Auditory evoked potentials reflect serotonergic neuronal activity - A study in behaving cats administered drugs acting on 5-HT1A autoreceptors in thedorsal raphe nucleus

A valid indicator of central serotonergic neurotransmission would be useful for various diagnostic and psychopharmacological purposes in psychiatry. H owever, known peripheral serotonergic measures only partially reflect serot onergic function in the brain. Previous findings suggest that the intensity dependence of auditory evoked potentials (AEPs) is closely related to cent ral serotonergic activity. The present study examines the effects of microi njection of a 5-HT1A agonist (8-OH-DPAT) and a 5-HT1A antagonist (spiperone ) ito the dorsal raphe nucleus (DRN) on AEP recorded epidurally from the pr imary and secondary auditory cortex in behaving cats. We found a stronger i ntensity dependence only of AEP from the primary auditory cortex after 8-OH -DPAT, which inhibits the firing rate of serotonergic DRN neurons, and a we aker intensity dependence after spiperone, which increases serotonergic cel l firing, as compared to baseline measurements. These results demonstrate t hat the intensity dependence of AEP is inversely related to serotonergic ne uronal activity and that it may be a promising tool for assessing central s erotonergic function in humans (e.g., identifying patients with low seroton ergic neurotransmission). [Neuropsychopharmacology 21:710-716, 1999] (C) 19 99 American College of Neuropsychopharmacology. Published by Elsevier Scien ce Inc.