Macrophage migration inhibitory factor (MIF) expression is induced by angiotensin II (Ang II) in normal rat neurons and serves a negative regulatory role by blunting the chronotropic actions of this peptide. The aim here was to determine whether hydrogen peroxide (H2O2), a reactive oxygen species (ROS) that is a key intracellular mediator of the neuronal actions of Ang II, is a trigger for MIF production in neurons. Thus, we tested the effects of H2O2 on MIF expression in primary neuronal Cultures from newborn normotensive (Wistar Kyoto [WKY] or Sprague-Dawley [SD]) rat brain, cells that respond to Ang II by increasing MIF levels. Treatment of WKY or SD rat neuronal cultures with a non-cytotoxic concentration of H2O2 elicited a significant, time-dependent increase in MIF mRNA and protein levels. Glucose oxidase, which produces H2O2 Via oxidation of glucose in the cell-culture medium, elicited a similar increase in neuronal MIF mRNA levels. The stimulatory action of H2O2 was not apparent in neuronal cultures from spontaneously hypertensive rats (SHR), cells that fail to express increased MIF in response to Ang II. Finally, preincubation of SD rat cultures with either polyethylene glycol-catalase or actinomycin D abolished the H2O2-induced increase in MIF, suggesting that this ROS is acting intracellularly to increase transcription of the MIF gene. These results suggest the presence of a redox regulatory mechanism for induction of MIF in normotensive rat neurons. (c) 2009 Elsevier Inc. All rights reserved.