Oleamide-mediated sleep induction does not depend on perturbation of membrane homeoviscosity

To verify whether the sleep-inducing properties of oleamide mere related to its ability to perturb membrane homeoviscosity, affecting 5-HT2A receptors , we compared the effects of oleamide and oleic acid, the latter lacking bo th the sleep-inducing effect and the action on 5-HT2A receptors, In binding studies the two compounds did not directly interact with rat brain cortex 5-HT2A receptors, nor did the; increase the affinity of a 5-HT2A agonist, e ither in vitro or ex vivo, They had simile; fluidizing effects, in vitro at high concentrations (greater than or equal to 10 mu M), and ex vivo after a dose of 100 mg/kg, and they reduced locomotor activity with similar poten cy, There thus appears to be no causal relationship between the fluidizing effects of oleamide and its sleep-inducing properties, (C) 1999 Federation of European Biochemical Societies.