Prolonged latency to CNS-O-2 toxicity induced by heat acclimation in rats is associated with increased antioxidative defenses and metabolic energy preservation
Israel Naval Medical Institute, Israel Defense Forces Medical Corps, Haifa, Israel. Journal of Applied Physiology
(Impact Factor: 3.06).
06/2012; 113(4):595-601. DOI: 10.1152/japplphysiol.00228.2012
We have previously shown that heat acclimation provides protection against central nervous system oxygen toxicity (CNS-OT). This was well correlated with increased levels of heat shock protein 72 (HSP72). We now examine other antioxidative defenses against CNS-OT that are correlated with heat acclimation. Two groups of male Sprague-Dawley rats were used. The heat-acclimated group (HA) was exposed for 4 wk to 32°C, and the control group (C) was maintained at 24°C. At the end of the acclimation period, rats were exposed to oxygen at 608 kPa. EEG was recorded continuously until appearance of the first electrical discharge. Brain samples were taken from each group after exposure to pressure. Levels of the antioxidant enzymes CuZnSOD, MnSOD, catalase, and glutathione peroxidase, as well as levels of HSP72, were quantified by Western blot. Comparative proteome analysis of the brains of HA and C rats was carried out using two-dimensional electrophoresis and mass spectrometry to define protein spot alterations. Levels of HSP72 and CuZnSOD were higher in HA rats. Levels of the other antioxidant enzymes were not affected significantly by heat acclimation. Differences in the levels of four protein spots identified as α-synuclein, valosin-containing protein, adenylate kinase 1 (AK1), and the mitochondrial H+-ATP synthase α subunit were found between HA and C rats. We conclude that elevation of HSP72, CuZnSOD, AK1, and the mitochondrial H+-ATP synthase α subunit and possible phosphorylation of α-synuclein--all proteins involved in oxidative stress or energy conservation--might contribute to the prolongation of latency to CNS-OT induced by heat acclimation.
Available from: Esther Shohami
- "Over the last decades we have shown that HA confers cardio protection against heat stress, ischemic insults  and hyperbaric oxygen . Moreover, HA provides neuroprotection against central nervous system oxygen toxicity  and against traumatic brain injury (TBI) . Investigation of the phenotypic changes involved in the neuroprotection in HA mice subjected to TBI revealed that activation of Akt by thr308 phosphorylation is an essential event . "
[Show abstract] [Hide abstract]
ABSTRACT: Preconditioning via heat acclimation (34°C 30 d) results in neuroprotection from traumatic brain injury due to constitutive as well as dynamic changes triggered by the trauma. Among these changes is Akt phosphorylation, which decreases apoptosis and induces HIF1α. In the present study we investigated the Akt downstream GSK3β/β -catenin pathway and focused on post injury alternations of β catenin and its impact on the cellular response in preconditioned heat acclimated mice. We found that the reduction in motor disability is accompanied with attenuation of depressive like behavior in heat acclimated mice that correlates with the GSK3β phosphorylation state. Concomitantly, a robust β catenin phosphorylation is not followed by its degradation, or by reduced nuclear accumulation. Enhanced tyrosine phosphorylation of β catenin in the injured area weakens the β catenin-N cadherin complex. Membrane β catenin is transiently reduced in heat acclimated mice and its recovery 7 days post TBI is accompanied by induction of the synaptic marker synaptophysin. We suggest a set of cellular events following traumatic brain injury in heat acclimated mice that causes β catenin to participate in cell-cell adhesion alternations rather than in Wnt signaling. These events may contribute to synaptogenesis and the improved motor and cognitive abilities seen heat acclimated mice after traumatic brain injury.
Available from: Hervé Colinet
[Show abstract] [Hide abstract]
ABSTRACT: Thermal acclimation drastically alters thermotolerance of ectotherms, but the mechanisms determining this plastic response are not fully understood. The present study investigates the proteomic response (2D-DIGE) of adult Drosophila melanogaster acclimated at 11, 25 or 31 °C. As expected 11 °C-acclimation improved cold tolerance and 31 °C-acclimation improved heat tolerance. We hypothesized that the marked organismal responses to acclimation could be detected at the proteomic level assuming that changes in the abundance of specific proteins are linked to the physiological changes underlying the phenotypic response. The 31 °C-acclimated flies displayed a particular divergent proteomic profile where molecular chaperones made up a large number of the proteins that were modulated during heat acclimation. Many other proteins showed significant modulation during acclimation including proteins involved in iron ion and cell redox homeostasis, carbohydrate and energy metabolism, chromatin remodeling and translation, and contractile machinery. Interestingly the changes in protein abundance were often unrelated to transcriptional activity of the genes coding for the proteins, except for the most strongly expressed proteins (e.g. Hsp70). The 11 °C-acclimation evoked weak proteomic response despite the marked effect on the organismal phenotype. Thus the acquired cold tolerance observed here may involve regulatory process such as posttranslational regulation rather than de novo protein synthesis.
[Show abstract] [Hide abstract]
ABSTRACT: Kidney-tonifying recipe can reduce the accumulation of advanced glycation end products, prevent neuronal degeneration and improve cognitive functions in ovariectomized rats. Radix Achyranthis Bidentatae alcohol extracts may dose-dependently inhibit non-enzymatic saccharification in vitro. This study aimed to examine the effect of Radix Achyranthis Bidentatae on advanced glycation end products and on learning and memory capabilities in ovariectomized rats. Ovariectomized rats were treated with Radix Achyranthis Bidentatae alcohol extracts (containing 1.5 g/kg crude drug) or 0.1% aminoguanidine for 12 weeks and behavioral testing was performed with the Y-electrical maze. This test revealed that Radix Achyranthis Bidentatae and aminoguanidine could improve the learning and memory capabilities of ovariectomized rats. Results of competitive enzyme-linked immunosorbent assay showed that treatment with Radix Achyranthis Bidentatae or aminoguanidine reduced the accumulation of advanced glycation end products in the frontal cortex of ovariectomized rats, while increasing content in the blood and urine. Biochemical tests showed that treatment with Radix Achyranthis Bidentatae or aminoguanidine decreased superoxide dismutase activity in the serum and frontal cortex, and increased serum levels of glutathione peroxidase in ovariectomized rats. In addition, there was no apparent effect on malondialdehyde levels. These experimental findings indicate that Radix Achyranthis Bidentatae inhibits production of advanced glycation end products and its accumulation in brain tissue, and improves learning and memory capabilities in ovariectomized rats. These effects may be associated with an anti-oxidative action of the extract.
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.