Increased intracellular localization of brain GLUT-1 transporter in response to ethanol during chick embryogenesis

Brain Metabolic Alterations in Rats Showing Depression-Like and Obesity Phenotypes

Current data suggest an important role of brain metabolic disturbances in the pathogenesis of depression and obesity, diseases that frequently co-occur. Our aim was to determine whether there are changes in markers characterizing glucose metabolism in prenatal stress (PS; animal model of depression), in rats fed a high-fat diet (HFD), and especially in the model of depression and obesity co-occurrence. The changes in glucose-6-phosphate, glycogen, glucose transporters (GLUT1, GLUT4), glucagon-like peptide-1 receptor (GLP-1R), and mitochondrial complexes levels in the frontal cortex and/or hippocampus were observed. In the case of the coexistence of depression and obesity, the most important changes were (1) the decrease in the membrane form of GLUT4, which may suggest weaker insulin action in the frontal cortex, and (2) the diminished GLP-1R, which could cause neurodegenerative changes in the hippocampus. However, presented results suggested that HFD weakened the PS effect of uncoupling oxidative phosphorylation in the frontal cortex.

The avian embryo as a model for fetal alcohol spectrum disorder

Prenatal alcohol exposure (PAE) remains a leading preventable cause of structural birth defects and permanent neurodevelopmental disability. The chicken (Gallus gallus domesticus) is a powerful embryological research model, and was possibly the first in which the teratogenicity of alcohol was demonstrated. Pharmacologically relevant exposure to alcohol in the range of 20-70 mmol/L (20-80 mg/egg) disrupt the growth of chicken embryos, morphogenesis, and behavior, and the resulting phenotypes strongly parallel those of mammalian models. The avian embryo's direct accessibility has enabled novel insights into the teratogenic mechanisms of alcohol. These include the contribution of IGF1 signaling to growth suppression, the altered flow dynamics that reshape valvuloseptal morphogenesis and mediate its cardiac teratogenicity, and the suppression of Wnt and Shh signals thereby disrupting the migration, expansion, and survival of the neural crest, and underlie its characteristic craniofacial deficits. The genetic diversity within commercial avian strains has enabled the identification of unique loci, such as ribosome biogenesis, that modify vulnerability to alcohol. This venerable research model is equally relevant for the future, as the application of technological advances including CRISPR, optogenetics, and biophotonics to the embryo's ready accessibility creates a unique model in which investigators can manipulate and monitor the embryo in real-time to investigate the effect of alcohol on cell fate.

Rat adult offspring serum lipoproteins are altered by maternal consumption of a liquid diet

Palatable liquid diets for the administration of ethanol (EtOH) to animals have proven to be a major advance for the study of the effects of EtOH consumption under conditions of isocaloric nutrition of the control animals. Using a liquid diet, the original aim of the reported studies was to examine the effect of maternal EtOH consumption during pregnancy on the lipoprotein (Lp) profiles of the adult offspring measured by means of nuclear magnetic resonance spectroscopy. However, initial data suggested that compared to a maternal chow diet, the basal maternal liquid diet (without EtOH) had a significant effect on specific serum Lp of the adult offspring. The adult offspring of mothers who had consumed a basal liquid diet without EtOH exhibited significant increases in their plasma triglycerides (TG) and cholesterol content compared to adult offspring whose mothers consumed a chow diet. Further, there were significant increases in the offspring's VLDL and low density Lp (LDL) subfractions' particle number, regardless of whether the maternal liquid diet was ad libitum-fed, pair-fed, or EtOH-containing. The increase in offspring plasma TG was due to increases in specific VLDL subfraction particle numbers and not to increased TG content per particle. Similarly, the increase in plasma cholesterol was the result of elevated level of the very small LDL particles but not to an increased amount of cholesterol per LDL particle. These findings should be further examined in light of the widespread use of liquid diets in research to administer EtOH, especially for studies of fetal alcohol syndrome.

GLYCOSYLATION IS ALTERED BY ETHANOL IN RAT HIPPOCAMPAL CULTURED NEURONS

AIMS

Glycoproteins, such as adhesion molecules and growth factors, participate in the regulation of nervous system development. Ethanol affects the synthesis, intracellular transport, distribution, and secretion of N-glycoproteins in different cell types, including astrocytes and hepatocytes, suggesting alterations in the glycosylation process. We analysed the effect of exposure to low doses of ethanol (30 mm, 7 days) on glycosylation in cultured hippocampal neurons.

METHODS

Neurons were incubated for short (5 min) and long (90 min) periods with the radioactively labelled carbohydrate precursors 2-deoxy-glucose, N-acetyl-D-mannosamine and mannose. The uptake and metabolism of these precursors, as well as the radioactivity distribution in protein gels, were analysed. The levels of the glucose transporters GLUT1 and GLUT3 were also determined.

RESULTS

Ethanol exposure reduces the synthesis of proteins, DNA and RNA and decreased the uptake of mannose, but not of 2-deoxy-glucose and N-acetyl-D-mannosamine, and it increased the protein levels of both glucose transporters. Moreover, it altered the carbohydrate moiety of several proteins. Finally, alcohol treatment results in an increment of cell surface glycoconjugates containing terminal non-reduced mannose.

CONCLUSIONS

Alcohol-induced alterations in glycosylation of proteins in neurons could be a key mechanism involved in the teratogenic effects of alcohol exposure on brain development.