An oxygen-rich atmosphere or systemic fluoxetine extend the time to respiratory arrest in a rat model of obstructive apnea.

Audiogenic seizure-prone mice can be protected from seizure-associated death by exposure to an oxygen atmosphere or treatment with selective serotonergic reuptake inhibitors (SSRIs). We have shown previously in a rat model that epileptic seizure activity can spread through brainstem areas to cause sufficient laryngospasm for obstructive apnea and that the period of seizure-associated obstructive apnea can last long enough for respiratory arrest to occur. We hypothesized that both the oxygen-rich atmosphere and SSRIs function by prolonging the time to respiratory arrest, thus ensuring that seizure activity stops before the point of respiratory arrest to allow recovery of respiratory function. To test this hypothesis, we evaluated each preventative treatment in a rat model of controlled airway occlusion where the times to respiratory arrest can be measured. Adult male Sprague Dawley rats (median age = 66 days) were studied in the absence of any seizure activity. By directly studying responses to controlled airway occlusion, rather than airway occlusion secondary to seizure activity, we could isolate the effects of manipulations that might prolong respiratory arrest from the effects of those manipulations on seizure intensity. All group sizes were ≥ 8 animals per group. We found that both oxygen exposure and fluoxetine significantly increased the time to respiratory arrest by up to 65% (p < .0001 for 5 min oxygen exposure; p = .031 for 25 mg/kg fluoxetine tested 60 min after injection) and, given that neither treatment has been shown to significantly alter seizure duration, these increases can account for the protection of either manipulation against death in sudden death models. Importantly, we found that 30 s of exposure to oxygen produced nearly the same protection as 5 min exposure suggesting that oxygen exposure could start after a seizure starts (p = .0012 for 30 s oxygen exposure). Experiments with 50% oxygen/50% air mixtures indicate that the oxygen concentration needs to be above about 60% to ensure that times to respiratory arrest will always be longer than a period of seizure-induced airway occlusion. Selective serotonin reuptake inhibitors, while instructive with regard to mechanism, require impractical dosing and may carry additional risk in the form of greater challenges for resuscitation. We conclude that oxygen exposure or SSRI treatment prevent seizure associated death by sufficiently prolonging the time to respiratory arrest so that respiratory function can recover after the seizure abates and eliminates the stimulus for seizure-induced apnea.

Diving responses elicited by nasopharyngeal irrigation mimic seizure-associated central apneic episodes in a rat model.

The spread of epileptic seizure activity to brainstem respiratory and autonomic regions can elicit episodes of obstructive apnea and of central apnea with significant oxygen desaturation and bradycardia. Previously, we argued that central apneic events were not consequences of respiratory or autonomic activity failure, but rather an active brainstem behavior equivalent to the diving response resulting from seizure spread. To test the similarities of spontaneous seizure-associated central apneic episodes to evoked diving responses, we used nasopharyngeal irrigation with either cold water or mist for 10 or 60 s to elicit the diving response in urethane-anesthetized animals with or without kainic acid-induced seizure activity. Diving responses included larger cardiovascular changes during mist stimuli than during water stimuli. Apneic responses lasted longer than 10 s in response to 10 s stimuli or about 40 s in response to 60 s stimuli, and outlasted bradycardia. Repeated 10 s mist applications led to an uncoupling of the apneic episodes (which always occurred) from the bradycardia (which became less pronounced with repetition). These uncoupled events matched the features of observed spontaneous seizure-associated central apneic episodes. The duration of spontaneous central apneic episodes correlated with their frequency, i.e. longer events occurred when there were more events. Based on our ability to replicate the properties of seizure-associated central apneic events with evoked diving responses during seizure activity, we conclude that seizure-associated central apnea and the diving response share a common neural basis and may reflect an attempt by brainstem networks to protect core physiology during seizure activity.

Seizure-associated central apnea in a rat model: Evidence for resetting the respiratory rhythm and activation of the diving reflex.

