This proposal will test the hypothesis that acetylcholine synapses in various brain regions will show specific neurochemical alterations in their developmental ontogeny when exposed to alcohol. Furthermore, these alterations will be dependent upon 1) the dose and duration of alcohol exposure; 2) the specific developmental stage of a particular brain region at the time of alcohol exposure, and (3) the developmental stage of the particular brain region during which analysis for specific alterations is conducted. Rat pups will be administered ethanol or isocaloric sucrose via twice daily intragastric intubation with a fine diameter Silastic tube. The pups will be kept with lactating dams in litters of ten. Exposure periods will inlcude post-natal day one (PN1) to PN5; PN1 to PN10; PN1 to PN15 and PN1 to PN20. Animals will be sacrificed and various brain regions dissected for analysis. For each period of exposure, dates of sacrifice will include the day following the last dose, five days following the last dose, PN20, PN60 and PN120. Brain regions to be dissected and analyzed include cortex, striatum, hippocampus, midbrain-thalamus, hypothalamus, medulla-pons and cerebellum. Regional neurochemical analyses will involve measurements of acetylcholinesterase activity, choline acetyltransferase activity and determinations of muscarinie selective receptor affinity (Kd), and density (Bmax) via saturation analysis using the radioligands (3H)-QNB and (3H)-pirenzepine. Further analysis of muscarine selective receptors will include competition studies to analyze receptor selectivity and ethanol-induced alterations in receptor specificity. The functionality of alcohol-induced alterations of receptor binding parameters and/or enzyme alterations will be assessed by studies on the muscarinic receptor stimulated release of inositol phosphates. Postnatally, the rat brain undergoes the same type of growth and development as does the human brain during the third trimester of pregancy. Accordingly, these studies in rats are designed to look for possible neurochemical outcomes of human fetal ethanol exposure.
