Effect of putrescine on oxyntic gland and colonic mucosal growth in rats

The effect of putrescine on oxyntic gland and colonic mucosal growth was studied by measuring the rate of [3H]-thymidine incorporation into mucosal DNA in vitro (DNA synthesis) and DNA, RNA and protein content of the mucosa following intramuscular injections of the compound (50 mumoles/100g). Saline injected animals served as controls. Multiple injections of putrescine during a 2-day fast produced a significant enhancement of mucosal DNA synthesis in oxyntic gland and colonic mucosa, with no apparent change in DNA, RNA or protein content in either of the tissues, compared to the corresponding saline-controls, when measurements were made 12-24 h after the last injection. However, when the animals were killed after 4 days, DNA, RNA and protein content of oxyntic gland mucosa, and DNA and protein content of colonic mucosa were found to be significantly higher than in the respective saline-controls. We conclude that putrescine, taken up from the blood, can stimulate growth of gastrointestinal mucosa.     

Role of exercise intensities in oxidized low-density lipoprotein-mediated redox status of monocyte in men.

Exercise significantly influences the progression of atherosclerosis. Oxidized LDL (ox-LDL), as a stimulator of oxidative stress, facilitates monocyte-related atherogenesis. This study investigates how exercise intensity impacts ox-LDL-mediated redox status of monocytes. Twenty-five sedentary healthy men exercised mildly, moderately, and heavily (i.e., 40, 60, and 80% maximal oxygen consumption, respectively) on a bicycle ergometer. Reactive oxygen species (ROS) production, cytosolic and mitochondrial superoxide dismutase (c-SOD and m-SOD, respectively) activities, and total and reduced-form gamma-glutamylcysteinyl glycine (t-GSH and r-GSH, respectively) contents in monocytes mediated by ox-LDL were measured. This experiment obtained the following findings: 1) ox-LDL increased monocyte ROS production and was accompanied by decreased c-SOD and m-SOD activities, as well as t-GSH and r-GSH contents, whereas treating monocytes with diphenyleneiodonium (DPI) (a NADPH oxidase inhibitor) or rotenone/2-thenoyltrifluoroacetone (TTFA) (mitochondrial complex I/II inhibitors) hindered ox-LDL-induced monocyte ROS production; 2) production of ROS and reduction of m-SOD activity and r-GSH content in monocyte by ox-LDL were enhanced by heavy exercise and depressed by mild and moderate exercise; and 3) heavy exercise augmented the inhibition of ox-LDL-induced monocyte ROS production by DPI and rotenone/TTFA, whereas these DPI- and rotenone/TTFA-mediated monocyte ROS productions were unchanged in response to mild and moderate exercise. We conclude that heavy exercise increases ox-LDL-induced monocyte ROS production, possibly by decreasing m-SOD activity and r-GSH content in monocytes. However, mild and moderate exercise likely protects individuals against suppression of anti-oxidative capacity of monocyte by ox-LDL.     

Impact of umbelliferone on erythrocyte redox status in STZ-diabetic rats

Oxidative stress is currently hypothesized to be a mechanism underlying diabetes. The present study was designed to evaluate the effect of umbelliferone (UMB), a derivative of coumarin, on erythrocyte lipid peroxidation, antioxidants, and lipid profile in normal and streptozotocin (STZ) diabetic rats. Diabetes was induced in adult male albino rats of Wistar strain, weighing 180 to 200 g, by the administration of STZ (40 mg/kg/b-wt) intraperitonially. The normal and diabetic rats were treated with UMB in 10 percent dimethyl sulfoxide (DMSO) dissolved in water for 45 days. The diabetic rats had elevated levels of blood glucose and lipid peroxidation markers such as thiobarbituric acid reactive substances (TBARS), conjugated dienes (CD), and lipid hydroperoxide (HP) and decreased levels of nonenzymatic antioxidants (Vitamin C and reduced glutathione [GSH]), elevated levels of vitamin E, and elevated levels of enzymatic antioxidants (superoxide dismutase [SOD], catalase [CAT], glutathione peroxidase [GPx]), elevated glucose-6-phosphate dehydrogenase activity, and altered lipid profile (cholesterol and phospholipids) in erythrocytes. These changes were reversed by treatment with UMB. Thus, our results indicate that the administration of UMB shows promising potential for the restoration of normal blood glucose levels, erythrocyte lipid peroxidation, antioxidants, and lipid profile in STZ-diabetic.     

