RESUMEN
Vitamin C is incorporated into the cerebrospinal fluid (CSF) through choroid plexus cells. While the transfer of vitamin C from the blood to the brain has been studied functionally, the vitamin C transporter, SVCT2, has not been detected in the basolateral membrane of choroid plexus cells. Furthermore, it is unknown how its expression is induced in the developing brain and modulated in scurvy conditions. We concluded that SVCT2 is intensely expressed in the second half of embryonic brain development and postnatal stages. In postnatal and adult brain, SVCT2 is highly expressed in all choroidal plexus epithelial cells, shown by colocalization with GLUT1 in the basolateral membranes and without MCT1 colocalization, which is expressed in the apical membrane. We confirmed that choroid plexus explant cells (in vitro) form a sealed epithelial structure, which polarized basolaterally, endogenous or overexpressed SVCT2. These results are reproduced in vivo by injecting hSVCT2wt-EYFP lentivirus into the CSF. Overexpressed SVCT2 incorporates AA (intraperitoneally injected) from the blood to the CSF. Finally, we observed in Guinea pig brain under scorbutic condition, that normal distribution of SVCT2 in choroid plexus may be regulated by peripheral concentrations of vitamin C. Additionally, we observed that SVCT2 polarization also depends on the metabolic stage of the choroid plexus cells.
Asunto(s)
Ácido Ascórbico/metabolismo , Encéfalo/metabolismo , Transportador de Glucosa de Tipo 1/sangre , Transportadores de Sodio Acoplados a la Vitamina C/sangre , Animales , Barrera Hematoencefálica/crecimiento & desarrollo , Barrera Hematoencefálica/metabolismo , Encéfalo/crecimiento & desarrollo , Membrana Celular/metabolismo , Células Cultivadas , Plexo Coroideo/metabolismo , Desarrollo Embrionario/genética , Células Epiteliales/metabolismo , Células Epiteliales/patología , Regulación del Desarrollo de la Expresión Génica/genética , Cobayas , Ratones , Transportadores de Ácidos Monocarboxílicos/genética , Neuronas/metabolismo , Transportadores de Sodio Acoplados a la Vitamina C/líquido cefalorraquídeo , Porcinos , Simportadores/genéticaRESUMEN
This study investigated the effect of early life stress on blood-brain barrier functional development in an altricial mammal, the Wistar rat. Forced swimming between gestational days 10-20 was used as a stress procedure in pregnant rats. After delivery, half of the control litters underwent 180 min maternal separation from postnatal day 2-20. Controls were kept without any stress manipulations. At sacrifice between postnatal days 1-30 subjects were given intracardiac Evans blue or the lectin wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP). Evans blue-stained brain slices were photographed and optical density quantified. WGA-HRP stained brains were processed for ultrastructural analysis. Plasma corticosterone at embryonic day 20 and postnatal days 1, 10, 20 and 30 was quantified by radioimmunoassay. At postnatal day 10, postnatal stress increased Evans blue entry to the neocortex, hippocampus, diencephalon, basal ganglia, olfactory bulb, brain stem, cerebellum, and spinal cord. At postnatal day 20, prenatal stress increased Evans blue concentration in the same regions as those affected after postnatal stress. Between postnatal days 10-20, both stress groups showed increased WGA-HRP caveolae-mediated transport in the hippocampal capillaries. By postnatal day 30, the blood-brain barrier was functionally mature in both control and stressed pups. Plasma corticosterone concentration was higher in pregnant stressed dams as compared to controls. Postnatal stress increased plasma corticosterone at postnatal days 10 and 20. The findings suggest that chronic perinatal stress alters blood-brain barrier functional development by increasing caveolae-mediated transport in brain endothelial cells.