RESUMEN
BACKGROUND: Intrauterine growth restriction (IUGR) is a major risk factor for both perinatal and long-term morbidity. Bovine lactoferrin (bLf) is a major milk glycoprotein considered as a pleiotropic functional nutrient. The impact of maternal supplementation with bLf on IUGR-induced sequelae, including inadequate growth and altered cerebral development, remains unknown. METHODS: IUGR was induced through maternal dexamethasone infusion (100 µg/kg during last gestational week) in rats. Maternal supplementation with bLf (0.85% in food pellet) was provided during both gestation and lactation. Pup growth was monitored, and Pup brain metabolism and gene expression were studied using in vivo (1)H NMR spectroscopy, quantitative PCR, and microarray in the hippocampus at postnatal day (PND)7. RESULTS: Maternal bLf supplementation did not change gestational weight but increased the birth body weight of control pups (4%) with no effect on the IUGR pups. Maternal bLf supplementation allowed IUGR pups to recover a normalized weight at PND21 (weaning) improving catch-up growth. Significantly altered levels of brain metabolites (γ-aminobutyric acid, glutamate, N-acetylaspartate, and N-acetylaspartylglutamate) and transcripts (brain-derived neurotrophic factor (BDNF), divalent metal transporter 1 (DMT-1), and glutamate receptors) in IUGR pups were normalized with maternal bLf supplementation. CONCLUSION: Our data suggest that maternal bLf supplementation is a beneficial nutritional intervention able to revert some of the IUGR-induced sequelae, including brain hippocampal changes.
Asunto(s)
Encéfalo/efectos de los fármacos , Suplementos Dietéticos , Crecimiento/efectos de los fármacos , Lactoferrina/administración & dosificación , Animales , Peso Corporal/efectos de los fármacos , Encéfalo/metabolismo , Dexametasona/administración & dosificación , Femenino , Retardo del Crecimiento Fetal/metabolismo , Retardo del Crecimiento Fetal/prevención & control , Expresión Génica/efectos de los fármacos , Lactancia , Lactoferrina/farmacología , Reacción en Cadena de la Polimerasa , Embarazo , Ratas , Aumento de Peso/efectos de los fármacosRESUMEN
The water diffusion characteristics of wild-type mouse brains have been studied in vivo by DTI to follow developmental changes. Here, axial (lambda(//)) and radial (lambda(perpendicular)) diffusivities and fractional anisotropy were measured from the fifth day of life (P5) and at three other post-natal ages (P12, P19 and P54). Magnetic resonance images were collected from a single sagittal slice in the middle of the two hemispheres; ROI were chosen in nine different structures of both grey and white matter. Fractional anisotropy (FA) from P5 onwards distinguished structures of both white and grey matter, even though myelination had yet to occur. Between P5 and P54, a significant increase in FA was observed in the genu of the corpus callosum due to a significant decrease in lambda(perpendicular) whereas lambda(//) remained stable. Many other significant variations of lambda(//) and lambda(perpendicular) were measured in different structures. They were substantially correlated with axon and myelin maturation which are responsible for the main evolutions of the brain during its post-natal development. These quantitative data show that in vivo characterization of the anatomy and microstructure of the normal mouse brain during development is possible. The normative data will greatly improve the characterization of abnormal development in the transgenic mouse brain.
Asunto(s)
Envejecimiento/fisiología , Química Encefálica , Encéfalo/fisiología , Imagen de Difusión por Resonancia Magnética/métodos , Espectroscopía de Resonancia Magnética/métodos , Animales , Ratones , Ratones Endogámicos C57BLRESUMEN
NMR provides a non-invasive tool for the phenotypic characterisation of mouse models. The aim of the present study was to apply reliable in vivo MRS techniques for non-invasive investigations of brain development in normal and transgenic mice, by monitoring metabolite concentrations in different brain regions. The conditions of anaesthesia, immobilisation and respiratory monitoring were optimized to carry out in vivo MRS studies in young mice. All the experiments were performed in normal mice, at 9.4 T, applying a point-resolved spectroscopy (PRESS) sequence (TR = 2,000 ms; TE = 130 ms). We obtained reproducible in vivo (1)H NMR spectra of wild-type mouse brains as early as post-natal day 5, which allowed us to follow brain maturation variations from post-natal days 5 to 21. The survival rate of animals was between 66 and 90% at post-natal days 5 and 21, respectively. Developmental changes of metabolite concentrations were measured in three brain regions: the thalamus, a region rich in cell bodies, the olfactory bulb, rich in fibre tracts actively myelinated during brain maturation, and the cerebellum. The voxel size varied from 2 to 8 microL according to the size of the brain structure analysed. The absolute concentrations of the total creatine, taurine, total choline, N-acetylaspartate and of the glutamate/glutamine pool were determined from (1)H NMR spectra obtained in the different brain regions at post-natal day 5, 10, 15 and 21. Variations observed during brain development were in accordance with those previously reported in mice using ex vivo MRS studies, and also in rats and humans in vivo. Possibilities of longitudinal MRS analysis in maturing mice brains provide new perspectives to characterise better the tremendous number of transgenic mutant mice generated with the aim of decrypting the complexity of brain development and neurodegenerative diseases but also to follow the impact of environmental and therapeutic factors.