Respiratory derangements, including irregular, tachypnic breathing and central or obstructive apnea can be consequences of seizure activity in epilepsy patients and animal models. Periods of seizure-associated central apnea, defined as periods >1s with rapid onset and offset of no airflow during plethysmography, suggest that seizures spread to brainstem respiratory regions to disrupt breathing. We sought to characterize seizure-associated central apneic episodes as an indicator of seizure impact on the respiratory rhythm in rats anesthetized with urethane and given parenteral kainic acid to induce recurring seizures. We measured central apneic period onsets and offsets to determine if onset-offset relations were a consequence of 1) a reset of the respiratory rhythm, 2) a transient pausing of the respiratory rhythm, resuming from the pause point at the end of the apneic period, 3) a transient suppression of respiratory behavior with apnea offset predicted by a continuation of the breathing pattern preceding apnea, or 4) a random re-entry into the respiratory cycle. Animals were monitored with continuous ECG, EEG, and plethysmography. One hundred ninety central apnea episodes (1.04 to 36.18s, mean: 3.2±3.7s) were recorded during seizure activity from 7 rats with multiple apneic episodes. The majority of apneic period onsets occurred during expiration (125/161 apneic episodes, 78%). In either expiration or inspiration, apneic onsets tended to occur late in the cycle, i.e. between the time of the peak and end of expiration (82/125, 66%) or inspiration (34/36, 94%). Apneic period offsets were more uniformly distributed between early and late expiration (27%, 34%) and inspiration (16%, 23%). Differences between the respiratory phase at the onset of apnea and the corresponding offset phase varied widely, even within individual animals. Each central apneic episode was associated with a high frequency event in EEG or ECG records at onset. High frequency events that were not associated with flatline plethysmographs revealed a constant plethysmograph pattern within each animal, suggesting a clear reset of the respiratory rhythm. The respiratory rhythm became highly variable after about 1s, however, accounting for the unpredictability of the offset phase. The dissociation of respiratory rhythm reset from the cessation of airflow also suggested that central apneic periods involved activation of brainstem regions serving the diving reflex to eliminate the expression of respiratory movements. This conclusion was supported by the decreased heart rate as a function of apnea duration. We conclude that seizure-associated central apnea episodes are associated with 1) a reset of the respiratory rhythm, and 2) activation of brainstem regions serving the diving reflex to suppress respiratory behavior. The significance of these conclusions is that these details of seizure impact on brainstem circuitry represent metrics for assessing seizure spread and potentially subclassifying seizure patterns.

Laryngospasm, central and obstructive apnea during seizures: Defining pathophysiology for sudden death in a rat model.

Seizure spread into the autonomic nervous system can result in life-threatening cardiovascular and respiratory dysfunction. Here we report on a less-studied consequence of such autonomic derangements-the possibility of laryngospasm and upper-airway occlusion. We used parenteral kainic acid to induce recurring seizures in urethane-anesthetized Sprague Dawley rats. EEG recordings and combinations of cardiopulmonary monitoring, including video laryngoscopy, were performed during multi-unit recordings of recurrent laryngeal nerve (RLN) activity or head-out plethysmography with or without endotracheal intubation. Controlled occlusions of a tracheal tube were used to study the kinetics of cardiac and respiratory changes after sudden obstruction. Seizure activity caused significant firing increases in the RLN that were associated with abnormal, high-frequency movements of the vocal folds. Partial airway obstruction from laryngospasm was evident in plethysmograms and was prevented by intubation. Complete glottic closure (confirmed by laryngoscopy) occurred in a subset of non-intubated animals in association with the largest increases in RLN activity, and cessation of airflow was followed in all obstructed animals within tens of seconds by ST-segment elevation, bradycardia, and death. Periods of central apnea occurred in both intubated and non-intubated rats during seizures for periods up to 33s and were associated with modestly increased RLN activity, minimal cardiac derangements, and an open airway on laryngoscopy. In controlled complete airway occlusions, respiratory effort to inspire progressively increased, then ceased, usually in less than 1min. Respiratory arrest was associated with left ventricular dilatation and eventual asystole, an elevation of systemic blood pressure, and complete glottic closure. Severe laryngospasm contributed to the seizure- and hypoxemia-induced conditions that resulted in sudden death in our rat model, and we suggest that this mechanism could contribute to sudden death in epilepsy.

