Transient expression of phospholipase D1 in developing rat hippocampus

We investigated the distribution of phospholipase Di (PLD1) protein in the developing rat hippocampus using an affinity-purified peptide antibody agai nst PLD1. Immunoreactivity for PLD1 was first seen in some scattered cells in the hippocampus at embryonic day 18. At postnatal day 1 (P1), many PLD1 immunoreactive cells were observed in the CA1 and CA3 sectors, subiculum an d the hilus of the dentate gyrus. During the first postnatal week, there wa s an abrupt increase of immunoreactive neurons in the hippocampus, and thei r number and intensity peaked at P7. During the second postnatal week, ther e was an abrupt decrease in the number of immunoreactive hippocampal neuron s. By P14, no significant labeling was found in the hippocampus. These resu lts corresponded well with those from Western blot analysis, suggesting tha t PLD1 may regulate the developmental processes of hippocampal neurons. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.