"People who abuse drugs tend to abuse many different drugs, yet much of the current research in the field focuses on single drug abuse," explained primary investigator, Robert Raffa, Ph.D., professor of pharmacology at Temple University School of Pharmacy.
Typically, abusers take several drugs together to multiply the pleasurable effects or manage the undesirable effects-for instance, using alcohol with cocaine. Because each type of drug affects the body differently, withdrawal is more complicated when more than one is involved. It would be impossible to conduct controlled scientific research on human subjects, so scientists have sought out alternatives.
As a study subject, the Planaria worm, a type of flatworm known for its regenerative powers, has several qualities attractive to scientists. First, it has such simple biochemistry and it readily absorbs any chemical in which it is soaked. This simplicity makes it a clean, easy-to-use model. But despite this simplicity, the Planaria worm has a brain and spinal cord, both key to studying the effects of drug abuse and withdrawal. Furthermore, Planaria have the same types of neurotransmitter systems as humans and thus respond to dopamine, opioids, cocaine and cannabinoids.
"Planaria offer a clean and uncomplicated model. We don't have to worry about potential interference from other organs or organ systems, as would be the case in other animal models," said Raffa. "Plus, Planaria display amazing behaviors. They can even learn."