Although originally restricted to their structural role as major constituents of membranes, lipids are now well-defined actors to integrate intracellular or extracellular signals. Accordingly, it has been known for decades that lipids, especially those coming from diet, are important to maintain normal physiological functions and good health. This is especially the case to maintain proper cognitive functions and avoid neuronal degeneration. But besides this empiric knowledge, the exact molecular nature of lipids in cellular signaling, as well as their precise mode of action are only starting to emerge. The recent development of novel pharmacological, molecular, cellular and genetic tools to study lipids in vitro and in vivo has contributed to this improvement in our knowledge. Among these important lipids, phosphatidic acid (PA) plays a unique and central role in a great variety of cellular functions. This article will review the different findings illustrating the involvement of PA generated by phospholipase D (PLD) and diacylglycerol kinases (DGK) in the different steps of neuronal development and neurosecretion. We will also present lipidomic evidences indicating that different species of PA are synthesized during these two key neuronal phenomena.