Blood cells are transported into the brain and are thought to participate in neurodegenerative processes following hypoxic ischemic injury. We examined the possibility that transient forebrain ischemia (TFI) causes the blood-brain barrier (BBB) to become permeable to blood cells, possibly via dysfunction and degeneration of endothelial cells in rats. Extravasation of Evans blue and immunoglobulin G (IgG) was observed in the hippocampal CA1-2 areas within 8 h after TFI, and peaked at 48 h. This extravasation was accompanied by loss of tight junction proteins, occludin, and zonula occludens-1, and degeneration of endothelial cells in the CA1-2 areas. Iron overload and mitochondrial free radical production were evident in the microvessel endothelium of the hippocampus before endothelial cell damage occurred. Administration of deferoxamine (DFO), an iron chelator, or Neu2000, an antioxidant, blocked free radical production and endothelial cell degeneration. Our findings suggest that iron overload and iron-mediated free radical production cause loss of tight junction proteins and degeneration of endothelial cells, opening of the BBB after TFI.
Animals ; Blood-Brain Barrier/*metabolism ; Capillary Permeability ; Endothelial Cells/*metabolism ; Evans Blue/metabolism ; Free Radicals/metabolism ; Hippocampus/*metabolism/pathology ; Iron/*metabolism ; Ischemic Attack, Transient/pathology/*physiopathology ; Male ; Membrane Proteins/metabolism ; Rats ; Rats, Sprague-Dawley

OBJECTIVE: To explore the expression profile of Ephrin-B2 in the ischemic penumbra after transient focal cerebral ischemia in rats, and to clarify the mechanism of Ephrin-B2 triggering angiogenesis. METHODS: Sprague-Dawley rats were randomly divided into a normal group, a sham operation group and ischemic-reperfusion 1, 3, 7, 14, and 28 d groups. Suture-occluded method was used to establish the focal middle cerebral artery occlusion model and the ischemic brain was reperfused 2 h after the occlusion. Western blot and quantitative real-time reverse-transcription polymerase chain reaction were used to detect the dynamic expression profile of Ephrin-B2 in the penumbra cortex. Double immunofluorescence was used to speculate the location and the co-expression of Ephrin-B2 in blood vessels, neurons and astrocytes. Microvessel density was quantified by the number of CD31+ cells. Rats were subjected to neurologic functional tests by modified neurological severity scores (mNSS) before sacrifice. RESULTS: Compared with the sham group, Ephrin-B2 protein and mRNA level of the penumbra cortex in the ischemic group increased 3 days (P<0.05) after the reperfusion, peaked at day 7 and 14 (P<0.01), and declined at day 28. Double immunofluorescence indicated that Ehprin-b2 was expressed in the neurons, blood vessels and astrocytes; mNSS peaked at day 7, and gradually declined at day 14. The microvessel density of penumbra cortex in the ischemic group increased 3 days (P<0.05) after the reperfusion, peaked at day 14 (P<0.01), and gradually declined at 48 h. CONCLUSION Cerebral ischemia reperfusion induces the over-expression of Ephrin-B2, with a dynamic trend, suggesting that Ehprin-b2 may improve post-stroke functional recovery by enhancing angiogenesis and neurogenesis.
Animals ; Astrocytes ; metabolism ; Brain ; pathology ; Brain Ischemia ; metabolism ; Cerebral Cortex ; metabolism ; Ephrin-B2 ; metabolism ; Infarction, Middle Cerebral Artery ; Ischemic Attack, Transient ; Neurons ; metabolism ; Rats ; Rats, Sprague-Dawley ; Reperfusion Injury ; metabolism

Neurogenesis can be induced by pathological conditions such as cerebral ischemia. However the molecular mechanisms or modulating reagents of the reactive neurogenesis after the cerebral ischemia are poorly characterized. Retinoic acid (RA) has been shown to increase neurogenesis by enhancing the proliferation and neuronal differentiation of forebrain neuroblasts. Here, we examined whether RA can modulate the reactive neurogenesis after the cerebral ischemia. In contrast to our expectation, RA treatment decreased the reactive neurogenesis in subventricular zone (SVZ), subgranular zone (SGZ) and penumbral region. Furthermore, RA treatment also decreased the angiogenesis and gliosis in penumbral region.
Animals ; Brain/blood supply ; Cell Differentiation ; Cell Proliferation ; Ischemic Attack, Transient/metabolism/*pathology ; Male ; Neovascularization, Pathologic ; Neuroglia/pathology/physiology ; Neurons/pathology/*physiology ; Rats ; Rats, Sprague-Dawley ; Tretinoin/*pharmacology/physiology

OBJECTIVETo study the changes of insulin-like growth factor-I (IGF-I) in focal cerebral ischemical reperfusion injury model.

METHODSFocal cerebral ischemia was induced in rats using filament method, and the expressions of IGF-I was detected with immunohistochemical staining.

RESULTSThe expression of IGF-I was very low in normal brain tissues, but increased in the infracted area and penumbra after cerebral ischemia. The expressions of IGF-I reached the peak level of 14.83-/+0.48 at days 3 after reperfusion.

