Sigma-2 receptor is a widely distributed protein, which can modulate cell proliferation and involved
in the pathogenesis of tumor. Photoaffinity labelling techniques testified that its molecular size is
about 18 kDa. Recent studies indicated that sigma-2 receptor modulates the cytosolic Ca2+ concentration, dopaminergic
transmission, and cocaine-induced addiction behavior. Some sigma-2 receptor ligands (ditolylguanidine,
afobazole, etc) display the neuroprotective effect. Although sigma-2 receptor hasn’t been cloned, tens of
sigma-2 receptor ligands, which demonstrate high affinity and selectivity, have been identified in the past decade. In this
review, we mainly focus on these series of selective sigma-2 receptor ligands, their neuropsychological effects, and molecular
probes for tracing sigma-2 receptors in central nervous system.