The effects of endothelin antagonist BQ-610 on cerebral vascular wall following experimental subarachnoid hemorrhage and cerebral vasospasm

Endothelin, a potent vasoconstrictor, has been found to increase in the cerebrospinal fluid and serum of patients following subarachnoid hemorrhage (SAH) and to play a major role in the development of cerebral vasospasm. The aim of this study is to investigate the role of endothelin-A antagonist BQ-610 in the experimentally performed cerebral vasospasm following SAH. Thirty New Zealand rabbits were divided into three groups (each n = 10): group A, control group; Group B, SAH group; Group C, treatment (endothelin antagonist BQ-610 treated) group. In the study, the rabbits developed vasospasm after injection of intracisternal autolog blood into the cisterna magna. After cerebral vasospasm development, in group C, endothelin antagonist BQ-610 was injected intracisternally. Morphometrically, basilar artery lumen was constricted 25% and 62% compared to the control group (group A) in the endothelin treated group (group C) and the endothelin untreated group (group B), respectively. Histopathological findings of the basilar artery wall confirmed the therapeutic effect of endothelin antagonist in vasospasm development. Endothelin-A receptor antagonist BQ-610 has a therapeutic effect in the cerebral vasospasm following experimentally performed subarachnoid hemorrhage when used intracisternally.

Interleukin-1β injected intracisternally inhibited NMDA-evoked behavioral response in the orofacial area of freely moving rats

The brain-derived interleukin-1beta (IL-1beta) has been involved in the modulation of nociceptive processing. The direction of the effects, however, analgesia or hyperalgesia, is controversial. Here, we report the role of IL-1beta injected intracisternally in orofacial pain transmission. Experiments were carried out on 90 male SD rats and surgical procedures were performed under pentobarbital sodium. Intracisternal injection of 0.3 or 0.6 microg of N-methyl-d-aspartic acid (NMDA) produced intense scratching behavioral responses including vocalization, agitation and a desire to escape in a dose-related manner. The intracisternal injection of 1 or 10 ng IL-1beta significantly decreased the NMDA-evoked scratching behavioral responses. Pretreatment with an IL-1 receptor antagonist or naloxone, an opioid receptor antagonist, blocked the IL-1beta-induced antinociceptive response. These results suggest that cytokine injected intracisternally seems to produce antinociceptive effects in the NMDA-evoked pain model of the orofacial area and the antinociceptive effect seems to be mediated by an opioid pathway.

Tissue plasminogen activator levels after single intracisternal injection in patients with subarachnoid hemorrhage

Tissue plasminogen activator (tPA) levels were investigated in the cisternal fluid of patients with subarachnoid hemorrhage treated with single intracisternal injection of recombinant tPA during radical surgery for ruptured aneurysms. Seven patients received different doses of tPA: two of 400 microg/ml, three of 500 microg/ml, one of 700 microg/ml, and one of 800 microg/ml in a total amount of 20 ml distilled water at pH 7. Cerebrospinal fluid samples were taken directly from the cisternal fluid at 15-minute incubation after injection, immediately after irrigation during surgery, and by lumbar tap 2 days after surgery. Cisternal tPA levels decreased to about 60% of the mean injected doses after 15-minute incubation. Simple linear regression analysis showed these tPA levels after incubation correlated with the initial doses. After copious irrigation with Ringer solution at pH 8, tPA levels decreased rapidly without correlation with the initial doses. After spinal drainage for 2 days, tPA levels further decreased by an order of 10(-4) to 10(-6) from the initial dose. These values were still greater than normal controls. The final values of tPA levels were not related to the initial dose. None of the patients suffered from systemic or wound complications. Cisternal tPA injection with increased doses and irrigation may be beneficial for the selective rapid removal of blood clots with controllable safety.

Isoflurane Facilitates Hiccup-Like Reflex Through Gamma Aminobutyric Acid (GABA)A- and Suppresses Through GABAB-Receptors in Pentobarbital-Anesthetized Cats

The mechanism by which volatile anesthetics exert inconsistent effects on hiccups is unknown. We elicited a hiccup-like reflex by mechanical stimulation of the dorsal epipharynx in mechanically ventilated cats. The magnitude of the hiccup-like reflex was measured as the peak negative esophageal pressure (nPes) generated against an occluded airway. First, we examined the effects of different end-expiratory concentrations of isoflurane on nPes. Second, we determined the effects of 1.0 minimum alveolar anesthetic concentration of isoflurane on nPes after a peripherally restricted gamma aminobutyric acid (GABA)(A)-receptor antagonist, bicuculline methiodide (BM), a GABA(B)-receptor antagonist, CGP 35348, a peripherally restricted GABA(B)-receptor antagonist, CGP 54626, or saline had been administered IV. Third, BM, CGP 35348, or artificial cerebrospinal fluid was administered intracisternally before 1.0 minimum alveolar anesthetic concentration of isoflurane exposure. During isoflurane anesthesia, nPes was inversely proportional to the end-expiratory isoflurane concentration. The rank order of nPes values obtained after IV drug pretreatment and isoflurane exposure was BM < saline < CGP54626 < CGP35348. After intracisternal drug pretreatment and isoflurane administration, the order of nPes was BM < artificial cerebrospinal fluid < CGP35348. Isoflurane modulates the hiccup-like reflex in opposite directions through both central and peripheral GABA(A) and GABA(B) receptors, with the net effect being a dose-dependent suppression.