CONCLUSIONFocal cerebral ischemia reperfusion injury enhances the expression of endogenous IGF-I.

Animals ; Female ; Immunohistochemistry ; Infarction, Middle Cerebral Artery ; metabolism ; pathology ; Insulin-Like Growth Factor I ; biosynthesis ; Ischemic Attack, Transient ; metabolism ; Male ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Reperfusion Injury ; metabolism

OBJECTIVETo investigate the effect of dauricine on the apoptosis of neuronal cells and the expression of apoptosis-related proteins in the brain penumbra of rats induced by transient focal cerebral ischemia-reperfusion injury.

METHODMale SD rats were randomly divided into five groups: sham group (Sham), model group (Model), and Dauricine groups of low, middle and high doses. To make the transient focal cerebral ischemia-reperfusion injury model, the middle cerebral artery on the right side of rat was occluded by inserting a nylon suture through the internal carotid artery for 1 h, followed by reperfusion for 24 h after withdrawing the suture. Dauricine groups, different doses of Dauricine (2.5, 5, 10 mg x kg(-1) as low, middle and high dose respectively) were administered intraperitoneally at the beginning of the cerebral ischemia, and at 11 h and 23 h after reperfusion. At the same time, Sham group and Model group was administered saline as controls. Brain samples of rats were treated with paraformaldehyde perfusion fixation 24 h after blood reperfusion and then collected for making pathological sections. Apoptotic changes of neuronal cells in the brain penumbra of rat were evaluated in situ by terminal deoxyribonucleotidyl transferasemediated dUTP-digoxigenin nick end-labelling (TUNEL). Cytochrome C (Cyt-C) release and the expression of caspase -3 and caspase -9 proteins of the ischemic-reperfusion brain tissue were determined by immunohistochemistry assay.

RESULTTUNEL-positive cells in groups of middle and high doses of dauricine (18.9 +/- 2.02 and 15.9 +/- 2.9 cells/mm2 respectively) decreased significantly compared with model group (25.5 +/- 3.3 cells/mm2, P<0.05). Cyt-C release and the expression of caspase-3 and caspase-9 proteins in groups of middle and high doses of dauricine were also inhibited compared with Model group (P<0.01).

CONCLUSIONThe mechanism of the neuroprotective effect of dauricine after cerebral ischemia-reperfusion injury may parly, related with an inhibition of neuronal cells apoptosis in the penumbra.

Animals ; Apoptosis ; drug effects ; Benzylisoquinolines ; pharmacology ; Caspases ; metabolism ; Cytochromes c ; metabolism ; Dose-Response Relationship, Drug ; Gene Expression Regulation ; drug effects ; Ischemic Attack, Transient ; surgery ; Male ; Neuroprotective Agents ; pharmacology ; Rats ; Reperfusion Injury ; metabolism ; pathology ; prevention & control ; Tetrahydroisoquinolines ; pharmacology

Artemisia capillaris Thunberg is a medicinal plant used as a traditional medicine in many cultures. It is an effective remedy for liver problems including hepatitis. Recent pharmacological reports have indicated that Artemisia species can exert various neurological effects. Previously, we reported a memory-enhancing effect of Artemisia species. However, the mechanisms underlying the neuroprotective effect of A. capillaris (AC) are still unknown. In the present study, we investigated the effect of an ethanol extract of AC on ischemic brain injury in a mouse model of transient forebrain ischemia. The mice were treated with AC for seven days, beginning one day before induction of transient forebrain ischemia. Behavioral deficits were investigated using the Y-maze. Nissl and Fluoro-jade B staining were used to indicate the site of injury. To determine the underlying mechanisms for the drug, we measured acetylcholinesterase activity. AC (200 mg·kg) treatment reduced transient forebrain ischemia-induced neuronal cell death in the hippocampal CA1 region. The AC-treated group also showed significant amelioration in the spontaneous alternation of the Y-maze test performance, compared to that in the untreated transient forebrain ischemia group. Moreover, AC treatment showed a concentration-dependent inhibitory effect on acetylcholinesterase activity in vitro. Finally, the effect of AC on forebrain ischemia was blocked by mecamylamine, a nonselective nicotinic acetylcholine receptor antagonist. Our results suggested that in a model of forebrain ischemia, AC protected against neuronal death through the activation of nicotinic acetylcholine receptors.
Acetylcholinesterase ; metabolism ; Animals ; Artemisia ; Cell Death ; drug effects ; Cholinergic Antagonists ; pharmacology ; Disease Models, Animal ; Ethanol ; chemistry ; Hippocampus ; pathology ; physiopathology ; Ischemic Attack, Transient ; drug therapy ; pathology ; physiopathology ; Male ; Mecamylamine ; pharmacology ; Memory ; drug effects ; Mice ; Mice, Inbred C57BL ; Models, Neurological ; Neuroprotective Agents ; administration & dosage ; pharmacology ; Phytotherapy ; Plant Components, Aerial ; chemistry ; Plant Extracts ; administration & dosage ; pharmacology ; Receptors, Cholinergic ; metabolism