-neuroprotective means it helps defend the brain, so it may alter brain chemistry for the better
-can cause addiction in some
-how does nicotine cause cancer? I know how the shit in smokeless and smoking tobacco can, but can nicotine; if so, how?
-how bad for ur heart and how, what mechanisms are at work
-list the e.t.c.
note: really not trying to be a dick with this post so dont take it as such, if u know more than I do im all ears and u do not need to give me studies and citations
I posted it before bed, so i'll try and flesh out what i said a bit more. I'll answer in a slightly different order than i posted, and one also needs to think long term with the effects of the drug in your system.
Addiction - You get addicted (physically and physiologically) to nicotine very easily, thats well documented. Addiction leads to tolerance which causes you to want and need more, leading to increases of side effects associated with higher levels of the drug. As someone who has been through a serious addiction to certain things, i'm always exceptionally warey of anything that causes even the most minor addiction.
Heart - Increases oxidative stress on the tissues, increases the amount of work the heart requires to do for a given workload (through stimulation of the sympathetic ANS causing catecholamine release), increases blood pressure (through increased heart loading), all of which are bad for your heart.
Cancer - (i'm not that well versed on cancer, so please excuse me if this sounds a little clunky) nictoine promotes the development of lung cancers via stimulation of the. Nictoine doesn't appear to cause cancer directly, but it seems to help once cells start heading that way.
Brain chemistry - !besker's post hadn't gone through by the time i'd posted, i was unawares that it had some neuroprotective effects, it's actually very interesting to read about! There also appears to be some relation to reducing dopamine levels in schizophrenic patients, which i find fascinating. But back to the subject at hand before i get too distracted by the biochemistry of mental illness
As mentioned before, the brain builds up a tolerance to nicotine that can cause dependance upon the drug for normal functioning (i would consider this a negative change). i've also just read a few studies that there is a link to the persons mood stability and the likelyhood of smoking, though this is a somewhat controversial area of study it seems. There is some suggestion that brain activation in various areas (e.g. frontal lobes) can be affected by nicotine intake.
Personally the negative aspects of nictotine on the brain far outweigh any neuroprotective effect one might gain.
As for e.t.c, i can't honestly remember! My apologies there. I do hope what i've written has cleared things up a bit, if not do say so.