endothelin-1 and Cerebral-Infarction

Serum biomarkers are associated with hemorrhagic transformation and brain edema after cerebral infarction. However, whether serum biomarkers predict hemorrhagic transformation in large vessel occlusion stroke even after mechanical thrombectomy, which has become widely used, remains uncertain. In this prospective study, we enrolled patients with large vessel occlusion stroke in the anterior circulation. We analyzed 91 patients with serum samples obtained on admission. The levels of matrix metalloproteinase-9 (MMP-9), amyloid precursor protein (APP) 770, endothelin-1, S100B, and claudin-5 were measured. We examined the association between serum biomarkers and hemorrhagic transformation within one week. Fifty-four patients underwent mechanical thrombectomy, and 17 patients developed relevant hemorrhagic transformation (rHT, defined as hemorrhagic changes ≥ hemorrhagic infarction type 2). Neither MMP-9 (no rHT: 46 ± 48 vs. rHT: 15 ± 4 ng/mL, P = 0.30), APP770 (80 ± 31 vs. 85 ± 8 ng/mL, P = 0.53), endothelin-1 (7.0 ± 25.7 vs. 2.0 ± 2.1 pg/mL, P = 0.42), S100B (13 ± 42 vs. 12 ± 15 pg/mL, P = 0.97), nor claudin-5 (1.7 ± 2.3 vs. 1.9 ± 1.5 ng/mL, P = 0.68) levels on admission were associated with subsequent rHT. When limited to patients who underwent mechanical thrombectomy, the level of claudin-5 was higher in patients with rHT than in those without (1.2 ± 1.0 vs. 2.1 ± 1.7 ng/mL, P = 0.0181). APP770 levels were marginally higher in patients with a midline shift ≥ 5 mm than in those without (79 ± 29 vs. 97 ± 41 ng/mL, P = 0.084). The predictive role of serum biomarkers has to be reexamined in the mechanical thrombectomy era because some previously reported serum biomarkers may not predict hemorrhagic transformation, whereas the level of APP770 may be useful for predicting brain edema.

Topics: Aged; Aged, 80 and over; Amyloid beta-Protein Precursor; Biomarkers; Brain Edema; Cerebral Infarction; Cerebrovascular Disorders; Claudin-5; Endothelin-1; Female; Gene Expression; Humans; Male; Matrix Metalloproteinase 9; Predictive Value of Tests; Prospective Studies; S100 Calcium Binding Protein beta Subunit; Stroke; Thrombectomy

Large cerebral infarctions are major predictors of death and severe disability from stroke. Conversely, data concerning these types of infarctions and the affected adjacent brain circuits are scarce. It remains to be determined if the co-morbid concurrence of large infarct and β-amyloid (Aβ) toxicity can precipitate the early development of dementia. Here, we described a dose-dependent effect of a unilateral striatal injection of vasoconstrictive endothelin-1 (ET-1) along with Aβ toxicity on CNS pathogenesis; driven by the anatomical and functional networks within a brain circuit. After 21 days of treatment, a high dose (60 pmol) of ET-1 (E60) alone caused the greatest increase in neuroinflammation, mainly in the ipsilateral striatum and distant regions with synaptic links to the striatal lesion such as white matter (subcortical white matter, corpus callosum, internal capsule, anterior commissure), gray matter (globus pallidus, thalamus), and cortices (cingulate, motor, somatosensory, entorhinal). The combined E60 + Aβ treatment also extended perturbation in the contralateral hemisphere of these rats, such as increased deposition of amyloid precursor protein fragments associated with the appearance of degenerating cells and the leakage of laminin from the basement membrane across a compromised blood-brain barrier. However, the cerebral damage induced by the 6 pmol ET-1 (E6), Aβ and E6 + Aβ rats was not detrimental enough to injure the complete network. The appreciation of the causal interactions among distinct anatomical units in the brain after ischemia and Aβ toxicity will help in the design of effective and alternative therapeutics that may disassociate the synergistic or additive association between the infarcts and Aβ toxicity.

Topics: Amyloid beta-Peptides; Animals; Brain; Cerebral Infarction; Endothelin-1; Injections, Intraventricular; Male; Nerve Net; Rats; Rats, Wistar

In preclinical stroke models, improvement in motor performance is associated with reorganization of cortical motor maps. However, the temporal relationship between performance gains and map plasticity is not clear.. This study was designed to assess the effects of rehabilitative training on the temporal dynamics of behavioral and neurophysiological endpoints in a rat model of focal cortical infarct.. Eight days after an ischemic infarct in primary motor cortex, adult rats received either rehabilitative training or were allowed to recover spontaneously. Motor performance and movement quality of the paretic forelimb was assessed on a skilled reach task. Intracortical microstimulation mapping procedures were conducted to assess the topography of spared forelimb representations either at the end of training (post-lesion day 18) or at the end of a 3-week follow-up period (post-lesion day 38).. Rats receiving rehabilitative training demonstrated more rapid improvement in motor performance and movement quality during the training period that persisted through the follow-up period. Motor maps in both groups were unusually small on post-lesion day 18. On post-lesion day 38, forelimb motor maps in the rehabilitative training group were significantly enlarged compared with the no-rehab group, and within the range of normal maps.. Postinfarct rehabilitative training rapidly improves motor performance and movement quality after an ischemic infarct in motor cortex. However, training-induced motor improvements are not reflected in spared motor maps until substantially later, suggesting that early motor training after stroke can help shape the evolving poststroke neural network.

