For many smokers, giving up cigarettes is often high up on the list of New Year’s resolutions. What makes it so difficult is the addictive compound nicotine, responsible for the relaxing sensation smokers crave. Nicotine addiction involves the habenula, a group of neurons in the brain, and the interplay between two neurotransmitters in this area: acetylcholine and glutamate. These molecules convey signals between neurons and interact with each other; in one part of the habenular circuit they closely overlap, as shown by the orange area in the mouse brain section pictured. Mice without acetylcholine in their habenula have reduced levels of glutamate, causing neurons to be less stimulated. Crucially, they don’t become addicted to nicotine, displaying no withdrawal symptoms when deprived of it. The interaction between acetylcholine and glutamate is likely to also be relevant to other addictions, as well as to a broader range of cognitive processes.
Written by Emmanuelle Briolat
BPoD stands for Biomedical Picture of the Day. Managed by the MRC London Institute of Medical Sciences the website aims to engage everyone, young and old, in the wonders of biomedicine. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.
BPoD is also available in Catalan at www.bpod.cat with translations by the University of Valencia.