Bioactive lipids and their role in the brain Bioactive lipids are molecules that have both intra- and intercellular roles, including mediation, modulation and control of neurobiological processes, such as ion channel and receptor activity, neurotransmitter release, synaptic plasticity, second messenger pathways and neuronal gene expression (Agranoff et al., 1998). Emphasis has been placed on AA and its metabolites, known collectively as eicosanoids. A major proportion of lipids in the brain consist of bioactive lipids such as AA and its metabolites, also referred to as EFA, which are mainly bound to GPL. Bioactive lipids are released through direct and indirect enzymatic pathways (e.g., phospholipases) from membrane GPL. AA is a precursor of prostaglandins, thromboxanes, leukotriens (5-HpETE) and prostacyclins. Animal studies and preliminary studies in humans have shown an association between bioactive lipid metabolism, behaviour and cognition (Zimmer et al., 2000).