Nicotine is a psychoactive substance found in tobacco. The text "Molecular Neuropharmacology" explains that nicotine interacts with the body by binding to special proteins called receptors on cells. The receptors that interact with nicotine are called nicotinic acetylcholine receptors, abbreviated as nAch receptors. When nicotine binds to nAch receptors, the cell is stimulated to release a neurotransmitter called acethylcholine. This chemical has an excitatory effect on tissues, which is why nicotine is sometimes called a stimulant.
Effects on the Brain
According to a review published in the August 2005 issue of the American Journal of Psychiatry, nicotine is thought to affect the brain by increasing the amount of a neurotransmitter called dopamine. When dopamine is released in an area of the brain known as the nucleus accumbens, the effect is a feeling of reward. Many addictive drugs are thought to exert some of their rewarding effects via this pathway.
Effects on the Body
Nicotine consumption causes cells that communicate with the autonomic nervous system, or ANS, to activate pathways that trigger the sympathetic "fight or flight" reaction to acute stress. ANS excitation is characterized by physiological symptoms such as an increase in heart rate, decrease in appetite and increased awareness. When a person consumes nicotine on a regular basis, the cells of the body make changes to compensate for the abnormally elevated state of the ANS. These changes make it possible for the ANS to resist the excitatory effects of nicotine.
Withdrawal Symptoms
The "Clinical Manual of Addiction Psychopharmacology" explains that withdrawal symptoms appear when a dependent person stops consuming nicotine as a consequence of the physical adaptations that resulted from habitual use. In the absence of nicotine, the metabolic balance established by these adaptations is suddenly disturbed, causing symptoms such as anxiety, increased appetite and irritability.
References
- "Molecular Neuropharmacology" ; Nestler, Hyman, and Malenka; 2009
- "The American Journal of Psychiatry"; Pharmacotherapy and Pharmacogenetics of Nicotine Dependence; Wade H. Berrettini, M.D., Ph.D. and Caryn E. Lerman, Ph.D.; August 2005
- "Clinical Manual of Addiction Psychopharmacology"; Henry R. Kranzler, M.D. and Domenic A. Ciraulo, M.D.; 2005
