Nicotine, one of more than 4,.000 chemicals found in the smoke from tobacco products, is absorbed through the skin and the mucosal lining of the mouth and nose or through inhalation of smoke into the lungs.
Depending on how tobacco is used, nicotine can reach peak levels in the bloodstream and brain rapidly; cigarette smoke reaches the brain within 10 seconds after inhalation.
Nicotine activates the brain circuitry that regulates feelings of pleasure, the so-called reward pathways. A key brain chemical involved in mediating the desire to consume drugs is the neurotransmitter dopamine, and research has shown that nicotine increases the levels of dopamine in the reward circuits.
Nicotine’s pharmacokinetic properties have been found to enhance its abuse potential.
Cigarette smoking produces a rapid distribution of nicotine to the brain, with drug levels peaking within 10 seconds of inhalation.
Using advanced neuroimaging technology, scientists can see the dramatic effect of cigarette smoking on the brain and are finding a marked decrease in the levels of monoamineoxidase (MAO), an important enzyme that is responsible for breaking down dopamine. The decrease in two forms of MAO, A and B, then results in higher dopamine levels and may be another reason that smokers continue to smoke — to sustain the high dopamine levels that result in the desire for repeated drug use.
National Institute on Drug Abuse Research Report Series. Nicotine Addiction. |