IMPLICATIONS

Isoflurane facilitated the hiccup-like reflex through activation of central and peripheral gamma aminobutyric acid (GABA)(A) receptors but suppressed it via activation of central and peripheral GABA(B) receptors. The net result was that the hiccup-like reflex was inhibited in proportion to the alveolar isoflurane concentration.

Effectiveness of the head-shaking method combined with cisternal irrigation with urokinase in preventing cerebral vasospasm after subarachnoid hemorrhage

OBJECT

The head-shaking method combined with cisternal irrigation has been proposed to be effective in preventing cerebral vasospasm after subarachnoid hemorrhage (SAH) by facilitating rapid washout of the clot from the subarachnoid space. This study was conducted to evaluate the effectiveness of this method.

METHODS

The inclusion criteria included the following: 1) Fisher Grade 3 SAH on admission computerized tomography (CT) scans; 2) aneurysm secured within 48 hours of SAH onset; and 3) no focal deficit and ability to obey commands within 24 hours postsurgery. Two hundred thirty patients treated between 1994 and 2002 fulfilled the criteria. Because only one machine was available and it required I month of maintenance every other month, 114 patients underwent irrigation combined with the head-shaking method (head-shaking group), whereas the remaining 116 patients received cisternal irrigation alone (control group). There were no significant differences in sex, age, site of aneurysm, or preoperative grade between the two groups. The incidence of symptomatic vasospasm with or without infarction, cerebral infarction on CT scans, and permanent ischemic neurological deficit was 25.7, 17.7, and 8.8%, respectively, in the control group and 15.2, 4.5, and 2.7% in the head-shaking group. The difference was statistically significant for symptomatic vasospasm, cerebral infarction, and permanent ischemic neurological deficit (p < 0.05). In a multivariate backward stepwise logistic regression analysis, absence of head shaking was the only variable that was predictive of permanent ischemic neurological deficit (p = 0.061). The outcomes evaluated using the modified Rankin Scale were better in the head-shaking group (p = 0.051).

CONCLUSIONS

The head-shaking method significantly reduced the incidence of symptomatic vasospasm, cerebral infarction, and permanent ischemic neurological deficit and improved the clinical outcomes in patients who underwent cisternal irrigation therapy after aneurysmal SAH.

Does Intracisternal Thrombolysis Prevent Vasospasm after Aneurysmal Subarachnoid Hemorrhage? A Meta-analysis

OBJECTIVE

Despite existing strategies for the treatment of vasospasm after aneurysmal subarachnoid hemorrhage, vasospasm remains a persistent contributor to death and disability. The intracisternal application of thrombolytic agents to dissolve subarachnoid clot has been advocated. The goal of this analysis was to assess the currently available evidence regarding the effectiveness of this treatment.

METHODS

We conducted a systematic review of the published literature; all controlled trials were included. The outcomes of interest were delayed ischemic neurological deficits, poor Glasgow Outcome Scale scores, and death. A formal meta-analysis was performed with a random-effects model.

RESULTS

The search revealed nine trials or trial subgroups (only one of which was randomized), with a total enrollment of 652 patients. Pooled results demonstrated beneficial effects of treatment, with absolute risk reductions of 14.4% (95% confidence interval, 6.5–22.5%; P &lt; 0.001) for delayed ischemic neurological deficits, 9.5% (95% confidence interval, 4.2–14.8%; P &lt; 0.01) for poor Glasgow Outcome Scale scores, and 4.5% (95% confidence interval, 1.5–7.5%; P &lt; 0.05) for death. Regression analysis revealed that treatment effects did not significantly differ among the studies on the basis of the type of thrombolytic agent used (tissue plasminogen activator versus urokinase) or the method of administration (intraoperative versus postoperative) (P &gt; 0.10). Studies that enrolled only patients at high risk for vasospasm seemed to demonstrate greater treatment effects.

CONCLUSION

The meta-analysis suggests a clinically relevant and statistically significant beneficial effect of intracisternal thrombolysis. However, the results of the analysis are limited by the predominance of nonrandomized studies. Further randomized, blinded, placebo-controlled trials of high-risk patients would be justified.

