Aging protects rat cortical slices against to oxygen-glucose deprivation induced damage.

Objective: In present study, we aimed to clarify effect of aging on the susceptibility of brain tissue to neurodegeneration induced by ischemia.Methods: Damage induced by oxygen-glucose deprivation (OGD) followed by reoxygenation (REO) were compared in cortical slices prepared from young (3 months of age) and aged (22-24 months of age) male Sprague Dawley rats.Results: After incubation of the slices in an oxygen and glucose containing control condition, 2,3,5-triphenyl tetrazolium chloride (TTC) staining intensity was found significantly high in aged cortical slices. Although thirty minutes incubation of the slices in OGD medium followed by REO (OGD-REO) caused similar decline in TTC staining in young and aged cortical slices, staining intensity was still significantly higher in the slices prepared from aged animals. Thirty minutes of OGD-REO, on the other hand, also caused more increase in lactate dehydrogenase (LDH) leakage from young slices. While water contents of the slices were almost equal under control condition, it was significantly high in young cortical slices after OGD-REO incubations. In contrary to these findings, OGD and REO caused more increases in S100B output from aged rat cortical slices. S100B levels in brain regions including the cerebral cortex were also found higher in aged rats.Conclusion: All these results indicate that, cortical slices prepared from aged male rats are significantly less responsive to in vitro OGD-REO induced alterations. Since protein S100B outputs were almost doubled from aged cortical slices, a possible involvement of this enhanced S100B output seems to be likely.

Impact of Menthol on Oral Nicotine Consumption in Female and Male Sprague Dawley Rats.

INTRODUCTION: One of the preferable flavors in oral nicotine delivery systems is menthol which masks the harshness of tobacco. However, possible interactions between oral menthol and nicotine on intake and preference remain unclear. Therefore, we aimed to determine the impact of menthol on oral nicotine consumption. METHODS: Adult Sprague Dawley female and male rats (n = 8 per group) were given a choice of water or drug solution by using two-bottle free choice paradigm for 2 weeks: vehicle (5% ethanol), nicotine (20 mg/L), menthol (1 g/L) and mentholated nicotine groups. At the end of the study, plasma nicotine levels were determined. RESULTS: When rats were given a choice of nicotine or water, nicotine intake was similar between female and male rats. Menthol addition to nicotine solution significantly increased nicotine intake and preference in male but not female rats without a considerable effect on total fluid intake and body weight change in either sex. The average nicotine intake in male rats was 0.5 ± 0.05 and 1.4 ± 0.12 mg/kg/day for nicotine and menthol-nicotine combination (p < .05), respectively. The average nicotine intake in female rats was 0.6 ± 0.05 and 0.6 ± 0.03 mg/kg/day for nicotine and menthol-nicotine combination (p > .05), respectively. Plasma nicotine levels were not significantly different between the groups in either male (nicotine group: 20.8 ± 4.9, mentholated nicotine group: 31.9 ± 3.2 ng/mL) or female (nicotine group: 24.0 ± 3.3, mentholated nicotine group: 17.8 ± 2.9 ng/mL) rats (p > .05). CONCLUSIONS: Menthol increases oral nicotine consumption in male, but not female, rats. IMPLICATIONS: This study may provide data on the co-use of menthol and nicotine in smokeless tobacco, particularly oral dissolvable tobacco products.

Assessment of neuron-specific enolase, S100B and malondialdehyde levels in serum and vitreous of patients with proliferative diabetic retinopathy.

PURPOSE: To assess the vitreous and serum levels of neuron-specific enolase (NSE), S100B and malondialdehyde (MDA) in proliferative diabetic retinopathy (PDR) cases and investigate the correlation between preoperative and postoperative anatomical and clinical features. MATERIALS AND METHODS: The study group included patients who had pars plana vitrectomy (PPV) for PDR. The control group included non-diabetic individuals who underwent PPV surgery for vitreoretinal interface disorders. Samples of serum were taken from all participants preoperatively, while vitreous samples were taken during the PPV. Vitreous and serum levels of NSE, S100B and MDA were measured, and comparisons were made between the groups. RESULTS: The study group consisted of 56 eyes of 56 cases with PDR. The control group consisted of 20 eyes of 20 cases. The concentrations of vitreous NSE, S100B and MDA were significantly higher than the control group (p < 0.0001, p < 0.05, p < 0.001, respectively). Serum levels were statistically different for NSE and S100B (p < 0.05). CONCLUSION: Our results clearly show that vitreous levels of S100B, NSE and MDA and serum concentrations of NSE and S100B increased significantly in patients with PDR. The findings may possibly indicate neurodegeneration and oxidative stress; therefore, these markers may have a diagnostic value in patients with PDR.

