Dexamethasone induces lipocalin-type prostaglandin D synthase gene expression in mouse neuronal cells

Lipocalin-type prostaglandin (PG)D synthase (L-PGDS) is responsible for the production of PGD(2), the main PG in the CNS, PGD, is an endogenous sleep inducer, and it is involved in the control of odor and pain responses and b ody temperature. In addition, PGD synthase transports lipophilic molecules in the subarachnoid space and CSF. By northern and western assays we show t hat the synthetic glucocorticoid dexamethasone, an inhibitor of PG producti on in most tissues, induces L-PGDS mRNA and protein in a dose- and time-dep endent fashion in mouse neuronal GT1-7 cells. Accordingly, dexamethasone in creases cellular L-PGDS enzymatic activity. Dexamethasone induced L-PGDS ge ne transcription in run-on assays and activated the mouse L-PGDS gene promo ter in transiently transfected cells. It is interesting that the tumor prom oter 12-O-tetradecanoylphorbol 13-acetate (TPA), which induces the synthesi s of PGs in many tissues, inhibited the increase in L-PGDS expression induc ed by dexamethasone, In contrast, neither dexamethasone nor TPA affected th e expression of cyclooxygenases-1 and -2. Our data demonstrate that dexamet hasone induces L-PGDS gene transcription in neuronal cells.