Carsten Fütterer

Tolerance Against Ischemic Neuronal Injury Can Be Induced by Volatile Anesthetics and Is Inducible NO Synthase Dependent

Background and Purpose— We tested whether volatile anesthetics induce neuroprotection that is maintained for a prolonged time. Methods— Rats were pretreated for 3 hours with 1 minimal anesthetic concentration of isoflurane or halothane in normal air (anesthetic preconditioning [AP]). The animals were subjected to permanent middle cerebral artery occlusion (MCAO) at 0, 12, 24, or 48 hours after AP. Halothane-pretreated animals were subjected to MCAO 24 hours after AP. Histological evaluation of infarct volumes was performed 4 days after MCAO. Cerebral glucose utilization was measured 24 hours after AP with isoflurane. Primary cortical neuronal cultures were exposed to 1.4% isoflurane for 3 hours. Oxygen-glucose deprivation (OGD) was performed 24 hours after AP. Injury was assessed 24 hours later by measuring the release of lactate dehydrogenase into the medium 24 hours after OGD. Results— Isoflurane anesthesia at 0, 12, and 24 hours before MCAO or halothane anesthesia 24 hours before MCAO significantly reduced infarct volumes (125±42 mm3, P =0.024; 118±51 mm3, P =0.008; 120±49 mm3, P =0.009; and 121±48 mm3, P =0.018, respectively) compared with control volumes (180±51 mm3). Three hours of isoflurane anesthesia in rats did not have any effect on local or mean cerebral glucose utilization measured 24 hours later. Western blot analysis from cortical extracts of AP-treated animals revealed an increase of the inducible NO synthase (iNOS) protein beginning 6 hours after AP. The iNOS inhibitor aminoguanidine (200 mg/kg IP) eliminated the infarct-sparing effect of AP. In cultured cortical neurons, isoflurane exposure 24 hours before OGD decreased the OGD-induced release of lactate dehydrogenase by 49% (P =0.002). Conclusions— Pretreatment with volatile anesthetics induces prolonged neuroprotection in vitro and in vivo, a process in which iNOS seems to be critically involved.

Alterations in Rat Brain Proteins after Desflurane Anesthesia

BackgroundVolatile anesthetics disappear from an organism after the end of anesthesia. Whether changes of protein expression persist in the brain for a longer period is not known. This study investigates the question of whether the expression of proteins is altered in the rat brain after the end of desflurane anesthesia. MethodsThree groups (n = 12 each) of rats were anesthetized with 5.7% desflurane in air for 3 h. Brains were removed directly after anesthesia, 24 h after anesthesia, or 72 h after anesthesia. Two additional groups (n = 12 each) served as naive conscious controls, in which the brains were removed without previous anesthesia 3 or 72 h after the start of the experiment. Cytosolic proteins were isolated. A proteome-wide study was performed, based on two-dimensional gel electrophoresis and mass spectrometry. ResultsCompared with conscious controls, significant (P < 0.05) increase/decrease was found: 3 h of anesthesia, 5/2 proteins; 24 h after anesthesia, 13/1 proteins; 72 h after anesthesia, 6/4 proteins. The overall changes in protein expression as quantified by the induction factor ranged from −1.67 (decrease to 60%) to 1.79 (increase by 79%) compared with the controls (100%). Some of these regulated proteins play a role in vesicle transport and metabolism. ConclusionDesflurane anesthesia produces changes in cytosolic protein expression up to 72 h after anesthesia in the rat brain, indicating yet unknown persisting effects.

Comprehensive proteome expression profiling of undifferentiated versus differentiated neural stem cells from adult rat hippocampus.

Adult neural stem cells can be isolated from various regions of the rat brain and seem to have multilineage differentiation potential. In this study, we investigated the hypothesis that global protein expression of adult neural stem cells isolated from rat hippocampus is changed during in vitro differentiation. After 2 days of differentiation, we separated total protein extracts by two-dimensional gel electrophoresis and used mass spectrometry and gel-matching for identification. We detected a differential expression in 367 regulated protein spots, of which 128 could be identified. Regulated proteins included participants in transcription and DNA metabolism; signal transduction and Ca2+-signaling; MAP kinase pathways; cytoskeletal rearrangement; regulation of cell cycle, proliferation, and survival; protein biosynthesis, folding, and degradation; and glycine and glutamate metabolic pathways. These results suggest a massive reorganization of the stem cell proteomic profile upon differentiation and indicate potential cellular targets mediating the differentiation of neural stem cells.