Protective Effects of Chlorogenic Acid and its Metabolites on Hydrogen Peroxide-Induced Alterations in Rat Brain Slices: A Comparative Study with Resveratrol.

The effectiveness of chlorogenic acid and its main metabolites, caffeic and quinic acids, against oxidative stress was investigated. Resveratrol, another natural phenolic compound, was also tested for comparison. Rat cortical slices were incubated with 200 µM H2O2 for 1 h, and alterations in oxidative stress parameters, such as 2, 3, 5-triphenyltetrazolium chloride (TTC) staining and the production of both malondialdehyde (MDA) and reactive oxygen species (ROS), were assayed in the absence or presence of phenolic compounds. Additionally, the effectiveness of chlorogenic acid and other compounds on H2O2-induced increases in fluorescence intensities were also compared in slice-free incubation medium. Although quinic acid failed, chlorogenic and caffeic acids significantly ameliorated the H2O2-induced decline in TTC staining intensities. Although resveratrol also caused an increase in staining intensity, its effect was not dose-dependent; the high concentrations of resveratrol tested in the present study (10 and 100 µM) further lessened the staining of the slices. Additionally, all phenolic compounds significantly attenuated the H2O2-induced increases in MDA and ROS levels in cortical slices. When the IC50 values were compared to H2O2-induced alterations, chlorogenic acid was more potent than either its metabolites or resveratrol for all parameters studied under these experimental conditions. In slice-free experimental conditions, on the other hand, chlorogenic and caffeic acids significantly attenuated the fluorescence emission enhanced by H2O2 with a similar order of potency to that obtained in slice-containing physiological medium. These results indicate that chlorogenic acid is a more potent phenolic compound than resveratrol and its main metabolites caffeic and quinic acids against H2O2-induced alterations in oxidative stress parameters in rat cortical slices.

Amino acid and vascular endothelial growth factor levels in subretinal fluid in rhegmatogenous retinal detachment.

PURPOSE: To study the concentrations of amino acids and vascular endothelial growth factor (VEGF) in subretinal fluid (SRF) of cases with rhegmatogenous retinal detachment (RRD). The relevance of the results with postoperative anatomic and functional success in RRD was investigated. METHODS: Fifty-three patients were included in this prospective study. The study group consisted of 46 patients who had scleral buckling surgery with the diagnosis of RRD, and SRF was obtained during the surgery. The control specimens consisted of vitreous samples of seven patients who were diagnosed with pars plana vitrectomy without RRD. Study cases were divided into three groups, corresponding to the duration of retinal detachment. Clinical characteristics, including best corrected visual acuity (BCVA) and anatomic status at month 6, were recorded. Concentrations of 15 selected amino acids were quantified by using high performance liquid chromatography, and VEGF levels were measured with enzyme immunoassay. RESULTS: When compared with the control group, SRF concentrations of aspartate, citrulline, glutamate, and glycine increased significantly in the study group (p<0.05). Statistical analysis showed that concentrations of alanine, isoleucine, leucine, methionine, phenylalanine, threonine, tyrosine, and valine decreased (p<0.05). SRF levels of glutamine, taurine, and serine had no significant change. SRF VEGF levels were significantly higher than the vitreous samples of the controls (p<0.001). Time-dependent changes and interactions between VEGF and amino acids were observed. There was no correlation between the concentrations of amino acids or VEGF with the parameters of BCVA and anatomical success. CONCLUSIONS: Significant changes occur in concentrations of amino acids and VEGF in SRF of cases with RRD. Our results suggest that several mechanisms contribute to the pathophysiology.

S100b protein levels in subretinal fluid in rhegmatogenous retinal detachment.

