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Changes in the Tyrosine Phosphorylation of Mitogen‐Activated Protein Kinase in the Rat Hippocampus During and Following Severe Hypoglycemia

Abstract: The changes in the levels of tyrosine‐phosphorylated proteins in the cytosolic fraction of the rat hippocampus subjected to severe hypoglycemia were analyzed. A marked increase in tyrosine phosphorylation of a 43‐kDa protein was observed at 30 min of isoelectric EEG and 30 min and 1 h of recovery. Immunostaining of the same blot with antibody against mitogen‐activated protein (MAP) kinas

Stress-induced inhibition of protein synthesis initiation : Modulation of initiation factor 2 and guanine nucleotide exchange factor activities following transient cerebral ischemia in the rat

Neuronal protein synthesis is severely depressed following stress such as heat-shock, hypoxia, and hypoglycemia. Following reversible cerebral ischemia, protein synthesis is transiently inhibited in ischemia-resistant areas, but persistently depressed in vulnerable brain regions. Eukaryotic initiation factor 2 (elF-2) activity, that is, the formation of the ternary complex elF-2 · GTP · initiator

Ischemia-induced upregulation of excitatory amino acid transport sites

The response of excitatory amino acid transporter binding sites in the rat brain to 10 min of cerebral ischemia induced by bilateral common carotid occlusion combined with hypotension was examined. We observed a transient increase in the density of transporter binding sites that was first noticeable at 5 min post-recovery and persisted for 48 h. The increase in binding sites was found throughout t

Time Course of the Translocation and Inhibition of Protein kinase C During Complete Cerebral Ischemia in the Rat

Abstract: The time course for the ischemia‐induced changes in the subcellular distribution of protein kinase C (PKC) (α), (β311). and (γ) and the activity of PKC were studied in the neocortex of rats subjected to 1, 2, 3, 5, 10, and 15 min of global cerebral ischemia. In the particulate fraction, a 14‐fold increase in PKC (γ) levels was seen at 3 min of ischemia, which further increased at 5–15 mi

Changes in tyrosine phosphorylation in neocortex following transient cerebral ischaemia

Growth factor receptors activate protein tyrosine kinases, which are important for cell growth and survival. The protein tyrosine kinase (PTK) activity and the levels of phosphotyrosine (Ptyr) containing proteins were studied in the rat neocortex exposed to 15 min of transient cerebral ischaemia. The levels of the Ptyr containing proteins increase during recovery in the synaptosomal fraction, whil

Changes in insulin-like growth factor 1 receptor density after transient cerebral ischemia in the rat : Lack of protection against ischemic brain damage following injection of insulin-like growth factor 1

Binding of 125I-insulin-like growth factor-1 (125I-IGF-1) to rat brain slices was studied after 15 min of two-vessel occlusion ischemia and 1 h to 4 days of recirculation. Ligand binding in the hippocampus increased at 6 h post ischemia in the CA1 and CA3 regions and the dentate gyrus, suggesting that the IGF-1 receptors were up-regulated, while no change was seen in neocortex and striatum. Intrac

Cerebral protection by AMPA- and NMDA-receptor antagonists administered after severe insulin-induced hypoglycemia

Excitatory amino acids are implicated in the development of neuronal cell damage following periods of reversible cerebral ischemia or insulin-induced hypoglycemic coma. To explore the importance of glutamate receptor activation in the posthypoglycemic phase, we exposed rats to 20 min of insulin-induced severe hypoglycemia. The rats were treated immediately after the hypoglycemic insult with four r

NMDA‐receptor blockers but not NBQX, an AMPA‐receptor antagonist, inhibit spreading depression in the rat brain

The effect of different glutamate‐receptor antagonists on the induction of cortical spreading depression of Leao and of cortical anoxic membrane depolarization were investigated in the anaesthetized rat. Spreading depression (SD), elicited by mechanical stimulation of the cortical surface, was inhibited by the non‐competitive N‐methyl‐d‐aspartate (NMDA)‐receptor blocker, (±)‐5‐methyl‐10,11‐dihydro

Brain cortical tissue levels of noradrenaline and its glycol metabolites : effects of ischemia and postischemic administration of idazoxan

