Nicotine: An overview
Nicotine is a naturally occurring alkaloid found in many plants, with the primary sources being the leaves and stems of Nicotiana tabacum and Nicotiana rustica [1, 2].
Nicotine, found in tobacco plants, has been utilized for millennia. American Indians used tobacco before Europeans arrived in the late 1400s. In the following centuries, It spread globally for its medicinal benefits, transitioning to recreational use like smoking and chewing. Smokeless tobacco, like snuff and chewing tobacco, remains popular worldwide.[3, 4]
Nicotine is the main component of tobacco, responsible for both the addiction associated with chronic exposure to tobacco products and the characteristic odor of tobacco [2].
Nicotine is an amine composed of pyridine and pyrrolidine rings, and it easily crosses biological membranes and the blood-brain barrier [1]. Once absorbed, nicotine and its metabolic products exert various physiological and pharmacological effects [2].
It affects a wide range of biological functions, including gene expression, regulation of hormone secretion, and enzyme activities [1]
How Nicotine Works
Nicotine works by mimicking neurotransmitters in the brain: Due to nicotine being similar in shape to acetylcholine, a neurotransmitter, it can mimic it when absorbed into the body, this causes signaling activity in the brain to increase, making you feel more energized [3].
Nicotine is highly addictive: With continued use, the neurons in the brain start to compensate for the increased activity by making fewer acetylcholine receptors. When nicotine levels go down, such as when a person stops smoking/stops taking nicotine in any form, the body craves nicotine because the brain isn't making enough acetylcholine on its own [3].
Nicotine can mimic dopamine: Dopamine is a "feel-good" chemical that is released in rewarding situations. Essentially, nicotine alters the chemical functions in the brain, which is a cause for concern among public health organizations and the medical community [3].
Side Effects of Nicotine
As discussed before Nicotine, has several side effects that impact both physical and mental health. One of the most immediate effects of nicotine is the release of dopamine, a neurotransmitter that creates a brief feeling of contentment and pleasure [4, 5]. However, this sensation of bliss can lead to a cycle of severe addiction, as the brain begins to associate nicotine use with feeling good [5].
Nicotine increases the risk of diseases Nicotine can lead to serious health complications. These include lung cancer, emphysema, chronic bronchitis, heart disease, stroke, diabetes, and various eye issues such as cataracts and macular degeneration. It can also cause infertility, impotence, and pregnancy complications. Other effects include a weakened immune system, loss of sense of taste or smell, gum disease, dental issues, premature aging, peptic ulcer disease, and osteoporosis [4].
Nicotine addiction is not only physical. Nicotine addiction is also psychological, with users consciously desiring nicotine's effects. It is also behavioral, with people becoming dependent on the actions involved with using tobacco and becoming accustomed to using tobacco in certain situations, such as after meals or when under stress [4]
The way nicotine is administered can also have side effects. For instance, cigarette smoke inhalation delivers high nicotine concentrations to the brain and other organs within 10 seconds of inhalation [6]. This rapid delivery and the quick dissipation of nicotine's effects encourage frequent smoking throughout the day to maintain its pleasurable effects and prevent withdrawal symptoms. Other methods of nicotine consumption, such as chewing tobacco, holding moist snuff in the mouth, inhaling dry snuff through the nose, inhaling smoke from a water pipe, and inhaling vapor from an electronic cigarette, can also have different side effects. These methods account for the vast majority of nicotine use [7, 8].
Benefits of Nicotine
Even though Nicotine has plenty of side effects, it has been found to have several potential benefits. It's important to note that these benefits are associated with nicotine itself, not with tobacco use, which is known to have numerous harmful effects on health.
Nicotine for smoking cessation. One of the critical benefits of nicotine is its potential therapeutic utility. Nicotine acts on nicotinic cholinergic receptors, influencing most organ systems in the body and possibly mediating complex actions described in tobacco users [9]. It's currently available as a gum, a transdermal delivery device, and a nasal spray, all of which are used for smoking cessation [9].
Nicotine has also been found to enhance overall mood and cognitive abilities, which can be solid reinforcements for smokers [10].
Nicotine replacement therapy (NRT) can prove to be an effective tool in helping with cravings and withdrawal symptoms associated with quitting smoking [11].
Nicotine in the treatment of other diseases. Beyond smoking cessation, nicotine is being investigated for its potential therapeutic effects on various medical conditions. For instance, it's being studied for the treatment of ulcerative colitis, Alzheimer's disease, Parkinson's disease, Tourette's syndrome, sleep apnea, and attention deficit disorder [9].
In Alzheimer's disease, nicotine has been found to improve cognitive impairment by enhancing protein kinase B activity and stimulating phosphoinositide 3-kinase/Akt signaling, which regulates learning and memory processes [9]. In Parkinson's disease, nicotine may slow the progression of the disease by inhibiting Sirtuin 6, a stress-responsive protein deacetylase, thereby decreasing neuronal apoptosis and improving neuronal survival [12].
It's important to note that while nicotine has potential benefits, as discussed in the previous sections, it also poses several health hazards, including an increased risk of cardiovascular, respiratory, and gastrointestinal disorders and potential impacts on the immune system [13, 14]. Therefore, the use of nicotine in the medical field should be carefully regulated and supervised by trained medical personnel.
Preventing Addiction
Preventing nicotine addiction primarily involves avoiding the use of tobacco products. Anyone who uses tobacco is at risk of developing an addiction, and the best way to prevent an addiction is to avoid tobacco altogether [4].
Factors that may increase the risk of addiction: People with a family history of nicotine addiction and people who grow up in homes with tobacco users are more likely to start smoking and develop an addiction. Also, people who start smoking when they are young are more likely to smoke into adulthood. One study notes that 80% of smokers began smoking by age 18 years [4].
People who abuse alcohol or drugs or who have a mental illness also have an increased risk of nicotine dependence [4]. Therefore, addressing these issues can also help in preventing nicotine addiction. Going into therapy might prove helpful.
Current research on Nicotine Vaccines: In addition to avoiding tobacco and addressing other risk factors, there are also some promising new approaches to preventing nicotine addiction. For example, there are ongoing studies into the use of a nicotine vaccine, which stimulates the immune system to produce nicotine-specific antibodies. These antibodies bind to nicotine, creating a complex that is too large to cross the blood-brain barrier, thereby blocking the addictive effects of nicotine [15].