Decreased food intake rather than zinc deficiency is associated with changes in plasma leptin, metabolic rate, and activity levels in zinc deficient rats( small star, filled)

This study investigated the hypothesis that the reduced food intake and poor weight gain in zinc deficient rats is due to: increased plasma leptin concentration, increased physical activity and/or increased metabolic rate. Weanling rats were assigned to three groups: controls fed ad libitum (C), zinc deficient (ZD), and pair-fed controls (PF), and tested in a metabolic chamber and activity monitor at baseline and weekly for four weeks. At the end of the study, all groups were compared for differences in plasma leptin concentrations. ZD and PF animals had markedly reduced food intake and weight gain. ZD had reduced stereotypic and locomotor activity compared to PF animals and both groups demonstrated an abolished peri-nocturnal activity spike and were much less active than controls. This was associated with a reduced total metabolic rate by day 30: ZD (0.73 +/- 0.07 kcal/hr, p = 0.0001) and PF (0.83 +/- 0.06 kcal/hr, p = 0.0001) groups vs. controls (1.82 +/- 0.09 kcal/hr). Plasma leptin concentrations in ZD (1.55 +/- 0.06 &mgr;g/L) were lower than controls (2.01 +/- 0.18 &mgr;g/L, p < 0.03), but neither ZD nor controls were statistically different from PF (1.68 +/- 0.05 &mgr;g/L). Both low leptin concentrations and low metabolic rates in the ZD and PF rats were associated with decreased food intake rather than zinc deficiency. The reduced food intake and poor weight gain observed in zinc deficient rats could not be explained by elevated leptin concentrations, hypermetabolism, or increased activity. Low serum leptin concentrations, hypometabolism, and decreased activity are more likely the result of the anorexia of zinc deficiency.     

Effects of excessive copper intake on hematological and hemorheological parameters

Copper plays an important role in the structure and function of metalloproteins and in the absorption of iron. The present study deals with the effects of excessive copper intake on hematological and hemorheological parameters. Drinking water containing 250 μg/mL copper for a period of 9 wk, Wistar albino rats showed increased erythrocyte count, blood viscosity, and hematocrit values (p<0.05) and lower hemoglobin (p<0.05) than controls fed a normal diet. The two groups also had differences in the erythrocyte deformability index. The results suggest that excessive copper intake results in hematological and hemorheological changes affecting both the protein content of the erythrocyte membrane and heme synthesis.     

Healing-promoting effect of bombesin treatment on chronic gastric ulcer in rats

To evaluate whether bombesin treatment has a facilitatory effect on the healing of chronic gastric ulcer, following the induction of ulcer by serosal application of acetic acid, rats were given bombesin (30 microg/kg/day; subcutaneously) or vehicle three times a day for 7, 14 or 21 days until they were decapitated. Neither food intake nor gastric emptying rate in either vehicle-treated or bombesin-treated groups was not statistically different from control rats. Similarly, ulcer indices and gastric myeloperoxidase (MPO) activities at the first and second weeks of injury were not different among the groups. However, in the 3-week ulcer group, bombesin treatment reduced tissue MPO level significantly back to control levels. Moreover, the analysis of the surface epithelium by scanning electron and light microscopy demonstrated a significant reduction in the severity of ulcers by bombesin treatment. Pretreatment with CCK antagonists (L-364,718 or L365,260; 25 micromol/kg/day) before bombesin treatment showed that neither of the CCK antagonists had a significant effect on the bombesin-mediated healing process, suggesting that CCK receptors are not involved in the action of bombesin. In accordance with the previous studies that show its acute gastroprotective effects, bombesin is also effective in promoting the healing process of chronic gastric ulcer in rats.     

Lipid peroxidation and scavenging enzyme levels in the liver of streptozotocin-induced diabetic rats

In this study, alterations in the liver antioxidant enzymes status and lipid peroxidation in short-term (8-weeks) and long-term (24-weeks) diabetic rats were examined. Glutathione peroxidase (GSH-Px) activity and malondialdehyde (MDA) levels were significantly increased, but superoxide dismutase (SOD) activity was significantly reduced in 8-weeks diabetic rats, compared to control. Catalase (CAT) activity, however, was found unchanged. In 24-weeks diabetic rats, while GSH-Px activity was unchanged, but SOD and CAT activities and MDA levels were significantly increased, compared to control. These results suggest that diabetes-induced alterations in tissue antioxidant system may reflect a generalized increase in tissue oxidative stress. It can be concluded that lipid peroxidation and antioxidant enzyme levels are elevated in diabetic condition. Hence, diabetes mellitus, if left untreated, may increase degenerative processes due to accumulation of oxidative free radicals.     