The brain noradrenaline (NA) system is known to modulate ischemic neuronal damage, and the turnover of NA has been suggested to increase in the early recovery period following cerebral ischemia. Using HPLC and gas chromatography-mass spectrometry we analyzed the tissue levels of NA and its metabolites, 3,4-dihydroxyphenylethyleneglycol (DHPG) and 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG), in

Ultrastructural changes in the hippocampal CA1 region following transient cerebral ischemia : evidence against programmed cell death

The ultrastructural changes in the pyramidal neurons of the CA1 region of the hippocampus were studied 6 h, 24 h, 48 h, and 72 h following a transient 10 min period of cerebral ischemia induced by common carotid occlusion combined with hypotension. The pyramidal neurons showed delayed neuronal death (DND), i.e. at 24 h and 48 h postischemia few structural alterations were noted in the light micros

Postischemic blockade of AMPA but not NMDA receptors mitigates neuronal damage in the rat brain following transient severe cerebral ischemia

Glutamatergic transmission is an important factor in the development of neuronal death following transient cerebral ischemia. In this investigation the effects of N-methyl-D-aspartate (NMDA) and non-NMDA receptor antagonists on neuronal damage were studied in rats exposed to 10 min of transient cerebral ischemia induced by bilateral common carotid occlusion combined with hypotension. The animals w

Effects of ischemia on regional ligand binding to adrenoceptors in the rat brain

Changes in ligand binding to adrenoceptors ([3H]prazosin to α1-receptors, [3H]idazoxan to α2-receptors and [125I]cyanopindolol to β-receptors) following transient cerebral ischemia were investigated using autoradiographic methods. The binding was quantified in brain sections from control rats, rats subjected to 15 min of 2-vessel occlusion ischemia, and rats with recirculation times of 1 h, 1 week

Changes in the Activity of Protein Kinase C and the Differential Subcellular Redistribution of Its Isozymes in the Rat Striatum During and Following Transient Forebrain Ischemia

Abstract: The changes in the levels of protein kinase C [PKC(α, βII, γ)] were studied in cytosolic and particulate fractions of striatal homogenates from rats subjected to 15 min of cerebral ischemia induced by bilateral occlusion of the common carotid arteries and following 1 h, 6 h, and 48 h of reperfusion. During ischemia the levels of PKC(βII) and ‐(γ) increased in the particulate fraction to

Hypothermia Prevents the Ischemia‐Induced Translocation and Inhibition of Protein Kinase C in the Rat Striatum

: The effect of hypothermia on the ischemia‐induced changes in the subcellular distribution of protein kinase C (PKC)(γ), ‐(βII), and ‐(α) and the activity of PKC was studied in striatal homogenates of rats subjected to 20 min of cerebral ischemia. The effect of post‐ischemic cooling was also studied. During normothermic ischemia, PKC(γ) and ‐(βII) increased 3.9‐and 2.9‐fold, respectively, in the

Lack of protection by the N-methyl-D-asparate receptor blocker dizocilpine (MK-801) after transient severe cerebral ischemia in the rat

Glutamate is an important factor in the mechanisms of neuronal damage following cerebral ischemia. Blockade of one type of glutamate receptor, the N-methyl-D-aspartate (NMDA) receptor, decreases brain infarct size in experimental models of permanent focal ischemia, but protection in models of transient reversible ischemia is ambiguous. We investigated the effect of the noncompetitive NMDA receptor

Changes in pyruvate dehydrogenase complex activity during and following severe insulin-induced hypoglycemia

The effect of severe insulin-induced hypoglycemia on the activity of the pyruvate dehydrogenase enzyme complex (PDHC) was investigated in homogenates of frozen rat cerebral cortex during burst suppression EEG, after 10, 30, and 60 min of isoelectric EEG, and after 30 and 180 min and 24 h of recovery following 30 min of hypoglycemic coma. Changes in PDHC activity were correlated to levels of labile

High-Resolution Proton Magnetic Resonance Study of Porcine Colipase and Its Interactions with Taurodeoxycholate

A high-resolution 270-MHz proton NMR study of procine colipase I has been performed, and the resonances in the aromatic region of the spectrum have been assigned to amino acid residues by pH titration and decoupling experiments. The apparent pKa values of the three tyrosines were calculated to be 10.2, 10.3, and 11.8 with one of the tyrosines having properties of a “buried” residue. A tentative as