Vagal afferent input from the acid-challenged rat stomach to the brainstem: Enhancement by interleukin-1β

Exposure of the gastric mucosa to back-diffusing concentrations of HCl (0.25 M, pH 0.51) stimulates vagal afferent input to the brainstem. Here we have examined whether pretreatment of rats with the proinflammatory cytokines interleukin-1beta and tumor necrosis factor-alpha causes sensitization of vagal afferent pathways to HCl. Rats were pretreated i.p. with interleukin-1beta, tumor necrosis factor-alpha (10 microg/kg) or their vehicle (sterile saline) 24, 48 and 96 h before intragastric administration of HCl (0.25 M, 1 ml/100 g). Activation of neurons in the nucleus tractus solitarii was visualized by c-Fos immunohistochemistry 2 h after the HCl challenge. I.p. administration of interleukin-1beta and tumor necrosis factor-alpha alone induced c-Fos in the brainstem, an effect that was gone after 24 h. At this time, however, the effect of HCl to cause expression of c-Fos in the nucleus tractus solitarii was significantly enhanced by pretreatment with interleukin-1beta and tumor necrosis factor-alpha. The sensitizing effect of i.p.-administered interleukin-1beta was sustained for more than 48 h and prevented by the interleukin-1 receptor antagonist anakinra. Intracisternal administration of interleukin-1beta and tumor necrosis factor-alpha (100 ng) failed to amplify the HCl-evoked expression of c-Fos in the brainstem. These results show that peripheral administration of the proinflammatory cytokines interleukin-1beta and tumor necrosis factor-alpha induces prolonged sensitization of vagal afferent pathways to gastric HCl challenge. This effect seems to arise from a peripheral action on vagal afferents and may be of relevance to gastric chemonociception.

Effect on Cerebral Vasospasm of Coil Embolization Followed by Microcatheter Intrathecal Urokinase Infusion Into the Cisterna Magna

Background and Purpose— Vasospasm remains the leading cause of death and permanent neurological disability in patients with aneurysmal subarachnoid hemorrhage (SAH). The objective of our prospective randomized trial of coil embolization followed by intrathecal urokinase infusion into the cisterna magna (ITUKI therapy) was to test its effectiveness in preventing or alleviating the severity of ischemic neurological deficits caused by vasospasm.

Methods— We enrolled 110 patients with ruptured intracranial aneurysms eligible for coil embolization and randomly assigned them to embolization with (n=57) or without (n=53) ITUKI therapy performed within 24 hours of aneurysmal SAH. The incidence of symptomatic vasospasms and the clinical outcomes, based on the Glasgow Outcome Scale, 6 months after SAH onset were assessed.

Results— There were no side effects or adverse reactions attributable to ITUKI therapy. Symptomatic vasospasm occurred in 5 patients (8.8%) with and 16 (30.2%) without ITUKI therapy; the difference was significant ( P =0.012). Although the mortality rate did not differ between the groups, patients with ITUKI therapy had significantly better outcomes than those without ( P =0.036).

Conclusions— Our results demonstrate that ITUKI therapy significantly reduced the occurrence of symptomatic vasospasm. Although it did not completely prevent vasospasms, ITUKI therapy resulted in a lower rate of permanent neurological deficits.

Contribution of neurokinin 1 receptors in the cutaneous orofacial inflammatory pain

This study investigated the role of neurokinin 1 receptors (NK1R) in inflammatory cutaneous orofacial pain. The effects of subcutaneous and intracisternal administration of the NK1R antagonist SR140333 on the face rubbing response provoked by injection of 50 micro l of 1.5% formalin into the vibrissa pad were examined. Subcutaneous administration of SR140333 (5, 15, 30 mg/kg) induced a dose-related depressant effect on both the first and second phases of the formalin test. In contrast, intracisternal administration of SR140333 (10, 30, 60, 90 microg) produced a decrease only on the second phase with an apparent ceiling effect at approximately 50%. These data suggest that persistent nociceptive effects associated with orofacial cutaneous inflammation depend at least in part on the activation of NK1R.

Involvement of calcitonin gene-related peptide and capsaicin-sensitive afferents in central thyrotropin-releasing hormone-induced hepatic cytoprotection

The involvement of capsaicin-sensitive afferent neurons and calcitonin gene-related peptide (CGRP) in central thyrotropin-releasing hormone (TRH)-induced hepatic cytoprotection was investigated in rats. Both systemic capsaicin pretreatment and intravenous administration of CGRP receptor antagonist, human CGRP-(8-37), completely abolished the protective effect of intracisternal TRH analog (RX-77368; p-Glu-His-(3,3'-dimethyl)-Pro-NH2, 5 ng) against carbon tetrachloride (CCl4)-induced acute liver injury, assessed by serum alanin aminotransferase levels and histological changes. These data demonstrate the involvement of capsaicin-sensitive afferent neurons and CGRP in central TRH-induced hepatic cytoprotection.

