endothelin-1 and Brain-Injuries

In brain disorders, reactive astrocytes, which are characterized by hypertrophy of the cell body and proliferative properties, are commonly observed. As reactive astrocytes are involved in the pathogenesis of several brain disorders, the control of astrocytic function has been proposed as a therapeutic strategy, and target molecules to effectively control astrocytic functions have been investigated. The production of brain endothelin-1 (ET-1), which increases in brain disorders, is involved in the pathophysiological response of the nervous system. Endothelin B (ET

Topics: Alzheimer Disease; Animals; Astrocytes; Brain Diseases; Brain Injuries; Brain Ischemia; Endothelin-1; Humans; Neuralgia; Receptor, Endothelin B

Despite intensive research efforts, by our own team and many others, the molecules responsible for acute neurological damage following subarachnoid hemorrhage (SAH) and contributing to delayed ischemic neurological deficit (DIND) have not yet been elucidated. While there are a number of candidate mechanisms, including nitric oxide (NO) scavenging, endothelin-1, protein kinase C (PKC) activation, and rho kinase activation, to name but a few, that have been investigated using animal models and human trials, we are, it seems, no closer to discovering the true nature of this complex and enigmatic pathology. Efforts in our laboratory have focused on the chemical milieu present in hemorrhagic cerebrospinal fluid (CSF) following SAH and the interaction of the environment with the molecules generated by SAH and subsequent events, including NO scavenging, immune response, and clot breakdown. We have identified and characterized a group of molecules formed by the oxidative degradation of bilirubin (a clot breakdown product) and known as BOXes (bilirubin oxidation products). We present a synopsis of the characterization of BOXes as found in human SAH patients' CSF and the multiple signaling pathways by which BOXes act. In summary, BOXes are likely to play an essential role in the etiology of acute brain injury following SAH, as well as DIND.

Topics: Animals; Bilirubin; Brain Injuries; Brain Ischemia; Endothelin-1; Humans; Models, Biological; Muscle, Smooth, Vascular; Nitric Oxide; Oxidation-Reduction; Protein Kinase C; rho-Associated Kinases; Signal Transduction; Subarachnoid Hemorrhage

Calponin (Cp) is an actin-binding protein first characterized in chicken gizzard smooth muscle (SM). This review discusses the role of Cp in mediating SM contraction, the biochemical process by which Cp facilitates SM contraction and the function of Cp in the brain. Recent work on the role of Cp in pathological states with emphasis on traumatic brain injury is also discussed. Based on past and present data, the case is presented for targeting Cp for novel genetic and pharmacological therapies aimed at improving outcome following traumatic brain injury (TBI).

Topics: Animals; Brain Injuries; Calcium-Binding Proteins; Calponins; Cerebrovascular Circulation; Endothelin-1; Microfilament Proteins; Muscle Contraction; Muscle, Smooth, Vascular; Receptor, Endothelin A; Signal Transduction

Severe pediatric traumatic brain injury (TBI) is associated with unfavorable outcomes secondary to injury from activation of the inflammatory cascade, the release of excitotoxic neurotransmitters, and changes in the reactivity of cerebral vessels, causing ischemia. Hypoperfusion of injured brain tissues after TBI is also associated with unfavorable outcomes. Therapeutic hypothermia is an investigational treatment strategy for use in patients with severe TBI that has shown differential effects on various cerebrospinal fluid (CSF) mediators in pediatric patients. Endothelin-1 (ET-1) is a powerful vasoconstrictor that exerts its effects on the cerebrovascular endothelium for sustained periods after TBI. The purpose of this study was to determine if CSF concentrations of ET-1 are increased after severe TBI in children, and if they are associated with demographics and outcomes that are affected by therapeutic hypothermia. This was an ancillary study to a prospective, randomized-controlled trial of early hypothermia in a tertiary care pediatric intensive care unit. Children (n = 34, age 3 months-15 years) suffering from severe TBI were randomized to hypothermia (n = 19) and normothermia (n = 15) as part of the efficacy study. Children undergoing diagnostic lumbar puncture (n = 11) to rule out infection were used as controls. Patients received either mild to moderate hypothermia (32-33°C) or normothermia as part of their treatment protocol. CSF was serially collected during the first 5 days after TBI. ET-1 concentrations were quantitated in patient and control CSF samples by a validated ELISA in duplicate with a limit of quantification of 0.195 pg/mL. CSF ET-1 concentrations were increased by two- to threefold in children after TBI compared to controls, and the increase was sustained for up to 5 days post-TBI. This relationship was not affected by hypothermia, and there were no differences in ET-1 response between children with inflicted and accidental TBI. Group-based trajectory analysis revealed two distinct groups with similar ET-1 levels over time. Univariate analysis showed a significant association between ET-1 levels and Glasgow Outcome Scale (GOS) scores, for which higher ET-1 levels over time were associated with unfavorable outcomes. ET-1 is increased in children with severe TBI and is associated with unfavorable outcomes. This increase in ET-1 may mediate the hypoperfusion or cerebrovascular dysfunction accompanying severe TBI in children. Importantly

Topics: Adolescent; Brain Injuries; Child; Child, Preschool; Endothelin-1; Enzyme-Linked Immunosorbent Assay; Female; Glasgow Outcome Scale; Humans; Hypothermia, Induced; Infant; Male; Prospective Studies; Treatment Outcome

Subarachnoid hemorrhage (SAH), especially aneurysmal subarachnoid hemorrhage, is a serious cerebrovascular disease with high mortality and morbidity. However, there is no effective treatment in clinics. In recent years, more and more studies have shown that early brain injury (EBI) may be an important reason for poor prognosis of SAH. Explore the mechanism of early brain injury after subarachnoid hemorrhage (SAH). In this study, 20 male New Zealand white rabbits were selected and divided into the experimental group and sham operation group, with 10 rabbits in each group. The neurobehavioral scores, food intake, and cerebral perfusion parameters, cerebral blood volume (CBV), cerebral blood flow velocity (CBF), ET-1, IL-1, and IL-6, in rabbit plasma were compared. The food intake scores and neurological dysfunction scores of the experimental group at 1 h, 6 h, 24 h, and 72 h after modeling were higher than those of the sham operation group, which had a statistical significance (

Topics: Animals; Brain Injuries; Endothelin-1; Female; Humans; Interleukin-1; Interleukin-6; Male; Microcirculation; Rabbits; Rats; Subarachnoid Hemorrhage

Pharmacological therapies for interrupting biochemical events of the ischaemic cascade and protecting against stroke in humans are as yet unavailable. Up to now, the neuroprotective activity in cerebral ischaemia of phycocyanobilin (PCB), a tetrapyrrolic natural antioxidant, has not been fully examined. Here, we evaluated if PCB protects PC12 neuronal cells against oxygen and glucose deprivation plus reperfusion, and its protective effects in a rat model of endothelin-1-induced focal brain ischaemia. PCB was purified from the cyanobacteria Spirulina platensis and characterized by spectrophotometric, liquid and gas chromatography and mass spectrometry techniques. In Wistar rats, PCB at 50, 100 and 200 μg/kg or phosphate-buffered saline (vehicle) was administered intraperitoneally at equal subdoses in a therapeutic schedule (30 minutes, 1, 3 and 6 hours after the surgery). Brain expression of myelin basic protein (MBP) and the enzyme CNPase was determined by immunoelectron microscopy. PCB was obtained with high purity (>95%) and the absence of solvent contaminants and was able to ameliorate PC12 cell ischaemic injury. PCB treatment significantly decreased brain infarct volume, limited the exploratory behaviour impairment and preserved viable cortical neurons in ischaemic rats in a dose-dependent manner, compared to the vehicle group. Furthermore, PCB at high doses restored the MBP and CNPase expression levels in ischaemic rats. An improved PCB purification method from its natural source is reported, obtaining PCB that is suitable for pharmacological trials showing neuroprotective effects against experimental ischaemic stroke. Therefore, PCB could be a therapeutic pharmacological alternative for ischaemic stroke patients.

Topics: Animals; Brain Injuries; Brain Ischemia; Endothelin-1; Male; PC12 Cells; Phycobilins; Phycocyanin; Rats; Rats, Wistar

Topics: Brain Injuries; Brain Injuries, Traumatic; Child; Endothelin-1; Humans

Cerebral palsy is an irreversible movement disorder resulting from cerebral damage sustained during prenatal or neonatal brain development. As survival outcomes for preterm injury improve, there is increasing need to model ischemic injury at earlier neonatal time-points to better understand the subsequent pathological consequences. Here we demonstrate a novel neonatal ischemic model using focal administration of the potent vasoconstrictor peptide, endothelin-1 (ET-1), in newborn rats. The functional and histopathological outcomes compare favourably to those reported following the widely used hypoxic ischemia (HI) model. These include a robust motor deficit sustained into adulthood and recapitulation of hallmark features of preterm human brain injury, including atrophy of subcortical white matter and periventricular fiber bundles. Compared to procedures involving carotid artery manipulation and periods of hypoxia, the ET-1 ischemia model represents a rapid and technically simplified model more amenable to larger cohorts and with the potential to direct the locus of ischemic damage to specific brain areas.

