Yeah tobacco WD is mostly a consequence of the long term effects of nicotine on nAChR (nicotinic acetylcholine receptors).
Nicotine or tobacco WD might not pleasant but it isn't dangerous either, it won't shock your body in a major way, although the mental/psychological aspects can be really strong as it's a very addictive drug (specially if you started as a teenager).
In fact, your body will be much better off without it as tobacco and nicotine itself are very bad for the cardiovascular system. Plus they actually mess with your blood-sugar levels and raise your odds of getting diabetes. Tobacco and likely nicotine itself also appear to increase the risk of Alzheimer's, though big tobacco has financed and promoted many studies that claim a protective effect...
Nicotinic receptors have been studied extensively so there's a ton of info available for those who are interested in the details. Said receptors are very common in both neuromuscular junctions (they're responsible for muscle contraction) and in the brain, but nicotine has a much higher affinity for the latter (otherwise it'd be pretty unpleasant).
Neuronal nicotinic receptors are found in many key areas of the brain, they modulate many important cognitive processes (learning, concentration, stress, memory formation, fear response, etc...).
Since they're often found in pre-synaptic neurons, their activation actually promotes the release of other well know neurotransmitters like dopamine, serotonin and gaba, but nicotine itself doesn't bind to those receptors (5HTP, gaba, etc.).
When you consume tobacco, specially if you smoke it, the effects of nicotine are amplified by the harmala alkaloids and a bunch of other compounds found in smoke, there's a synergistic effect going on. It has been found that smokers have lower levels of monoamine oxidases in the brain, so they're likely used to having higher levels of dopamine, serotonin and noradrenaline (MAO enzymes are responsible for the degradation of those neurotransmitters).