PURPOSE: To investigate the relevance of the concentration of S100B in subretinal fluid (SRF) with the postoperative anatomical and functional success and proliferative vitreoretinopathy (PVR) formation parameters in rhegmatogenous retinal detachment (RRD). METHODS: Fifty-three patients (34 male, 19 female) were included in this prospective study. Study group consisted of 46 patients who had scleral buckling (SB) surgery with the diagnosis of RRD. Control group consisted of six patients who had pars plana vitrectomy (PPV) for either full-thickness macular hole or subluxated intraocular lens. SRFs were obtained during SB surgery. Study cases were divided into three groups, corresponding to the duration of retinal detachment (DRD). Clinical characteristics including best-corrected visual acuity (BCVA), anatomical status at 6 months, the presence of postoperative PVR that resulted in recurrent detachment and any possible re-operations were recorded. The concentration of S100B was quantified by using an enzyme immunoassay test kit. RESULTS: The concentration of S100B in SRF increased significantly after RRD. And, S100B levels were evidently elevated in concordance with DRD. There was no correlation between the concentration of SRF - S100B with preoperative or postoperative BCVA. Again, S100B levels were not related to the extent of RRD or postoperative PVR formation. CONCLUSION: Concentration of S100B in SRF is good marker of retinal stress and increases in concordance with DRD. However it would not help to predict the possible anatomical and functional success or postoperative PVR formation.

Protein S100B release from rat brain slices during and after ischemia: comparison with lactate dehydrogenase leakage.

One hour of ischemia significantly increased protein S100B release from rat brain slices without altering lactate dehydrogenase leakage. Reoxygenation of the ischemic slices, however, increased the levels of these biochemical markers in the medium. Although removal of extracellular Ca(+2) ions from the medium did not alter the basal lactate dehydrogenase leakage from cortical slices, an excessive increase in basal protein S100B release was seen under this condition. Ischemia and/or reoxygenation induced enhancements in these markers were attenuated by removal of Ca(+2) ions from the medium. Ischemia significantly increased glutamate release, but neither ischemia nor reoxygenation induced rises in protein S100B and lactate dehydrogenase levels were altered by glutamate receptor antagonists. Rising the glutamate levels in the medium by each ouabain or exogenous glutamate, moreover, failed in exerting an ischemia like effect on protein S100B and LDH outputs. In contrast, exogenous glutamate added into the medium protected the slices against reoxygenation induced increments in protein S100B and lactate dehydrogenase levels. These results indicate that protein S100B has a greater sensitivity against ischemia than lactate dehydrogenase in in vitro brain slice preparations. Since neither exogenous glutamate nor enhancements of the extracellular glutamate levels by ouabain had an ischemia like effect, and since glutamate receptor antagonists were also unsuccessful, it seems unlikely that ischemia-induced increase in glutamate release is directly involved in protein S100B release or lactate dehydrogenase leakage determined in the present study.

Effects of ketamine and thiopental on ischemia reoxygenation-induced LDH leakage and amino acid release from rat striatal slices.

Increased release of glutamate is thought to contribute to ischemia-induced neuronal damage. Since general anesthetics such as thiopental and ketamine are thought to provide some degree of cerebral protection, this study was intended to 1) compare the effectiveness of ketamine and thiopental on ischemia-induced tissue damage; and, if so, 2) determine whether attenuation of the increased amino acid release is the sole mechanism for the protective effects demonstrated. Striatal slices prepared from Wistar Albino rats were incubated in an ischemic medium for 1 hour followed by 5 hours in a reoxygenation (REO) medium. Ketamine and thiopental were added medium during ischemia and/or REO periods, and the medium was collected at the end of each incubation period for measurement of amino acid release and lactate dehydrogenase (LDH) leakage. Ischemia significantly increased amino acid release without altering LDH leakage. Ischemia-induced increments in glutamate and aspartic acid releases returned to control levels during REO, but LDH leakage increased (P > 0.001) during this period. Although ketamine (100 microM) and thiopental (100 microM) failed to decrease ischemia-induced excitatory amino acid release, they protected the slices against REO-induced LDH leakage. Ketamine, but not thiopental, was effective even if added after ischemia (P < 0.05). These results indicate that ketamine and thiopental protect the slices against REO-induced LDH leakage. However, mechanisms other than attenuation of the enhanced glutamate release might be responsible for their protective effects.