sigma(2) Receptors induce apoptosis in various cell types. The sphingolipid, ceramide as well as the sphingoid bases are involved in cell proliferation. Sphingolipids of MCF-7/Adr- and T47D breast tumor cells were metabolically radiolabeled. The sigma(2) receptor agonists (+)-1R,5R-E-8-(3,4-dichlorobenzylidene)-5-(3-hydroxyphenyl)-2-methylmorphan-7-one (CB-184) and 1S,2R-(--)-cis-N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(1-pyrrolidinyl)-cyclohexylamine (BD737) caused dose-dependent increases in [(3)H]ceramide, with concomitant decreases in [(3)H]sphingomyelin. Both effects were attenuated by the novel sigma(2) receptor antagonist, N-phenethylpiperidine oxalate (AC927). sigma(2) Receptors may produce effects on cell growth and apoptosis by regulating the sphingolipid pathway.