Up-regulation of sigma(1) receptor mRNA in rat brain by a putative atypical antipsychotic and sigma receptor ligand

Sigma(1) (sigma(1)) receptor mRNA expression was studied in the prefrontal cortex, striatum, hippocampus and cerebellum of rat brain by northern blot and in situ hybridization. The effects of a chronic treatment with antipsyc hotic drugs (haloperidol and clozapine), and with E-5842, a sigma(1) recept or ligand and putative atypical antipsychotic on sigma(1) receptor expressi on were examined. A significant increase in the levels of sigma(1) receptor mRNA in the prefrontal cortex and striatum after E-5842 administration was observed, while no apparent changes were seen with either haloperidol or c lozapine. Our results suggest a long-term adaptation of the alpha(1) recept or at the level of mRNA expression in specific areas of the brain as a resp onse to a sustained treatment with E-5842. (C) 2000 Elsevier Science Irelan d Ltd. All rights reserved.