Topics: Animals; Animals, Newborn; Brain; Brain Injuries; Disease Models, Animal; Endothelin-1; Female; Hypoxia; Hypoxia-Ischemia, Brain; Pregnancy; Rats

Endothelin-1 (ET-1), tissue plasminogen activator (tPA), and extracellular signal-regulated kinases-mitogen activated protein kinase (ERK-MAPK) are mediators of impaired cerebral hemodynamics after fluid percussion brain injury (FPI) in piglets. Microparticles (MPs) are released into the circulation from a variety of cells during stress, are pro-thrombotic and pro-inflammatory, and may be lysed with polyethylene glycol telomere B (PEG-TB). We hypothesized that MPs released after traumatic brain injury impair hypotensive cerebrovasodilation and that PEG-TB protects the vascular response via MP lysis, and we investigated the relationship between MPs, tPA, ET-1, and ERK-MAPK in that process. FPI was induced in piglets equipped with a closed cranial window. Animals received PEG-TB or saline (vehicle) 30-minutes post-injury. Serum and cerebrospinal fluid (CSF) were sampled and pial arteries were measured pre- and post-injury. MPs were quantified by flow cytometry. CSF samples were analyzed with enzyme-linked immunosorbent assay. MP levels, vasodilatory responses, and CSF signaling assays were similar in all animals prior to injury and treatment. After injury, MP levels were elevated in the serum of vehicle but not in PEG-TB-treated animals. Pial artery dilation in response to hypotension was impaired after injury but protected in PEG-TB-treated animals. After injury, CSF levels of tPA, ET-1, and ERK-MAPK were all elevated, but not in PEG-TB-treated animals. PEG-TB-treated animals also showed reduction in neuronal injury in CA1 and CA3 hippocampus, compared with control animals. These results show that serum MP levels are elevated after FPI and lead to impaired hypotensive cerebrovasodilation via over-expression of tPA, ET-1, and ERK-MAPK. Treatment with PEG-TB after injury reduces MP levels and protects hypotensive cerebrovasodilation and limits hippocampal neuronal cell injury.

Topics: Animals; Animals, Newborn; Brain Injuries; CA1 Region, Hippocampal; CA3 Region, Hippocampal; Cell-Derived Microparticles; Disease Models, Animal; Endothelin-1; Extracellular Signal-Regulated MAP Kinases; Female; Hypotension; Male; Swine; Tissue Plasminogen Activator; Vasodilation

The therapeutic effects of atorvastatin on early brain injury (EBI), cerebral edema and its association with aquaporin 4 (AQP4) were studied in rabbits after subarachnoid hemorrhage (SAH) using western blot analysis and the dry-wet method. Seventy-two healthy male New Zealand rabbits weighing between 2.5 and 3.2 kg were randomly divided into three groups: the SAH group (n=24), sham-operated group (n=24) and the SAH + atorvastatin group (n=24). A double SAH model was employed. The sham-operated group were injected with the same dose of saline solution, the SAH + atorvastatin group received atorvastatin 20 mg/kg/day after SAH. All rabbit brain samples were taken at 72 h after the SAH model was established successfully. Brain edema was detected using the dry-wet method after experimental SAH was induced; AQP4 and caspase-3 expression was measured by western blot analysis, and neuronal apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) staining at 72 h after SAH. The results indicated that brain edema and injury appeared soon after SAH, while brain edema and EBI were ameliorated and increased behavior scores were noted after prophylactic use of atorvastatin. Compared with the SAH group, the level of AQP4 and the cerebral content of water was significantly decreased (P<0.01) by atorvastatin, and TUNEL staining and studying the expression of caspase-3 showed that the apoptosis of neurons was reduced markedly both in the hippocampus and brain cortex by atorvastatin. The results suggest that atorvastatin ameliorated brain edema and EBI after SAH, which was related to its inhibition of AQP4 expression. Our findings provide evidence that atorvastatin is an effective and well-tolerated approach for treating SAH in various clinical settings.

Topics: Animals; Apoptosis; Aquaporin 4; Atorvastatin; Brain; Brain Edema; Brain Injuries; Caspase 3; Endothelin-1; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Male; Neuroprotective Agents; Rabbits; Subarachnoid Hemorrhage; Water

The cylinder test is routinely used to predict focal ischemic damage to the forelimb motor cortex in rodents. When placed in the cylinder, rodents explore by rearing and touching the walls of the cylinder with their forelimb paws for postural support. Following ischemic injury to the forelimb sensorimotor cortex, rats rely more heavily on their unaffected forelimb paw for postural support resulting in fewer touches with their affected paw which is termed forelimb asymmetry. In contrast, focal ischemic damage in the mouse brain fails to result in comparable consistent deficits in forelimb asymmetry. While forelimb asymmetry deficits are infrequently observed, mice do demonstrate a novel behaviour post stroke termed "paw-dragging". Paw-dragging is the tendency for a mouse to drag its affected paw along the cylinder wall rather than directly push off from the wall when dismounting from a rear to a four-legged stance. We have previously demonstrated that paw-dragging behaviour is highly sensitive to small cortical ischemic injuries to the forelimb motor cortex. Here we provide a detailed protocol for paw-dragging analysis. We define what a paw-drag is and demonstrate how to quantify paw-dragging behaviour. The cylinder test is a simple and inexpensive test to administer and does not require pre-training or food deprivation strategies. In using paw-dragging analysis with the cylinder test, it fills a niche for predicting cortical ischemic injuries such as photothrombosis and Endothelin-1 (ET-1)-induced ischemia--two models that are ever-increasing in popularity and produce smaller focal injuries than middle cerebral artery occlusion. Finally, measuring paw-dragging behaviour in the cylinder test will allow studies of functional recovery after cortical injury using a wide cohort of transgenic mouse strains where previous forelimb asymmetry analysis has failed to detect consistent deficits.

Topics: Animals; Brain Injuries; Brain Ischemia; Disease Models, Animal; Endothelin-1; Forelimb; Male; Mice; Motor Cortex; Rats; Recovery of Function; Stroke

Blood-brain-barrier (BBB) disruption, inflammation and thrombosis are important steps in the pathophysiology of acute ischemic stroke but are still inaccessible to therapeutic interventions. Rolipram specifically inhibits the enzyme phosphodiesterase (PDE) 4 thereby preventing the inactivation of the intracellular second messenger cyclic adenosine monophosphate (cAMP). Rolipram has been shown to relief inflammation and BBB damage in a variety of neurological disorders. We investigated the therapeutic potential of rolipram in a model of brain ischemia/reperfusion injury in mice. Treatment with 10mg/kg rolipram, but not 2 mg/kg rolipram, 2 h after 60 min of transient middle cerebral artery occlusion (tMCAO) reduced infarct volumes by 50% and significantly improved clinical scores on day 1 compared with vehicle-treated controls. Rolipram maintained BBB function upon stroke as indicated by preserved expression of the tight junction proteins occludin and claudin-5. Accordingly, the formation of vascular brain edema was strongly attenuated in mice receiving rolipram. Moreover, rolipram reduced the invasion of neutrophils as well as the expression of the proinflammatory cytokines IL-1β and TNFα but increased the levels of TGFβ-1. Finally, rolipram exerted antithrombotic effects upon stroke and fewer neurons in the rolipram group underwent apoptosis. Rolipram is a multifaceted antiinflammatory and antithrombotic compound that protects from ischemic neurodegeneration in clinically meaningful settings.

Topics: Animals; Blood-Brain Barrier; Brain Edema; Brain Injuries; Cytokines; Disease Models, Animal; Encephalitis; Endothelin-1; Hemodynamics; Infarction, Middle Cerebral Artery; Laser-Doppler Flowmetry; Male; Mice; Mice, Inbred C57BL; Nerve Tissue Proteins; Occludin; Phosphodiesterase 4 Inhibitors; Rolipram; Stroke; Thrombosis

Traumatic brain injury (TBI) is associated with loss of cerebrovascular autoregulation, which leads to cerebral hypoperfusion. Mitogen activated protein kinase (MAPK) isoforms ERK, p38, and JNK and endothelin-1 (ET-1) are mediators of impaired cerebral hemodynamics after TBI. Excessive tissue plasminogen activator (tPA) released after TBI may cause loss of cerebrovascular autoregulation either by over-activating N-methyl-D-aspartate receptors (NMDA-Rs) or by predisposing to intracranial hemorrhage. Our recent work shows that a catalytically inactive tPA variant (tPA-S(481)A) that competes with endogenous wild type (wt) tPA for binding to NMDA-R through its receptor docking site but that cannot activate it, prevents activation of ERK by wt tPA and impairment of autoregulation when administered 30 min after fluid percussion injury (FPI). We investigated the ability of variants that lack proteolytic activity but bind/block activation of NMDA-Rs by wt tPA (tPA-S(481)A), do not bind/block activation of NMDA-Rs but are proteolytic (tPA-A(296-299)), or neither bind/block NMDA-Rs nor are proteolytic (tPA-A(296-299)S(481)A) to prevent impairment of autoregulation after TBI and the role of MAPK and ET-1 in such effects. Results show that tPA-S(481)A given 3 h post-TBI, but not tPA-A(296-299) or tPA-A(296-299)S(481)A prevents impaired autoregulation by upregulating p38 and inhibiting ET-1, suggesting that tPA-S(481)A has a realistic therapeutic window and focuses intervention on NMDA-Rs to improve outcome.

Topics: Animals; Animals, Newborn; Brain Injuries; Disease Models, Animal; Endothelin-1; Female; Male; p38 Mitogen-Activated Protein Kinases; Receptors, N-Methyl-D-Aspartate; Swine; Time Factors; Tissue Plasminogen Activator; Up-Regulation

Traumatic brain injury contributes to morbidity in children and boys are disproportionately represented. Autoregulation is impaired more in male compared with female piglets after traumatic brain injury through sex-dependent up-regulation of the spasmogen endothelin-1 and extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase (MAPK), a family of three kinases: ERK, p38, and JNK). Elevation of mean arterial pressure leading to increased cerebral perfusion pressure via phenylephrine improves impairment of autoregulation after traumatic brain injury in female but not male piglets through modulation of endothelin-1 and ERK MAPK up-regulation, blocked in females, but aggravated in males. We hypothesized that pressor choice to elevate cerebral perfusion pressure is important in improving cerebral hemodynamics after traumatic brain injury and that dopamine will prevent impairment of autoregulation in both male and female piglets through blockade of endothelin-1 and ERK MAPK.. Prospective, randomized animal study.. University laboratory.. Newborn (1-5 days old) pigs.. Cerebral perfusion pressure and pial artery diameter were determined before and after lateral fluid percussion brain injury was produced in piglets equipped with a closed cranial window. Dopamine (15 µg/kg/min IV) was administered 30 mins post fluid percussion injury. Cerebrospinal fluid ERK MAPK was determined by enzyme-linked immunosorbent assay.. Dopamine increased cerebral perfusion pressure equivalently in both sexes and prevented sex-dependent reductions in pial artery diameter after fluid percussion injury. Loss of pial artery dilation during hypotension was greater in male than in female piglets after fluid percussion injury, but dopamine prevented such impairment equivalently in both sexes post injury. endothelin-1 and ERK MAPK release was greater in male compared to female piglets after fluid percussion injury, but dopamine also blocked their up-regulation equivalently in male and female piglets after fluid percussion injury.. These data indicate that dopamine is protective of autoregulation after fluid percussion injury in both sexes. These observations advocate for the consideration of development of sex based therapies for treatment of hemodynamic sequalae of pediatric traumatic brain injury.