[Critical illness polyneuropathy and myopathy as neurological complications of sepsis]. / Critical-illness-Polyneuropathie und -Myopathie als neurologische Komplikationen der Sepsis.

Intensive care unit acquired weakness (ICUAW) is a frequent and severe complication of intensive care management. Within ICUAW critical illness polyneuropathy (CIP) and myopathy (CIM) can be differentiated. The major symptom of ICUAW is progressive quadriparesis, which makes weaning from the respirator more difficult, can appear early after admission to an ICU and can often be detected several months after discharge from the ICU. The pathophysiology of ICUAW is multifactorial and complex. Potential therapeutic approaches are the early and sufficient therapy of mulitorgan dysfunction, optimal control of glucose levels as well as early and intensive physiotherapy. This review article discusses the data on incidence, pathophysiology, diagnostic approaches and prognosis of ICUAW.

Lithium alters the morphology of neurites regenerating from cultured adult spiral ganglion neurons.

The small-molecule drug lithium (as a monovalent ion) promotes neurite regeneration and functional recovery, is easy to administer, and is approved for human use to treat bipolar disorder. Lithium exerts its neuritogenic effect mainly by inhibiting glycogen synthase kinase 3, a constitutively-active serine/threonine kinase that is regulated by neurotrophin and "wingless-related MMTV integration site" (Wnt) signaling. In spiral ganglion neurons of the cochlea, the effects of lithium and the function of glycogen synthase kinase 3 have not been investigated. We, therefore, set out to test whether lithium modulates neuritogenesis from adult spiral ganglion neurons. Primary cultures of dissociated spiral ganglion neurons from adult mice were exposed to lithium at concentrations between 0 and 12.5 mM. The resulting neurite morphology and growth-cone appearance were measured in detail by using immunofluorescence microscopy and image analysis. We found that lithium altered the morphology of regenerating neurites and their growth cones in a differential, concentration-dependent fashion. Low concentrations of 0.5-2.5 mM (around the half-maximal inhibitory concentration for glycogen synthase kinase 3 and the recommended therapeutic serum concentration for bipolar disorder) enhanced neurite sprouting and branching. A high concentration of 12.5 mM, in contrast, slowed elongation. As the lithium concentration rose from low to high, the microtubules became increasingly disarranged and the growth cones more arborized. Our results demonstrate that lithium selectively stimulates phases of neuritogenesis that are driven by microtubule reorganization. In contrast, most other drugs that have previously been tested on spiral ganglion neurons are reported to inhibit neurite outgrowth or affect only elongation. Lithium sensitivity is a necessary, but not sufficient condition for the involvement of glycogen synthase kinase 3. Our results are, therefore, consistent with, but do not prove lithium inhibiting glycogen synthase kinase 3 activity in spiral ganglion neurons. Experiments with additional drugs and molecular-genetic tools will be necessary to test whether glycogen synthase kinase 3 regulates neurite regeneration from spiral ganglion neurons, possibly by integrating neurotrophin and Wnt signals at the growth cone.

Long-term outcome in patients with Guillain-Barré syndrome requiring mechanical ventilation.