Hindquarters vasoconstriction through central GABA(B) receptors in conscious rats

The exogenous application of GABA into the cisterna magna of the freely moving rat decreases hindquarters vascular tone as well as arterial pressure. GABA could influence GABA receptor subtypes A, B or C. However, the hindquarters vascular response to the stimulation of each receptor subtype has not yet been investigated. The present study therefore characterized the response to the GABA(B) receptor agonist baclofen injected into the cisterna magna of the conscious rat. Intracisternally injected baclofen induced long-lasting increases in hindquarters vascular resistance and arterial pressure in a dose-dependent manner. Both actions induced by baclofen were completely blocked by a prior intracisternal injection with the GABA(B) receptor antagonist CGP 35348 (p-[3-aminopropyl]-p-diethoxymethylphosphinic acid), and systemically by ganglionic blockade. These actions of baclofen were also abolished centrally by sodium pentobarbital anaesthesia. The results suggest that GABA(B) receptor stimulation via the cisterna magna induced hindquarters vasoconstriction, probably due to central disinhibition of sympathetic activity.

An alternative method of chronic cerebrospinal fluid collection via the cisterna magna in conscious rhesus monkeys

Models of chronic cerebrospinal fluid (CSF) collection previously have been established for nonhuman primates and canines; many of these methods implement stainless-steel cannulas into the lateral or 4th ventricles or catheters into the cerebral or spinal subarachnoid space. These models have proved successful and reliable but unfortunately require invasive techniques to pass through the skull or require a laminectomy to enter the spinal subarachnoid space, involve the use of expensive and highly specialized stereotaxic equipment for the precise placement of the implants, and may require exteriorized hardware which is cumbersome to maintain and unaesthetic. The model we developed for the rhesus monkey allows for direct access to CSF outflow from the cisterna magna by using a 3.5-French fenestrated silicone catheter which was placed 1.0 cm into the cisterna. The catheter was attached to a titanium port placed subcutaneously between the scapulae to permit easy access for sampling CSF in a conscious, chaired rhesus monkey. We currently have instrumented animals from which we have consistently collected CSF for over 18 months. This novel, economical, less-invasive method permits chronic, reliable collection of CSF in conscious rhesus monkeys and has the additional advantages that the model is easier to maintain and more aesthetic.

Effects of TNF-alpha injected intracisternally on the nociceptive jaw-opening reflex and orofacial formalin test in freely moving rats

The present study was performed to investigate the effects of central cytokines on the modulation of nociception in the orofacial area. A nociceptive jaw-opening reflex (JOR) and an orofacial formalin test were monitored after intracisternal administration of tumor necrosis factor (TNF)-alpha in freely moving rats. Experiments were carried out on 83 male rats weighing 300-350 g and surgical procedures were performed under pentobarbital sodium. After intracisternal injection of Tnf-alpha, digastric electromyogram (dEMG) and noxious behavioral responses were monitored. In the nociceptive JOR, dEMG was not significantly changed after intracisternal injection of 200 pg and 2 ng Tnf-alpha. However, 20 ng Tnf-alpha suppressed dEMG to 72+/-6% of the control values. The orofacial formalin responses showed two distinct phases separated by a time of relative inactivity with an early short-lasting response (0-9 min, first phase) and a continuous prolonged response (10-45 min, second phase). In the inflammatory orofacial formalin test, intracisternal injection of 20 pg Tnf-alpha did not change the number of noxious behavioral responses produced by formalin injection. However, 200 pg Tnf-alpha injected intracisternally significantly increased the number of noxious behavioral responses produced by formalin injection in both the early and late phases, and 2 ng Tnf-alpha increased formalin induced noxious behavioral responses in only the late phase. A higher dose of 20 ng Tnf-alpha did not change the number of noxious behavioral responses produced by formalin injection. The hyperalgesic action of Tnf-alpha injected intracisternally was blocked by pretreatment with the interleukin-1 (IL-1) receptor antagonist. These results suggest that central Tnf-alpha modulates the transmission of nociceptive information in the orofacial area. However, the hypo/hyperalgesic response of central Tnf-alpha seems to depend on the orofacial pain model or in a dose-related manner. The hyperalgesic response of central Tnf-alpha seems to be mediated by the IL-1 receptor.

Intracisternal application of endotoxin enhances the susceptibility to subsequent hypoxic-ischemic brain damage in neonatal rats

Perinatal brain damage is associated not only with hypoxic-ischemic insults but also with intrauterine inflammation. A combination of antenatal inflammation and asphyxia increases the risk of cerebral palsy >70 times. The aim of the present study was to determine the effect of intracisternal (i.c.) administration of endotoxin [lipopolysaccharides (LPS)] on subsequent hypoxic-ischemic brain damage in neonatal rats. Seven-day-old Wistar rats were subjected to i.c. application of NaCl or LPS (5 microg/pup). One hour later, the left common carotid artery was exposed through a midline neck incision and ligated with 6-0 surgical silk. After another hour of recovery, the pups were subjected to a hypoxic gas mixture (8% oxygen/92% nitrogen) for 60 min. The animals were randomized to four experimental groups: 1) sham control group, left common carotid artery exposed but not ligated (n = 5); 2) LPS group, subjected to i.c. application of LPS (n = 7); 3) hypoxic-ischemic study group, i.c. injection of NaCl and exposure to hypoxia after ligation of the left carotid artery (n = 17); or 4) hypoxic-ischemic/LPS study group, i.c. injection of LPS and exposure to hypoxia after ligation of the left carotid artery (n = 19). Seven days later, neonatal brains were assessed for neuronal cell damage. In a second set of experiments, rat pups received an i.c. injection of LPS (5 microg/pup) and were evaluated for tumor necrosis factor-alpha expression by immunohistochemistry. Neuronal cell damage could not be observed in the sham control or in the LPS group. In the hypoxic-ischemic/LPS group, neuronal injury in the cerebral cortex was significantly higher than in animals that were subjected to hypoxia/ischemia after i.c. application of NaCl. Injecting LPS intracisternally caused a marked expression of tumor necrosis factor-alpha in the leptomeninges. Applying LPS intracisternally sensitizes the immature rat brain to a subsequent hypoxic-ischemic insult.

