A single injection of a naturally occurring neuro protein, BDNF (Brain Derived Neurotrophic Factor), made rats act as in the same manner that opiate-addicted rats do, leaving preferred environments in search of a fix. Addicts often have increased levels of BDNF, which led to the research.
So now, you can string someone out in one blow, eliminating the need for a drug. Some pretty promising treatment possibilities, but also some scary scenarios. Imagine shooting someone up with BDNF as a coercive tactic, or maybe someone who's skipped the middleman and is straight addicted to BDNF. What the hell would one have to do to keep up a good supply?
It is of course the pinnacle of Western science to create the addition without the high, but not the high without the addiction. This really does say something deep about our cultural sensibilities, here.