Reduced circulating oxidized LDL is associated with hypocholesterolemia and enhanced thiol status in Gilbert syndrome

A protective association between bilirubin and atherosclerosis/ischemic heart disease clearly exists in vivo. However, the relationship between bilirubin and in vivo oxidative stress parameters in a clinical population remains poorly described. The aim of this study was to assess whether persons expressing Gilbert syndrome (GS; i.e., unconjugated hyperbilirubinemia) are protected from thiol oxidation and to determine if this, in addition to their improved lipoprotein profile, could explain reduced oxidized low-density lipoprotein (oxLDL) status in them. Forty-four matched GS and control subjects were recruited and blood was prepared for the analysis of lipid profile and multiple plasma antioxidants and measures of oxidative stress. GS subjects possessed elevated plasma reduced thiol (8.03±1.09 versus 6.75±1.39 nmol/mg protein; P<0.01) and glutathione concentrations (12.7±2.39 versus 9.44±2.45 μM; P<0.001). Oxidative stress status (reduced:oxidized glutathione; GSH:GSSG) was significantly improved in GS (0.49±0.16 versus 0.32±0.12; P<0.001). Protein carbonyl concentrations were negatively associated with bilirubin concentrations and were significantly lower in persons with >40 μM bilirubin versus controls (<17.1 μmol/L; P<0.05). Furthermore, absolute oxLDL concentrations were significantly lower in GS subjects (P<0.05). Forward stepwise regression analysis revealed that bilirubin was associated with increased GSH:GSSG ratio and reduced thiol concentrations, which, in addition to reduced circulating LDL, probably decreased oxLDL concentrations within the cohort. In addition, a marked reduction in total cholesterol concentrations in hyperbilirubinemic Gunn rats is presented (Gunn 0.57±0.09 versus control 1.69±0.40 mmol/L; P<0.001), arguing for a novel role for bilirubin in modulating lipid status in vivo. These findings implicate the physiological importance of bilirubin in protecting from atherosclerosis by reducing thiol and subsequent lipoprotein oxidation, in addition to reducing circulating LDL concentrations.     

Temporal expression of hypoxia-regulated genes is associated with early changes in redox status in irradiated lung

The development of normal lung tissue toxicity after radiation exposure results from multiple changes in cell signaling and communication initiated at the time of the ionizing event. The onset of gross pulmonary injury is preceded by tissue hypoxia and chronic oxidative stress. We have previously shown that development of debilitating lung injury can be mitigated or prevented by administration of AEOL10150, a potent catalytic antioxidant, 24h after radiation. This suggests that hypoxia-mediated signaling pathways may play a role in late radiation injury, but the exact mechanism remains unclear. The purpose of this study was to evaluate changes in the temporal expression of hypoxia-associated genes in irradiated mouse lung and determine whether AEOL10150 alters expression of these genes. A focused oligo array was used to establish a hypoxia-associated gene expression signature for lung tissue from sham-irradiated or irradiated mice treated with or without AEOL10150. Results were further verified by RT-PCR. Forty-four genes associated with metabolism, cell growth, apoptosis, inflammation, oxidative stress, and extracellular matrix synthesis were upregulated after radiation. Elevated expression of 31 of these genes was attenuated in animals treated with AEOL10150, suggesting that expression of a number of hypoxia-associated genes is regulated by early development of oxidative stress after radiation. Genes identified herein could provide insight into the role of hypoxic signaling in radiation lung injury, suggesting novel therapeutic targets, as well as clues to the mechanism by which AEOL10150 confers pulmonary radioprotection.     