Topics: Animals; Biomechanical Phenomena; Brain Ischemia; Brain Mapping; Cerebral Infarction; Disease Models, Animal; Electric Stimulation; Endothelin-1; Forelimb; Male; Motor Activity; Physical Conditioning, Animal; Psychomotor Performance; Rats; Rats, Long-Evans; Recovery of Function

In a porcine ischemic stroke model, we sought to compare the acute predicted infarct core volume (PIV) defined by CT perfusion (CTP)-hemodynamic parameters and MR-diffusion-weighted imaging (MR-DWI)/apparent diffusion coefficient (ADC), with the true infarct core volume (TIV) as defined by histology. Ten Duroc-cross pigs had a CTP scan prior to injection of endothelin-1 (ET-1) into the left striatum. CTP scans were used to monitor ischemic progression. A second dose of ET-1 was injected 2 h from the first injection. The animal was moved to a 3-T MRI scanner where DWI was performed. CTP imaging was acquired immediately after the MR imaging. Next, the brain was removed and stained with tetrazolium chloride (TTC). Linear regression and Bland-Altman plots were used to correlate the PIV measured by each imaging modality to that of the TIV from the histological gold standard. The CTP-cerebral blood flow (CBF) parameter had the highest R (2) value and slope closest to unity, while the CTP-cerebral blood volume (CBV) had the lowest R(2) value and slope furthest away from unity. The CTP-CBF • CBV product parameter had a higher R(2) value but lower slope than both MR parameers. The best Bland-Altman agreement was observed with the CTP-CBF parameter. PIV from MR-DWI, ADC, and CTP-CBF overestimated the TIV defined with histology. We show that the PIV defined with absolute gray and white matter CT-CBF thresholds correlates best with the TIV and is similar to both MR-DWI and ADC-defined PIVs. Further, the acute CBF • CBV mismatch may not indicate penumbral tissue in the acute stroke setting.

Topics: Animals; Brain; Cerebral Infarction; Corpus Striatum; Diffusion Magnetic Resonance Imaging; Disease Models, Animal; Endothelin-1; Neuroimaging; Regression Analysis; Stroke; Swine; Tomography, X-Ray Computed

The angiotensin-converting enzyme 2/angiotensin-(1-7)/Mas axis represents a promising target for inducing stroke neuroprotection. Here, we explored stroke-induced changes in expression and activity of endogenous angiotensin-converting enzyme 2 and other system components in Sprague-Dawley rats. To evaluate the clinical feasibility of treatments that target this axis and that may act in synergy with stroke-induced changes, we also tested the neuroprotective effects of diminazene aceturate, an angiotensin-converting enzyme 2 activator, administered systemically post stroke. Among rats that underwent experimental endothelin-1-induced ischemic stroke, angiotensin-converting enzyme 2 activity in the cerebral cortex and striatum increased in the 24 hours after stroke. Serum angiotensin-converting enzyme 2 activity was decreased within 4 hours post stroke, but rebounded to reach higher than baseline levels 3 days post stroke. Treatment after stroke with systemically applied diminazene resulted in decreased infarct volume and improved neurological function without apparent increases in cerebral blood flow. Central infusion of A-779, a Mas receptor antagonist, resulted in larger infarct volumes in diminazene-treated rats, and central infusion of the angiotensin-converting enzyme 2 inhibitor MLN-4760 alone worsened neurological function. The dynamic alterations of the protective angiotensin-converting enzyme 2 pathway after stroke suggest that it may be a favorable therapeutic target. Indeed, significant neuroprotection resulted from poststroke angiotensin-converting enzyme 2 activation, likely via Mas signaling in a blood flow-independent manner. Our findings suggest that stroke therapeutics that target the angiotensin-converting enzyme 2/angiotensin-(1-7)/Mas axis may interact cooperatively with endogenous stroke-induced changes, lending promise to their further study as neuroprotective agents.

Topics: ADAM Proteins; ADAM17 Protein; Angiotensin II; Angiotensin-Converting Enzyme 2; Animals; Cerebral Cortex; Cerebral Infarction; Cerebrovascular Circulation; Corpus Striatum; Diminazene; Disease Models, Animal; Endothelin-1; Enzyme Activation; Imidazoles; Infarction, Middle Cerebral Artery; Infusions, Intraventricular; Leucine; Male; Neuroprotective Agents; Peptide Fragments; Peptidyl-Dipeptidase A; Proto-Oncogene Mas; Proto-Oncogene Proteins; Random Allocation; Rats; Rats, Sprague-Dawley; Receptors, G-Protein-Coupled; Renin-Angiotensin System; RNA, Messenger

Small subcortical infarcts account for 25% of all ischemic strokes. Although once considered to be a small vessel disease with a favorable outcome, recent studies have reported relatively poor long-term prognoses following small subcortical infarcts. Limited pre-clinical modeling has hampered understanding of the etiology and development of treatments for this disease. Therefore, we attempted to develop a new experimental model of small subcortical infarcts in mice to investigate pathophysiological changes in the corticospinal tract and assess long-term behavioral performance. The vasoconstrictor peptide, endothlin-1 (ET-1), in combination with the nitric oxide synthase inhibitor, N(G)-nitro-l-arginine methyl ester (l-NAME), were injected into the internal capsule of mice. Histological and behavioral tests were performed 0-8 weeks after the injection. The ET-1/l-NAME injection resulted in severe neurological deficits that continued for up to 8 weeks. The loss of axons and myelin surrounded by reactive gliosis was identified in the region of the injection, in which the vasoconstriction of microvessels was also observed. Moreover, a tract-tracing study revealed an interruption in axonal flow at the internal capsule. The present model of small subcortical infarcts is unique and novel due to the reproduction of neurological deficits that continue for a long period, up to 8 weeks, as well as the use of mice as experimental animals. The reproducibility, simplicity, and easy adoptability make the present model highly appealing for use in further pre-clinical studies on small subcortical infarcts.

