Short-term hypoxia/reoxygenation activates the angiogenic pathway in rat caudate putamen.

In response to hypoxia, tissues have to implement numerous mechanisms to enhance oxygen delivery, including the activation of angiogenesis. This work investigates the angiogenic response of the hypoxic caudate putamen after several recovery times. Adult Wistar rats were submitted to acute hypoxia and analysed after 0 h, 24 h and 5 days of reoxygenation. Expression of hypoxia-inducible factor-1 alfa (HIF-1 alpha) and angiogenesis-related genes including vascular endothelial growth factor (VEGF), adrenomedullin (ADM) and transforming growth factor-beta 1 (TGF- beta 1) was determined by both RT-PCR and ELISA. For vessel labelling, lectin location and expression were analysed using histochemical and image processing techniques (fractal dimension). Expression of Hif-1 alpha, Vegf, Adm and Tgf- beta 1 mRNA rose immediately after hypoxia and this increase persisted in some cases after 5 days post-hypoxia. While VEGF and TGF-beta 1 protein levels increased parallel to mRNA expression, ADM remained unaltered. The quantification of the striatal vessel network showed a significant augmentation at 24 h of reoxygenation. These results reveal that not only short-term hypoxia, but also the subsequent reoxygenation period, up-regulate the angiogenic pathway in the rat caudate putamen as a neuroprotective mechanism to hypoxia that seeks to maintain a proper blood supply to the hypoxic tissue, thereby minimizing the adverse effects of oxygen deprivation.

Upregulation of cardiac NO/NOS system during short-term hypoxia and the subsequent reoxygenation period.

Hypoxia/reoxygenation (H/R) reportedly influences nitric oxide (NO) production and NO synthase (NOS) expression in the heart. Nonetheless, a number of works have shown controversial results regarding the changes that the cardiac NO/NOS system undergoes under such situations. Therefore, this study aims to clarify the behaviour of this system in the hypoxic heart by investigating seven different reoxygenation times. Wistar rats were submitted to H/R (hypoxia for 30 min; reoxygenation of 0, 2, 12, 24, 48, 72 h, and 5 days) in a novel approach to address the events provoked by assaults under such circumstances. Endothelial and inducible NOS (eNOS and iNOS) mRNA and protein expression, as well as enzymatic activity and enzyme location were determined. NO levels were indirectly quantified as nitrate/nitrite, and other S-nitroso compounds (NOx), which would act as NO-storage molecules. The results showed a significant increase in eNOS mRNA, protein and activity, as well as in NOx levels immediately after hypoxia, while iNOS protein and activity were induced throughout the reoxygenation period. These findings indicate that, not only short-term hypoxia, but also the subsequent reoxygenation period upregulate cardiac NO/NOS system until at least 5 days after the hypoxic stimulus, implying major involvement of this system in the changes occurring in the heart in response to H/R.

Is endothelial-nitric-oxide-synthase-derived nitric oxide involved in cardiac hypoxia/reoxygenation-related damage?

Nitric oxide (NO) has been reported to act both as a destructive and a protective agent in the pathogenesis of the injuries that occur during hypoxia/reoxygenation (H/R). It has been suggested that this dual role of NO depends directly on the isoform of NO synthase (NOS) involved. In this work, we investigate the role that NO derived from endothelial NOS (eNOS) plays in cardiac H/R-induced injury. Wistar rats were submitted to H/R (hypoxia for 30 min; reoxygenation of 0 h, 12 h and 5 days), with or without prior treatment using the selective eNOS inhibitor L-NIO (20 mg/kg). Lipid peroxidation, apoptosis and protein nitration, as well as NO production (NOx), were analysed. The results showed that L-NIO administration lowered NOx levels in all the experimental groups. However, no change was found in the lipid peroxidation level, the percentage of apoptotic cells or nitrated protein expression, implying that eNOS-derived NO may not be involved in the injuries occurring during H/R in the heart. We conclude that LNIO would not be useful in alleviating the adverse effects of cardiac H/R.

Age and sex-related serum changes in nitric oxide: correlations with serological markers.

Serum nitric oxide levels, systematically determined in 200 men and women from 18 to 65 year-old, undergo age and sex changes that strongly correlate with serological markers such as those related with cardiovascular functions and lipid profile.

Aging affects but does not eliminate the enzymatic antioxidative response to hypoxia/reoxygenation in cerebral cortex.

