Nicotine is complicated. So let's start with that. It seems the general perception of nicotine is that its linked to the release of dopamine and therefore that explains the addictive properties and also the good feeling effect. If it was that simple, some of the pharmaceutical drugs such as bupropion branded Wellbutrin would work almost instantly. It would take away the cravings of the dopamine released by the nicotine and would substitute it almost right away. But obviously it doesn't work like that. Bupropion is widely available to any smoker who asks it to their doctor, and it was patented back in the 60s. If it was that amazing, smoking would not be such problem as it is today.
Dopamine accounts for maybe 20% of the wonders of nicotine, maybe even less. Obviously no one has an exact number, but by digging in deeper on the exact mechanisms of nicotine; this would be a good estimate. It would also explain why there is no crash or anxiety produced by the release of dopamine. No one suffers from anxiety or depression from dopamine activity due to nicotine consumption. It occurs during withdrawal, but not directly from the use of nicotine. If we take the example of cocaine, which acts as a strong dopamine reuptake inhibitor, once all the dopamine is used and gone, within hours, often even after 30 minutes, a person will start feeling a down. This is common with every drug and amphetamines and methylphenidate as well, but not nicotine. Why? The main mode of action of nicotine is not dopamine, but through nicotinic acetylcholine receptors, there is almost no other drug that acts on these receptors, hence the name nicotine. These receptors respond to acetylcholine. Those will be discussed in detail in the next post.