Stimulation of rat colonic mucosal prostaglandin synthesis by calcium and carbamylcholine: Relationship to alterations in cyclic nucleotide metabolism

The present study examined the relationships between prostaglandin (PG) synthesis and cyclic nucleotide metabolism in rat colonic mucosal slices. Ca²⁺, Ca²⁺ plus A23187 and carbamylcholine all increased [¹⁴C]-arachidonate release from prelabeled slices and stimulated production of PGE. Actions of A23187 and carbamylcholine required Ca²⁺ and were suppressed by tetracaine or mepacrine, whose known actions include inhibition of acyl hydrolase activity. Exogenous arachidonate or linoleate stimulated PGE synthesis in the absence of Ca²⁺ or in the presence of the inhibitors, suggesting a role for Ca²⁺ dependent acyl hydrolase activity in the mediation of the actions of Ca²⁺, A23187 and carbamylcholine on PGE synthesis. Accumulation of both cAMP and cGMP in colonic mucosal slices was enhanced by carbamylcholine, Ca²⁺, Ca²⁺ plus A23187, arachidonate or linoleate. Stimulatory actions of each of these agents on PGE production and cyclic nucleotide accumulation were inhibited by O₂ exclusion or indomethacin (100 μg/ml). The results support a role for local PG production in the mediation of carbamylcholine and Ca²⁺ actions on cyclic nucleotides. Endogenous ionic, neurohumoral and dietary factors may modulate colonic mucosal PG synthesis and cyclic nucleotide content, and thereby influence the physiologic expression of the actions of these putative local cellular regulators.     

Lipid hydroperoxide-induced apoptosis in human colonic CaCo-2 cells is associated with an early loss of cellular redox balance.

Apoptosis plays a critical role in maintaining homeostasis of the intestinal epithelium. Dietary oxidants like peroxidized lipids could perturb cellular redox status and disrupt mucosal turnover. The objective of this study was to delineate the role of lipid hydroperoxide (LOOH) -induced redox shifts in intestinal apoptosis using the human colonic CaCo-2 cell. We found that subtoxic concentrations of LOOH increased CaCo-2 cell apoptosis. This LOOH-induced apoptosis was associated with a significant decrease in the ratio of reduced glutathione-to-oxidized glutathione (GSH/GSSG), which preceded DNA fragmentation by 12 to 14 h, suggesting a temporal relationship between the two events. Oxidation of GSH with the thiol oxidant diamide caused significant decreases in cellular GSH and GSH/GSSG at 15 min that correlated with the activation of caspase 3 (60 min) and cleavage of PARP (120 min), confirming a temporal link between induction of cellular redox imbalance and initiation of apoptotic cell death. These kinetic studies further reveal that oxidant-mediated early redox change (within 1 h) was a primary inciting event of the apoptotic cascade. Once initiated, the recovery of redox balance did not prevent the progression of CaCo-2 cell apoptosis to its biological end point at 24 h. Collectively, the study shows that subtoxic levels of LOOH disrupt intestinal redox homeostasis, which contributes to apoptosis. These results provide insights into the mechanism of hydroperoxide-induced mucosal turnover that have important implications for understanding oxidant-mediated genesis of gut pathology.     

Reduced glucose‐induced insulin secretion in low‐protein‐fed rats is associated with altered pancreatic islets redox status

In the present study, we investigated the relationship between early life protein malnutrition‐induced redox imbalance, and reduced glucose‐stimulated insulin secretion. After weaning, male Wistar rats were submitted to a normal‐protein‐diet (17%‐protein, NP) or to a low‐protein‐diet (6%‐protein, LP) for 60 days. Pancreatic islets were isolated and hydrogen peroxide (H₂O₂), oxidized (GSSG) and reduced (GSH) glutathione content, CuZn‐superoxide dismutase (SOD1), glutathione peroxidase (GPx1) and catalase (CAT) gene expression, as well as enzymatic antioxidant activities were quantified. Islets that were pre‐incubated with H₂O₂ and/or N‐acetylcysteine, were subsequently incubated with glucose for insulin secretion measurement. Protein malnutrition increased CAT mRNA content by 100%. LP group SOD1 and CAT activities were 50% increased and reduced, respectively. H₂O₂ production was more than 50% increased whereas GSH/GSSG ratio was near 60% lower in LP group. Insulin secretion was, in most conditions, approximately 50% lower in LP rat islets. When islets were pre‐incubated with H₂O₂ (100 μM), and incubated with glucose (33 mM), LP rats showed significant decrease of insulin secretion. This effect was attenuated when LP islets were exposed to N‐acetylcysteine.     