The effect of aging on basal and hypoxia/reoxygenation levels of both oxidative stress (protein carbonyl and TBARS) and antioxidative-enzyme activity (Cu/Zn-SOD; Mn-SOD; Catalase, CAT; Se-independent and Se-dependent glutathione peroxidase, GPX; glutathione transferase, GST and glutathione reductase, GR) has been studied in the cerebral cortex of adult and old rats. Oxidative stress markers increased with aging and show an age-dependent post-hypoxic response. Moreover, aging caused either no change (GST, GR and CAT) or an increase (Se-GPX, Cu/Zn-SOD, Mn-SOD) in the basal activity of the enzymes analysed. Only Se-independent GPX activity decreases. However, we detected an age-dependent response of SODs to the hypoxic injury. The early and sustained Cu/Zn-SOD activity rise in adult animals became late and weak in aged animals. Meanwhile, aging slowed the Mn-SOD post-hypoxic response although this activity was consistently higher in aged rats. Aging eliminated the post-hypoxic CAT response, but, perhaps offset by increased GPX activity, did not affect the GST response and slightly reduced post-hypoxic GR activity. In conclusion, aging rise basal ROS production, does not diminish or even increase the antioxidative-enzyme activity, and may slow but does not usually eliminate the enzymatic antioxidant response to the increased post-hypoxic ROS generation.

Constitutive nitric oxide synthases are responsible for the nitric oxide production in the ischemic aged cerebral cortex.

Aged brain shows reduced biological plasticity to meet emergency conditions such as ischemia, a process in which nitric oxide (NO) and apoptosis have been shown to play important roles. Using a model of transient global ischemia, we have analyzed the NO system and the p53, bax and bcl-2 response in the cerebral cortex of aged rats. Although immediately after ischemia the NO level is maintained, the reperfusion period increases NO concentrations together with the following: (i) greater bulk-protein nitration mainly due to a 50-kDa immunoreactive band; (ii) an increase in p53 protein; and (iii) an up-regulation of Bax together with a down-regulation of Bcl-2. These results match up with induced endothelial nitric oxide synthase expression immediately after ischemia and in neuronal nitric oxide synthase with the reperfusion. However, inducible nitric oxide synthase was not altered with ischemia/reperfusion. Altogether, these data suggest that NO production in cerebral cortex of aged ischemic animals is due to the constitutive NO synthase isoforms. This response is accompanied by the increased expression of pro-apoptotic proteins.

Upregulation of endothelial nitric oxide synthase maintains nitric oxide production in the cerebellum of thioacetamide cirrhotic rats.

This study examines the expression and cellular distribution pattern of nitric oxide synthase (NOS) isoforms, nitrotyrosine-derived complexes, and the nitric oxide (NO) production in the cerebellum of rats with cirrhosis induced by thioacetamide (TAA). The results showed local changes in the tissue distribution pattern of the NOS isoforms and nitrated proteins in the cerebellum of these animals. Particularly, eNOS immunoreactivity in perivascular glial cells of the white matter was detected only in TAA-treated animals. In addition, although neither neuronal NOS (nNOS) nor inducible NOS (iNOS) cerebellar protein levels appeared to be affected, the endothelial NOS (eNOS) isoform significantly increased its expression, and NO production slightly augmented in TAA-treated rats. These NOS/NO changes may contribute differently to the evolution of the hepatic disease either by maintaining the guanosine monophosphate-NO signal transduction pathways and the physiological cerebellar functions or by inducing oxidative stress and cell damage. This model gives rise to the hypothesis that the upregulation of the eNOS maintains the physiological production of NO, while the iNOS is silenced and the nNOS remains unchanged. The differential NOS-distribution and expression pattern may be one of the mechanisms involved to balance cerebellar NO production in order to minimize TAA toxic injury. These data help elucidate the role of the NOS/NO system in the development and progress of hepatic encephalopathy associated with TAA cirrhosis.

Immunohistochemical localisation of neuronal nitric oxide synthase in the rainbow trout kidney.

The distribution of nitrergic nervous structures in the trout kidney was studied by peroxidase-linked ABC immunostaining procedures using a polyclonal antibody raised against the neuronal isoform of nitric oxide synthase. The nitrergic plexus reaches the kidney along the vasculature, mainly running with the postcardinal vein where nitrergic fibres, microganglia like cellular clusters and isolated neurones were detected. The atubular head-kidney only showed isolated nitrergic fibres close to the larger arteries. On the other hand, the collecting tubules, collecting ducts, large arteries and glomerular arterioles of the tubular middle and posterior trunks were innervated by nitrergic fibres even though immunoreactive neurones were also observed in close apposition to some tubular elements and large arteries. These results suggest that, according to morphofunctional differences between the fish and mammalian kidneys, nitrergic neural structures may be involved in the control of particular renal functions in the rainbow trout.

Neuronal nitric oxide synthase immunoreactivity in the guinea-pig liver: distribution and colocalization with neuropeptide Y and calcitonin gene-related peptide.