Topics: Animals; Cerebral Infarction; Disease Models, Animal; Endothelin-1; Internal Capsule; Male; Mice; Mice, SCID; NG-Nitroarginine Methyl Ester; Psychomotor Performance; Stroke; Time Factors

To investigate the protective effect of catalpol on cerebral ischaemia/reperfusion (CI/R) injury in gerbils and further explore the underlying mechanism.. A gerbil model of CI/R was prepared by bilateral common carotid occlusion for 10 min followed by 6 h reperfusion. Catalpol (5, 10 or 20 mg/kg per day) was injected intraperitoneally for 3 days before the carotid occlusion. Stroke index was measured during the reperfusion. The contents of endogenous neuropeptides, endothelin-1 (ET-1) and calcitonin gene-related peptide in plasma were evaluated by radioimmunoassay. Superoxide dismutase (SOD) and malondialdehyde (MDA) in brain tissue homogenate were also examined.. The results showed that catalpol significantly improved the stroke index compared with CI/R control group (P < 0.05 or P < 0.01). Catalpol significantly increased the activity of SOD at the doses of 10 and 20 mg/kg (P ≤ 0.05), decreased the brain MDA content and the plasma level of ET-1 at the doses of 10 and 20 mg/kg (P ≤ 0.01).. These data suggested that the efficacy of catalpol pretreatment on CI/R injury may be attributed to reduction of free radicals and inhibition of lipid peroxidation and ET-1 production.

Topics: Animals; Brain; Brain Ischemia; Calcitonin Gene-Related Peptide; Cerebral Infarction; Disease Models, Animal; Endothelin-1; Female; Free Radicals; Gerbillinae; Injections, Intraperitoneal; Iridoid Glucosides; Lipid Peroxidation; Male; Malondialdehyde; Neuropeptides; Oxidative Stress; Phytotherapy; Plant Extracts; Rehmannia; Reperfusion Injury; Stroke; Superoxide Dismutase

Small subcortical white matter infarcts are a common stroke subtype often associated with cognitive deficits. The lack of relevant models confined to white matter has limited the investigation of its pathophysiology. Here, we examine tissue and functional outcome after an ischemic lesion within corpus callosum in wild-type (WT) mice and in mice null for a gene, NOTCH3, linked to white matter ischemic injury in patients.. WT and NOTCH3 knockout mice were subjected to stereotactic microinjections of the potent vasoconstrictor endothelin-1 at the level of periventricular white matter to induce a focal ischemic lesion. Infarct location was confirmed by MRI, and brains were examined for lesion size and histology; behavioral deficits were assessed ≤1 month in WT mice.. Ischemic damage featured an early cerebral blood flow deficit, blood-brain barrier opening, and a lesion largely confined to white matter. At later stages, myelin and axonal degeneration and microglial/macrophage infiltration were found. WT mice displayed prolonged cognitive deficit when tested using a novel object recognition task. NOTCH3 mutants showed larger infarcts and greater cognitive deficit at 7 days post stroke.. Taken together, these data show the usefulness of microinjections of endothelin-1 into periventricular white matter to study focal infarcts and cognitive deficit in WT mice. In short-term studies, stroke outcome was worse in NOTCH3 null mice, consistent with the notion that the lack of the NOTCH3 receptor affects white matter stroke susceptibility.

Topics: Animals; Behavior, Animal; Cerebral Infarction; Corpus Callosum; Disease Models, Animal; Endothelin-1; Genetic Predisposition to Disease; Leukoencephalopathies; Male; Memory Disorders; Mice; Mice, Inbred C57BL; Mice, Knockout; Random Allocation; Receptor, Notch3; Receptors, Notch; Recognition, Psychology

Aging is a major risk factor for cerebrovascular disease. Growth hormone (GH) and its anabolic mediator, insulin-like growth factor (IGF)-1, decrease with advancing age and this decline has been shown to promote vascular dysfunction. In addition, lower GH/IGF-1 levels are associated with higher stroke mortality in humans. These results suggest that decreased GH/IGF-1 level is an important factor in increased risk of cerebrovascular diseases. This study was designed to assess whether GH/IGF-1-deficiency influences the outcome of cerebral ischemia. We found that endothelin-1-induced middle cerebral artery occlusion resulted in a modest but nonsignificant decrease in cerebral infarct size in GH/IGF-1 deficient dw/dw rats compared with control heterozygous littermates and dw/dw rats with early-life GH treatment. Expression of endothelin receptors and endothelin-1-induced constriction of the middle cerebral arteries were similar in the three experimental groups. Interestingly, dw/dw rats exhibited reduced brain edema and less astrocytic infiltration compared with their heterozygous littermates and this effect was reversed by GH-treatment. Because reactive astrocytes are critical for the regulation of poststroke inflammatory processes, maintenance of the blood-brain barrier and neural repair, further studies are warranted to determine the long-term functional consequences of decreased astrocytic activation in GH/IGF-1 deficient animals after cerebral ischemia.