Contribution of 5-hydroxytryptamine1B receptors and 20-hydroxyeiscosatetraenoic acid to fall in cerebral blood flow after subarachnoid hemorrhage

BACKGROUND AND PURPOSE

This study examined the interaction between 5-hydroxytryptamine1B (5-HT1B) receptors and 20-hydroxyeiscosatetraenoic acid (20-HETE) in contributing to the acute fall in regional cerebral blood flow (rCBF) after subarachnoid hemorrhage (SAH) in rats.

METHODS

The effects of intracisternal injection of 0.3 mL of arterial blood, artificial cerebrospinal fluid, and 5-HT on rCBF and the levels of 20-HETE and 5-HT in cerebrospinal fluid were measured in rats pretreated with vehicle, a 5-HT1B receptor antagonist (isamoltane hemifumarate), or an inhibitor of the synthesis of 20-HETE (HET0016). The effects of HET0016 and isamoltane on the vasoconstrictor response and changes in [Ca2+]i to 5-HT were also studied in middle cerebral arteries and vascular smooth muscle cells isolated from these vessels.

RESULTS

20-HETE and 5-HT levels in cerebrospinal fluid rose from 172+/-10 to 629+/-44 ng/mL and from 6+/-4 to 1163+/-200 nmol/mL, respectively, after SAH. rCBF fell by 30% 10 minutes after SAH, and it remained at this level for the next 2 hours. Blockade of 5-HT1B receptors prevented the sustained fall in rCBF seen after SAH. Intracisternal injection of 5-HT mimicked SAH by increasing 20-HETE levels in cerebrospinal fluid to 475+/-94 ng/mL and reducing rCBF by 30%. Blockade of the synthesis of 20-HETE with HET0016 prevented the fall in rCBF produced by 5-HT. Isamoltane and HET0016 reduced the vasoconstrictor response of isolated MCA to 5-HT by >60% and diminished the rise in [Ca2+]i produced by 5-HT in vascular smooth muscle cells isolated from these arteries.

CONCLUSIONS

These results suggest that the release of 5-HT after SAH activates 5-HT1B receptors and the synthesis of 20-HETE and that 20-HETE contributes to the acute fall in rCBF by potentiating the vasoconstrictor response of cerebral vessels to 5-HT.

Enhanced depressor response to endothelial nitric oxide synthase gene transfer into the nucleus tractus solitarii of spontaneously hypertensive rats

Previously, we demonstrated that endothelial nitric oxide synthase (eNOS) gene transfer into the nucleus tractus solitarii (NTS) decreased blood pressure, heart rate and sympathetic nerve activity in conscious normotensive Wistar-Kyoto rats (WKY). In order to determine whether overexpression of eNOS in the NTS causes different effects on blood pressure and heart rate between spontaneously hypertensive rats (SHR) and WKY, we transfected adenovirus vectors encoding either eNOS (AdeNOS) or beta-galactosidase (Ad beta gal) into the NTS of SHR and WKY in vivo. The local expression of eNOS in the NTS was confirmed by Western blot analysis for eNOS protein, and the magnitude of expression did not differ between SHR and WKY. Blood pressure and heart rate were monitored by the use of a radio-telemetry system in a conscious state before and 7 days after the gene transfer. Systolic blood pressure (SBP) and heart rate decreased on day 7 in both AdeNOS-transfected SHR and WKY. However, the magnitude of decreases in SBP of AdeNOS-transfected SHR was greater than that of AdeNOS-transfected WKY (-24.1 +/- 2.9 vs. -15.9 +/- 2.1 mmHg, p < 0.05). Transfection of Ad beta gal into the NTS did not alter SBP in either group. A depressor response evoked by microinjection of L-glutamate into the NTS did not differ between the two strains. These results suggest that overexpression of eNOS in the NTS causes a greater depressor response in SHR than in WKY in a conscious state. An abnormality of the L-arginine-NO pathway in the NTS may be related to the hypertensive mechanism(s) of SHR.