AIMS/BACKGROUND: The innervation pattern of the guinea-pig liver is similar to that of the human liver. However, many aspects of the distribution of the neuronal isoform of the enzyme nitric oxide synthase (nNOS) in the guinea-pig liver and its colocalization with neuropeptides remain to be elucidated. METHODS: The distribution of nNOS was studied in fixed guinea-pig liver by light microscopic immunohistochemistry. Confocal analysis was used to determine its colocalization with neuropeptide Y (NPY) or calcitonin gene-related peptide (CGRP). RESULTS: nNOS-immunoreactive (nNOS-IR) nerves were observed in relation to hilar and interlobar vessels and in Glisson's capsule. A few nNOS-IR ganglia were observed in the extrahepatic bile duct and close to the interlobar portal triads. In addition, nNOS-IR fibers were located in the interlobular portal triads and pervading the parenchyma. Moreover, nNOS-IR nerves were demonstrated for the first time in the larger central veins and in the hepatic vein. nNOS-NPY and nNOS-CGRP colocalizations were detected in the fibromuscular layer of the bile duct and periductal plexus, respectively. CONCLUSIONS: These results support the phylogenetic conservation of the nNOS-IR hepatic innervation and its possible contribution to the regulation of hepatic blood flow and certain hepatic functions.

[Aging and neurodegeneration: molecular and cellular bases]. / Envejecimiento y neurodegeneración: bases moleculares y celulares.

OBJECTIVE: A review about the possible cellular and molecular mechanisms of aging and related neurodegenerative diseases. DEVELOPMENT: The mechanisms involved in neuronal decrease, connectivity losses and glial reactivity, detected both in neurodegenerative (Alzheimer's disease) and physiological aging, are analyzed from the morphological and histological point of view to provide the morphofunctional base of the cognitive and intellectual alterations characterizing the senescence process. Taken together, these data are correlated to the possible genetical aspects implied in this process, reviewing the most relevant results on senescence and cellular death obtained from yeast, fruit fly and nematodes; besides this, a brief review of the molecular biology of gerontogenes was carried out, and the possible mechanisms inducing aging and neurodegenerative processes are analyzed according to the state-of-the-art related theories. Finally, cellular, biochemical and genetical data are correlated in the signal transduction way implied in the increase of the intracellular calcium level as the starting point of cell death. CONCLUSIONS: The main process implied in the neuronal cell death responsible for aging and the related neurodegenerative diseases are started by different agents such as the lacking of neurotrophic factors, hypoxia, hypoglycemia, excitotoxicity, and oxygen and nitrogen free radicals.

Effect of thioacetamide and dexamethasone on serum lipids in rats fed on high-fat sunflower or olive oil diets.

We have previously reported that high-fat diets develop hepatic steatosis and, depending on the fat quality, affect serum lipid levels differently (J Nutr Sci Vitaminol, 1997, 43, 155-160). The aim of this work is to study the influence of high-fat diets (14% sunflower or olive oils) on serum lipids in a model of hepatic acute damage induced by thioacetamide, and their influence when dexamethasone is administered before thioacetamide injection. Serum lipids and hepatic collagen have been evaluated using biochemical methods, and the steatotic process by histological staining. The results showed that hepatic steatosis and fibrosis are developed either by high-fat diets or thioacetamide injection. Pretreatment with dexamethasone did not decrease the hepatic collagen content. Thioacetamide injection alone or pretreatment with dexamethasone produced increase in serum tryglicerides (TG), total cholesterol (TC) and LDL-C in both high-fat diet groups, and a HDL-C increase in the olive-oil group, even though the atherogenic indices (HDL/TC and HDL/TG) were different depending on the enriched diet. The administration of high-fat diets to study the influence of the fat quality on health and disease should be interpreted carefully due to the ability of the diets themselves to cause hepatic damage.

The innervation of rainbow trout (Oncorhynchus mykiss) liver: protein gene product 9.5 and neuronal nitric oxide synthase immunoreactivities.

We have explored the innervation of the rainbow trout (O. mykiss) liver using immunohistochemical procedures and light microscopy to detect in situ protein gene product 9.5 and neuronal nitric oxide synthase immunoreactivities (PGP-IR and NOS-IR). The results showed PGP-IR nerve fibres running with the extralobular biliary duct (EBD), hepatic artery (EHA) and portal vein (EPV) that form the hepatic hilum, as well as following the spatial distribution of the intrahepatic blood vessel and biliary channels. These nerve fibres appear as single varicose processes, thin bundles, or thick bundles depending on their diameter and location in the wall of the blood vessel or biliary duct. No PGP-IR fibres were detected in the liver parenchyma. NOS-IR nerve fibres were located only in the vessels and ducts that form the hepatic hilum (EBD, EHA, EPV); in addition, NOS-IR nerve cell bodies were found isolated or forming ganglionated plexuses in the peribiliary fibromuscular tissue of the EBD. No PGP-IR ganglionated plexuses were detected in the EBD. The location of the general (PGP-IR) and nitrergic (nNOS-IR) intrinsic nerves of the trout liver suggest a conserved evolutionary role of the nervous control of hepatic blood flow and hepatobiliary activity.

