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Nicotine is one of the most well known components of inhaled cigarette smoke. But is it addictive? Yes and no. The details that make clear that paradoxical statement are interesting.
Nicotine itself is not addictive. But then, neither is heroin. It's what the body does with that compound that produces the result. Think that's quibbling over words? Read on...
The average cigarette delivers between 1.2 – 2.9 mg of nicotine, according to data from the National Institute of Drug Abuse. But, of course, very few smokers limit themselves to one per day. The average one pack-per-day user will absorb between 20-40 mg per day. That may not sound like much, but the effects are considerable.
Nicotine stimulates regions of the brain in the area of the hypothalamus and the pituitary gland. Big words, but important ones. These areas play a large role in the endocrine system, the part of the body that regulates hormones.
Small doses of nicotine produce alertness, making cigarette smoke a stimulant. Larger doses act more like a sedative. So the impetus for smoking to become a habit is two-fold: cigarettes both stimulate and relax.
They do that by producing several effects.
Many drugs can't penetrate the blood-brain barrier, the system that selectively allows only certain molecules into the brain. But nicotine manages to indirectly defeat that protective function. Nicotine increases the levels of endorphins, the well-known 'runners high' compounds.
It also affects the availability of dopamine in the brain, which is responsible to a large degree for the positive feelings associated with smoking. Dopamine is a neurotransmitter that plays a role in the brain associated with reinforcing desirable behavior. Signals are sent that say 'smoking is pleasurable'. Unfortunately, it doesn't send signals that inform the smoker that 'smoking is also harmful'.
In addition, nicotine stimulates the adrenal glands. That causes them to release the hormone named after them, adrenaline. That in turn causes a spike in glucose levels, leading to increased respiration and heart rate, raising blood pressure.
Within limits, those latter effects are perceived as desirable. That's the stimulating effect. But at the same time, over time, that result can wear arteries more rapidly than they otherwise would. Along with other compounds like carbon monoxide, CO, which tends to produce fatty deposits and harden vessels, the arteries are 'aged'. They're less effective at their purpose: delivering blood.
Nicotine has other effects on the body.
It suppresses insulin release from the pancreas. That hormone plays a critical role in regulating glucose. Excess glucose in the blood encourages the development of diabetes. Cigarette smoking doesn't directly cause diabetes, but it slightly ups the odds. Combined with a statistical increase in obesity in many countries, upping the odds isn't helpful.
Reducing the regular dosage of nicotine by reducing or quitting smoking, reverses many of the perceived pleasurable effects. As a result, quitting is more difficult. But using willpower, patches and other stop-smoking methods means keeping in mind that 'long-term harmful' outweighs 'short-term pleasurable' by any rational calculation.
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