Intrathecal urokinase infusion through a microcatheter into the cisterna magna to prevent cerebral vasospasm: experimental study in dogs

BACKGROUND AND PURPOSE

Our preliminary report on intrathecal urokinase (UK) infusion into the cisterna magna (CM) with a microcatheter showed good results in terms of vasospasm prevention in humans. In this study, we evaluated the relationship between different urokinase (UK) infusion sites and their effect on vasospasm prevention by using our canine subarachnoid hemorrhage (SAH) model.

METHODS

At 24 hours after SAH induction, we injected 1000 IU/kg UK into the cisterna magna (CM) or lumbar sac (LS) of dogs by using a microcatheter inserted at the lumbar region. We then obtained serial angiograms and chronologically examined the changes in the mean diameter of the basilar artery (BA) during a 14-day period to determine the effect of the different injection sites on vasospasm prevention. At 24 hours after UK injection, one dog from each group was killed for gross inspection of the subarachnoid clot. To measure its concentration in the CM and sylvian fissure, UK (1000 IU/kg) was injected into the CM or LS of dogs without SAH; measurements were taken at 15-minute intervals until 4 hours after injection.

RESULTS

At 24 hours after UK injection, subarachnoid clot in front of the brain stem persisted strongly in the LS group; it had almost disappeared in the CM group. In the LS group, there was severe and persistent BA constriction during the 14-day observation period. In the CM group, the BA was constricted on day 3; however, gradual dilatation occurred over time. The mean diameter of the BA on days 7, 10, and 14 was 48.2%, 53.9%, and 58.9% in the LS group and 62.6%, 70.5%, and 82.3% in the CM group. The difference between the two groups was significant on days 7, 10, and 14 (P <.05). In dogs without SAH, the average maximum UK concentration in the CM and the sylvian fissure was 2.5 and 6.7 times higher, respectively, in the CM group than in the LS group.

CONCLUSIONS

In our canine SAH model, the administration of UK into the CM was significantly more effective in preventing cerebral vasospasms than was administration into the LS.

Intracisternal administration of Angiotensin II AT1 receptor antisense oligodeoxynucleotides protects against cerebral ischemia in spontaneously hypertensive rats

Pharmacological blockade of peripheral and brain Angiotensin II (Ang II) AT(1) receptors protects against brain ischemia. To clarify the protective role of brain AT(1) receptors, we examined the effects of specific antisense oligodeoxynucleotides (AS-ODN) targeted to AT(1) receptor mRNA administered intracisternally to spontaneously hypertensive rats (SHRs), 4 and 7 days before middle cerebral artery (MCA) occlusion, and we determined the infarct size and tissue swelling 24 h after surgery. A single intracisternal injection of AT(1) mRNA receptor antisense oligodeoxynucleotides reduced systemic blood pressure for 5 days and AT(1) receptor binding for at least 4 days in the area postrema and the nucleus of the solitary tract. A similar injection of scrambled oligodeoxynucleotides (SC-ODN) was without effect. Both blood pressure and AT(1) receptor binding returned to normal 7 days after antisense receptor mRNA administration. Both the infarction size and the tissue swelling after middle cerebral artery occlusion were reduced when the antisense oligodeoxynucleotide was administered 7 days, but not 4 days, before the operation. We conclude that 4 to 5 days of decrease in brain AT(1) receptor binding by a single administration of an AT(1) receptor mRNA oligodeoxynucleotide are sufficient to significantly protect the brain against ischemia resulting from total occlusion of a major cerebral vessel.

A murine model of subarachnoid hemorrhage-induced cerebral vasospasm

Cerebral vasospasm remains a major cause of morbidity and mortality after subarachnoid hemorrhage (SAH). The availability of a mouse model of SAH that is simple, replicable and has low mortality would provide a powerful approach for understanding cellular and molecular mechanisms contributing to post-SAH pathologies. The present study characterizes a mouse model of experimental SAH, which produces consistent constriction of large cerebral arteries. Adult mice received injections of autologous blood into the cisterna magna, and the diameters of large intracranial vessels were measured 1 h to 7 days post-SAH. A diffuse blood clot was evident in both the anterior and posterior circulations after SAH. Vascular wall thickening, lumenal narrowing and corrugation of the internal elastic lamina were observed. Both acute (6-12 h) and delayed (1-3 days) phases of vasoconstriction occurred after SAH. Overall mortality was only 3%. A reproducible, low mortality model of SAH-induced cerebral vasospasm in mice is described. This mouse model should facilitate the delineation of cellular and molecular mechanisms of SAH-induced pathologies because of the widespread availability of various technologies for this species (e.g. genetically-altered animals and gene expression arrays). This model also represents a replicable and inexpensive approach for screening therapeutic candidates.

