<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>An agent that exerts a physiologic effect on neurotransmission or on any anatomic entity that is part of the nervous system, including the central nervous system (CNS) and peripheral nervous system (PNS).</n0:def-definition><n0:def-source>NCI</n0:def-source></n0:ComplexDefinition>