Nicotine is one of the most
heavily used addictive drugs in the United States. Nicotine is highly
addictive. It is both a stimulant and a sedative to the central nervous
system. The ingestion of nicotine results in an almost immediate "kick"
because it causes a discharge of epinephrine from the adrenal cortex.
This stimulates the central nervous system, and other endocrine glands,
which causes a sudden release of glucose. Stimulation is then followed
by depression and fatigue, leading the abuser to seek more nicotine.
Nicotine is absorbed readily from tobacco smoke in
the lungs, and it does not matter whether the tobacco smoke is from
cigarettes, cigars, or pipes. Nicotine also is absorbed readily when
tobacco is chewed. With regular use of tobacco, levels of nicotine
accumulate in the body during the day and persist overnight. Thus,
daily smokers or chewers are exposed to the effects of nicotine for 24
hours each day. Nicotine taken in by cigarette or cigar smoking takes
only seconds to reach the brain but has a direct effect on the body for
up to 30 minutes. Research has shown that stress and anxiety affect
nicotine tolerance and dependence. The stress hormone corticosterone
reduces the effects of nicotine; therefore, more nicotine must be
consumed to achieve the same effect. This increases tolerance to
nicotine and leads to increased dependence. Studies in animals have
also shown that stress can directly cause relapse to nicotine
self-administration after a period of abstinence.