Grant: $378,773 - National Institutes of Health - Aug. 20, 2009
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Award Description: This project seeks to determine the mechanisms whereby ingestion of ethanol by dams increases the concentration of atRA (all-trans-retinoic acid) in vivo in embryo hippocampus during normal vitamin A (retinol) nutriture. We developed a LC/MS/MS assay with femtomol sensitivity for specific quantitation of atRA in small biological samples, and used it to generate reference values for atRA and its isomers in serum and multiple tissues of several strains of mice. The assay was applied to determine the impact of ethanol on steady-state atRA concentrations during normal vitamin A nutriture. Contrary to the prevailing hypothesis, ethanol feeding (Lieber-DeCarli liquid diet, 36% of calories, 1 month) did not alter atRA concentrations in liver, kidney, olfactory bulb, striatum, thalamus and cerebellum of C57BL/6 adult mice, but caused 2 to 50-fold increases in atRA concentrations in hippocampus, cortex, testis and serum. Ethanol, fed in the same manner to dams from e13 through e18 of pregnancy increased atRA in the hippocampus and cortex of e19 embryos in proportion to dam blood alcohol concentrations. A dam BAC of 0.08% caused 4 and 30-fold increases, respectively, in hippocampus and cortex atRA. We also have showed that hippocampus astrocytes biosynthesize atRA and secrete atRA for uptake by neurons. We also showed that ethanol not exert these affects in CRBPI-null mice. We seek to apply these insights and techniques to determine the mechanisms whereby dam ethanol ingestion increases atRA concentrations in embryo hippocampus. The hypothesis to be tested is: ethanol ingestion by dams increases endogenous concentrations of atRA in the hippocampus of their embryos by: increasing delivery of retinol to hippocampus astrocytes via serum RBP; increasing uptake of retinol by increasing both the membrane RBP receptor, Stra6, and the intracellular retinol binding protein, CRBPI (CRBPI removes retinol from Stra6 and chaperones retinol metabolism); ethanol increases Rdh (retinol dehydrogenase) and Raldh (retinal dehydrogenase) activities; increased atRA cannot be compensated by increased catabolism in the hippocampus. The specific aim is to determine the effects of chronic ethanol on mechanisms of atRA biosynthesis and secretion by hippocampus astrocytes. The studies will be done in primary astroctyes prepared from the hippocampus and cortex of CRBPi-null and WT mice. The data generated with WT will be compared to CRBPI-null, and the data generated with hippocampus astrocytes will be compared to data generated with cortex astrocytes, because ethanol does not affect atRA concentrations in the cortex. These studies will provide mechanistic insight into ethanol disruption of retinoid homeostasis, and should influence approaches to treating alcoholism.
Project Description: This project will determine the mechanisms whereby ethanol impacts the ability of astrocytes to deliver retinoic acid to neurons in the brain.
Jobs Summary: ARRA funds used to support 1 Post-doctoral researcher. (Total jobs reported: 0)
Project Status: Less Than 50% Completed
This award's data was last updated on Aug. 20, 2009. Help expand these official descriptions using the wiki below.