Topics: Analysis of Variance; Animals; Blood Pressure; Brain Injuries; Cerebrovascular Circulation; Dopamine; Endothelin-1; Extracellular Signal-Regulated MAP Kinases; Female; Hypotension; Male; MAP Kinase Signaling System; Sex Factors; Swine; Sympathomimetics; Up-Regulation; Vasodilation

Traumatic brain injury (TBI) contributes to morbidity in children, and boys are disproportionately represented. Endothelin-1 (ET-1) contributes to impaired autoregulation via oxygen (O₂⁻) after TBI in piglets, but its relative role in males compared with females has not been previously investigated. Increased cerebral perfusion pressure (CPP) via phenylephrine (Phe) sex dependently improves impairment of autoregulation after TBI through modulation of extracellular signal-related kinase (ERK) mitogen-activated protein kinase (MAPK) upregulation, aggravated in males, but blocked in females. Activation of adenosine-5'-triphosphate (ATP) and Ca sensitive K channels produce vasodilation, contributing to autoregulation. We hypothesized that ET-1 upregulation is greater in males after TBI and that disturbed autoregulation will be prevented by Phe in a sex-dependent manner through modulation of ET-1, O₂⁻, and ERK. Results show that ET-1 release was greater in males after fluid percussion injury (FPI), blunted by Phe in females, but aggravated in males. K channel vasodilation was impaired more in males than in females after TBI. Phe prevented reductions in K channel vasodilation in females, but further reduced dilation in males after TBI. Co-administration of BQ-123, U0126, or PEG-SOD (ET-1, ERK antagonist, and O₂⁻ scavenger) with Phe restored dilation to K agonists and hypotension in males after TBI. ERK upregulation was blocked by BQ-123 and PEG-SOD. These data indicate that TBI upregulates ET-1 more in males than in females. Elevation of CPP with Phe sex dependently prevents impairment of cerebral autoregulation after TBI through modulation of ET-1, O₂⁻, and ERK mediated impairment of K channel vasodilation. These observations advocate for the consideration of development of sex-based therapies for the treatment of hemodynamic sequelae of pediatric TBI.

Topics: Animals; Animals, Newborn; Brain Injuries; Endothelin-1; Female; Homeostasis; Male; Phenylephrine; Sex Characteristics; Swine; Up-Regulation

Endothelin-1 (ET-1) is a potent vasoconstrictor and is thought to be responsible for secondary ischemia and vasogenic edema after traumatic brain injury (TBI). Both CSF and plasma concentrations have been shown to be increased after TBI, but there is little evidence to confirm an intracranial site of production.. Using paired arterial and jugular venous bulb sampling, we measured arterial and jugular levels of ET-1 and its precursor, big endothelin (Big ET), and calculated juguloarterial (JA) gradients for the first 5 days post-TBI.. Arterial levels of both Big ET and ET-1 were maximal on day 1 post-TBI, and decreased thereafter (P < 0.05). Arterial levels of Big ET and ET-1 showed correlation across all 5 days of the study (r(2) = 0.25, P < 0.001). While there was no significant JA gradient for Big ET, significant gradients were observed for ET-1 on days 1-4 post-TBI (P < 0.05). There was no correlation between JA gradients for Big ET and ET-1 (r(2) < 0.1, P > 0.9). These data suggest parenchymal production of ET-1 by brain tissue with spill over into the blood, rather than local intraluminal cleavage of Big ET in the cerebral vasculature. Systemic ET-1 levels and JA gradients of ET-1 were unrelated to the injury severity, APACHE II score, Marshall Grade, the presence of subarachnoid or subdural hemorrhage, or eventual outcome.. These findings confirm the synthesis of Big ET and its cleavage to ET-1 within the brain after TBI. More work is needed to elucidate the pathophysiological role and the outcome impact of ET-1 generation after TBI.

Topics: Adolescent; Adult; Aged; Brain; Brain Injuries; Cerebral Arteries; Critical Care; Disease Progression; Endothelin-1; Female; Humans; Jugular Veins; Male; Middle Aged; Trauma Severity Indices; Young Adult

Vasospasm of the cerebrovasculature is a common manifestation of blast-induced traumatic brain injury (bTBI) reported among combat casualties in the conflicts in Afghanistan and Iraq. Cerebral vasospasm occurs more frequently, and with earlier onset, in bTBI patients than in patients with other TBI injury modes, such as blunt force trauma. Though vasospasm is usually associated with the presence of subarachnoid hemorrhage (SAH), SAH is not required for vasospasm in bTBI, which suggests that the unique mechanics of blast injury could potentiate vasospasm onset, accounting for the increased incidence. Here, using theoretical and in vitro models, we show that a single rapid mechanical insult can induce vascular hypercontractility and remodeling, indicative of vasospasm initiation. We employed high-velocity stretching of engineered arterial lamellae to simulate the mechanical forces of a blast pulse on the vasculature. An hour after a simulated blast, injured tissues displayed altered intracellular calcium dynamics leading to hypersensitivity to contractile stimulus with endothelin-1. One day after simulated blast, tissues exhibited blast force dependent prolonged hypercontraction and vascular smooth muscle phenotype switching, indicative of remodeling. These results suggest that an acute, blast-like injury is sufficient to induce a hypercontraction-induced genetic switch that potentiates vascular remodeling, and cerebral vasospasm, in bTBI patients.

Topics: 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; Algorithms; Arteries; Blast Injuries; Blotting, Western; Brain Injuries; Calcium; Calcium Channel Blockers; Cells, Cultured; Cytosol; Endothelin-1; Gene Expression; Humans; Military Medicine; Models, Biological; Muscle Contraction; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Myosin Heavy Chains; Reverse Transcriptase Polymerase Chain Reaction; Stress, Mechanical; Tissue Engineering; Vasospasm, Intracranial; Warfare

This study characterized the association between endothelin-1, cerebral hemodynamics, and histopathology after fluid percussion brain injury in the newborn pig.. Lateral fluid percussion injury was induced in newborn pigs equipped with a closed cranial window. Cerebral blood flow was determined with radiolabeled microspheres and cerebrospinal fluid endothelin-1 was measured by radioimmunoassay.. Cerebrospinal fluid endothelin-1 was increased from 26±4 to 296±37 pg/ml (∼10(-10) M) at 8 hours following fluid percussion injury. Post-injury treatment (30 minutes) with the endothelin-1 antagonist BQ-123 (1 mg/kg, intravenous) blocked pial artery vasoconstriction to topical endothelin-1 (∼10(-10) M) and blunted fluid percussion injury-induced reductions in cerebral blood flow at 8 hours post-insult (56±6 and 26±4 ml/minute versus 57±6 and 40± ml/minute; 100 g for cerebral blood flow before injury and 8 hours post-fluid percussion injury in vehicle and BQ-123 post-treated animals, respectively). Fluid percussion injury resulted in neuronal cell loss and decreased microtubule associated protein 2 immunoreactivity in the parietal cortex, which were blunted by BQ-123.. These data indicate that fluid percussion injury-induced changes in cerebral hemodynamics are associated with neuronal damage and that endothelin-1 contributes to fluid percussion injury-induced histopathologic changes.

Topics: Animals; Animals, Newborn; Brain Injuries; Cerebrovascular Disorders; Child; Disease Models, Animal; Endothelin-1; Female; Hemodynamics; Humans; Male; Nerve Degeneration; Sus scrofa

This work was designed to compare levels of endothelin-1 following brain injury in both rat and porcine models of head injury. In a broader sense, this work also determines the feasibility of testing traumatic brain injury-related phenomenology across species and models.. Male Sprague-Dawley rats (400-450 g) were subjected to traumatic brain injury using a weight acceleration impact injury device (n = 5 per group). Following impact, cerebrospinal fluid was collected for enzyme-linked immunosorbent assay analysis of endothelin-1 concentration using a standard endothelin-1 detection kit at 4 hours, 24 hours, 48 hours, and 7 days post-traumatic brain injury. Sham operated animals (n = 5) were used as controls. In another set of experiments, traumatic brain injury was induced in newborn and juvenile pigs (n = 6 per group) using a lateral fluid percussion model of brain injury. Cerebrospinal fluid was collected at 4 hours, 8 hours, 72 hours, and 7 days post-injury and endothelin-1 levels were measured using a radiolabeled kit.. Endothelin-1 levels rapidly increased from ∼35 in sham operated animals to over 200 pg/g tissue 4 hours post-impact in both rat cortex and hippocampus. This elevation was sustained through 48 hours post-impact. By 7 days post-injury, endothelin-1 levels returned to normal, control concentrations. This trend was consistent with the porcine model, being more pronounced in newborn versus juvenile pigs.. These results show that endothelin-1 peptide concentration elevation is a consistent finding between rat and pig and between weight acceleration and fluid percussion models of traumatic brain injury. This suggests that endothelin-1 elevation is not only a conserved phenomenon in different models of traumatic brain injury, but that it is a likely target for understanding the observed enhanced vascular response to traumatic brain injury and ultimately developing strategies to improve outcome following traumatic brain injury.

