According to the Center for Disease Control and Prevention, nicotine activates receptors known as nAChRs and, remarkably, unlike most other drugs of abuse, it acts as a "pharmacological chaperone" to stabilize assembly of its receptors within the Endoplasmic Reticulum (ER) and increase their abundance at the cell surface (up-regulation).
Up-regulation of nAChRs plays a major role in nicotine addiction and, possibly, in the decreased susceptibility of smokers to Parkinson's disease.
Receptors containing an alpha6 subunit (alpha6* nAChRs) are abundant in several specific brain regions.
Researchers from the California Institute of Technology in Pasadena used mice expressing alpha6 labeled with a fluorescent protein to show that exposure to nicotine-at a level comparable to that in human smokers-up-regulated alpha6* nAChRs in these areas of the brain.
The study has been published in The Journal of General Physiology.