We aimed to determine long-term disability and quality of life in patients with Guillain-Barré syndrome (GBS) who required mechanical ventilation (MV) in the acute phase. Our retrospective cohort study included 110 GBS patients admitted to an intensive care unit and requiring MV (01/1999-08/2010) in nine German tertiary academic medical centers. Outcome was determined 1 year or longer after hospital admission using the GBS disability scale, Barthel index (BI), EuroQuol-5D (EQ-5D) and Fatigue Severity Scale. Linear/multivariate regression analysis was used to analyze predicting factors for outcome. Mean time to follow up was 52.6 months. Hospital mortality was 5.5 % and long-term mortality 13.6 %. Overall 53.8 % had a favorable outcome (GBS disability score 0-1) and 73.7 % of survivors had no or mild disability (BI 90-100). In the five dimensions of the EQ-5D "mobility", "self-care", "usual activities", "pain" and "anxiety/depression" no impairments were stated by 50.6, 58.4, 36.4, 36.4 and 50.6 % of patients, respectively. A severe fatigue syndrome was present in 30.4 % of patients. Outcome was statistically significantly correlated with age, type of therapy and number of immunoglobulin courses. In GBS-patients requiring MV in the acute phase in-hospital, and long-term mortality are lower than that in previous studies, while long-term quality of life is compromised in a large fraction of patients, foremost by immobility and chronic pain. Efforts towards improved treatment approaches should address autonomic dysfunction to further reduce hospital mortality while improved rehabilitation concepts might ameliorate long-term disability.

[EuroHYP-1 trial: EU-funded therapy study on the effectiveness of mild therapeutic hypothermia for acute ischemic stroke]. / EuroHYP-1-Studie : EU-geförderte Therapiestudie zur Effektivität milder therapeutischer Hypothermie beim akuten ischämischen Schlaganfall.

Therapeutic hypothermia (TH) improves the neurological outcome in experimental brain trauma models as well as in patients suffering from cardiac arrest and perinatal asphyxia. So far the efficacy of TH has not been proven in acute ischemic stroke due to lack of clinical data. The EuroHYP-1 study will investigate whether TH with an individual target range temperature between 34 and 35 °C administered for 24 h will improve the neurological outcome in ischemic stroke patients treated within 6 h from symptom onset. The target patient number of 1,500 to be included in EuroHYP-1 is sufficiently powered to detect the efficacy of TH.

[Therapeutic hypothermia in acute brain injury]. / Therapeutische Hypothermie bei akuten Hirnschädigungen.

Induced therapeutic hypothermia (TH) is defined as a controlled reduction of the core body temperature below the physiological range. While TH is neuroprotective in many different models of brain injury, it is only recommended for patients after cardiopulmonary resuscitation and newborns suffering from perinatal hypoxic-ischemic encephalopathy (HIE). Although a strong association exists between elevated body core temperature (fever) and worsening of outcome, TH has so far not been proven to influence outcome after ischemic stroke, intracerebral hemorrhage or subarachnoidal hemorrhage because of insufficient clinical data. This review summarizes the data on TH for different clinical indications and discusses relevant aspects of its use in neurological intensive care units.

[Therapeutic hypothermia in neurological critical care]. / Therapeutische Hypothermie in der neurologischen Intensivmedizin.

Therapeutic hypothermia (TH) is very effective for the treatment of acute experimental brain injury. In contrast to other neuroprotective methods or pharmacological agents, TH represents the only clinically proven neuroprotective therapy. TH led to a decreased mortality rate and improved functional outcome in patients with cardiac arrest. Investigations in severe head trauma are inconclusive up to now. Other important indications such as ischemic stroke remain to be investigated properly. Recent phase II studies are on the way to test safety and feasibility in the early time window of stroke including thrombolysis. The recent article describes the status and perspectives including open questions for hypothermia in neurological intensive care.

[Antipyretic strategies for acute stroke: a nationwide survey among German stroke units]. / Antipyretische Strategien bei akutem Schlaganfall: Eine bundesweite Erhebung auf zertifizierten Stroke-Units.

