Question

What in the human brain do addictive substances like nicotine react with?

Answer 1

The answer your probably looking for is (Chemical Receptors)

Hope I Helped

:D

Nullgaming650

Answer 2

Nicotine, once in the brain, will work specifically on nicotinic receptors in the brain. However, there is a common "addiction" pathway in the brain that pretty much all addictive substances go through.