Topics: Animals; Animals, Newborn; Brain Injuries; Cerebral Cortex; Disease Models, Animal; Endothelin-1; Hippocampus; Male; Rats; Rats, Sprague-Dawley; Species Specificity; Sus scrofa; Up-Regulation

Endothelin-1 is a 21-amino acid peptide that together with specific receptors, A (ETrA) and B (ETrB) is induced following traumatic brain injury (TBI) and has been closely linked to regulation of cerebral vasospasm, oxidative stress, and hypoperfusion. Specific endothelin receptor antagonists have been shown to ameliorate early evidence of neuronal cell injury, activation of microglial cells, and hypoperfusion following TBI. The exact mechanism involved in TBI-induced hypoperfusion is still unclear; however, it is thought that endothelin-1 engagement of ETrA is primarily responsible for changes in blood flow. In this study we question the role of the microvascular pericyte in endothelin-1-mediated pathophysiology in TBI.. Pericyte expression of endothelin-1, ETrA, and ETrB was examined in primary culture and in sham and impacted rat brain. Adult male rats were also given intracerebroventricular injections of ETrA (BQ-123) before being subjected to TBI using a closed head acceleration impact model.. Primary pericytes express both endothelin-1 and its receptors ETrA and ETrB. Following TBI, the number of alpha-smooth muscle actin (SMA) positive pericytes located in microvessels is significantly increased by 4 hours post-traumatic impact. Increases in pericyte expression of alpha-SMA correlated with evidence of a reduction in both arteriolar and capillary diameter. Capillary endothelin-1, ETrA, and ETrB transcript and protein was also increased. Increased endothelin-1 expression was seen by 2-4 hours post-impact. Upregulation of receptors was observed by 4-8 hours and maximum by 24 hours. ETrA antagonists decreased the number of alpha-SMA(+) pericytes as well as changes in microvascular diameter.. These results suggest that decreased vasoconstriction following TBI may be due to an endothelin-1-induced pericyte-mediated regulation of microvessel blood flow following TBI. Furthermore, results suggest that ETrA antagonists ameliorate trauma induced hypoperfusion, in part, by inhibiting endothelin-1-mediated upregulation of alpha-SMA in pericytes.

Topics: Animals; Brain Injuries; Cells, Cultured; Cerebral Arteries; Cerebrovascular Circulation; Cerebrovascular Disorders; Disease Models, Animal; Endothelin-1; Male; Microcirculation; Pericytes; Rats; Rats, Sprague-Dawley; Vasoconstriction

While endothelin-1 and its receptors have traditionally been associated with mediating vasoreactivity, we have recently shown that the vast majority of endothelin receptor A expression following traumatic brain injury is localized within the neuron. While it has been suggested that endothelin receptor A plays a role in influencing neuronal integrity, the significance of neuronally expressed endothelin receptor A remains unclear. One report suggests that endothelin-1 signaling mediates diffuse axonal injury. Therefore, this work sought to determine whether treatment with BQ-123, a selective endothelin receptor A antagonist, diminishes the extent of diffuse axonal injury following trauma.. A total of 12 male Sprague-Dawley rats (350-400 g) were used in this study. Two groups (n = 6 per group) were generated as follows: sham operation and traumatic brain injury+1·0 mg/kg BQ-123 delivered intravenously 30 minutes prior to the injury. Trauma was induced using a weight acceleration impact device. Animals were terminated 24 or 48 hours after trauma, and a series of six coronal sections through the entire anterior-posterior extent of the corpus callosum were selected from each brain for quantification of diffuse axonal injury by beta-amyloid precursor protein immunostaining.. Our data indicated that animals treated with BQ-123 30 minutes prior to trauma showed a significant reduction in diffuse axonal injury in corpus callosum at both 24 and 48 hours post-injury.. The results show that endothelin receptor A antagonism reduced the extent of diffuse axonal injury, demonstrating a potential influence of the endothelin system on the intra-axonal cascade of molecular events underlying diffuse axonal injury.

Topics: Animals; Antihypertensive Agents; Axons; Brain Injuries; Diffuse Axonal Injury; Disease Models, Animal; Endothelin A Receptor Antagonists; Endothelin-1; Injections, Intravenous; Male; Neuroprotective Agents; Peptides, Cyclic; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; Signal Transduction; Treatment Outcome

Stroke is the second most common cause of death and major cause of disability worldwide. Actual treatment involves surgery and/or thrombolytic drugs, but there is an urgent need for new approaches. Periodic acceleration, a rocking headward to footward movement of the whole body, is a non-invasive method to induce pulsatile shear stress on the vascular endothelium eliciting an enhanced production and secretion of endothelium-derived products such as nitric oxide, prostacyclin, prostaglandin E2, tissue plasminogen activator (tPA), and adrenomedullin. All these products have been shown to protect the brain from ischemic injuries. A rat model of focal brain ischemia was treated with application of periodic acceleration for 3 h immediately after the onset of ischemia. Controls remained static for the same period of time. Brain damage was assessed by magnetic resonance imaging (MRI) and biochemical markers. A significant reduction in brain damage was observed, 7 days post-ischemia, in rocked rats when compared with the static controls, through MRI. Furthermore, rocked animals had significantly lower levels of Beclin 1 and fractin than their static counterparts, and some isoforms of nitric oxide synthase were regulated by periodic acceleration. Our results show that periodic acceleration may provide a novel, affordable, non-invasive therapeutic option for the treatment of stroke.

Topics: Acceleration; Animals; Apoptosis Regulatory Proteins; Beclin-1; Brain Injuries; Brain Ischemia; Caspase 3; Disease Models, Animal; Endothelin-1; Exercise Therapy; Gene Expression Regulation; Magnetic Resonance Imaging; Male; Nitric Oxide Synthase; Periodicity; Rats; Rats, Wistar; Time Factors

Endothelin 1 (ET-1) is one of the most powerful vasoconstrictors in the brain. Its expression is upregulated after traumatic brain injury (TBI) and is a major factor in the ensuing hypoperfusion. Attenuation of ET-1 effects has been mainly achieved by blockade of its receptors. The result of a direct blockade of ET-1 mRNA synthesis is not known. We used the Marmarou's model to inflict injury to male Sprague-Dawley rats injected with antisense ET-1 oligodeoxynucleotides (ODNs) before injury. Laser Doppler flowmetry in noninjured rats (2 groups, i.e., untreated and animals that received cODNs) revealed a constant cerebral blood flow of approximately 14 mL.min-1.100 g-1, whereas the values from injured animals pretreated with control ODNs (cODNs) or from animals subjected to TBI alone were approximately 8.0 mL.min-1.100 g-1 during the 18-48 h time period post-TBI. After antisense ET-1 ODNs pretreatment, however, cerebral blood flow in injured animals was approximately 17 mL.min-1.100 g-1 during the 6-48 h time period. Antisense ET-1 ODNs-treated animals also had 19%-29% larger microvessel cross-sectional area and approximately one-third less ET-1 immunoreactivity in the 50-75% range after injury than did cODNs-treated animals after TBI. The results indicate that this direct in vivo approach is an effective therapeutic intervention for the restoration of cerebral blood flow after TBI.

Topics: Animals; Brain Injuries; Cerebrovascular Circulation; Chemokine CCL2; Endothelin-1; Male; Oligodeoxyribonucleotides, Antisense; Rats; Rats, Sprague-Dawley

Nitric oxide (NO) is an important regulatory molecule for the host defense that plays a fundamental role in the cardiovascular, immune, and nervous systems. NO is synthesized through the conversion of L-arginine to L-citrulline by the enzyme NO synthase (NOS), which is found in three isoforms classified as neuronal (nNOS), inducible (iNOS), and endothelial (eNOS). Recent evidence supports the theory that this bioactive molecule has an influential role in the disruption of normal brain and vascular homeostasis, a condition known to elucidate chronic hypoperfusion which ultimately causes the development of brain lesions and the pathology that typify Alzheimer disease (AD). In addition, vascular NO activity appears to be a major contributor to this pathology before any overexpression of NOS isoforms is observed in the neuron, glia, and microglia of the brain tree, where the overexpression the NOS isoforms causes the formation of a large amount of NO. We hypothesize that since an imbalance between the NOS isoforms and endothelin-1 (ET-1), a human gene that encodes for blood vessel constriction, can cause antioxidant system insufficiency; by using pharmacological intervention with NO donors and/or NO suppressors, the brain lesions and the downstream progression of brain pathology and dementia in AD should be delayed or minimized.

Topics: Alzheimer Disease; Animals; Brain; Brain Injuries; Cardiovascular Diseases; Disease Progression; Endothelin-1; Humans; Nitric Oxide; Nitric Oxide Synthase; Oxidative Stress; Protein Isoforms

Severe traumatic brain injury (TBI) is characterized by a high mortality and poor outcome. The pathomechanisms involved are cytokine-mediated proinflammatory and anti-inflammatory reactions and significant cerebral microcirculatory disorders. The role of endothelin 1 (ET-1), a very potent vasoconstrictive peptide, in the deterioration of cerebral perfusion after trauma is still unclear. The presented study investigated the changes in ET-1 in the cerebrospinal fluid (CSF) and plasma after TBI in humans, with special regard to the presence of subarachnoid hemorrhage (SAH) and clinical outcome. Twenty patients with TBI were consecutively enrolled into the study, 10 patients without SAH (TBI group) and 10 patients with SAH (TBI-H group). Paired samples of plasma and CSF were collected for 10 days after trauma. Analysis of the ET-1 concentrations showed that TBI is associated with initially increased ET-1 values in plasma (TBI, day 1; TBI-H, days 2-3) and significantly increased (P < 0.05, vs. control) CSF concentrations (TBI, days 1-2; TBI-H, days 1-3) in the first days after trauma. In the further time course, ET-1 values declined in both groups, reaching reference values in plasma. The CSF values remained significantly (P < 0.05 vs. control) elevated. Both groups showed a second peak on the beginning of the second week after trauma in plasma and CSF. Whereas plasma concentrations failed to reach significance, CSF values showed a significant peak on day 7 in both groups. The TBI-H patients had significantly (P < 0.05) higher values in the secondary peak compared with patients of the TBI group. The kinetics of traumatic SAH-dependent ET-1 needs to be assessed in further investigations.