Quantitative and ultrastructural changes in glia and pericytes in the parietal cortex of the aging rat.

The frequency of astrocytes, microglia plus oligodendrocytes, and pericytes displaying nuclei was analyzed and quantified in 160-microm-wide strips of the parietal cortex (Par1 region) from young and aged Wistar rats. The study was performed on two groups of rats aged 3-4 and 32-36 months. Quantifications of the glial cell types and pericytes were made in 1-microm-thick sections stained with toluidine blue. Ultrathin sections were also made to analyze the ultrastructural features of these cells during aging. Astrocytes and pericytes increased in number by about 20% and 22%, respectively, with age. These increases were most significant in layers II-IV and V for both cellular types. Clusters of astrocytes were common in these layers of aging rats. The ultrastructural analysis also indicated changes in all cell types that stored inclusions and vacuoles with age, which were particularly abundant in microglial cells. End-feet astrocytes and pericytes surrounding the vascular wall also contained vacuoles and inclusions, and consequently the vascular wall increased in thickness. In conclusion, the aging process increased astrocyte and pericyte populations, but not microglia plus oligodendrocyte populations, in the rat parietal cortex. Although no significant change in nuclear size could be observed in any cell type, all glial cells as well as pericytes underwent morphological ultrastructural changes. These modifications may result from the need to correct possible homeostatic imbalances during aging.

Nitrergic innervation of the cat liver.

The aim of this work was to study the nitrergic innervation in the liver of the cat using immunocytochemical procedures. At the hepatic hilus, a rich plexus of neuronal nitric oxide synthase immunoreactive (nNOS-IR) nerve fibers and ganglia was detected around the interlobular branch of the bile duct. nNOS-IR nerve fibers were observed running with the components of the intralobular portal triads located close to the hepatic hilus, as well as with a few vessels and ducts of the deeper parenchyma. These latter fibers, beside others located in Glisson's capsule, occasionally showed short ramifications entering the parenchyma itself. The present results suggest that, in the cat liver, nNOS is involved in the autonomic control of hepatic blood flow, with a limited role in the regulation of hepatobiliary excretory activity and hepatocellular metabolic function.

Light microscopic quantification of morphological changes during aging in neurons and glia of the rat parietal cortex.

BACKGROUND: Different changes in neuronal and glial population of the aging brain have been described; however, the degree and extent of these changes are controversial. This study evaluates the quantitative and cytomorphometric effects of aging on neuronal and glial populations in the parietal cortex of the rat. METHODS: The study was performed in two groups of rats aged 4-6 and 30-32 months. Cortical volume, neuronal density, glial density, and neuronal area, and shapes of the soma and nucleus were analyzed in cortical layers I, II-IV, V, and VI using serial sections stained with cresyl-fast-violet, and quantitative morphometric techniques. RESULTS: No changes with age were found in volume of the cortex or neuronal density. Glial density increased significantly (mean for all layers 17%) in older rats. Layers II-IV, V, and VI showed an age-related decrease in the area of the neuronal soma. Neuronal shape, as revealed by the major/minor diameter ratio, also showed a decrease in old rats but only in layer II-IV. Nuclear area decreased with age only in layer VI. CONCLUSIONS: The stability of neuronal density together with the increased number of glial cells and the changes in neuronal soma size suggest that aged-related cognitive impairment could be a consequence of neuronal dysfunction rather than actual neuronal losses.

High-fat sunflower and olive oil diets affect serum lipid levels in steatotic rat liver differently.

This work describes the long-term effects of two different diets, one rich in olive oil and the other in sunflower oil, on serum lipid and lipoprotein levels after the establishment of fatty liver in rats 8 and 15 months old. The serum lipid and lipoprotein levels as well as the steatotic process have been evaluated by biochemical and histological methods, respectively. The results showed that fatty liver was well developed with both long-term high-fat diets, and hepatocytes were filled with many lipid droplets. This process was more evident in the portal zones, where fat hepatocytes were more numerous. Serum total cholesterol (TC) and HDL-C levels were highest in the sunflower oil fed rats, whereas the TG and LDL-C levels were highest in the olive oil group. Finally, the atherogenic indexes (HDL/TC, HDL/LDL, HDL/(TC-HDL)) were higher in the sunflower oil diet group than in the olive oil group.