BACKGROUND: Fever in acute stroke is associated with poor prognosis, but evidence-based recommendations on antipyretic therapy are lacking. METHODS: A nation-wide survey was carried out among all certified stoke units in Germany about principles and organization of antipyretic strategies. RESULTS: In all cases antipyretic treatment is the standard of care. The use of paracetamol is part of the first-line therapy in 94%. In cases of non-response, distinct heterogeneity of therapeutic methods and intensities becomes apparent leading potentially to insufficient antipyretic treatment. CONCLUSION: So far, there is uncertainty about the optimal antipyretic treatment strategy after acute stroke. While current guidelines are not very explicit, efforts should be made to define a standardized, evidence-based antipyretic protocol to improve patient care, outcome on stroke units and comparability of therapeutic strategies.

Expression of Wnt receptors in adult spiral ganglion neurons: frizzled 9 localization at growth cones of regenerating neurites.

Little is known about signaling pathways, besides those of neurotrophic factors, that are operational in adult spiral ganglion neurons. In patients with sensorineural hearing loss, such pathways could eventually be targeted to stimulate and guide neurite outgrowth from the remnants of the spiral ganglion towards a cochlear implant, thereby improving the fidelity of sound transmission. To systematically identify neuronal receptors for guidance cues in the adult cochlea, we conducted a genome-wide cDNA microarray screen with 2-month-old CBA/CaJ mice. A meta-analysis of our data and those from older mice in two other studies revealed the presence of neuronal transmembrane receptors that represent all four established guidance pathways--ephrin, netrin, semaphorin, and slit--in the mature cochlea as late as 15 months. In addition, we observed the expression of all known receptors for the "wingless-related MMTV integration site" (Wnt) morphogens, whose neuronal guidance function has only recently been recognized. In situ hybridizations located the mRNAs of the Wnt receptors frizzled 1, 4, 6, 9, and 10 specifically in adult spiral ganglion neurons. Finally, frizzled 9 protein was found in the growth cones of adult spiral ganglion neurons that were regenerating neurites in culture. We conclude from our results that adult spiral ganglion neurons are poised to respond to neurite damage, owing to the constitutive expression of a large and diverse collection of guidance receptors. Wnt signaling, in particular, emerges as a candidate pathway for guiding neurite outgrowth towards a cochlear implant after sensorineural hearing loss.

The early immunological response to acute ischemic stroke: differential gene expression in subpopulations of mononuclear cells.

UNLABELLED: Peripheral blood mononuclear cells (PBMCs), i.e. lymphocytes, monocytes and macrophages are key players in the development of innate and adaptive immune responses. However, little is known about their properties in patients with acute stroke. EXPERIMENTAL PROCEDURES: We presently characterized the early time course of PBMC subpopulations in 19 patients with acute ischemic stroke and symptom onset below 6 h compared to 19 age-matched healthy subjects. Immediately after acute ischemic stroke, as well as 1 and 3 days thereafter, PBMC subpopulations (cluster of differentiation [CD]3+, CD14+, CD19+, CD68+) were isolated by magnetic bead system and the expression of proinflammatory (CD40, tumor necrosis factor-alpha [TNFalpha]), proapoptotic (caspase-3 [CPP32], poly(ADP-ribose) polymerase [PARP]) and adhesion relevant (CD38) genes was measured by quantitative polymerase chain reaction (PCR). Furthermore, besides routine parameters, plasma levels of oxidized low-density lipoproteins (oxLDL) were studied. RESULTS: In comparison to healthy subjects, patients revealed (i) twofold elevated plasma oxLDL concentrations, (ii) decreased (15%) blood cholesterol levels, and (iii) a 40% decrease in total number of lymphocytes. Furthermore, the majority of PBMC subpopulations revealed an increased expression of proinflammatory, proapoptotic or adhesion-relevant genes. Significant positive correlations were observed between expression of most of these genes in PBMCs and individual plasma oxLDL concentrations. CONCLUSION: Elevated expression of proinflammatory, proapoptotic and adhesion genes in subsets of PBMCs after ischemic stroke may contribute to an immunodepressive syndrome, possibly due to increased plasma oxLDL levels.

Safety and outcome after thrombolysis in stroke patients with mild symptoms.