Topics: Adolescent; Adult; Aged, 80 and over; Brain Injuries; Endothelin-1; Female; Glasgow Coma Scale; Hemorrhage; Humans; Male; Microcirculation; Middle Aged; Peptides; Treatment Outcome

Stroke is a health hazard that affects all age groups, however the impact of age on brain injury following ischemia remains largely unexamined. We examined the extent to which age, from the newborn to mature adult, affects behavioral recovery following similar degrees of ischemic brain damage. We utilized a model that produces comparable volumes of brain damage between the different ages. Endothelin-1, a potent vasoconstrictor, was injected into the brain of 10, 63 and 180-day-old rats, at the level of the right middle cerebral artery. On days 3, 7, 14, 28 and 56 post-insult, behavioral tests including rota-rod, foot-fault, open-field, inclined screen, tape-removal test and postural reflex were performed. Control animals underwent sham surgery, but ischemia was not induced. Neuropathology was assessed on day 63 post-insult. Volume of damage was determined for each brain as a percentage of the contralateral hemisphere (which remains undamaged). Our results indicated that the volume of damage for each age group was 22.97, 19.97, and 18.85% for 10, 63 and 180-day-old rats, respectively, and were not significantly different from each other. Overall, ischemic animals did significantly more poorly on behavioral testing than did controls. When broken down by age, the difference between ischemics and controls was only evident in the 63 and 180-day-old animals. The tape-removal test revealed main effects of age, group, and day (p<0.001). In addition, significant interactions were noted for day of testing by age (p<0.001), day of testing by group with ischemics performing more slowly than controls, and an age by group interaction which indicated that the 63 and 180-day-old ischemic rats did not recover completely during the testing period and remained significantly slower than their controls (p<0.001). In the foot-fault task, the 63 and 180-day-old ischemic animals performed significantly more poorly on days 3, 7, and 14 of recovery, returning to control values by day 28. The 180-day olds performed more poorly on day 3 of recovery, but then returned to control values. For open-field testing, the results indicate an overall difference between ischemics and controls, with the 63 and 180-day-old animals improving with time though they did not achieve control values. In conclusion our data suggest functional performance is poorly and inconsistently correlated with the extent of morphologic injury across all age groups. The immature rat clearly recovers more completely

Topics: Age Factors; Aging; Analysis of Variance; Animals; Animals, Newborn; Behavior, Animal; Brain Injuries; Brain Ischemia; Disease Models, Animal; Endothelin-1; Exploratory Behavior; Motor Activity; Psychomotor Performance; Rats; Rats, Wistar; Recovery of Function; Rotarod Performance Test; Time Factors

To prospectively identify histologically and endoscopically the effect of omeprazole on the expression of endothelin-1 (ET-1), inducible nitric oxide synthase (iNOS) and macrophage inflammatory protein-1alpha (MIP-1alpha) in the gastric mucosa of neurosurgical patients with stress ulcer.. Twenty-five patients with severe acute intracranial lesions caused by trauma were enrolled in this study. A 40 mg intravenous bolus of omeprazole (OME) was given daily for 7 days. The intragastric pH was continuously recorded for 24 hours on day 1 and 8. Endoscopic evaluation of the gastric corpus, antrum, and duodenal bulb was performed in the ICU, within 24 hours after brain injury, and at follow-up on the 7th day after admission. Paired biopsies were obtained for histologic examinations and immunohistochemical analysis was performed using a LSAB method for MIP-1alpha, ET-1, and iNOS.. There were 72% and 70% of gastroduodenal mucosal lesions at the initial and follow-up endoscopies, respectively. However, the severity of mucosal lesions showed significant improvement in most patients at follow-up (p < 0.05). Mean percentages of time intragastric pH were greater than or equal to 4.0 were 20 +/- 11% and 70 +/- 17% on day 1 and 8, respectively (p < 0.05). The incidences of ET-1, iNOS and MIP-1alpha expression were not significantly different between the patients before and after OME prophylaxis.. Prophylactic OME is effective in reducing the severity of stress ulcerations in severe neurotraumatic patients. High incidence of tissue ET-1 expression combined with increased activity of iNOS and MIP-1alpha may be responsible for the gastric mucosal injury. We also show that OME fails to counter the enhancement in the mucosal expression of ET-1, iNOS, and MIP-1alpha caused by severe brain damage.

Topics: Adult; Aged; Anti-Ulcer Agents; Brain Injuries; Chemokine CCL3; Chemokine CCL4; Endothelin-1; Female; Gastric Mucosa; Humans; Hydrogen-Ion Concentration; Macrophage Inflammatory Proteins; Male; Middle Aged; Nitric Oxide Synthase Type II; Omeprazole; Stomach Ulcer; Wounds and Injuries

To study the roles of nitric oxide (NO) and ET-1 in brain injury after hind limbs ischemia/reperfusion in rats and to investigate the effect of NO/ ET-1 balance on brain injury.. On a model of the hind limbs ischemia/reperfusion (LI/R) of rats, we used L-Arg(L-arginine, L-Arg), one of the substrates in the process of nitric oxide, aminoguanidine (AG) which inhibits nitric oxide synthase(NOS) and ETA receptor antagonist BQ123, to observe the changes of NO, ET-1, MDA, XOD, SOD, LDH in plasma and tNOS, iNOS, cNOS, NO, ET-1, MDA, XOD, MPO, SOD in brain tissue.. Compared with the control group, the content of MDA, XOD, LDH in plasma and MDA, XOD, MPO in brain tissue increased. The activity of SOD decreased (P < 0.01). The content of tNOS, iNOS in brain tissue increased, cNOS decreased (P < 0.01). The content of NO, ET-1 in I/R group in plasma and brain tissue increased, the ratio of NO/ET-1 decreased. The brain injury was deteriorated. After using L-Arg and BQ123, the ratio of NO/ET-1 in plasma and brain tissue increased, the brain injury lightened. Whereas after using AG, the ratio of NO/ET-1 decreased, brain injury became more serious.. The NO/ET-1 ratio decreased after LI/R, brain injury became more serious.

Topics: Animals; Brain Injuries; Endothelin-1; Extremities; Male; Nitric Oxide; Rats; Rats, Wistar; Reperfusion Injury

This study investigated the effect of amphetamine (AMP) on skilled forelimb use following focal cortical ischaemic lesions in the rat. Unilateral lesions were produced by a novel method of intracortical microinjection of endothelin-1 (ET-1), intended to principally target the forelimb representation zone in primary motor-primary somatosensory cortex. Lesions were placed in the hemisphere contralateral to the preferred limb and produced deficits in skilled forelimb use on two tasks: the paw reach (PR) test and the foot fault (FF) test. Beginning on post-lesion day (D) 2, animals received injections of 2 mg/kg AMP and were injected every third day until D26. Animals were tested both during, and 24 h after, AMP administration. AMP facilitated recovery of skilled forelimb use on the PR test when assessed during drug-free test sessions. No such effect was seen on the FF test. These results demonstrate that sub-acute administration of AMP following a unilateral focal ischaemic lesion of FL can facilitate task-dependent recovery of skilled forelimb use in the rat. They also demonstrate that different behavioural tasks measuring superficially similar behavioural outputs may show different sensitivities to such drug effects.

Topics: Amphetamine; Analysis of Variance; Animals; Brain Injuries; Brain Ischemia; Central Nervous System Stimulants; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Administration Schedule; Endothelin-1; Forelimb; Functional Laterality; Male; Motor Cortex; Motor Skills; Rats; Rats, Inbred Strains; Recovery of Function; Stroke; Stroke Rehabilitation

Nitric oxide (NO, a vasodilator) and endothelin-1 (ET-1, a powerful vasoconstrictor) participate in the regulation of brain's microcirculation influencing each other's expression and synthesis. Following injury to the brain, NO is derived largely from the inducible form of nitric oxide synthase (iNOS). We used Marmarou's model of traumatic brain injury (TBI) to study the cerebral blood flow and expression (mRNA) of ET-1 in rats that were pretreated with antisense iNOS oligodeoxynucleotides (ODNs). Intracerebroventricular application of iNOS ODNs resulted in reduced synthesis of iNOS as detected by Western blot analysis. The cerebral blood flow (measured by laser Doppler flowmetry), generally decreased after TBI, was further markedly reduced in the treated animals and remained at low levels up to 48 h post-TBI. The expression of ET-1 (detected by in situ hybridization in cortex and hippocampus) was increased 2-3-fold following TBI alone and this increase reached 5-6-fold in animals pretreated with antisense iNOS ODNs. The results indicate that most likely, NO, generated primarily by iNOS, suppresses ET-1 production and that a decrease of NO results in upregulation of ET-1 via transcriptional and translational mechanisms. Increased availability of ET-1 at the vascular bed and the neuropil may contribute to the altered microvascular reactivity and reduced perfusion of the brain following TBI.

Topics: Animals; Blotting, Western; Brain Injuries; Cerebral Cortex; Cerebrovascular Circulation; Endothelin-1; Fluorescein-5-isothiocyanate; Hippocampus; In Situ Hybridization; Laser-Doppler Flowmetry; Male; Microcirculation; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Oligodeoxyribonucleotides, Antisense; Rats; RNA, Messenger; Up-Regulation

We used Marmarou's rat model of traumatic brain injury to demonstrate colocalization of mRNAs for endothelin-1 (ET-1, a powerful vasoconstrictor) and inducible nitric oxide synthase (iNOS, generator of NO, a vasodilator) in individual cells that form the brain's microvascular wall. The results were confirmed with double immunocytochemistry. After trauma endothelial, smooth muscle cells and macrophages contributed to the abnormal synthesis of ET-1 and iNOS which may underlie a dysfunctional brain microcirculation. This is the first in vivo single cell demonstration of ET-1 and iNOS colocalization, suggesting reciprocal regulation of each other's expression both at the transcriptional and translational levels. The results further indicate that interaction between ET-1 and iNOS occurs at the cytosol and possibly the nuclear membranes, implicating mediation via endothelin receptors.

