Does Nicotine depress the central nervous system?

Answer 1

No. It does the opposite. Nicotine is a stimulant to the nervous system and stimulates the release of epinephrine.

When a cigarette is smoked, nicotine-rich blood passes from the lungs to the brain within seven seconds and immediately stimulates the release of many chemical messengers including acetylcholine, norepinephrine, dopamine, and beta-endorphin. This results in enhanced pleasure, decreased anxiety, and a state of alert relaxation. Nicotine enhances concentration and memory due to the increase of acetylcholine. The effects of nicotine last from five minutes to two hours. Most people who use nicotine do so several times a day (the average smoker smokes about 20 cigarettes in a 24 hour period). They do this in an effort to keep the pleasant effects of nicotine throughout the day and to avoid withdrawal.

Check out this link for more information:
http://en.wikipedia.org/wiki/Nicotine

Answer 2

nicotine speeds up the CNS. It is a stimulant not a depressant