Topics: Aging; Animals; Astrocytes; Brain Edema; Brain Ischemia; Cerebral Infarction; Disease Models, Animal; Dwarfism; Endothelin-1; Female; Growth Hormone; Insulin-Like Growth Factor I; Male; Rats; Rats, Inbred Lew; Rats, Mutant Strains

Constraint-induced movement therapy (CIMT) is an effective treatment promoting motor recovery of upper extremity function in stroke patients. The objective of the present study was to determine the effect of CIMT on the evoked potentials in rats with focal cerebral cortical ischemia induced by endothelin-1 (ET-1). Thirty rats were randomly assigned to the sham, infarct or CIMT groups. ET-1 was injected stereotaxically into the forelimb area of the cerebral cortex in the dominant hemisphere. Custom-made constraint jackets were applied to limit movement of the unaffected forelimb in the CIMT group. Motor and sensory function of the forelimb was evaluated by a pellet retrieval task and forearm asymmetry test. Electrophysiologic changes were evaluated by motor-evoked potentials (MEPs) and somatosensory-evoked potentials (SEPs). The location and extent of cerebral ischemia were confirmed and compared histologically. The CIMT group showed better recovery in the pellet retrieval task. Forelimb use was more symmetrical in the CIMT group. The waveform of the SEP was reversed and delayed in the infarct group, but it was preserved in the CIMT group with amplitude decrease only. The estimated volume of infarction was smaller in the CIMT group, although statistically not significant. The results demonstrate that CIMT can promote recovery of motor function in focal cerebral cortical infarcts, and that recovery may be related to reorganization of the cerebral neuronal network in the somatosensory pathway.

Topics: Animals; Cerebral Cortex; Cerebral Infarction; Endothelin-1; Evoked Potentials, Motor; Evoked Potentials, Somatosensory; Forelimb; Male; Motion Therapy, Continuous Passive; Movement; Rats; Rats, Sprague-Dawley

In young adult rats, unilateral lesions of the sensorimotor cortex lead to neuronal structural plasticity and synaptogenesis in the contralateral motor cortex, which is connected to the lesion site by transcallosal fibers. The contralesional neural plasticity varies with lesion size and results from the convergence of denervation-induced reactive plasticity and behavioral asymmetries. It was unknown whether similar effects occur in older animals. Furthermore, the coordination of synaptic responses with that of perisynaptic astrocytes had not been investigated. In this study, middle-aged rats (14-16 months old) were given sham-operations or unilateral ischemic lesions of the sensorimotor cortex. Fifty days later, numerical densities of neurons and synapses and morphological characteristics of astrocytic processes in layer V of the contralesional motor cortex were measured using stereological light and electron microscopy methods. Lesions resulted in behavioral asymmetries, but no significant synapse addition in the contralesional motor cortex. Synapse number per neuron was negatively correlated with lesion size and reduced opposite larger lesions compared with smaller ones. Astrocytic changes were also lesion size-dependent. Astrocytic hypertrophy was observed only after smaller lesions and was associated with greater coverage and greater numbers of synapses. These findings are consistent with those in younger rats indicating an inverse relationship between lesion size and adaptive neuronal restructuring in denervated cortex. However, they indicate that the synaptogenic reaction to this lesion is relatively limited in older animals. Finally, the results indicate that structural plasticity of perisynaptic astrocytes parallels, and could play a role in shaping, synaptic responses to postischemic denervation.

Topics: Animals; Astrocytes; Axons; Behavior, Animal; Brain Ischemia; Cerebral Cortex; Cerebral Infarction; Dendrites; Endothelin-1; Forelimb; Functional Laterality; Male; Microscopy, Electron, Transmission; Motor Cortex; Nerve Degeneration; Neurons; Neuropil; Posture; Rats; Rats, Long-Evans; Somatosensory Cortex; Synapses; Vasoconstrictor Agents

Diabetes increases the risk of as well as poor outcome after stroke. Matrix metalloprotease (MMP) activation disrupts blood-brain barrier integrity after cerebral ischemia. We have previously shown that type 2 diabetes promotes remodeling of middle cerebral arteries (MCA) characterized by increased media/lumen (M/L) ratio and MMP activity in an endothelin (ET)-1-dependent manner in the Goto-Kakizaki (GK) rat model. In the present study, we examined the effects of ET-1-mediated vascular remodeling on neurovascular damage following cerebral ischemic injury in GK rats 5 and 12 weeks after the onset of diabetes. The MCA structure, cerebral perfusion as well as infarct size, and hemorrhage were measured in control and diabetic rats subjected to transient MCA occlusion. M/L ratio was increased after 12 but not 5 weeks of diabetes. The baseline cerebral perfusion was lower and the infarct volume smaller in diabetic rats in both age groups. The incidence of hemorrhagic transformation was higher after 5 weeks of diabetes as compared to that after 12 weeks or in the control groups. These findings provide evidence that ET-1-mediated cerebrovascular remodeling does not worsen the neurovascular damage of ischemic brain injury in diabetes. It is possible that this early remodeling response is compensatory in nature to regulate vascular tone and integrity, especially when ischemia is layered on diabetic vascular disease.

