Search results

Abstract: Activation of trophic factor receptors stimulates tyrosine phosphorylation on proteins and supports neuronal survival. We report that in the recovery phase following reversible cerebral ischemia, tyrosine phosphorylation increases in the membrane fraction of the resistant hippocampal CA3/dentate gyrus (DG) region, whereas in the sensitive CA1 region or striatum, tyrosine phosphorylation

Protein synthesis, measured as [14C]-leucine incorporation into proteins, was studied in the normothermic rat brain following 15 min of transient cerebral ischaemia and 1 h, 24 h and 48 h of recirculation, and in the hypothermic (33°C) brain following 1 h and 48 h of recirculation. Ischaemia was induced by bilateral common carotid occlusion combined with hypotension. Following normothermic ischaem

Stress, such as heat-shock, hypoxia and hypoglycemia, inhibits the initiation of protein synthesis. The effects of heat-shock on protein synthesis, eucaryotic initiation factor 2 (eIF-2) activity, protein kinase C (PKC), and casein kinase II (CKII) activities were studied in primary cortical neuronal cultures. In neurons exposed to heat-shock at 44°C for 20 min, protein synthesis is inhibited by m

Abstract: Casein kinase II (CKII) is a protein kinase acting in the intracellular cascade of reactions activated by growth factor receptors, and that has a profound influence on cell proliferation and survival. In this investigation, we studied the changes in the activity and levels of CKII in the rat brain exposed to 10. 15 and 20 min of transient forebrain ischemia followed by variable periods o

Intraischemic moderate hypothermia generally protects the brain against ischemic cell death, while hypothermia instigated several hours into the reperfusion phase is considered to be less effective. Here we report the effect of hypothermia (32.5°-33.5°C) of 5-h duration, initiated at 2, 6, 12, 24 and 36 h into the recirculation phase following 10 min of transient cerebral ischemia, on ischemic neu

Abstract— Growth factors stimulate cellular protein synthesis, but the intracellular signaling mechanisms that regulate initiation of mRNA translation in neurons have not been clarified. A rate‐limiting step in the initiation of protein synthesis is the formation of the ternary complex among GTP, eukaryotic initiation factor 2 (elF‐2), and the initiator tRNA. Here we report that genistein, a speci

Following stress such as heat shock or transient cerebral ischemia, global brain protein synthesis initiation is depressed through modulation of eucaryotic initiation factor (eIF) activities, and modification of ribosomal subunits. Concomitantly, expression of a certain class of mRNA, heat-shock protein (HSP) mRNA, is induced. Here we report that the activity of eucaryotic initiation factor-2 (eIF

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

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

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

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

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

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

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

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

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

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

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

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