Pergamon Life Seicnces, Vol. 57, No. 18, pp. 1667-1673, 1995 Copyright 0 1995 FIscvier Science Inc. Printed in the USA. All rights resewed @X24-3205/95 $950 + .OU 0024-3205(95)02146-9 INTERACTION OF ETHANOL AND ANOXIA WITH MUSCARINIC RECEPTOR - STIMULATED PHOSPHOINOSITIDE METABOLISM DURING BRAIN DEVELOPMENT Walter Balduini, Filippo Renb and Lucia G. Costa’ Department of Environmental Health, SC-34, University of Washington, Seattle, Washington, 98195. (Received in fiial form August 24, 1995) Summary The mechanism(s) by which ethanol induces alterations in brain development may involve direct actions (e.g. changes in specific biochemical pathways), or indirect effects, such as cerebral hypoxia resulting from ethanol - induced circulatory changes. Since both ethanol and hypoxia are known to affect the metabolism of phosphoinositides, which has been suggested as a possible target for ethanol’s developmental neurotoxicity, in the present study we have investigated the in zyxwvutsrqponmlkji vitro effects of both severe hypoxia (anoxia) and ethanol (alone or in combination) on muscarinic receptor- stimulated phosphoinositide metabolism in cerebral cortex slices from neonatal rats. Anoxia markedly inhibited carbachol - stimulated phosphoinositide metabolism in adult rats (67%) but only slightly (10%) in neonatal animals. Reoxygenation reversed the effect of anoxia at both ages. On the other hand, ethanol’s inhibitory effect was pronounced in neonatal rats only, and was additive to that of anoxia. The presence of ethanol did not affect the recovery of carbachol - stimulated phosphoinositide metabolism following anoxia and reoxygenation. These results indicate that ethanol and anoxia differently and independently affect muscarinic receptor - stimulated phosphoinositide metabolism and may mutually contribute to the CNS effects observed following developmental ethanol exposure. Key Woruk ethanol, anoxia, muscarinic receptors, phosphoinositide metabolism, brain development One of the major features of the Fetal Alcohol Syndrome is central nervous system (CNS) dysfunction, characterized by microencephaly, mild to moderate mental retardation, tremors, poor attention spans, and hyperactivity (1). The mechanism(s) by which ethanol induces alterations in brain development has yet to be determined, and could involve both direct effects of ethanol on the brain, or indirect effects, such as cerebral hypoxia resulting from ethanol-induced circulatory changes (2-4). In support of a possible role of hypoxia-ischemia in the developmental neurotoxicity of ethanol is the observation that some of the nemopathological changes observed in animals treated with ethanol during pregnancy (5) are similar to those observed after ischemia-hypoxia h adult rats (6). Severe hypoxia, on the other hand, can cause marked alterations of synaptic transmission in the brain. For instance, anoxia interferes with the synthesis of various neurotransmitters, including acetylcholine (7,8), and increases the concentration of glutamate in the synaptic cleft, both by enhancing presynaptic release of glutamate (9,lO) and by inhibiting its uptake by glial cells (11). Anoxia can also induce changes in receptor-activated phosphoinositide metabolism. Ninomiya et al. (12) have shown that in vitro exposure of cortical slices from adult rats to anoxia causes a severe t Correspondence