The proteome of neural stem cells from adult rat hippocampus

BackgroundHippocampal neural stem cells (HNSC) play an important role in cerebral plasticity in the adult brain and may contribute to tissue repair in neurological disease. To describe their biological potential with regard to plasticity, proliferation, or differentiation, it is important to know the cellular composition of their proteins, subsumed by the term proteome.ResultsHere, we present for the first time a proteomic database for HNSC isolated from the brains of adult rats and cultured for 10 weeks. Cytosolic proteins were extracted and subjected to two-dimensional gel electrophoresis followed by protein identification through mass spectrometry, database search, and gel matching. We could map about 1141 ± 209 (N = 5) protein spots for each gel, of which 266 could be identified. We could group the identified proteins into several functional categories including metabolism, protein folding, energy metabolism and cellular respiration, as well as cytoskeleton, Ca2+ signaling pathways, cell cycle regulation, proteasome and protein degradation. We also found proteins belonging to detoxification, neurotransmitter metabolism, intracellular signaling pathways, and regulation of DNA transcription and RNA processing.ConclusionsThe HNSC proteome database is a useful inventory which will allow to specify changes in the cellular protein expression pattern due to specific activated or suppressed pathways during differentiation or proliferation of neural stem cells. Several proteins could be identified in the HNSC proteome which are related to differentiation and plasticity, indicating activated functional pathways. Moreover, we found a protein for which no expression has been described in brain cells before.

Local coupling of cerebral blood flow to cerebral glucose metabolism during inhalational anesthesia in rats: desflurane versus isoflurane.

BACKGROUND It is not known whether the effects of desflurane on local cerebral glucose utilization (LCGU) and local cerebral blood flow (LCBF) are different from those of other volatile anesthetics. METHODS Using the autoradiographic iodoantipyrine and deoxyglucose methods, LCGU, LCBF, and their overall means were measured in 60 Sprague-Dawley rats (10 groups, n = 6 each) during desflurane and isoflurane anesthesia and in conscious controls. RESULTS During anesthesia, mean cerebral glucose utilization was decreased compared with conscious controls: 1 minimum alveolar concentration (MAC) desflurane: -52%; 1 MAC isoflurane: -44%; 2 MAC desflurane: -62%; and 2 MAC isoflurane: -60%. Local analysis showed a reduction of LCGU in the majority of the 40 brain regions analyzed. Mean cerebral blood flow was increased: 1 MAC desflurane: +40%; 1 MAC isoflurane: +43%; 2 MAC desflurane and 2 MAC isoflurane: +70%. LCBF was increased in all brain structures investigated except in the auditory cortex. No significant differences (P < 0.05) could be observed between both anesthetics for mean values of cerebral glucose use and blood flow. Correlation coefficients obtained for the relation between LCGU and LCBF were as follows: controls: 0.95; 1 MAC desflurane: 0.89; 2 MAC desflurane: 0.60; 1 MAC isoflurane: 0.87; and 2 MAC isoflurane: 0.68. CONCLUSION Differences in the physicochemical properties of desflurane compared with isoflurane are not associated with major differences in the effects of both volatile anesthetics on cerebral glucose utilization, blood flow, and the coupling between LCBF and LCGU.

Influence of blood viscosity on blood flow in the forebrain but not hindbrain after carotid occlusion in rats.

That cerebral blood flow remains unchanged at an increased blood viscosity, as long as the vascular supply is not compromised, was tested. To induce a reduced blood supply of some parts of the brain and to keep the supply unchanged in others both carotid arteries were occluded in anesthetized, ventilated rats. By this procedure, blood supply to the rostral brain, but not to the brainstem and cerebellum, was compromised. Blood viscosity was increased by intravenous infusion of 20% polyvinylpyrrolidone (high viscosity group) or decreased by infusion of 5% albumin (low viscosity group). Cerebral blood flow was measured by the [14C]iodoantipyrine method in 50 complete coronal sections of the rostral brain and 22 complete coronal sections of the brainstem and cerebellum in each rat. In the high viscosity group, mean cerebral blood flow of the rostral brain was significantly lower (46 ± 7 mL/100 g−1 · min−1) than in the low viscosity group (82 ± 18 mL/100 g−1 · min−1). No differences could be observed in brainstem and cerebellum between both groups (162 ± 29 mL/100 g−1 · min−1 vs. 156 ± 18 mL/100 g−1 · min−1). Local analysis of cerebral blood flow in different brain structures of the coronal sections showed the same identical results; i.e., in 29 of the 31 brain structures analyzed in rostral brain, local cerebral blood flow was lower in the high viscosity group, whereas no differences could be observed in the 11 brain structures analyzed in the brainstem and cerebellum. It is concluded that under normal conditions cerebral blood flow can be maintained at an increased blood viscosity by a compensatory vasodilation. When the capacity for vasodilation is exhausted by occlusion of supplying arteries, an increased blood viscosity results in a decrease of cerebral blood flow.