Human brain glycogen content and metabolism: implications on its role in brain energy metabolism

The adult brain relies on glucose for its energy needs and stores it in the form of glycogen, primarily in astrocytes. Animal and culture studies indicate that brain glycogen may support neuronal function when the glucose supply from the blood is inadequate and/or during neuronal activation. However, the concentration of glycogen and rates of its metabolism in the human brain are unknown. We used in vivo localized 13C-NMR spectroscopy to measure glycogen content and turnover in the human brain. Nine healthy volunteers received intravenous infusions of [1-(13)C]glucose for durations ranging from 6 to 50 h, and brain glycogen labeling and washout were measured in the occipital lobe for up to 84 h. The labeling kinetics suggest that turnover is the main mechanism of label incorporation into brain glycogen. Upon fitting a model of glycogen metabolism to the time courses of newly synthesized glycogen, human brain glycogen content was estimated at approximately 3.5 micromol/g, i.e., three- to fourfold higher than free glucose at euglycemia. Turnover of bulk brain glycogen occurred at a rate of 0.16 micromol.g-1.h-1, implying that complete turnover requires 3-5 days. Twenty minutes of visual stimulation (n=5) did not result in detectable glycogen utilization in the visual cortex, as judged from similar [13C]glycogen levels before and after stimulation. We conclude that the brain stores a substantial amount of glycogen relative to free glucose and metabolizes this store very slowly under normal physiology.     

The effect of taurine on renal ischemia/reperfusion injury

Summary. Ischemia-reperfusion (I/R) injury is one of the most common causes of renal dysfunction. Taurine is an endogenous antioxidant and a membrane-stabilizing, intracellular, free beta-amino acid. It has been demonstrated to have protective effects against I/R injuries to tissues other than kidney. The aim of this study was to determine whether taurine has a beneficial role in renal I/R injury. Forty Wistar-Albino rats were allocated into four groups as follows: sham, taurine, I/R, and I/R + taurine. Taurine 7.5 mg/kg was given intra-peritoneally to rats in the groups taurine and I/R + taurine. Renal I/R was achieved by occluding the renal arteries bilaterally for 40 min, followed by 6 h of reperfusion. Immediately thereafter, blood was drawn and tissue samples were harvested to measure 1) serum levels of BUN and creatinine; 2) serum and/or tissue levels of malondialdehyde (MDA), glutathione (GSH), glucose 6-phosphate dehydrogenase (G-6PD), 6-phosphogluconate dehydrogenase (6-PGD) and glutathione reductase (GSH-red); 3) renal morphology; and 4) immunohistochemical staining for P-selectin. Taurine administration reduced I/R-induced increases in serum BUN and creatinine, and serum and tissue MDA levels (p < 0.05). Additionally, taurine lessened the reductions in serum and tissue glutathione levels secondary to I/R (p < 0.05). Taurine also attenuated histopathologic evidence of renal injury, and reduced I/R-induced P-selectin immunoreactivity (p < 0.05). Overall, then, taurine administration appears to reduce the injurious effects of I/R on kidney.     

Evaluation of insulin resistance and plasma levels for visfatin and resistin in obese and non-obese patients with polycystic ovary syndrome