Topics: Animals; Brain Injuries; Endothelin-1; Gene Expression Regulation; Intracellular Fluid; Male; Muscle, Smooth, Vascular; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Rats; Rats, Sprague-Dawley

Vasoactive intestinal contractor (VIC) is a member of the endothelin (ET) family. We have investigated the regional distribution of VIC/ET-2 and of ET-1 gene expression in the adult murine brain and pituitary gland. We used real-time quantitative reverse transcription-linked polymerase chain reaction. VIC/ET-2 gene expression was observed at high levels in the pituitary gland and medulla oblongata in both the mouse and rat. Moderate to low levels of expression were observed in other brain regions. On the contrary, ET-1 gene expression was quite low in the pituitary gland in comparison with the levels observed in the cerebral cortex, striatum, and midbrain. Cold injury to the mouse cerebral cortex caused a significant decrease in VIC/ET-2 gene expression in this structure, whilst expression of the ET-1 gene was increased. These results suggest that VIC/ET-2 may have certain physiological roles that differ from those of ET-1 in the brain and pituitary gland.

Topics: Animals; Brain; Brain Chemistry; Brain Injuries; Cryosurgery; Disease Progression; Endothelin-1; Endothelin-2; Gene Expression Regulation; Intercellular Signaling Peptides and Proteins; Male; Mice; Organ Specificity; Peptides; Pituitary Gland; Rats; Reverse Transcriptase Polymerase Chain Reaction; Time Factors

Previous studies have observed that endothelin-1 (ET-1) concentration is elevated in CSF and contributes to impaired cerebral hemodynamics following fluid percussion brain injury (FPI) in an age-dependent manner. This study was designed to characterize the effects of FPI on the vascular activity of two activators of a pertussin toxin-sensitive G protein, mastoparan and mastoparan-7, as a function of age and the role of ET-1 in such effects in newborn (1-5 days old) and juvenile (3-4 weeks old) pigs equipped with a closed cranial window. Mastoparan (10(-8), 10(-6) M) elicited pial artery dilation that was blunted more by FPI in newborn versus juvenile pigs (9 +/- 1 and 16 +/- 1 vs. 3 +/- 1 and 5 +/- 1%, newborn; 9 +/- 1 and 15 +/- 1 vs. 6 +/- 1 and 9 +/- 1%, juvenile). Similar results were observed for mastoparan-7, but the inactive analogue mastoparan-17 had no effect on pial diameter. BQ123 (10(-6) M), an ET-1 antagonist, partially restored impaired mastoparan dilation after FPI in the newborn but not in the juvenile (3 +/- 1 and 5 +/- 1 vs. 7 +/- 1 and 11 +/- 1%, newborn; 6 +/- 1 and 9 +/- 1 vs. 6 +/- 1 and 10 +/- 1%, juvenile). These data show that G protein activation elicits cerebrovasodilation that is blunted following FPI in an age-dependent manner. These data suggest that ET-1 contributes to the impairment of G protein-mediated vasodilation in an age-dependent manner after FPI.

Topics: Age Factors; Animals; Animals, Newborn; Brain Injuries; Carbon Dioxide; Cerebrovascular Circulation; Endothelin-1; Female; GTP-Binding Proteins; Hydrogen-Ion Concentration; Intercellular Signaling Peptides and Proteins; Male; Oxygen; Peptides; Pertussis Toxin; Pia Mater; Signal Transduction; Swine; Vasodilation; Wasp Venoms

Astrocytes play an important role in neuroprotective responses. Recent studies indicate that endothelin-1, a neuropeptide upregulated during brain injury, increases levels of the endocannabinoid anandamide, a lipid with neuroprotective properties, in astrocytes in primary cultures. However, whether this neuropeptide also alters levels of 2-arachidonoyl glycerol (2-AG), the most abundant endocannabinoid in the CNS, in astrocytes remains unknown. In addition, 2-AG levels in astrocytes have never been measured. In this report we use chemical ionization gas chromatography/mass spectrometry to quantify picomole amounts of 2-AG in primary cultures of mouse astrocytes. We also demonstrate that endothelin-1 increases 2-AG production by 5-fold in these cells, a response that requires extracellular calcium and endothelin-1(A) receptor engagement. Immunocytochemistry showed that although cultured mouse neurons and microglia express cannabinoid receptors, cultured astrocytes do not. The data suggest that endothelin-1 modulates 2-AG production in astrocytes and that this endocannabinoid may participate in paracrine signaling toward neurons and microglia.

Topics: Animals; Animals, Newborn; Arachidonic Acids; Astrocytes; Brain; Brain Injuries; Calcium Signaling; Cells, Cultured; Endocannabinoids; Endothelin-1; Glycerides; Mice; Paracrine Communication; Receptors, Cannabinoid; Up-Regulation

Endothelin 1 (ET-1) exerts normally a powerful vasoconstrictor role in the control of the brain microcirculation. In altered states, such as following traumatic brain injury (TBI), it may contribute to the development of ischemia and/or secondary cell injury. Because little is known of ET-1's cellular compartmentalization and its association to vulnerable neurons after TBI, we assessed its expression (both mRNA and protein) in cerebral cortex and hippocampus using correlative in situ hybridization and immunocytochemical techniques.Sprague-Dawley male rats were killed at 4, 24 or 48 h after TBI (450 g from 2 m, Marmarou's model). Semiquantitative analysis of our in situ hybridization results indicated a 2.5- and a 2.0-fold increase in ET-1 mRNA content in the hippocampus and cortex respectively which persisted up to 48 h post TBI. At 4 and 24 h after TBI enzyme-linked immunosorbent assay showed a tendency for increased ET-1 synthesis. In animals subjected to TBI, qualitative immunocytochemical analysis revealed a shift in ET-1 expression from astrocytes (in control animals) to endothelial cells, macrophages and neurons. Astrocytes and macrophages were identified unequivocally by using double immunofluorescence revealing ET-1 and glial fibrillary acidic protein or ED-1, respectively, the markers being specific for these cellular types. While this redistribution was most prominent at 4 and 24 h post TBI, at 48 h the endothelial cells remained strongly ET-1 immunopositive. The results suggest that cellular types which in the intact animal synthesize little or no ET-1 provide novel sources of the peptide after TBI. These sources may contribute to the sustained cerebrovascular hypoperfusion observed post TBI.

Topics: Animals; Brain Injuries; Cerebral Cortex; Endothelin-1; Hippocampus; Male; Rats; Rats, Sprague-Dawley; RNA, Messenger

This study was designed to characterize the role of endothelin-1 (ET-1) in nociceptin/orphanin FQ (NOC/oFQ) induced impairment of NMDA cerebrovasodilation after fluid percussion brain injury (FPI) as a function of age in newborn (1-5 days old) and juvenile (3-4 weeks old) pigs equipped with a closed cranial window. Previous studies have observed that NOC/oFQ is released into CSF and contributes to impaired NMDA induced pial artery dilation following FPI to a greater extent in newborn vs juvenile pigs. Topical ET-1 (10(-10) M), a concentration approximating that observed in CSF following FPI in the newborn, increased CSF NOC/oFQ from 67 +/- 4 to 119 +/- 7 pg/ml under non FPI conditions. CSF NOC/oFQ was elevated within 60 min of FPI (70 +/- 3 to 444 +/- 51 pg/ml) but such release was attenuated by the ET-1 antagonist BQ123 in the newborn (66 +/- 3 to 145 +/- 10 pg/ml). CSF ET-1 and NOC/oFQ were not elevated as greatly in the juvenile following FPI and BQ123 correspondingly did not attenuate CSF NOC/oFQ release as much as in the newborn. Under non injury conditions, ET-1 (10(-10) M) coadministered with NMDA attenuated pial dilation to this excitatory amino acid. Following FPI in the newborn, NMDA (10(-8), 10(-6) M) induced pial artery dilation was reversed to vasoconstriction and both NOC/oFQ and ET-1 receptor antagonists partially prevented such alterations (9 +/- 1 and 16 +/- 1, sham control; -7 +/- 1 and -12 +/- 1, FPI; -2 +/- 1 and -3 +/- 1, FPI-NOC/oFQ antagonist; and 2 +/- 1 and 5 +/- 1 %, FPI-ET-1 antagonist). NMDA induced pial dilation was only attenuated following FPI in the juvenile and modestly restored by NOC/oFQ and ET-1 receptor antagonists. These data show that ET-1, in concentrations present in CSF following FPI, contributes to the release of CSF NOC/oFQ following such an insult. The greater release of such ET-1 following FPI in the newborn contributes to the corresponding greater release of NOC/oFQ in the newborn vs the juvenile. Moreover, ET-1 also contributes to the impairment of NMDA cerebrovasodilation after brain injury to a greater extent in newborns vs juveniles. These data suggest that ET-1 contributes to NOC/oFQ induced impairment of NMDA cerebrovasodilation after brain injury in an age dependent manner.

Topics: Age Factors; Animals; Brain Injuries; Endothelin-1; N-Methylaspartate; Nociceptin; Opioid Peptides; Swine; Vasodilation; Vasodilator Agents

We characterized the time-course, intensity of expression and cellular origin of components of the endothelin (ET) system in the rat brain after a standardized neurotrauma (cryogenic lesion of the parietal cortex). ET mRNAs were expressed at sham level after neurotrauma, whereas immunoreactivity for ET-1 was enhanced in glia and endothelium of the lesioned hemisphere and both hippocampi. The number of ET-3 positive mononuclear cells in the lesion perimeter increased starting at 24h after injury. At 48h after neurotrauma, ET-receptor immunoreactivity was increased in astrocytes. In basilar artery endothelium, ETB-immunoreactivity was reduced at 48h to 72h recovering at 7 days whereas ETA-receptor and ET-peptide immunoreactivities were not altered. In summary, neurotrauma leads to a multicellular stimulation of endothelins in the brain along with a delayed selective loss of vascular ETB-receptors. These changes seem to be posttranscriptional and cell type specific. They favor vasoconstriction increasing the risk of late vasospasm and ischemia.