Mitochondrial respiratory chain in the colonic mucosal of patients with ulcerative colitis

Ulcerative colitis (UC) is a chronic inflammatory disease of the large bowel. Its pathogenesis remains unclear, but it appears to result from a deregulated immune response, with infiltration of leukocytes into the mucosal interstitium. Several studies link oxidative stress and mitochondrial dysfunction to the pathogenesis of UC. Thus, the aim of this study was to evaluate the activities of mitochondrial respiratory chain complexes in the colonic mucosal of UC patients. Colonic biopsies were obtained from UC patients (n = 13). The control specimens were taken from patients without any history of inflammatory bowel disease (n = 8). Colon mucosal was removed by colonoscopy and homogenized. Mitochondrial respiratory chain complexes activities were then measured. Our results showed that the activity of complex I was not altered in UC patients, when compared to the control group. On the other hand, complexes II, III, and IV were decreased around 50–60% in the colonic mucosal of UC patients. Based on the present findings, we hypothesize that mitochondrial dysfunction may play a role in pathogenesis of UC.     

Stimulation of the prostate growth in rats by milk casomorphins]

Thymidine kinase activity of the ventral prostate from adult rats could be stimulated by administration to the animal of casomorphin or casomorphin (morphiceptin). On the other hand addition of both drugs to the culture medium of prostatic cells from immature rats enhanced the cells growth. In both cases, morphiceptin was more efficient than casomorphin. These results suggest than casomorphins have other properties than their morphinomimetic effects previously described.     

Reproducibility of counting immunoglobulin-containing cells in colonic mucosal biopsies

Counting immunoglobulin (Ig)-containing cells in colonic mucosal biopsies can help to objectively support the differential diagnosis of ulcerative colitis and Crohn's disease. Before a method for counting Ig-containing cells can be applied in a clinical setting, however, its reproducibility must be determined. This study investigated the reproducibility of two different methods for counting such cells. The use of a light microscope with an ocular grid resulted in a slightly better reproducibility than did the use of a projection microscope with a graphics tablet. Moreover, the ocular grid method had a higher efficiency. The counting of IgM- and IgG-containing cells had a considerably higher reproducibility than did the counting of IgA-containing cells. To determine the minimal number of cells to be counted in order to ascertain a stabilized mean number of Ig-containing cells, the running means of counts of Ig-containing cells were calculated for two observers. When at least 600 Ig-containing cells (i.e., two to four fields) were counted, the interobserver variation of the running means was less than 10% for IgA and IgG counts and less than 5% for IgM counts. Since earlier studies showed differences in the counts of IgA-, IgG- and IgM-containing cells between ulcerative colitis and Crohn's disease to be, respectively, 3%, 25% and 28%, the results of the present study suggest that the proposed counting method can be useful in the differentiation between these entities.     

Possible mechanism of gastric mucosal protection by epidermal growth factor in rats

The mechanism of the protection by human epidermal growth factor (hEGF) against the gastric mucosal lesions induced by acidified ethanol was studied in rats. At different times following the subcutaneous administration of hEGF (30 micrograms/kg), intragastric acidified ethanol (EtOH: 0.125 M HC1 = 50:50 v/v%) was administered to induce an experimental gastric mucosal lesion. Mean length of the lesion in the gastric mucosa was used as a lesion index. Extravasation of intravenously injected Evans blue into the gastric wall and gastric contents was used as an indicator of vascular permeability. Pretreatment with hEGF decreased both the gastric mucosal lesions and the increase of vascular permeability caused by acidified ethanol with similar time profiles relative to pretreatment with hEGF. Maximal protective actions of hEGF occurred about 10 to 30 min after the observed peak plasma concentration of hEGF. Indomethacin and N-ethylmaleimide, but not iodoacetamide, blocked the protective action of hEGF, indicating that endogenous prostaglandins and/or sulfhydryls may participate in the protective action of hEGF. The content of endogenous nonprotein sulfhydryls in the gastric mucosa decreased markedly after acidified ethanol. However, pretreated hEGF did not restore the sulfhydryl contents. Thus, it seemed that endogenous prostaglandins, but not sulfhydryls, are the probable mediators for protection against gastric mucosal injury caused by acidified ethanol.     