Topics: Animals; Blood Glucose; Cerebral Hemorrhage; Cerebral Infarction; Cerebrovascular Circulation; Collagen; Diabetes Mellitus, Type 2; Disease Models, Animal; Endothelin-1; Male; Middle Cerebral Artery; Rats; Rats, Inbred Strains; Rats, Wistar; Reperfusion Injury; Tunica Media

Brain edema is detrimental in ischemic stroke and its treatment options are limited. Kinins are proinflammatory peptides that are released during tissue injury. The effects of kinins are mediated by 2 different receptors (B1 and B2 receptor [B1R and B2R]) and comprise induction of edema formation and release of proinflammatory mediators.. Focal cerebral ischemia was induced in B1R knockout, B2R knockout, and wild-type mice by transient middle cerebral artery occlusion. Infarct volumes were measured by planimetry. Evan's blue tracer was applied to determine the extent of brain edema. Postischemic inflammation was assessed by real-time reverse-transcriptase polymerase chain reaction and immunohistochemistry. To analyze the effect of a pharmacological kinin receptor blockade, B1R and B2R inhibitors were injected.. B1R knockout mice developed significantly smaller brain infarctions and less neurological deficits compared to wild-type controls (16.8+/-4.7 mm(3) vs 50.1+/-9.1 mm(3), respectively; P<0.0001). This was accompanied by a dramatic reduction of brain edema and endothelin-1 expression, as well as less postischemic inflammation. Pharmacological blockade of B1R likewise salvaged ischemic tissue (15.0+/-9.5 mm(3) vs 50.1+/-9.1 mm(3), respectively; P<0.01) in a dose-dependent manner, even when B1R inhibitor was applied 1 hour after transient middle cerebral artery occlusion. In contrast, B2R deficiency did not confer neuroprotection and had no effect on the development of tissue edema.. These data demonstrate that blocking of B1R can diminish brain infarction and edema formation in mice and may open new avenues for acute stroke treatment in humans.

Topics: Animals; Bradykinin; Bradykinin B1 Receptor Antagonists; Bradykinin B2 Receptor Antagonists; Brain Edema; Cerebral Arteries; Cerebral Infarction; Cerebrovascular Circulation; Disease Models, Animal; Dose-Response Relationship, Drug; Down-Regulation; Encephalitis; Endothelin-1; Gene Expression; Infarction, Middle Cerebral Artery; Mice; Mice, Inbred C57BL; Mice, Knockout; Receptor, Bradykinin B1; Receptor, Bradykinin B2; RNA, Messenger

Mouse models have not paralleled rat models of stroke in advances in sensitive, species appropriate measures of neurological and behavioral recovery. Most available tests of mouse sensorimotor function are adaptations of those originally developed in rats and may not be as sensitive in detecting behavioral deficits after small cortical lesions in mice. Our purpose was to test the use of a vasoconstricting peptide, endothelin-1 (ET-1), to produce focal infarcts of the mouse sensorimotor cortex and to establish a behavioral test battery sensitive to resulting sensorimotor deficits. Young adult (3-5-month-old) male C57BL/6 mice received intracortical infusions of ET-1 that produced unilateral lesions of the forelimb region of the sensorimotor cortex, intracortical infusions of sterile saline, or sham surgeries. Pre-operatively and at various time points over 3 weeks post-surgery, they were administered a test battery that included measures of sensorimotor asymmetry (Corner and Bilateral Tactile Stimulation Tests), coordinated forepaw use (Cylinder and Ladder Rung Tests), and dexterous forepaw function (Pasta Matrix Reaching Test). ET-1 infusions resulted in consistently placed, focal cortical infarcts and forelimb impairments as measured with the Ladder Rung, Bilateral Tactile Stimulation, and Pasta Matrix Reaching Tests. On the Bilateral Tactile Stimulation and Pasta Matrix Reaching Tests, impairments persisted throughout the time span of observation (26 days). These results support ET-1 as a viable option for creating small, reproducible lesions of anatomical subregions in the mouse neocortex that result in lasting functional impairments in the forelimb, as observed with sufficiently sensitive measures.

Topics: Animals; Behavior, Animal; Cerebral Infarction; Endothelin-1; Gait Disorders, Neurologic; Locomotion; Male; Mice; Mice, Inbred C57BL; Physical Stimulation; Posture; Psychomotor Performance; Upper Extremity

Endogenous levels of angiotensin II (Ang II) are increased in the cortex and hypothalamus following stroke, and Ang II type 1 receptor blockers (ARBs) have been shown to attenuate the deleterious effects in animal stroke models using middle cerebral artery (MCA) intraluminal occlusion procedures. However, the endothelin-1 (ET-1)-induced middle cerebral artery occlusion (MCAO) model of cerebral ischaemia is thought to more closely mimic the temporal events of an embolic stroke. This method provides rapid occlusion of the MCA and a gradual reperfusion that lasts for 16-22 h. The aim of the present study was to evaluate whether systemic administration of an ARB prior to ET-1-induced MCAO would provide cerebroprotection during this model of ischaemic stroke. Injection of 3 microl of 80 microM ET-1 adjacent to the MCA resulted in complete occlusion of the vessel that resolved over a period of 30-40 min. Following ET-1-inducedMCAO, rats had significant neurological impairment, as well as an infarct that consisted of 30% of the ipsilateral grey matter. Systemic pretreatment with 0.2 mg kg(-1) day(-1) candesartan for 7 days attenuated both the infarct size and the neurological deficits caused by ET-1-induced MCAO without altering blood pressure. This study confirms the cerebroprotective properties of ARBs during ischaemic stroke and validates the ET-1-induced MCAO model for examination of the role of the brain renin-angiotensin system in ischaemic stroke.

