Impact of geographical region on urinary metabolomic and plasma fatty acid profiles in subjects with the metabolic syndrome across Europe: the LIPGENE study.

The application of metabolomics in multi-centre studies is increasing. The aim of the present study was to assess the effects of geographical location on the metabolic profiles of individuals with the metabolic syndrome. Blood and urine samples were collected from 219 adults from seven European centres participating in the LIPGENE project (Diet, genomics and the metabolic syndrome: an integrated nutrition, agro-food, social and economic analysis). Nutrient intakes, BMI, waist:hip ratio, blood pressure, and plasma glucose, insulin and blood lipid levels were assessed. Plasma fatty acid levels and urine were assessed using a metabolomic technique. The separation of three European geographical groups (NW, northwest; NE, northeast; SW, southwest) was identified using partial least-squares discriminant analysis models for urine (R² X: 0·33, Q²: 0·39) and plasma fatty acid (R² X: 0·32, Q²: 0·60) data. The NW group was characterised by higher levels of urinary hippurate and N-methylnicotinate. The NE group was characterised by higher levels of urinary creatine and citrate and plasma EPA (20 : 5 n-3). The SW group was characterised by higher levels of urinary trimethylamine oxide and lower levels of plasma EPA. The indicators of metabolic health appeared to be consistent across the groups. The SW group had higher intakes of total fat and MUFA compared with both the NW and NE groups (P≤ 0·001). The NE group had higher intakes of fibre and n-3 and n-6 fatty acids compared with both the NW and SW groups (all P< 0·001). It is likely that differences in dietary intakes contributed to the separation of the three groups. Evaluation of geographical factors including diet should be considered in the interpretation of metabolomic data from multi-centre studies.

Alterations in hepatic one-carbon metabolism and related pathways following a high-fat dietary intervention.

Obesity frequently leads to insulin resistance and the development of hepatic steatosis. To characterize the molecular changes that promote hepatic steatosis, transcriptomics, proteomics, and metabolomics technologies were applied to liver samples from C57BL/6J mice obtained from two independent intervention trials. After 12 wk of high-fat feeding the animals became obese, hyperglycemic, and insulin resistant, had elevated levels of blood cholesterol and VLDL, and developed hepatic steatosis. Nutrigenomic analysis revealed alterations of key metabolites and enzyme transcript levels of hepatic one-carbon metabolism and related pathways. The hepatic oxidative capacity and the lipid milieu were significantly altered, which may play a key role in the development of insulin resistance. Additionally, high choline levels were observed after the high-fat diet. Previous studies have linked choline levels with insulin resistance and hepatic steatosis in conjunction with changes of certain metabolites and enzyme levels of one-carbon metabolism. The present results suggest that the coupling of high levels of choline and low levels of methionine plays an important role in the development of insulin resistance and liver steatosis. In conclusion, the complexities of the alterations induced by high-fat feeding are multifactorial, indicating that the interplay between several metabolic pathways is responsible for the pathological consequences.

Analyzing the effects of psychotropic drugs on metabolite profiles in rat brain using 1H NMR spectroscopy.

The mechanism of action of standard drug treatments for psychiatric disorders remains fundamentally unknown, despite intensive investigation in academia and the pharmaceutical industry. So far, little is known about the effects of psychotropic medications on brain metabolism in either humans or animals. In this study, we investigated the effects of a range of psychotropic drugs on rat brain metabolites. The drugs investigated were haloperidol, clozapine, olanzapine, risperidone, aripiprazole (antipsychotics); valproate, carbamazapine (mood stabilizers) and phenytoin (antiepileptic drug). The relative concentrations of endogenous metabolites were determined using high-resolution proton nuclear magnetic resonance (1H NMR) spectroscopy. The results revealed that different classes of psychotropic drugs modulated a range of metabolites, where each drug induced a distinct neurometabolic profile. Some common responses across several drugs or within a class of drug were also observed. Antipsychotic drugs and mood stabilizers, with the exception of olanzapine, consistently increased N-acetylaspartate (NAA) levels in at least one brain area, suggesting a common therapeutic response on increased neuronal viability. Most drugs also altered the levels of several metabolites associated with glucose metabolism, neurotransmission (including glutamate and aspartate) and inositols. The heterogenic pharmacological response reflects the functional and physiological diversity of the therapeutic interventions, including side effects. Further study of these metabolites in preclinical models should facilitate the development of novel drug treatments for psychiatric disorders with improved efficacy and side effect profiles.

Metabolic characterization of the R6/2 transgenic mouse model of Huntington's disease by high-resolution MAS 1H NMR spectroscopy.

The metabolic consequences of Huntington's disease in the R6/2 mouse model were investigated using NMR spectroscopy and pattern recognition to characterize selected brain regions, muscle, blood, and urine. Global increases in relative brain concentrations of osmolytes, creatine, glutamine, and lactate, and decreases in acetate and N-acetylaspartate were found together with striatal-specific lower concentrations of GABA and choline. Clear differentiation of R6/2 and wild-type mice was also obtained for urine and blood metabolite profiles that may have applicability for monitoring HD in human populations.

Identification of 11 pseudogenes in the DNA methyltransferase gene family in rodents and humans and implications for the functional loci.

DNA (cytosine-5-)-methyltransferase genes are important for normal development in mice and humans. We describe here 11 pseudogenes spread among human, mouse, and rat belonging to this gene family, ranging from 1 pseudogene in humans to 7 in rat, all belonging to the Dnmt3 subfamily. All except 1 rat Dnmt3b pseudogene appear to be transcriptionally silent. Dnmt3a2, a transcript variant of Dnmt3a starting at an alternative promoter, had the highest number of processed pseudogenes, while none were found for the canonical Dnmt3a, suggesting the former transcript is more highly expressed in germ cells. Comparison of human, mouse, and rat Dnmt3a2 sequences also suggests that human exon 8 is a recent acquisition. Alignment of the 3'UTR of Dnmt3a2 among the functional genes and the processed pseudogenes suggested that a second polyadenylation site downstream of the RefSeq poly(A) was being used in mice, resulting in a longer 3'UTR, a finding confirmed by RT-PCR in mouse tissues. We also found conserved cytoplasmic polyadenylation elements, usually implicated in regulating translation in oocytes, in Dnmt3b and Dnmt1. Expression of DNMT3B in the mouse oocyte was confirmed by immunocytochemistry. These results clarify the structure of a number of loci in the three species examined and provide some useful insights into the structure and evolution of this gene family.