Asunto(s)
Envejecimiento/metabolismo , Cerebelo/fisiología , Espectroscopía de Resonancia Magnética/métodos , Proteínas del Tejido Nervioso/metabolismo , Neurotransmisores/metabolismo , Bulbo Olfatorio/fisiología , Tálamo/fisiología , Animales , Animales Recién Nacidos , Protones , Distribución TisularRESUMEN
Transferrin (Tf), the iron transport glycoprotein found in biological fluids of vertebrates, is synthesized mainly by hepatocytes. Tf is also synthesized by oligodendrocytes (Ol), and several lines of evidence indicate that brain Tf could be involved in myelinogenesis. Because Tf is postnatally expressed in the brain, we sought to investigate whether Tf could intervene in Ol differentiation. For this purpose, we analyzed transgenic mice overexpressing the complete human Tf gene in Ol. We show that the hTf transgene was expressed only from 5 days postpartum onward. In the brain of 14-day-old transgenic mice, the DM-20 mRNA level was decreased, whereas the PLP, MBP, CNP, and MAG mRNA levels were increased. We counted a higher proportion of Ol expressing the O4 (Ol-specific antigens) and PLP in brain cells cultured from transgenic mice. These results support the idea that overexpressing Tf in the brain accelerates the oligodendrocyte lineage maturation. Accordingly, by NMR imaging acquisition of diffusion tensor in hTf transgenic mice, we observed early maturation of the cerebellum and spinal cord and more myelination in the corpus callosum. In addition, hTf overexpression led to an increase in Sox10 mRNA and protein. Increases in Sox10 and in Tf expression occur simultaneously during brain development. The Olig1 mRNA level also increased, but long after the rise of hTf and Sox10. The Olig2 mRNA level remained unchanged in the brain of transgenic mice. Our findings suggest that Tf could influence oligodendrocyte progenitor differentiation in the CNS.
Asunto(s)
Diferenciación Celular/genética , Regulación del Desarrollo de la Expresión Génica/genética , Ratones Transgénicos/fisiología , Oligodendroglía/citología , Transferrina/genética , 2',3'-Nucleótido Cíclico Fosfodiesterasas/genética , 2',3'-Nucleótido Cíclico Fosfodiesterasas/metabolismo , Factores de Edad , Análisis de Varianza , Animales , Animales Recién Nacidos , Northern Blotting/métodos , Western Blotting/métodos , Peso Corporal/genética , Encéfalo/citología , Recuento de Células/métodos , Células Cultivadas , Ensayo de Inmunoadsorción Enzimática/métodos , Humanos , Inmunohistoquímica/métodos , Imagen por Resonancia Magnética/métodos , Ratones , Ratones Endogámicos C57BL , Proteína Básica de Mielina/genética , Proteína Básica de Mielina/metabolismo , Proteína Proteolipídica de la Mielina/genética , Proteína Proteolipídica de la Mielina/metabolismo , Glicoproteína Asociada a Mielina , Proteínas del Tejido Nervioso/genética , Proteínas del Tejido Nervioso/metabolismo , Oligodendroglía/fisiología , ARN Mensajero/aislamiento & purificación , Radioinmunoensayo/métodos , Receptores de Superficie Celular/genética , Receptores de Superficie Celular/metabolismo , Transferrina/metabolismoRESUMEN
High concentrations of certain amino acids are known to affect hormonal secretion, immune function, electrolyte balance or metabolic functions. However, there is a lack of knowledge regarding the molecular mechanisms responsible for these effects. We showed that, as well as spermidine transport, the activity of ornithine decarboxylase (ODC), the first and rate-limiting enzyme in polyamine biosynthesis, is decreased in human colon adenocarcinoma cells, Caco-2, following a 4-h supplementation with one of the two polyamine precursor amino acids, L-arginine or L-methionine. Dose-response assays indicated that the inhibitory effect of supplemental L-methionine was stronger than that of supplemental L-arginine. However, it was transient, being even replaced by ODC induction after 8 h, whereas the inhibitory effect of L-arginine lasted for at least 8 h. Unlike L-cysteine, neither L-methionine nor L-arginine could inhibit ODC activity in a crude acellular preparation of the enzyme. The inhibition of ODC activity in cells exposed to L-methionine or L-arginine was due to a decreased abundance of ODC protein without change at the mRNA level and each of these amino acids could counteract ODC induction by a glycine supplement. Contrary to the latter, supplemental L-methionine or L-arginine induced a marked decrease in ODC half-life, concomitantly with an increase in the activity of antizyme, an ODC inhibitory protein. Thus, depending on their nature, amino acids can up- or downregulate ODC activity at the protein stability level.