ABSTRACT

A complete understanding of drug effects and the mechanisms of addiction include a mo­lecular characterization of changes in neurotransmitter and ion channel pathways and their consequences for remodeling of the nervous system and the control of adult stem and terminal somatic cell populations. The planarian offers unprecedented advantages in this area because of a powerfrd suite of physiological, behavioral, cell-biological and genetic tools, as well as an accessible and plentiful adult stem cell population. Most crucially, planarians possess power­ ful regenerative abilities, able to restore the entire body (including brain and peripheral nervous systems) from small fragments of the animal. On-going and future work on the role of ion flows, neurotransmitters and other mechanisms controlling regenerative pattern and adult remodeling will allows insight into the most crucial aspects of drug action on the brain and other organ systems.