Topics: Angiotensin II Type 1 Receptor Blockers; Animals; Benzimidazoles; Biphenyl Compounds; Brain Ischemia; Cerebral Infarction; Disease Models, Animal; Endothelin-1; Infarction, Middle Cerebral Artery; Male; Rats; Rats, Sprague-Dawley; Stroke; Tetrazoles

The influence of anaesthesia in experimental stroke research is controversial. We addressed this problem using the model of endothelin-1-induced occlusion of the middle cerebral artery (eMCAO). This model provided the opportunity to compare the infarct volumes of rats which were under halothane anaesthesia during eMCAO induction with the lesions of rats which were without anaesthesia during eMCAO. All animals were implanted with guide cannulae which allowed the induction of ischaemia in freely moving animals. For comparison, one group of animals was exposed to halothane during the induction of ischaemia. Seven days after eMCAO, the average infarct volume of halothane-anaesthetised rats was significantly larger than the lesion in freely moving animals. This difference was mainly due to increased cortical damage, whereas the striatum was much less influenced. The cortical infarct volume 21 days after induction of eMCAO under anaesthesia was significantly reduced compared to the infarct volume 7 days after eMCAO under anaesthesia. Our results indicate that halothane anaesthesia during eMCAO can cause a transient cortical increase in ischaemic infarct volume. The influence of volatile anaesthetics on ischaemic pathophysiology should be taken into consideration when preclinically testing potential neuroprotective drugs for clinical applications.

Topics: Anesthetics, Inhalation; Animals; Brain Ischemia; Cerebral Infarction; Endothelin-1; Endothelium, Vascular; Halothane; Male; Middle Cerebral Artery; Rats; Rats, Sprague-Dawley

We investigated the effect of small cortical ischemic lesions, produced by intracerebral injection of the vasoconstrictor endothelin-1, on neurogenesis in the adult mouse subventricular zone. Endothelin-1 (0.5-1 microg) produced infarcts restricted to the cortex, and associated neurobehavioral deficits that largely resolved by 3 days. Bromodeoxyuridine labeling of proliferating cells in the subventricular zone was elevated by about 50% in endothelin-1-treated mice, and cells reactive for doublecortin, a marker for immature neurons, were similarly increased in number. These findings indicate that small ischemic lesions restricted to adult cerebral cortex can stimulate neuroproliferation at a distance.

Topics: Animals; Biomarkers; Brain Ischemia; Cell Differentiation; Cell Proliferation; Cerebral Infarction; Dose-Response Relationship, Drug; Doublecortin Domain Proteins; Endothelin-1; Male; Mice; Mice, Inbred C57BL; Microtubule-Associated Proteins; Nerve Regeneration; Neuronal Plasticity; Neuropeptides; Recovery of Function; Stem Cells; Vasoconstrictor Agents

Unilateral sensorimotor cortical (SMC) lesions in rats impair reaching and grasping movements of the contralateral forelimb. These impairments can be improved using motor rehabilitative training on a skilled reaching task, but the training may be far from sufficient to return animals to pre-lesion levels of performance. Because D-amphetamine (AMPH) has been found to promote neuroplastic responses to injury and to be very beneficial when combined with some (but not all) types of rehabilitative training, we asked in this experiment whether it could improve the efficacy of rehabilitative training in skilled reaching. Ten to 14 days after unilateral ischemic (endothelin-1 induced) lesions of the SMC, adult rats were given a 3-week regimen of AMPH (1mg/kg) coupled with daily rehabilitative training on a skilled reaching task, the single pellet retrieval task. AMPH treatment not only dramatically improved reaching performance compared with saline-injected controls, the AMPH treated rats surpassed pre-lesion levels of performance by the end of the rehabilitative training period. The greater performance in AMPH compared to saline-treated rats was still evident at 1 month, but not at 2 and 3 months, after the end of rehabilitative training. Thus, AMPH treatment can greatly enhance the efficacy of rehabilitative training on a skilled reaching task after unilateral SMC lesions, but alternate injection and training regimes may be needed to produce permanent improvements.

Topics: Animals; Brain Ischemia; Central Nervous System Stimulants; Cerebral Infarction; Denervation; Dextroamphetamine; Disease Models, Animal; Dose-Response Relationship, Drug; Endothelin-1; Male; Motor Cortex; Motor Skills; Movement Disorders; Neuronal Plasticity; Paresis; Physical Conditioning, Animal; Rats; Rats, Long-Evans; Recovery of Function; Treatment Outcome