BACKGROUND: Thrombolytic therapy is frequently withheld in patients with minor stroke symptoms. However, recent studies demonstrate that a substantial proportion of these patients dies or remains permanently disabled because of underestimation of symptom severity at baseline or secondary deterioration. We aimed to assess the safety and outcome of thrombolysis therapy in patients with minor but disabling stroke symptoms. METHODS: 32 patients presenting with mild symptoms were treated with intravenous recombinant tissue-type plasminogen activator between April 2006 and April 2008. Data were extracted from a prospectively collected database. Baseline demographic data, and clinical, laboratory and imaging findings were analyzed. Outcome was assessed using the modified Rankin Scale (mRS) score at 3 months and was dichotomized into favorable (mRS 0-1) versus unfavorable (mRS 2-6). RESULTS: In the majority of patients, the left hemisphere was affected, with aphasia representing the most common symptom leading to treatment decision. The frequency of perfusion lesion (46%) and vessel occlusion (35%) at baseline was high but had no effect on the outcome at 3 months in our series of treated patients. Outcome was favorable in 94% of patients, and 47% recovered without any persisting symptom. Only one asymptomatic and no symptomatic hemorrhage was observed. CONCLUSION: Our data support current guidelines and international licenses which give no lower National Institutes of Health Stroke Scale (NIHSS) limit for intravenous thrombolysis (IVT). Considering the accumulating evidence that the natural course in patients with mild symptoms is not as favorable as often assumed and taking the low risk of bleeding in those patients into account, patients with mild but disabling symptoms should be treated with IVT regardless of their baseline NIHSS score.

Ischaemic stroke: acute management, intensive care, and future perspectives.

Recently, a number of developments in the acute management of stroke have necessitated active involvement of neurocritical care. This review focuses on the immediate care, including intensive care, that may make a difference to the patient outcome. Recent research, that highlights the importance of acute management of stroke in terms of thrombolysis, thrombolytic agents, decompressive surgery, and hypothermia, has been reviewed.

[Acute cerebral circulation problems]. / Akute zerebrale Durchblutungsstörung.

Acute stroke is the third most common cause of death and also the most common cause of permanent disability in industrialized countries. Ischemic stroke is caused by occlusion of a cerebral artery leading to a critical reduction in brain perfusion in the respective brain area (penumbra). Most acute stroke treatment strategies are based on the penumbra concept: attaining rapid and persistent reperfusion is followed by the protection of critically ischemic and not yet infarcted (penumbral) tissue by, e.g., neuroprotection. Examination of the acute stroke patient includes a brief history, neurostatus and imaging (CT or MRI) for the exclusion of intracerebral hemorrhage. The diagnostic standard is CT; modern stroke MRI protocols provide an improved selection in later time windows. Intravenous thrombolysis with rt-PA within 3 h of symptom onset is the only approved therapy with a proven significant benefit for the patient. The effect is smaller but still significant if treatment occurs up to 4.5 h, and may still be present in MRI selected patients up to 9 h. More aggressive forms of therapy include interventional reperfusion techniques and therapy of malignant MCA infarction such as hemicraniectomy and hypothermia, which at present, however, are not routine and are only performed in specialized centers.

Effect of brain-derived neurotrophic factor treatment and forced arm use on functional motor recovery after small cortical ischemia.