Topics: Animals; Base Sequence; Brain; Brain Injuries; DNA Primers; Endothelin-1; Immunohistochemistry; Male; Rats; Rats, Sprague-Dawley; Receptors, Endothelin; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger

Previous studies observed that endothelin-1 (ET-1) contributed to ATP-sensitive K+ (K(ATP)) channel impairment 1 h following fluid percussion brain injury (FPI) in the newborn pig. The present study was designed to determine the effect of FPI on K(ATP) channel activity as a function of time in newborn (1-5 days old) and juvenile (3-4 weeks old) pigs equipped with a closed cranial window. FPI of moderate severity (1.9-2.1 atm) was produced by using a pendulum to strike a piston on a saline-filled cylinder that was fluid coupled to the brain via a hollow screw inserted through the cranium. Cromakalim, a K(ATP) agonist, produced dilation that was blunted for at least 72 h post FPI, but dilator responsiveness was restored within 168 h post FPI in the newborn pig (15+/-1% and 27+/-2% vs. 5+/-1% and 11+/-1% vs. 13+/-1% and 26+/-2% for responses to 10(-8), 10(-6) M cromakalim before, and 72 and 168 h after FPI). Similar inhibited responses were observed for calcitonin gene-related peptide, 8-Bromo cGMP, and the nitric oxide (NO) releasers SNP and SNAP. In contrast, cromakalim-induced dilation was blunted for at least 4 h, but dilator responsiveness was restored within 8 h post FPI in the juvenile pig (15+/-1% and 27+/-1% vs. 9+/-1% and 15+/-2% vs. 18+/-1% and 28+/-1% for 10(-8), 10(-6) M cromakalim before, and 4 and 8 h post FPI). Similar inhibition of dilations of other agonists also occurred in the juvenile. CSF ET-1 increased to a greater level and remained elevated for a longer period of time in the newborn compared to the juvenile pig. BQ123, an ET-1 antagonist, pretreatment partially restored decremented agonist induced dilation following FPI in the newborn and juvenile pig (5+/-1% and 11+/-1% vs. 11+/-1% and 21+/-1% for responses to 10(-8), 10(-6) M cromakalim 72 h post FPI in the newborn in the absence and presence of BQ123). These data indicate that K(ATP) channel function is impaired to a greater extent and for a longer time period in the newborn versus the juvenile pig. These data also show that ET-1 contributes to such impaired vascular responsiveness to a greater extent in the newborn versus the juvenile pig. These data furthermore suggest that the newborn is more sensitive to traumatic vascular injury than the juvenile.

Topics: Aging; Animals; Animals, Newborn; Arterioles; Brain; Brain Injuries; Calcitonin Gene-Related Peptide; Cerebrovascular Circulation; Cromakalim; Cyclic GMP; Endothelin Receptor Antagonists; Endothelin-1; Female; Male; Nitric Oxide Donors; Penicillamine; Peptides, Cyclic; Pia Mater; Potassium Channels; S-Nitroso-N-Acetylpenicillamine; Swine; Vasodilation

This study was designed to compare the effect of fluid percussion brain injury (FPI) on the hypotensive cerebrovascular response in newborn and juvenile pigs as a function of time postinsult and to determine the role of endothelin-1 (ET-1) in any age-dependent differences in hypotensive cerebrovascular regulation after injury. Ten minutes of hypotension (10-15 ml blood/kg) decreased mean arterial blood pressure uniformly in both groups ( approximately 45%). In the newborn, hypotensive pial artery dilation (PAD) was blunted within 1 h, remained diminished for at least 72 h, but was resolved within 168 h postinjury (66 +/- 4, 69 +/- 4, 71 +/- 4, and 64 +/- 4% inhibition at 1, 4, 8, and 72 h post-FPI). During normotension, regional cerebral blood flow (rCBF) was decreased by FPI, and hypotension further reduced the already decremented rCBF for at least 72 h. Cerebrospinal fluid (CSF) ET-1 was increased from 26 +/- 4 to 206 +/- 25 pg/ml within 72 h post-FPI, whereas an ET-1 antagonist partially restored impaired hypotensive PAD and altered hypotensive rCBF. In contrast, hypotensive PAD and altered CBF were only inhibited for 4 h post-FPI in the juvenile (56 +/- 3 and 34 +/- 4% inhibition at 1 and 4 h post-FPI). CSF ET-1 was only increased from 27 +/- 4 to 67 +/- 9 pg/ml at 4 h, whereas the concentration returned to preinjury value by 8 h post-FPI. ET-1 antagonism similarly partially restored impaired hypotensive PAD and altered hypotensive rCBF. These data show that FPI disturbs cerebral autoregulation during hypotension both to a greater magnitude and for a longer duration in the newborn than in the juvenile. These data suggest that the greater FPI-induced ET-1 release in the newborn could contribute to age-dependent differences in impaired hypotensive cerebral autoregulation after FPI.

Topics: Aging; Animals; Animals, Newborn; Arteries; Blood Pressure; Brain Injuries; Cerebrovascular Circulation; Endothelin-1; Female; Homeostasis; Hypotension; Male; Pia Mater; Swine; Time Factors; Vasodilation; Wounds, Nonpenetrating

Endothelin-1 (ET-1) is a 21 amino acid peptide that has been closely linked to cerebral vasospasm and more recently to oxidative stress after traumatic brain injury. In this study, we have examined the effects of the endothelin receptor subtype A antagonist, Ro 61-1790, on acute cortical neuronal injury and delayed neuronal death in the cerebellum after mild traumatic brain injury. Rats were administered Ro 61-1790 or vehicle for 24 h after injury and euthanized at 1 day, 3 days, or 7 days. Heat shock protein70 (HSP70), a marker of neuronal stress/injury, was immunolocalized in the cortex. Induction of heme oxygenase-1 (HO-1) and enhanced immunoexpression of the complement C3bi receptor, both of which are indicators of cerebellar glial reactivity, and Purkinje cell loss were evaluated in the cerebellum. There was maximal induction of HSP70 in cortical neurons at 24 h postinjury in all animals. Drug treated animals showed significantly fewer HSP70 labeled cortical neurons at this time point. There were fewer reactive glia in the cerebellum of drug treated animals as compared to vehicle controls at 3 days postinjury. However, at 7 days postinjury glial reactivity and Purkinje cell loss were similar in both groups. These findings demonstrate that Ro 61-1790, when administered for the first 24 h postinjury, limits acute neuronal injury in the cortex, transiently influences glial reactivity in the cerebellum, and does not attenuate delayed Purkinje cell death. The latter finding may reflect the duration of infusion of the drug.

Topics: Animals; Antibodies, Monoclonal; Brain Injuries; Cell Count; Cell Death; Cerebral Cortex; Dioxanes; Endothelin Receptor Antagonists; Endothelin-1; Heme Oxygenase (Decyclizing); Heme Oxygenase-1; HSP70 Heat-Shock Proteins; Macrophage-1 Antigen; Male; Microglia; Nerve Degeneration; Purkinje Cells; Pyridines; Pyrimidines; Rats; Rats, Sprague-Dawley; Receptor, Endothelin A; Receptors, Endothelin; Sulfonamides; Tetrazoles

The aim of this study was to measure vascular reactivity in the isolated middle cerebral artery (MCA) after brain injury. Segments of MCA were prepared from control, sham-operated, and cold-lesioned rats. Cold lesion was induced by application of a precooled (-78 degrees C) copper cylinder (diameter 5 mm) for 60 sec to the intact dura over the parietal cortex. Endothelin-1 (ET-1) (10(-12) to 3 x 10(-7) M) induced a dose-dependent contraction with a pD2 (-log10 EC50) of 8.36+/-0.12 (mean+/-SEM) and an Emax (maximal response) of 2.41+/-0.15 mN (millinewton) at 10(-7) M in sham-operated animals under resting conditions. This maximum contraction induced by 10(-7) M ET-1 was significantly (p < 0.05) reduced 24 and 48 h after cold lesion by 41% and 30%, respectively. After precontraction with 10(-5) M prostaglandin (PG) F2alpha, ET-3 (10(-12) to 10(-8) M) relaxed the MCA with an Emax of 0.42+/-0.07 mN at 10(-8) M and a pD2 of 9.20+/-0.19 in sham-operated animals. This relaxation was reduced 24 and 48 h after cold lesion by 19% and 62% at 10(-8) M, respectively. Concentration-effect curves for bradykinin (BK, 10(-8) to 10(-5) M) in uridine triphosphate (UTP, 10(-4) M)-precontracted MCA segments revealed relaxation with a pD2 of 7.08+/-0.10 and an Emax of 0.65+/-0.06 mN at 10(-6) M in sham-treated animals. This effect of BK was reduced by 35% and 20% at 10(-6) M 24 and 48 h after cold lesion, respectively. In addition, the contractile responses to 124 mM K+, 10(-5) M PGF2alpha and the dilation induced by 10(-3) sodium nitroprusside (SNP) were reduced in MCA segments taken 24 and 48 h after lesion compared with shams. We conclude that attenuation of ET effects can be explained, at least in part, by tachyphylaxis to ETs. The unspecific reduction of vascular reactivity may result from spreading depression.

