Hypobaric hypoxia and reoxygenation induce proteomic profile changes in the rat brain cortex.

Brain, due to its high metabolism, is severely affected by hypoxia/reoxygenation. In this study, cerebral cortexes from rats subjected to hypobaric hypoxia followed by several reoxygenation periods (0 h, 24 h, and 5 days) were compared with normobaric normoxic controls to identify protein-expression differences using proteomic approaches. Only 2-fold differences in spot abundance between controls and experimental groups from each reoxygenation period were considered. The proteins identified were grouped into categories, according to their similarity in function or to their involvement in the same metabolic pathway. We distinguished five groups: (1) glycolysis, including γ-enolase (NSE), and glyceraldehyde 3-phosphate dehydrogenase (GAPDH); (2) tricarboxylic acid cycle, such as aconitate hydratase (ACO2); (3) oxidative phosphorylation, like F1-ATPase chains α and ß; (4) cytoskeletal, including Spna2, α-tubulin, ß-tubulin, ß-actin, and microtubule-associated protein RP/EB family member 3 (EB3); and (5) chaperones, like heat-shock protein 72 kDa (HSP72). NSE was upregulated while GAPDH was downregulated, both peaking at 5 days post-hypoxia. ACO2 and F1-ATPase decreased in all the reoxygenation periods. Spna2 and EB3 were expressed neither in control nor at 0 h, but 5 days post-hypoxia new expression took place. The α- and ß-tubulin levels significantly fell at 0 h, but after 24 h strongly increased. Also, ß-actin and HSP72 were downregulated, and the last one reached the lowest level at 24 h of reoxygenation. We conclude that the molecular mechanisms underlying hypoxia/reoxygenation in the rat cortex might consist of a close relationship between energy metabolism, cytoskeleton, and chaperones. These findings may shed light on therapeutic targets against hypoxia-related damage.

Glutathione S-transferase isoenzymatic response to aging in rat cerebral cortex and cerebellum.

Aging is associated with increased oxidant generation. One mechanism involved in the defense of oxidative products is the family of glutathione transferases (GST). We have analyzed the activity, distribution and expression of GSTP1 and GSTA4 isoenzymes in the cerebral cortex and cerebellum of young, adult and aged rats. The total GST activity, measured with the universal substrate 1-chloro-2,4-dinitrobenzene (CDNB), increased only with the maturation process; however GSTA4 activity, using the specific substrate 4-hydroxynonenal (HNE), did show an age-dependent increase in both brain regions. Cellular location of GSTA4 in astrocytes was not changed except for young cerebral cortex and adult/aged cerebellum that also showed immunoreactivity in layer III pyramidal neurons and Bergman radial glia, respectively. Distribution of GSTP1 was similar among groups and only an increased number of positive oligodendrocytes was found in the Purkinje and granular layer of adult/aged cerebellum. The GSTA4 and GSTP1 expression increased from young to adult/aged brain and GSTA4 even augmented in the aged cerebral cortex. These results suggest a GST isoenzymatic response with aging, but above all with the maturation process.

Histochemical and ultrastructural study of the chicken salivary palatine glands.

Salivary glands are a good model to investigate the relationship between cell secretion and glandular structure. Most studies of this organ deal with mammals, but we are interested in a morphofunctional characterization of these glands in poultry in relation with particular feeding habits. For this purpose, conventional and lectin histochemical methods as well as ultrastructural methods have been applied to the chicken lateral and medial palatine salivary glands. It was found that periodic acid-Schiff (PAS)-positive, alcianophilic, and metachromatic or orthochromatic cells were present with a more homogeneous distribution pattern in lateral glands than in medial palatine glands. Lectin staining depended on the lectin type that was applied, but also on the glandular part both in lateral and medial glands. Ultrastructural studies showed cytoplasmic membranous structures with a scattered granular or filamentous content depending on the secretory cell. In conclusion, morphofunctional characteristics of salivary glands of chicken suggest that their products are involved in lubrication and humidification of food ingested, and probably in protection of the oral surface, as has been previously described for other animals showing similar histochemical staining patterns.