The Many Faces of Smoking: the effects of nicotine on brain and behavior - Prof. Marina Picciotto
Professor Marina Picciotto opens the sixth season of Tilde Cafe discussions. While nicotine is a plant alkaloid, we (and even the electric eel and insects, among other organisms) have nicotinic acetylcholine receptors where nicotine can bind. The native molecule that binds to this receptor is acetylcholine. But we have two types of acetylcholine receptors, both of which respond very differently when acetylcholine binds to them, so in order to distinguish them, they are referred to as either nicotinic (binds nicotine) or muscarinic acetylcholine receptor, binds muscarine, which is also not native to our bodies.
Broadly, nicotinic acetylcholine receptors while located primarily in the nervous system and skeletal muscles, they are found almost everywhere in our bodies. More specifically though, the details of the receptor makeup varies with where the receptor is located, and consequently, when nicotine binds to it, the receptor response is dictated by its makeup. Further, the receptor is not a single protein, but made up of multiple subunits, and nicotine does not bind all the subunits, only some, and with varying degrees of affinity -- the highest affinity binding subunit (beta-2) is a component of the receptor found in the brain, in the specific regions that are part of the reward circuitry. And from reward circuitry, a term one sees associated with excessive eating, we also learned a little about how chemicals that resemble nicotine have been shown to play a role in reducing food intake -- and for the rest of the story, check the footage of the afternoon.