There are many reported effects of nicotine use including: feelings of relaxation, calmness, alertness and reduced appetite. Nicotine appears to enhance concentration and memory as well as increasing arousal. (1) As the dosage of nicotine is increased, its effect changes from stimulant to sedative and pain killer. There have also been reports of anxiety reduction.
Nicotine is a potent alkaloid found in the family of plants known as Nightshade (Solanaceae). In small doses – around 1 to 2 mg – it acts as a stimulant in mammals. In larger doses it acts as a sedative and pain killer.
Nicotine has several different actions in the body that can produce the effects mentioned previously. Shortly after exposure to nicotine, the adrenal glands are stimulated resulting in a discharge of adrenaline. (7) This causes a sudden release of glucose from the liver and creates the stimulant effect that users note. (2) A few seconds after nicotine is ingested, the nicotine-rich blood passes from the lungs to the brain and there is a release of numerous neurotransmitters. The most well-studied of these is serotonin, norepinephrine and dopamine. In addition to the increase in the release of these chemicals, nicotine also appeared to increase the metabolism of the chemicals. These increases continue for about 2 ½ hours before declining again. (8)
It is the release and increased metabolism of these chemicals that produce many of the effects of nicotine in the body. The presence of dopamine is generally associated with our brain’s pleasure or reward mechanisms. While the most studied actions of serotonin involve the GI tract, its role in the central nervous system is thought to be a contribution to feelings of well-being and happiness. Serotonin also has roles in the regulation of appetite, sleep, as well as cognitive functions including memory and learning. Norepinephrine is the neurotransmitter most responsible for the body’s ability to concentrate. It also affects the area of the brain where attention is controlled. In concert with epinephrine, norepinephrine underlies the ‘fight-or-flight’ response by directly increasing heart rate, triggering the release of glucose from energy stores, and increasing blood flow to muscles throughout the body.
While the main therapeutic use for nicotine is the treatment of nicotine dependence, there are a few other medical uses. When nicotine is used as a component of tobacco, it has been shown to reduce the risk of ulcerative colitis (3) and preeclampsia (4) possibly related to nicotine’s role as a vaso-constrictive agent. While the use of tobacco increases the risk of Alzheimer’s disease, there is also some evidence that nicotine – separate from tobacco use – can treat Alzheimer’s disease (5) and delay the onset of Parkinson’s disease (6).
There are many different routes for ingesting nicotine. The most common is smoking – as in smoking tobacco, however there are obviously many health warnings associated with smoking cigarettes. The vaporized nicotine found in electronic cigarettes is becoming increasingly popular. Nicotine can also be chewed, as it is in tobacco gum or chewing tobacco; directly inhaled with a nicotine inhaler; absorbed through the skin, such as a nicotine patch; or through the cheek lining.
Nicotine increases blood pressure and heart rate through its action as a vaso-constrictor. Because nicotine use causes an increase in dopamine levels in the pleasure centers of the brain, it has intense addictive properties. Nicotine is currently listed in Pregnancy Category D. This means that there is positive evidence for fetal risk based on adverse reaction data in investigational or marketing experience or studies in humans. There is increasing evidence regarding the prenatal use of nicotine separate from tobacco smoke that finds that the drug interacts with fetal brain development by disrupting normal neurotransmitter function. (9) Some forms of nicotine are not appropriate for use by people with certain medical conditions. Those with allergies, nasal polyps, or sinusitis could have trouble using the nasal spray form of nicotine; those with some skin conditions may have adverse reactions to a transdermal patch; and mouth or dental problems could affect the safe use of nicotine gum or lozenges. It is not safe to smoke or use any tobacco product while using nicotine in any form.
(1)Rusted J, Graupner L, O'Connell N, Nicholls C (August 1994). "Does nicotine improve cognitive function?". Psychopharmacology (Berl.) 115 (4): 547–9. doi:10.1007/BF02245580. PMID 7871101
(2)Lagrue G, Lebargy F, Cormier A (June 2001). "From nicotinic receptors to smoking dependence: therapeutic prospects". Alcoologie et Addictologie 23 (2S): 39S–42.
(3)Green JT, Richardson C, Marshall RW, Rhodes J, McKirdy HC, Thomas GA, Williams GT (November 2000). "Nitric oxide mediates a therapeutic effect of nicotine in ulcerative colitis". Aliment. Pharmacol. Ther. 14 (11): 1429–34. doi:10.1046/j.1365-2036.2000.00847.x
(4)Lain KY, Powers RW, Krohn MA, Ness RB, Crombleholme WR, Roberts JM (November 1999). "Urinary cotinine concentration confirms the reduced risk of preeclampsia with tobacco exposure". Am. J. Obstet. Gynecol. 181 (5 Pt 1): 1192–6. doi:10.1016/S0002-9378(99)70107-9.
(5)Henningfield JE, Zeller M (2009). "Nicotine psychopharmacology: policy and regulatory". Handb Exp Pharmacol. Handbook of Experimental Pharmacology 192 (192): 511–34. doi:10.1007/978-3-540-69248-5_18. ISBN 978-3-540-69246-1. PMID 19184661.
(6)DeNoon D (2006-08-11). "Nicotine Slows Parkinson's Disease". Retrieved 2009-12-27.
(7)Meeker-O’Connell, A. How Nicotine Works. Retrieved from http://science.howstuffworks.com/nicotine3.htm on 21 Oct 2013.
(8)Singer, S, et. al. Nicotine-induced changes in neurotransmitter levels in brain areas associated with cognitive function. Neurochem Res. 2004 Sep; 29(9):1779-92.
(9)Wickstrom, R. Effects of Nicotine During Pregnancy: Human and Experimental Evidence. Current Neuropharmacology. 2007 September. 5(3): 213-222.
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