Extraventricular intracisternal obstructive hydrocephalus--a hypothesis to explain successful 3rd ventriculostomy in communicating hydrocephalus

The basis of successful 3rd ventriculostomy in cases of communicating hydrocephalus is not yet understood. We performed 3rd ventriculostomies in 5 patients with free cerebrospinal fluid (CSF) communication from the ventricles to the cisterna magna. Preoperative magnetic resonance images (MRIs) showed dilated ventricles, a downward bulging floor of the 3rd ventricle (interpreted as a sign of pressure gradient between the ventricles and basal cisterns) and a free communication to an enlarged cisterna magna. The other basal cisterns were of normal or smaller size. All patients recovered from their clinical symptoms and none of them needed a shunt. The hypothesis of an intracisternal CSF pathway obstruction (e.g. between the cisterna magna and the prepontine cistern) could explain the MRI findings, although such an obstruction cannot be directly visualized. It would also explain the successful 3rd ventriculostomies in these cases.

Mechanism of the reduced elimination clearance of benzylpenicillin from cerebrospinal fluid in rats with intracisternal administration of lipopolysaccharide

The mechanism responsible for the reduced clearance of benzylpenicillin (BPC) from the cerebrospinal fluid (CSF) was investigated in rats that received an intracisternal administration of lipopolysaccharide (LPS). BPC was intraventricularly injected and its elimination from the CSF studied. During the inflammation created by the LPS administration to the cisterna magna, the clearance of BPC and taurine from the CSF was significantly reduced but reverted to the control level when N-nitro-L-arginine, a nitric oxide (NO) synthase inhibitor, was intracisternally administered. The in vitro uptake of BPC and taurine was significantly reduced in the choroid plexus (CP, the blood-CSF barrier) of rats with experimental inflammation and in control CP that had been pretreated with sodium nitroprusside (SNP, an NO donor). Interestingly, the clearance and CP uptake of formycin B, a substrate for a nucleoside transporter, were not affected by the experimental inflammation or by pretreatement with SNP. These observations suggest that the BPC transporter, and probably other transport systems as well, is functionally sensitive to NO in the blood-CSF barrier. Therefore, functional impairment of BPC transport in the CP by NO may be partly responsible for the increase in BPC concentration in the CSF during inflammation such as that caused by meningitis.

Prevention of experimental cerebral vasospasm by intracranial delivery of a nitric oxide donor from a controlled-release polymer: toxicity and efficacy studies in rabbits and rats

BACKGROUND AND PURPOSE

A reduction in the local availability of nitric oxide (NO) may play a role in the etiology of chronic cerebral vasospasm after subarachnoid hemorrhage (SAH). We investigated the toxicity and efficacy of a locally delivered NO donor from a controlled-release polymer in preventing experimental cerebral vasospasm in rats and rabbits, respectively.

METHODS

Diethylenetriamine/NO (DETA/NO) was incorporated into controlled release ethylene-vinyl acetate (EVAc) polymers. Twenty-eight rats were used in a dose-escalation toxicity study to establish a maximally tolerated dose of DETA/NO-EVAc polymer. In the efficacy experiment, 20 rabbits were assigned to 4 experimental groups (n=5 per group): sham operation; SAH only; SAH+empty EVAc polymer; and SAH+DETA/NO-EVAc polymer. Treatment was initiated 30 minutes after blood deposition. Basilar artery lumen patency was assessed 72 hours after hemorrhage to evaluate the efficacy of DETA/NO in preventing cerebral vasospasm.

RESULTS

In the toxicity study, a dose of 3.4 mg/kg was identified as the LD(20) (dose with 20% mortality during the study period) of this DETA/NO formulation. Brain histology revealed hemorrhage and ischemic changes at the implantation site associated with high concentrations of DETA/NO. In the efficacy study, treatment with DETA/NO-EVAc polymer resulted in a significant decrease in basilar artery vasospasm compared with no treatment (93.0+/-4.9% versus 71.4+/-11.9%; P=0.035) or compared with treatment with blank EVAc polymer (93.0+/-4.9% versus 73.2+/-6.4%; P=0.003).

CONCLUSIONS

Local delivery of DETA/NO prevents vasospasm in the rabbit basilar artery. Local delivery of DETA/NO via polymers is a safe and effective strategy for preventing cerebral vasospasm after SAH in this model.

Intracranial administration of transforming growth factor-beta3 increases fat oxidation in rats

The effects of intracranial transforming growth factor (TGF)-beta3 on spontaneous motor activity and energy metabolism were examined in rats. After injection of TGF-beta3 into the cisterna magna of the rat, spontaneous motor activity decreased significantly for 1 h. The intracranial injection of TGF-beta3 produced an immediate decrease in respiratory exchange ratio (RER). No significant changes were observed in energy expenditure. TGF-beta3 induced a significant increase in total fat oxidation and a decrease in total carbohydrate oxidation. Furthermore, the serum substrates associated with fat metabolism were significantly altered in rats injected with TGF-beta3. Both lipoprotein lipase activity in skeletal muscle and the concentration of serum ketone bodies increased, suggesting that the increase in fat oxidation caused by TGF-beta3 may have occurred in the liver and muscle. Intracranial injection of TGF-beta3 appeared to evoke a switch in the energy substrates accessed in energy expenditure. These results suggest that the release of TGF-beta3 in the brain by exercise is a signal for regulating energy consumption.