This study was designed to evaluate insulin resistance and plasma levels of visfatin and resistin in obese and non-obese patients with polycystic ovary syndrome (PCOS).A total of 37 premenopausal PCOS patients with (n = 18, mean (SD) age: 27.5 (5.7 years) or without obesity (n = 19, mean (SD) age: 23.7 (3.1) years) and healthy volunteers (n = 18, mean (SD) age:29.8 (4.1) years) were included in this study. Data on clinical characteristics, glycemic parameters and lipid parameters were recorded for each subject as were plasma visfatin and resistin levels. Mean (SD) HOMA-IR values were significantly higher in obese PCOS patients (3.4 (1.7)) compared with non-obese PCOS patients (2.0 (1.2), p<0.01) and controls (1.6 (0.8), p<0.01). No significant difference was noted between study groups in terms of plasma resistin (ng/mL) or visfatin (ng/mL) levels. There was no correlation between serum plasma visfatin (r = 0.127, p = 0.407) and resistin (r = -0.096, p = 0.544) levels and HOMA-IR. In conclusion, our findings revealed increased likelihood of metabolic and dyslipidemic manifestations in obese compared to non-obese PCOS patients, while no significant difference was noted in visfatin and resistin levels among PCOS patients in terms of co-morbid obesity and in comparison to controls.     

Effects of simvastatin treatment on oxidant/antioxidant state and ultrastructure of streptozotocin-diabetic rat lung

In the present study, we investigated the effects of simvastatin, a 3-hydroxy-3-methyl-glutaryl coenzyme A reductase inhibitor, on lipid metabolism, lipid peroxidation, antioxidant enzyme activities and ultrastructure of diabetic rat lung. Diabetes was induced by a single injection of streptozotocin (45 mg kg(-1), i.p.). After 8 weeks induction of diabetes, some control and diabetic rats were treated with simvastatin (10 mg kg(-1) rat day(-1); orally) for 4 weeks. Diabetes resulted in significantly high levels of blood glucose and plasma lipids. Malondialdehyde levels were unchanged after 12-week-old diabetic rats, whereas catalase activity significantly decreased in the lung. Glutathione peroxidase activity and nitric oxide level were significantly elevated in the diabetic lung. Histological analysis of the diabetic lung revealed some deterioration in the structure. Simvastatin treatment reduced plasma lipid levels and partially decreased the severity of hyperglycaemia. Catalase, glutathione peroxidase activities and nitric oxide levels were partially restored and accompanied by improved structure in diabetic lung by the simvastatin treatment. These results suggest that structural disturbances and alteration of antioxidative enzyme activities occurred in diabetic lung. Simvastatin treatment may provide some benefits in the maintenance of antioxidant status and structural organization of diabetes-induced injury of lung.     

Antioxidants as novel therapy in a murine model of colitis

Reactive oxygen species (ROS) are increased in inflammatory bowel disease (IBD) and have been implicated as mediators of intestinal inflammation. We investigated the hypothesis that antioxidants with diverse properties attenuate disease progression in a murine dextran sodium sulfate (DSS)-induced colitis model. These antioxidants were (A) S-adenosylmethionine, a glutathione (GSH) precursor; (B) green tea polyphenols, a well-known antioxidant; and (C) 2(R,S)-n-propylthiazolidine-4(R)-carboxylic acid (PTCA), a cysteine prodrug, involved in GSH biosynthesis. BALB/c mice were divided into four groups and provided with the above mentioned antioxidants or the vehicle incorporated into chow. The animals were further divided into two subgroups and given normal drinking water (control) or water supplemented with DSS (to induce colitis), and the progression of the disease was studied. DSS-treated mice developed severe colitis as shown by bloody diarrhea, weight loss and pathological involvement (P<.001). However, all the antioxidants significantly improved diarrhea and colon lesions (P<.01), and increased body weights (P<.05). Hematocrits were significantly less affected in DSS-treated animals receiving antioxidants (P<.01). Colon lengths were significantly decreased due to mucosal inflammation in DSS-treated animals, but antioxidant therapy normalized this pathological finding (P<.001). The blood level of reduced GSH was decreased in DSS-treated mice (P<.05) and returned to normal when treated with antioxidants. Serum amyloid A (acute phase protein; P=.0015) and tumor necrosis factor-alpha (TNF-alpha; pro-inflammatory cytokine; P<.01) were significantly increased in DSS-treated animals (161+/-40 pg/ml) and improved with antioxidant treatment (P<.01). Finally, actin cytoskeleton was distorted and fragmented in the mucosa of DSS-treated mice and improved with antioxidant therapy. In conclusion, three structurally dissimilar antioxidants provided protection against DSS-induced colitis in this murine model, supporting a possible role for antioxidant therapy in IBD patients.