Topics: Animals; Bradykinin; Brain Chemistry; Brain Injuries; Cerebral Arteries; Cerebrovascular Circulation; Cold Temperature; Dinoprost; Dose-Response Relationship, Drug; Endothelin Receptor Antagonists; Endothelin-1; Endothelin-3; Male; Nitroprusside; Parietal Lobe; Peptides, Cyclic; Potassium; Rats; Rats, Inbred WKY; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Endothelin; Uridine Triphosphate; Vasodilator Agents

Traumatic brain injury conveys significant morbidity and mortality to infants and children. In the newborn pig, opioids contribute to pial artery vasconstriction after fluid percussion injury (FPI). FPI attenuates vasodilation and cGMP production by methionine enkephalin (Met) and leucine enkephalin (Leu) and reverse dynorphin (Dyn) from a dilator to a constrictor. Superoxide anion (O2-) production contributes to altered cerebral hemodynamics after FPI, and O2- scavengers partially restore decreased dilator responses after FPI. Endothelin-1 (ET-1), a purported mediator of cerebral vasospasm, has been suggested to alter nitric oxide function and cGMP concentration. The present study was designed to determine the contribution of ET-1 to altered opioid-induced dilation after FPI and the role of O2- in such altered responses.. Injury of moderate severity (1.9 to 2.3 atm) was produced by the lateral FPI technique in anesthetized newborn pigs equipped with a closed cranial window. Superoxide dismutase (SOD)-inhibitable nitroblue tetrazolium (NBT) reduction was determined as an index of O2- generation.. FPI increased cerebrospinal fluid ET-1 from 20 +/- 2 to 93 +/- 6 pg/mL (approximately 10(-10) mol/L). Topical ET-1 (10(-10) mol/L) increased SOD-inhibitable NBT reduction from 1 +/- 1 to 16 +/- 3 pmol/mm2, similar to previously reported NBT reduction after FPI (14 +/- 2 pmol/mm2). BQ123 (10(-6) mol/L), an ET-1 antagonist, blunted the NBT reduction observed after FPI (4 +/- 1 pmol/mm2). Met produced pial vasodilation that was attenuated by FPI and partially restored by BQ123 pretreatment (7 +/- 1%, 11 +/- 1%, and 17 +/- 1% versus 3 +/- 1%, 6 +/- 1%, and 9 +/- 2% versus 5 +/- 1%, 9 +/- 1%, and 14 +/- 2% for 10(-10), 10(-8), and 10(-6) mol/L Met during control conditions, after FPI, and after FPI pretreated with BQ123, respectively). Met-induced dilation was associated with increased cerebrospinal fluid cGMP, and these biochemical changes were likewise blunted by FPI and partially restored by BQ123 (357 +/- 12, 455 +/- 15, 500 +/- 19, and 632 +/- 11 versus 264 +/- 4, 267 +/- 4, 295 +/- 12, and 305 +/- 15 versus 309 +/- 19, 432 +/- 11, 529 +/- 10, and 593 +/- 4 pg/mL for resting conditions, 10(-10), 10(-8), and 10(-6) mol/L Met during control conditions, after FPI, and after FPI pretreated with BQ123, respectively). Similar partial restoration of vascular and biochemical parameters was observed for Leu and Dyn.. These data show that ET-1, in concentrations similar to that present in cerebrospinal fluid after FPI, increases O2- production. These data also indicate the opioid-induced vasodilation and cGMP production are partially restored after FPI by ET-1 receptor blockade. These data suggest that ET-1 contributes to altered cerebral hemodynamics after FPI, at least in part, through elevated O2- production.

Topics: Analysis of Variance; Animals; Animals, Newborn; Arterioles; Brain Injuries; Cerebral Arteries; Dynorphins; Endothelin Receptor Antagonists; Endothelin-1; Enkephalin, Leucine; Enkephalin, Methionine; Female; Male; Muscle, Smooth, Vascular; Peptides, Cyclic; Pia Mater; Superoxides; Swine; Vasoconstriction; Vasodilation

We examined the possibility of the involvement of endothelin (ET)-1, a potent vasoactive peptide, in the process of astrocyte proliferation after brain injury. Acute brain damage in rats was induced by cold-injury. Astrocytes changed from a differentiated state to an immature, RC-1-positive state immediately after the injury. In the injured site, the level of ET-1-like immunoreactivity in the tissue was significantly increased on the first postoperative day and was sustained at a high level for 5 days. ET(B) receptor mRNA was markedly but transiently down-regulated only on the first day after the injury. Brain extracts (BE) were prepared from the injured tissues, and their effects on the proliferative characteristics of astrocytes were examined in primary culture of astrocytes. The flat morphology, which was observed in association with cell proliferation, and DNA synthesis of astrocytes were enhanced by treatment with each of the BE from 1 (D1-BE), 3 and 5 days after the injury. A monoclonal antibody that recognizes the C-terminus of rat ET-1 and ET-3 inhibited the DNA synthesis of astrocytes induced by D1-BE. These results provide experimental evidence that ET-1 may participate in the initiation of gliosis in the acute phase of brain damage.

Topics: Acute Disease; Animals; Antibodies, Monoclonal; Astrocytes; Brain; Brain Injuries; Cells, Cultured; Cold Temperature; DNA; Down-Regulation; Endothelin-1; Male; Rats; Rats, Wistar; Receptor, Endothelin B; Receptors, Endothelin; Thymidine; Time Factors; Tissue Extracts

In piglets, pial arteries constrict, ATP-sensitive K+ (KATP) channel function is impaired, and cerebrospinal fluid endothelin-1 (ET-1) increases to 10(-10) M after brain injury [fluid percussion injury (FPI)]. Nitric oxide (NO) elicits dilation via guanosine 3',5'-cyclic monophosphate (cGMP) and KATP channel activation. This study was designed to characterize the relationship between ET-1 and impaired function of KATP channels after FPI. Injury was produced via the lateral FPI technique in piglets equipped with a closed cranial window. Cromakalim, a KATP agonist, produced dilation that was attenuated by FPI and partially restored by BQ-123, an ET-1 antagonist (11 +/- 1 and 23 +/- 2 vs. 2 +/- 1 and 4 +/- 1 vs. 8 +/- 1 and 17 +/- 2% for responses to 10(-8) and 10(-6) M cromakalim before FPI, after FPI, and after FPI with BQ-123, respectively). Because ET-1 constriction may antagonize dilation, separate experiments were conducted under conditions of equivalent baseline diameter in the absence and presence of ET-1 (10(-10) M). Cromakalim dilation was attenuated by ET-1 and partially restored by the protein kinase C (PKC) inhibitor staurosporine (12 +/- 1 and 28 +/- 1 vs. 2 +/- 1 and 21 +/- 3 vs. 9 +/- 1 and 29 +/- 2% for 10(-8) and 10(-6) M cromakalim, cromakalim with ET-1, and cromakalim with ET-1 + staurosporine, respectively). Similar interactions were observed with calcitonin gene-related peptide, 8-bromoguanosine 3',5'-cyclic monophosphate, and the NO releasers sodium nitroprusside and S-nitroso-N-acetylpenicillamine. These data show that ET-1 blunts KATP channel-, NO-, and cGMP-mediated dilation. These data suggest that ET-1 contributes to altered cerebral hemodynamics after FPI through impairment of KATP channel function via PKC activation.

Topics: Animals; Animals, Newborn; Arterioles; Brain Injuries; Calcitonin Gene-Related Peptide; Cerebral Arteries; Cromakalim; Endothelin-1; Female; Male; Muscle Contraction; Muscle, Smooth, Vascular; Nitroprusside; Penicillamine; Pia Mater; Potassium Channels; S-Nitroso-N-Acetylpenicillamine; Swine

Pial artery constriction following fluid-percussion injury to the brain is associated with elevated cerebrospinal fluid (CSF) vasopressin concentration in newborn pigs. It has also been observed that fluid-percussion injury reverses the function of vasopressin from that of a dilator to a constrictor. Endothelin-1 (ET-1), a purported mediator of cerebral vasospasm, can be released by several stimuli, including vasopressin. The present study was designed to investigate the role of ET-1 in pial artery constriction and in the reversal of vasopressin from a dilator to a constrictor, which is observed after fluid-percussion injury. Brain injury of moderate severity (1.9-2.3 atm) was produced in anesthetized newborn pigs that had been equipped with a closed cranial window. Endothelin-1 elicited pial dilation at low concentrations and vasoconstriction at higher concentrations. Fluid-percussion injury reversed the process of dilation to that of constriction at the low ET-1 concentration and potentiated this constriction at high ET-1 concentrations (10% +/- 1%, -8% +/- 1%, and -15% +/- 1% vs. -6% +/- 1%, -17% +/- 1%, and -26% +/- 2% for 10(-12), 10(10),10(-8) M ET-1 before and after fluid-percussion injury, respectively). Vasopressin modestly increased CSF ET-1 concentration before fluid-percussion injury. Fluid-percussion injury markedly increased CSF ET-1 concentration and the ability of vasopressin to release ET-1 (20 +/- 2, 26 +/- 3, and 40 +/- 4 pg/ml vs. 93 +/- 6, 141 +/- 9, and 247 +/- 31 pg/ml for control, 40 pg/ml vasopressin, and 400 pg/ml vasopressin before and after fluid-percussion injury, respectively). An ET-1 antagonist, BQ 123 (10(-6) M) blunted pial artery constriction following fluid-percussion injury (146 +/- 5 microns -127 +/- 6 microns vs.144 +/- 5 microns-136 +/- 4 microns). The BQ 123 also blocked the reversal of vasopressin's function from that of a dilator to a constrictor after fluid-percussion injury (8% +/- 1%, 21% +/- 3%, and -5% +/- 1%, -14% +/- 2% vs. 8% +/- 1%, 21% +/- 2% and 4% +/- 1%, 2% +/- 1% for 40 and 4000 pg/ml vasopressin before and after fluid-percussion injury in the absence and presence of BQ 123, respectively). The BQ 123 blocked the constrictor component to ET-1, whereas it had no effect on the dilator component. These data show that ET-1 contributes to pial constriction after fluid-percussion injury. These data also indicate that vasopressin-induced release of ET-1 contributes to the reversal of vasopressin from a dila

Topics: Animals; Animals, Newborn; Brain Injuries; Cerebral Arteries; Dose-Response Relationship, Drug; Endothelin-1; Female; Male; Swine; Vasoconstriction; Vasopressins