What is nicotine?

A Natural Substance

Nicotine is a natural substance known as an alkaloid (a chemical compound containing nitrogen atoms). "Alkaloid" derives from the word "alkaline," which describes any nitrogen-containing base. Alkaloids are produced by plants, animals and other organisms.

When nicotine enters the body, it is distributed through the blood. It takes about seven seconds for it to reach the brain when inhaled, and it's half-life in the body is about two hours.  
Nicotine increases the levels of several neurotransmitters. The increased levels of dopamine in the reward circuits of the brain causes pleasure, relaxation and addiction.
Nicotine has many of the same qualities of caffeine. Although it can be addictive and a stimulant, it has not been proven to be a cause of cancer.


Nicotine's effects on your mood

The way nicotine affects one's mood differs from person to person. Since it causes a release of glucose from the liver and adrenaline from the adrenal medulla, nicotine use results in stimulation. Smokers experience relaxation, sharpness, calmness and alertness. By reducing the appetite and raising the metabolism, many smokers lose weight. Research suggests that when smokers want a stimulating effect, they take short, quick puffs. This produces a low level of blood nicotine and stimulates nerve transmission. When they want a relaxing effect, they take deep puffs. This produces a high level of blood nicotine, which depresses the passage of nerve impulses and produces a mild sedative effect.

Nicotine is unique because its profile changes from stimulant to sedative/pain killer in increasing dosages and use. At low doses, nicotine enhances the actions of norepinephrine and dopamine in the brain, causing a stimulant effect. At higher doses, nicotine enhances the effect of serotonin and opiate activity, producing a calming, pain-killing effect.

Addiction

Nicotine produces a number of effects in the brain. It activates reward pathways, which are the circuitry within the brain that regulates feelings of pleasure and euphoria. Dopamine is one of the key neurotransmitters in the brain. Since nicotine increases the levels of dopamine within the reward circuits of the brain, it has intense addictive qualities.


Therapeutic use

The primary therapeutic use of nicotine is in treating nicotine dependence to eliminate tobacco smoking. Controlled levels of nicotine are given to patients through chewing gum, patches, lozenges, electronic cigarettes or nasal sprays.

Nicotine itself, however, has also been shown to be of therapeutic value to patients. For example, a large body of evidence suggests that the risks of Parkinson's disease or Alzheimer's disease might be twice as high for non-smokers than for smokers.

Recent studies have also indicated that nicotine can be used to help adults suffering from autosomal dominant nocturnal frontal lobe epilepsy. The same areas that cause seizures in that form of epilepsy are also responsible for processing nicotine in the brain.

All of these studies are based only on observation, and no interventional (randomized) studies have been done. Researchers have discovered that nicotine therapy has a positive and profound effect on the symptoms of ulcerative colitis, known as Crohn's Disease. Research on nicotine as administered through a patch or gum is ongoing.