Decreased colonic mucus in rats with loperamide-induced constipation

Constipation is a risk factor of colorectal cancer. Mucin is a major component of lumenal mucus, which protects the colorectal mucosa against mechanical and chemical damage. The aim of this study was to evaluate mucus production and to quantitate lumen mucus in a rat model of spastic constipation. We induced constipation with loperamide (1.5 mg/kg), and histochemically evaluated mucus production and the thickness of the mucus layer at the fecal surface. We quantitated the mucus attached to the mucosal surface using colonic perfusion with N-acetylcysteine. While more feces remained in the colon, there was less fecal excretion and lower fecal water content in loperamide-administered rats than in control rats. Crypt epithelial cells contained less mucus in constipated rats than in control rats. The mucus layer at the fecal surface was thinner and less mucus was recovered from the mucosal surface in constipated rats than in control rats. Mucus production of crypt epithelial cells and mucus at the fecal and mucosal surface were reduced by loperamide-induced constipation.     

Epithelial cell production and mucosal morphology in colonic obstruction

The purpose of this study was to determine the temporal course of changes in epithelial cell production and mucosal morphology following ligation of the rat's ascending colon. Control animals were sham ligated with a loose tie of suture, and ligated and control rats were pair red after surgery. Between the 12th and 24th postoperative h, crypt mitotic and [3H] thymidine labelling indices in the obstructed colon increased to a level of 75% greater than values obtained from unoperated rats. This response was accompanied by gains in the proportion of crypt cells engaged in the division cycle. By 72 h, the numbers of cells per total crypt length and crypt circumference were increased by 40 and 47%, respectively. In addition, morphometrical measurements revealed that crypt cell size in the obstructed colon was significantly greater than control value at 72 h. Colonic ligation had relatively minor effects on cell production and villus and crypt cell number in the terminal ileum. Contrasted with the obstructed bowel, proliferative indices distal to the ligature and in the ileum and colon of control rats diminished rapidly after surgery. Thus, limitation of the hyperproliferative response to the intestine immediately proximal to the ligature strongly suggests that the proliferative stimulus in colonic obstruction is local in action.     

Synthetic ceramides induce growth arrest or apoptosis by altering cellular redox status

Reactive oxygen species (ROS) and ceramide are each partly responsible for the signal transduction of a variety of extracellular agents. Furthermore, the application of synthetic, short-chain ceramides mimics the cellular responses to these extracellular agents. However, the significance of ROS involvement in ceramide signaling pathways is poorly understood. Here we describe that the cellular responses to C2-/C6-ceramide of growth arrest in U937 monocytes and apoptosis in Jurkat T-cells are preceded by a rise in mitochondrial peroxide production. In Jurkat T-cells, this is associated with a large time- and dose-dependent loss of cellular glutathione. However, in U937 monocytes, glutathione loss is transient. Differences in the magnitude and kinetics of this alteration in cellular redox state associate with discrete outcomes, namely growth arrest or apoptosis.     

Disulfiram moderately restores impaired hepatic redox status of rats subchronically exposed to cadmium

Examination of cadmium (Cd) toxicity and disulfiram (DSF) effect on liver was focused on oxidative stress (OS), bioelements status, morphological and functional changes. Male Wistar rats were intraperitoneally treated with 1?mg CdCl₂/kg BW/day; orally with 178.5?mg DSF/kg BW/day for 1, 3, 10 and 21 days; and co-exposed from 22nd to 42nd day. The co-exposure nearly restored previously suppressed total superoxide dismutase (SOD), catalase (CAT) and increased glutathione peroxidase (GPx) activities; increased previously reduced glutathione reductase (GR) and total glutathione-S-transferase (GST) activities; reduced previously increased superoxide anion radical (O₂^·?) and malondialdehyde (MDA) levels; increased zinc (Zn) and iron (Fe), and decreased copper (Cu) (yet above control value), while magnesium (Mg) was not affected; and decreased serum alanine aminotransferases (ALT) levels. Histopathological examination showed signs of inflammation process as previously demonstrated by exposure to Cd. Overall, we ascertained partial liver redox status improvement, compared with the formerly Cd-induced impact.     

