Neurogenesis in the dentate gyrus of adult rodents is elicited by transient global ischemia. Cyclooxygenase (COX) -2, a rate-limiting enzyme for prostanoid synthesis, is also induced by ischemia. We recently found that the administration of a non-selective COX inhibitor to ischemic animals suppressed cell proliferation in the subgranular zone (SGZ) at the dentate gyrus of the hippocampus. To clarify whether prostaglandin E2 (PGE2) synthesis by COX's is involved in neurogenesis, sulprostone, an analogue of PGE2, was injected into the rat hippocampus. Sulprostone injection increased the number of 5-bromo-2'-deoxyuridine (BrdU)-positive cells in the SGZ. BrdU-positive cells also expressed polysialylated isoforms of neural cell adhesion molecule and neuronal nuclear antigen. These results suggest that PGE2 plays an important role in the proliferation of cells in the SGZ.