Nicotine is actually a nicotinic acetylcholine receptor agonist.


As far as what it does (I think most of this is brain research):


http://molpharm.aspetjournals.org/co...53/5/950.short

http://legacy.library.ucsf.edu/docum.../Svry36d00.pdf


(Mestinon is also a partial agonist -- if anyone wants to wade through this:

http://www.rand.org/content/dam/rand...18.2.chap3.pdf )


Related:

http://www.ncbi.nlm.nih.gov/pubmed/14758171


A definition:

http://en.wikipedia.org/wiki/Downreg...d_upregulation