consumption of alcohol can temporarily reduce serotonin production, which the body then compensates for by making more of it. Of course, if the reduced serotonin production lasts longer than the euphoria of alcohol, the same effect as the OP posited could still happen, albeit caused by the lingering effects of alcohol rather than serotonin "depletion". I must state that to be fair, I also was of the theory that alcohol and many other substances were addictive due to depletion before looking it up.