Rats like to party. This from a study of opium, alcohol, amphetamines, psilocybin, nicotine, and cannabis use in rodents. Specifically, any one drug acted as a gateway for others. For example, rats who smoked pot (clinically speaking) more highly self-administered heroin when given the chance (and vice versa all the way around the circle). Were test subjects released into the wild? Did they form bands and join the Bonnaroo festival circuit? Did researchers fail to notice the data potential of Keith Richards?
Regardless, once the brain gets a taste of artificially generated dopamine release, it’s likely to look for more of the same in the future—no matter the source.