Seizure-induced changes in mitochondrial redox status

The aim of this study was to determine seizure-induced oxidative stress by measuring hippocampal glutathione (GSH) and glutathione disulfide (GSSG) levels in tissue and mitochondria. Kainate-induced status epilepticus (SE) in rats resulted in a time-dependent decrease of GSH/GSSG ratios in both hippocampal tissue and mitochondria. However, changes in GSH/GSSG ratios were more dramatic in the mitochondrial fractions compared to hippocampal tissue. This was accompanied by a mild increase in glutathione peroxidase activity and a decrease in glutathione reductase activity in hippocampal tissue and mitochondria, respectively. Since coenzyme A (CoASH) and its disulfide with GSH (CoASSG) are primarily compartmentalized within mitochondria, their measurement in tissue was undertaken to overcome problems associated with GSH/GSSG measurement following subcellular fractionation. Hippocampal tissue CoASH/CoASSG ratios were decreased following kainate-induced SE, the time course and magnitude of change paralleling mitochondrial GSH/GSSG levels. Cysteine, a rate-limiting precursor of glutathione was decreased following kainate administration in both hippocampal tissue and mitochondrial fractions. Together these changes in altered redox status provide further evidence for seizure-induced mitochondrial oxidative stress.     

Changes in colonic mucosal permeability in mouse colitis induced with dextran sulfate sodium.

In this study we examined changes in colonic mucosal permeability induced by dextran sulfate sodium (DSS) during the acute phase of mouse colitis. To induce colitis, the mice were given drinking water containing 5% (w/v) DSS (MW = 40,000) ad libitum. Colonic mucosal permeability was evaluated by the permeation of Evans blue (EB) from the lumen into the wall of the colon on 1, 2, 3 and 7 days postadministration of DSS. Mucosal changes were also histologically examined daily for 7 days postadministration. The permeation of EB increased significantly by days 3 and 7 postadministration. Histological analysis showed that crypt loss was the initial change, with no inflammatory process and the surface mucosal epithelial cells remained morphologically intact. These histological changes developed on 2 to 3 days postadministration. Erosion was first recognized at 5 days postadministration. These findings indicated that the increase in colonic mucosal permeability may have occurred in 3 days postadministration, and the increase in mucosal permeability occurred before the appearance of the inflammatory process. This suggests that an increase in colonic mucosal permeability, leading to the destruction of mucosal barrier function, may play an important role in the induction of DSS-induced murine colitis.     

Imaging in vivo redox status in high spatial resolution with OMRI

Redox-reactions are playing a significant role in regulation of homeostasis of organism. Disorder of the redox-status is related with the onset and/or propagation of oxidative diseases such as lifestyle-related diseases, including cancers and cardiac diseases, etc. In vivo imaging of redox-status is thereby important in the analysis of mechanisms of oxidative diseases and developments of new medicines for the diseases. Aminoxyl radicals are redox-sensitive reporter molecules, which lose their paramagnetic moiety by reactions of free radicals or reducing compounds. Electron spin resonance (ESR) technique has been used to measure the molecules in vivo. In vivo spatial resolution in ESR imaging is in the range of a few millimeters and is not sufficient for the detailed diagnosis of disease models. Overhauser enhanced MRI (OMRI) is an emerging free radical imaging technique, which utilised electron-proton coupling to image the distribution of free radicals. In vivo imaging of redox-status is applicable with OMRI/aminoxyl radical technique. The detailed imaging analysis was demonstrated in oxidative diseases, such as tumour-bearing, neurodegeneration or gastric ulcer models. The OMRI/aminoxyl radical technique has a large potential as a diagnostic system for biomedical applications in the future.