate, and Jade J. Bito-Onon of the Preclinical Development Group at the Gallo Center.

The study was supported by funds from the state of California for medical research on alcohol and substance abuse through UCSF, and from the US Department of Defense.  The UCSF-affiliated Ernest Gallo Clinic and Research Center is a leading academic center for the study of the biological basis of alcohol and substance use disorders.

The findings are published online in the online journal, PLoS One.

University of California