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I had a discussion with a high school student about the effect and production of nicotine. He mentioned that nicotine is naturally produced in our brain so when the person takes to smoking, the brain stops producing its own nicotine and starts craving it from an external source. According to him, this is how nicotine addiction develops. How true is this?

The students also claimed that nicotine in cigarettes is harmless. I have already seen the answer about how toxic it is to humans, but I would love to know:

  1. What's the lethal dose for nicotine via ingestion (not inhaling)?
  2. How does nicotine compare to other toxic substances - for example, cyanide or any other known poison? Is it more toxic or less toxic?

THANK YOU

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No, the human brain does not produce nicotine. The brain has nicotinic acetylcholine receptors, but the endogenous agonist for these receptors is acetylcholine, not nicotine; they aren't named "nicotinic" because they are for nicotine but just because nicotine happens to act on them. Many other human receptors are named similarly, based on discovering the molecular basis for sensitivity to exogenous compounds.

The human LD50 for nicotine is reported between 0.5-13 mg/kg depending on age and other factors, but LD50 is only appropriate for evaluating acute toxins; many substances, including nicotine, are most often encountered in small chronic amounts, but concentrated availability of nicotine in insecticides or vape juice can be a plausible source for sufficient doses for acute toxicity. Studies of nicotine toxicity in relationship to smoking are going to be based on much smaller doses over many more administrations.

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  • $\begingroup$ Thank you very much for your answer. Could you please provide some info on your educational background? I want to show your answer to my students and I don't want them to say "you cannot believe random people on the Internet". Thanks one more time. $\endgroup$ – treehugger Feb 8 '19 at 17:57
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    $\begingroup$ @treehugger My educational background shouldn't be relevant; I do have a PhD in a biological science but I could also say I'm an astronaut and the head of state of a major country; since I am ultimately a person on the internet you should use other information to decide whether to believe me. Your question is fairly basic, so I've left some links to Wikipedia articles. Of course, Wikipedia is not an ideal source, but you can follow sources on each of those linked pages to reputable scientific publications. $\endgroup$ – Bryan Krause♦ Feb 8 '19 at 18:02
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    $\begingroup$ @treehugger I understand, I'm just trying to give you another perspective. As a scientist, I'd much prefer a ninth grader learn how to find and evaluate scientific information from credible sources rather than appeal to authority of an individual. They should learn to be skeptical of their own intuition, skeptical of unsourced claims, skeptical of sources with other motives or unclear provenance, and learn about how scientists themselves reach their conclusions. All those skills are much easier to learn as a high school student than as an adult - we adults tend to be quite stubborn. $\endgroup$ – Bryan Krause♦ Feb 8 '19 at 18:14
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No nicotine is a special type of drug which is never secreted by the brain. Each person has their immunity -- it's based on what amount you take and how your body responds towards it because for some there is a small amount require to become toxic but for some, it can't. As compared to cyanide it is less toxic because cyanide is very harmful

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  • $\begingroup$ Needs a citation. $\endgroup$ – theforestecologist♦ Feb 9 '19 at 4:32
  • $\begingroup$ The answer is poorly written. Needs links and references. $\endgroup$ – treehugger Feb 9 '19 at 14:30
  • $\begingroup$ cvi.asm.org/content/11/3/563 $\endgroup$ – treehugger Feb 9 '19 at 14:35
  • $\begingroup$ It is a good link and there is a lot of explanation and a lot of knowledge in it $\endgroup$ – user212298 Feb 9 '19 at 14:54

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