Lipid signaling in experimental epilepsy

Glutamate release activates signaling pathways important for learning and memory, and over-stimulation of these pathways during seizures leads to aberrant synaptic plasticity associated with hyper-excitable, seizure-prone states. Seizures induce rapid accumulation of membrane lipid-derived fatty acids at the synapses which, evidence suggests, regulate maladaptive connectivity. Here we give an overview of the significance of the arachidonyl- and inositol-derived messengers, prostaglandins (PGs) and diacylglycerol (DAG), in experimental models of epilepsy. We use studies conducted in our own laboratory to highlight the pro-epileptogenic role of cyclooxygenase-2 (COX-2) and its products, the PGs, and we discuss the possible mechanisms by which PGs may regulate membrane excitability and synaptic transmission at the cellular level. We conclude with a discussion of AA-DAG signaling in synaptic plasticity and seizure susceptibility with an emphasis on recent studies in our laboratory involving DAG kinase epsilon (DGK epsilon)-knockout mice.