This proposal intends to focus on the opioid peptides and the opiate receptors of the CNS as they may be effected by prenatal ethanol exposure. The studies are designed to be carried out in timed-pregnant rats that will be given one of a series of liquid diets designed to control for nutritional inadequacies attendant to ingesting large amounts of alcohol. Included in the design is a casein-based solid pellet diet group, pair-fed controls, and a group that receives a nutritionally inadequate diet along with ethanol that may mimic more closely the situation in human Fetal Alcohol Syndrome (FAS). Other dietary treatments are designed to determine which effects are due to ethanol alone, which to undernutrition alone, and which may be due to their interaction. The principal investigator has extensive experience with these diets, and has shown rather large increases in brain Beta-endorphin at birth in newborn rats exposed to pre-natal alcohol. There are two reasons for focusing on the opioid systems of the brain. First is their role as neurotransmitters in three anatomically separate neuronal systems. Beta-endorphin, the enkephalins and the dynophin-containing neurons are genetically and anatomically distinct systems, and each has been implicated in different CNS functions. Since the human FAS is characterized by mental retardation and other behavioral sequellae, these neuronal systems and their receptor molecules may be targets of the teratogenic effects of ethanol. Another salient reason for emphasizing the opioid peptides is the accumulating evidence of their role in early neurotropic actions during brain development. Several of the peptides derived from the Beta-endorphin precursor, POMC, have been implicated in tropic effects during the neurogenesis stage; similarly for the opiate receptors, there is strong evidence for their involvement in developmental processes, at times when the peptide transmitters are at either very low levels or undetectable. We propose to use six separate antisera, coupled with HPLC chromatography to characterize the changes that occur in the three neuropeptide families, as well as their post-natal time-course. Similarly, a series of labelled ligands will be used to estimate the populations of mu, delta and kappa opiate receptors in the offspring brains. The studies proposed will provide enough detail of the opioid systems that will make feasible testing of pharmacological intervention of the endogenous opioid systems for amelioration of FAS in the future.