BACKGROUND AND PURPOSE: Both the administration of growth factors and physical therapy such as forced arm use (FAU) are promising approaches to enhance recovery after stroke. We explored the effects of these therapies on behavioral recovery and molecular markers of regeneration after experimental ischemia. METHODS: Rats were subjected to photothrombotic ischemia: sham (no ischemia), control (ischemia), brain-derived neurotrophic factor (BDNF; ischemia plus BDNF, 20 microg), and FAU (ischemia plus FAU, 1-sleeve plaster cast ipsilateral limb). Animals survived 1 or 6 weeks and underwent behavioral testing (Rotarod, beam balance, adhesive removal, plantar test, neuroscore). After the rats were killed, brain sections were immunostained for semiquantitative analysis of MAP1B, MAP2, synaptophysin, GFAP expression, and quantification of infarct volumes. RESULTS: Infarct volumes were not different between the groups 1 or 6 weeks after ischemia. BDNF-treated animals had better functional motor recovery (Rotarod, beam balance, neuroscore) compared with all other groups (P<0.05). There was no significant adverse effect of early FAU treatment on motor recovery, although sensorimotor function (adhesive removal test) was impaired (P<0.05). There were no differences between groups as measured by nociception of the left and right forepaw (plantar test). BDNF treatment transiently induced MAP1B expression in the ischemic border zone and synaptophysin expression within the contralateral cortex 6 weeks after ischemia (P<0.05). Both BDNF and FAU reduced astrogliosis compared with controls (P<0.05). CONCLUSIONS: Postischemic intravenous BDNF treatment improves functional motor recovery after photothrombotic stroke and induces widespread neuronal remodeling. Early FAU treatment after stroke does not increase infarct size, impairs sensorimotor function, but leaves motor function unchanged. Postischemic astrogliosis was reduced by both treatments.

[Acute meningitis after transrectal prostate biopsy]. / Akute Meningitis nach transrektaler Prostatapunktion.

Acute meningitis caused by Escherichia coli is a rare disease in adulthood. Medical procedures, e.g. surgical interventions, have been described as a cause. Infection by blood transmission of fecal E. coli is also known. We report a case of acute meningitis after transrectal prostate biopsy. E. coli could be identified both in the cerebrospinal fluid and in the blood culture. A broad initial antibiotic therapy was administered. After cultural isolation of E. coli the therapy was switched to cefotaxime. The initially comatose patient recovered swiftly.

Neuroprotective effect of granulocyte colony-stimulating factor after focal cerebral ischemia.

BACKGROUND AND PURPOSE: The potential neuroprotective effect of the granulocyte colony-stimulating factor (G-CSF) after glutamate-induced excitotoxicity in cell culture and after focal cerebral ischemia in rats was studied. We hypothesized the existence of the G-CSF receptor (G-CSFR) as a main G-CSF effector on neurons, and immunohistochemistry, immunoblotting, and polymerase chain reaction were performed. The G-CSFR-mediated action was studied by activation of signal transducer(s) and activator(s) of transcription-3 (STAT3) in the periphery of the infarction. METHODS: Neuroprotection of various G-CSF concentrations on glutamate-induced excitotoxicity was studied in cell culture. In vivo, ischemia was induced by use of a suture occlusion model of the middle cerebral artery (90-minute occlusion) in the rat. Thirty minutes after the induction of ischemia, the animals (n=12 per group) received G-CSF at 60 microg/kg body wt IV for 90 minutes or vehicle (saline). Infarct volume was calculated on the basis of 2,3,5-triphenyltetrazolium chloride staining 24 hours after ischemia. Expression of the G-CSFR was studied by immunohistochemistry and verified by reverse transcription-polymerase chain reaction and immunoblotting. Expression of STAT3 was determined by immunohistochemistry. RESULTS: In cell culture, G-CSF exhibited a significant neuroprotective effect after glutamate-induced excitotoxicity (P<0.05). A G-CSF concentration of 10 ng/mL was maximally effective, resulting in a nearly complete protection. In vivo, G-CSF reduced infarct volume to 47% (132.0+/-112.7 mm3 versus 278.9+/-91.6 mm3 [P<0.05] in the control group). Immunohistochemistry, Western blotting, and reverse transcription-polymerase chain reaction revealed the existence of G-CSFRs in neurons and glial cells. Animals treated with G-CSF significantly upregulated STAT3 in the periphery of the infarction compared with control animals (P<0.05). CONCLUSIONS: G-CSF achieved a significant neuroprotective effect in cell culture and after intravenous administration after stroke. Increased STAT3 expression in the penumbra of G-CSF-treated rats suggests mediation by G-CSFR.