Previously, we showed that treatment with resuscitative, post-ischaemic mild hypothermia (34 degrees C for 2 h) reduced apoptosis in the penumbra (cortex), but not in the core (striatum) of an endothelin-1 (Et-1)-induced focal cerebral infarct in the anaesthetized rat. Therefore, the purpose of this study was to investigate by which pathways resuscitative mild hypothermia exerts its neuroprotective effect in this model. The amino acids glutamate, serine, glutamine, alanine, taurine, arginine and the NO-related compound citrulline were sampled from the striatum and cortex of the ischaemic hemisphere using in vivo microdialysis. The in vivo salicylate trapping method was applied for monitoring hydroxyl radical formation via 2,3 dihydroxybenzoic acid (2,3 DHBA) detection. Caspase-3, neuronal nitric oxide synthase (nNOS) immunoreactivity and the volume of ischaemic damage were determined 24 h after the insult. In both the striatum and the cortex, Et-1-induced increases in glutamate, taurine and alanine were refractory to mild hypothermia. However, mild hypothermia significantly attenuated the ischaemia-induced 2,3 DHBA levels and the nNOS immunoreactivity in the cortex, but not in the striatum. These observations were associated with a decreased caspase-3 immunoreactivity. These results suggest that mild hypothermia exerts its neuroprotective effect in the penumbra partially by reducing nNOS activity and thereby preventing oxidative stress. Furthermore, we confirm our previous findings that the neuroprotective effect of resuscitative hypothermia is not mediated by changes in ischaemia-induced amino acid release as they could not be associated with the ischaemia-induced damage in the Et-1 rat model.

Topics: Amino Acids; Animals; Apoptosis; Body Temperature; Brain Ischemia; Caspase 3; Caspases; Cerebral Cortex; Cerebral Infarction; Endothelin-1; Enzyme Inhibitors; Extracellular Space; Hydroxyl Radical; Hypothermia; Immunohistochemistry; Male; Microdialysis; Neostriatum; NG-Nitroarginine Methyl Ester; Oxidants; Rats; Rats, Wistar

To determine the protective effect of ONO-1078, a leukotriene receptor antagonist, on focal cerebral ischemia induced by endothelin-1 in rats.. Slow microinjection of endothelin-1 (120 pmol in 6 microL, for > 6 min) into the region near the middle cerebral artery was used to induce focal cerebral ischemia. ONO-1078 (0.1 mg.kg-1) was i.p. injected 1 h before endothelin-1 injection. Neurological symptoms, brain edema, brain infarction size, and the survival neurons in cortex and striatum were observed 24 h after ischemia.. Intracerebral microinjection of endothelin-1 induced remarkable neurological symptoms, brain infarction, brain edema, and decrease of survival neurons in the cortex and striatum. In rats pretreated with ONO-1078, endothelin-1-induced brain edema and brain infarction size were decreased. The numbers of survival neurons in striatum and cortex were increased significantly. The neurological symptoms were improved but not significantly.. ONO-1078 possesses neuroprotective effect against cerebral ischemic injury induced by endothelin-1, therefore, leukotrienes may play a role in the injury of cerebral ischemia.

Topics: Animals; Behavior, Animal; Brain Edema; Brain Ischemia; Cerebral Cortex; Cerebral Infarction; Chromones; Corpus Striatum; Endothelin-1; Leukotriene Antagonists; Male; Neurons; Neuroprotective Agents; Rats; Rats, Sprague-Dawley

In vivo studies on cerebral glucose and lactate metabolism following a brain insult require fast and sensitive monitoring techniques. Here we report on-line monitoring of ischemic events and metabolic changes following reperfusion in striatum of freely moving rats subjected to endothelin-1 (60-240 pmol) induced, transient focal cerebral ischemia using slow microdialysis (0.5 microl/min), fast sampling (every minute) and flow-injection analysis with biosensors for glucose and lactate. The high-time resolution provides detailed information on lactate rise times and duration of low glucose. In rats, developing large striatal lesions, lactate increased from 1.0 +/- 0.1 to 4.2 +/- 0.7 mM within 37 +/- 1 min, whereas glucose dropped from 0.3 +/- 0.1 mM to below detection levels (<0.05 mM) for a period of 80 +/- 18 min. The lactate increase measured over a 2-h period after endothelin-1 infusion was highly correlated with striatal infarct size. In some rats oscillatory changes are observed which cannot be detected in traditional assays. The here-described monitoring technique applied in a clinically relevant rat model is a sensitive tool to study post-ischemic energy metabolism, effects of therapeutic interventions and its relationship with histological outcome.

Topics: Animals; Biosensing Techniques; Cerebral Infarction; Cerebrovascular Circulation; Corpus Striatum; Disease Models, Animal; Endothelin-1; Energy Metabolism; Flow Injection Analysis; Glucose; Ischemic Attack, Transient; Lactic Acid; Male; Microdialysis; Neurochemistry; Rats; Rats, Sprague-Dawley; Signal Processing, Computer-Assisted; Time Factors; Up-Regulation

Hyperthermia during or after stroke is known to worsen neuronal damage. Paradoxically, when hyperthermia precedes stroke, it can protect against a subsequent ischemic insult. Other stressors including restraint also have a similar pre-conditioning effect. In the present study, we report the unanticipated finding that conscious rats, restrained for the purpose of intravenous infusion, had markedly reduced neuronal and functional deficits after middle cerebral artery occlusion compared with unrestrained rats. Restrained rats had significantly higher body temperature prior to stroke than unrestrained rats. The findings suggest restraint leading to mild hyperthermia may be sufficient to induce adaptive processes which protect against subsequent ischemia.

