“The negative side of our reward system is that it can also cause us to develop addictions such as alcoholism and compulsive eating. If we can find out more about how the neurochemical mechanisms work, we will be able to find new ways of treating the illnesses caused by the reward system," says pharmacologist Elisabet Jerlhag.

 Ghrelin is a substance that increases the appetite and our food intake. The substance´s effects have previous been thought to relate the areas of the brain that regulate the energy balance. This dissertation shows that the substance activates the reward system.

“In mice, we have been able to see that the reward system is activated by ghrelin, which causes a rewarding search for food, which increases the likelihood of the animal or person surviving," says Elisabet Jerlhag.

The dissertation also shows that nicotine receptors of a certain appearance play an important role when the ghrelin activates the reward system, and also that alcohol activates the reward system via the same type of nicotine receptors. As alcohol and ghrelin activate the system similarly, this particular type of nicotine receptors may be a potential target for future treatments for addiction. A medication that blocks these receptors would provide a treatment for the prevention of both alcoholism and compulsive eating.

“We were also able to see that ghrelin increased alcohol consumption in mice, which opens up the possibility of affecting the ghrelin system. This could mean a completely new approach in the development of medication for the treatment of alcoholism and we have even applied for a patent," says Elisabet Jerlhag.

Dissertation for medical doctor´s exam at the Sahlgrenska Academy , Institute of Neuroscience and physiology, Pharmacology department.

Title: The cholineric-dopaminergic reward link and addictive behaviors special emphasis on ethanol and ghrelin

Tutor: Professor Jörgen Engel,
Senior Lecturer Lennart Svensson