Substituted heterocyclic diarylamine analogues of Formula I are provided: wherein X, Y and Z are independently N or optionally substituted C, and other variables are as described in the specification. Such compounds are ligands that may be used to modulate specific receptor activity in vivo or in vitro, and are particularly useful in the treatment of conditions associated with pathological receptor activation in humans, domesticated companion animals and livestock animals. Pharmaceutical compositions and methods for using them to treat such disorders are provided, as are methods for using such ligands for receptor localization studies.