Topics: Adaptation, Physiological; Animals; Body Temperature; Brain Ischemia; Cerebral Cortex; Cerebral Infarction; Corpus Striatum; Endothelin-1; Hyperthermia, Induced; Male; Motor Activity; Rats; Rats, Wistar; Restraint, Physical; Stroke

We studied the association of endothelin (ET)-1 with carotid atherosclerosis and asymptomatic cerebrovascular lesions in patients with essential hypertension. Neurologically normal patients with essential hypertension (n=293; 138 male, 155 female; mean age, 65 years) and age-matched control subjects (n=242) were studied with B-mode ultrasonography of the common and internal carotid arteries and magnetic resonance imaging of the brain. Plasma ET-1 was measured by enzyme immunoassay. Hypertensive patients were divided into groups with carotid plaques and low ET-1 concentrations (< 0.75 pg/ml; PL group); carotid plaques and mid-range ET-1 (0.75 to 1.55 pg/ml; PM group); carotid plaques and high ET-1 (> or = 1.55 pg/ml; PH group); no plaques and low ET-1 (NPL); no plaques and mid-range ET-1 (NPM); and no plaques and high ET-1 (NPH). Overall, ET-1 concentrations were significantly higher in patients than in control subjects. Carotid plaque prevalence was significantly related to ET-1 in hypertensive patients. ET-1 showed a significant positive relationship with the number of asymptomatic lacunar infarcts of the brain in hypertensive patients with carotid plaques (rho=0.48, p<0.001). No significant relationship was seen between ET-1 and periventricular hyperintensity scores in patients with plaques. ET-1 did not show a relationship to either brain lesion type in patients without carotid plaques. Thus, ET-1 may foster asymptomatic lacunar cerebral infarcts by promoting carotid atherosclerosis in patients with essential hypertension.

Topics: Adult; Aged; Carotid Artery Diseases; Cerebral Infarction; Cerebrovascular Disorders; Endothelin-1; Female; Humans; Hypertension; Intracranial Arteriosclerosis; Magnetic Resonance Imaging; Male; Middle Aged; Osmolar Concentration; Reference Values; Ultrasonography

Levels of endothelin-1 (ET-1), a potent endogenous vasoconstrictor, are elevated in plasma and cerebrospinal fluid (CSF) following cerebral ischemia and reperfusion injury. The present study sought insight into the potential differential vasoactive effects on the cerebral vasculature and resultant neural damage of ET-1 during normoxic vs. ischemic conditions and upon reperfusion. Under normoxic conditions, intrastriatal stereotaxic injection of exogenous ET-1 (40 pmol) induced a significant (P<0.05) reduction (

Topics: Animals; Cerebral Infarction; Corpus Striatum; Endothelin-1; Hypoxia; Injections; Oxygen; Rats; Rats, Long-Evans; Reference Values

These studies were performed in an attempt to clarify some of the pathophysiologic mechanisms which occur during and after global ischemia. Both nitric oxide and endothelin were demonstrated in gerbils to participate in responses to ischemia. It was shown that endogenous nitric oxide influences early postischemic reperfusion, systemic blood pressure and postischemic dopamine metabolism. Furthermore, the results indicated that nitric oxide played a role in dopamine release and that preischemic intracerebral nitric oxide formation significantly decreased ischemic dopamine release. In addition, ischemic release of endothelin-1 was detected; participation of nitric oxide in this release was observed. Further indication of functional interactions between nitric oxide and endothelin-1 in postischemic reperfusion were indicated by observations that endothelin-1 antagonists inhibited early hypoperfusion caused by Nitro-L-arginin and late hypoperfusion caused by endogenous endothelin-1. Nitric oxide was shown to decrease edema formation during the early postischemic period but contribute to edema formation during the late postischemic period. The findings indicate the importance of nitric oxide in stroke and ischemia.

Topics: Animals; Blood Pressure; Brain; Brain Edema; Cerebral Infarction; Cerebrovascular Circulation; Dopamine; Endothelin-1; Gerbillinae; Nitric Oxide; Reperfusion Injury

Synthesis and release of the potent vasoconstrictor peptide endothelin-1 (ET-1) increases following cerebral ischemia and has previously been shown to mediate the delayed hypoperfusion associated with transient global ischemia. In this study we assessed the impact of ET-1 on perfusion and infarct volume in a focal model of cerebral ischemia by use of the selective ET(A) receptor antagonist Ro 61-1790 (affinity for ET(A) receptor 1000 fold greater than ETB receptor). Control rats subjected to permanent middle cerebral artery occlusion (MCAO) showed extensive reductions in microvascular perfusion 4 h post-MCAO that were significantly attenuated by Ro 61-1790 pretreatment (10 mg/kg, i.v.). Ro 61-1790 concomitantly and significantly reduced the ischemic lesion volume in the same animals. This effect was maintained 24 h post-MCAO providing that the animals received additional i.v. injections of 5 mg/kg Ro 61-1790 at 5 h and 8 h after MCAO. These findings demonstrate that ET(A) receptor antagonism partially preserves tissue perfusion following focal ischemia and that this effect is associated with significant neuroprotection. The results also support the hypothesis that vasoactive mediators, and ET-1 in particular, are important contributors to the pathogenesis of cerebral ischemic injury.

Topics: Animals; Brain Ischemia; Cerebral Infarction; Dioxanes; Endothelin Receptor Antagonists; Endothelin-1; Male; Microcirculation; Middle Cerebral Artery; Pyridines; Pyrimidines; Rats; Rats, Inbred SHR; Receptor, Endothelin A; Sulfonamides; Tetrazoles