Intracisternal sodium nitroprusside fails to prevent vasospasm in nonhuman primates

OBJECTIVE

Hemoglobin contributes to vasospasm after subarachnoid hemorrhage. One mechanism may involve binding of nitric oxide, destruction of nitric oxide, or both. Support for this mechanism would be evidence that nitric oxide donors prevent vasospasm. This study attempted to provide such evidence.

METHODS

A randomized, blinded study was conducted in which 13 monkeys underwent cerebral angiography and creation of a right subarachnoid hemorrhage. Subcutaneous osmotic pumps were implanted to deliver sodium nitroprusside (n = 7) or vehicle (n = 6) via catheters into the right basal cisterns. Seven days later, angiography was repeated, and the animals were humanely killed. Levels of cyclic nucleotides, hemoglobins, and thiocyanate were measured.

RESULTS

Significant vasospasm of the right middle cerebral artery was present in animals treated with sodium nitroprusside (35 +/- 22% reduction in diameter, P < 0.05, paired t test) and placebo (28 +/- 20% reduction, P < 0.05, not significantly different from nitroprusside group by unpaired t test). Adequate delivery of sodium nitroprusside was supported by the finding of a significant increase in cyclic guanosine monophosphate levels in the cerebral arteries of treated animals compared with placebo (P < 0.05, unpaired t test). Thiocyanate was not present in significantly increased amounts in animals treated with nitroprusside, although this group did display elevated concentrations of nitrosyl hemoglobin (measured by electron paramagnetic resonance spectroscopy) and cyanomethemoglobin (measured by spectrophotometry) in the cerebrospinal fluid on Day 7.

CONCLUSION

The lack of effect of sodium nitroprusside was not the result of inadequate drug delivery because cyclic guanosine monophosphate levels were significantly increased in vasospastic arteries. Vasospasm may not have been prevented because of a toxic effect of sodium nitroprusside metabolites, involvement of smooth muscle relaxation or contraction processes downstream of cyclic guanosine monophosphate, or both.

Gyrus cinguli transection abolishes delta-opioid receptor-induced gastroprotection and alters alpha 2 adrenoceptor activity in the lower brainstem in rats

Previously, using the acidified ethanol-induced ulcer model in rats, we demonstrated that the mainly vagus-dependent gastroprotective effect of intracerebroventricularly injected clonidine was mediated by beta-endorphin release in the lower brainstem. Presently, retroarcuate transections were used to evaluate the contribution of forebrain beta-endorphinergic projection in this mechanism. Since the transection trajectory affected the cingulate cortex and other forebrain structures, matching lesions were also performed. In control and sham-operated rats intracisternal injection of clonidine and the direct opioid receptor (delta type) stimulant peptide (D-Ala(2), D-Leu(5))-enkephalin caused a potent and fully naloxone-reversible (i.e. opioid receptor-mediated) protection against acidified ethanol-induced mucosal damage. In gyrus cinguli-transected rats (as well as in groups with midline hippocampal, thalamic and hypothalamic lesions) gastric mucosal protection induced centrally by direct delta-opioid receptor stimulation in the lower brainstem was completely abolished. The protective effect of clonidine was significantly reduced but it was still present in these animals. The residual protection by clonidine was naloxone-resistant, i.e. independent of an opioid mediation. Transections of the cingulate gyrus as well as thalamic but not the retroarcuate transections elevated plasma corticosterone levels. The changes seen in the clonidine/opioid-induced gastroprotection did not show any correlation with the changes in plasma corticosterone levels. It was concluded that (i) the transection of the cingulate cortex strongly influences the neural input to the nucleus tractus solitarii-dorsal motor vagal nucleus complex that is required for the activation of gastroprotective vagus outflow by delta-opioid receptor stimulation; (ii) the transection uncovers a direct, clonidine-induced gastroprotective pathway which is probably suppressed in intact animals.

Propranolol blocks the tachycardia induced by galanin (1-15) but not by galanin (1-29)

The efferent pathways involved in the tachycardia induced by intracisternal injections of the N-terminal galanin fragment (1-15) (GAL (1-15)) and galanin (GAL (1-29)) has been evaluated in rats pretreated with the cholinergic antagonist atropine or the beta-antagonist propranolol. The pretreatment with propranolol significantly blocked the tachycardic and vasopressor effect produced by intracisternal injection of GAL (1-15) (p<0.05), but the pretreatment with atropine did not modify these cardiovascular effects. However, the cardiovascular response elicited by GAL (1-29) is modified by the pretreatment with atropine (p<0.05) but not by propranolol. These findings demonstrate that the central cardiovascular action of GAL (1-15), but not GAL (1-29), is mediated by beta-receptor stimulation and this suggests the existence of a different pathway involved in the cardiovascular response produced by the N-terminal galanin fragment as compared with the parent molecule GAL (1-29).

Influence of the type and rate of subarachnoid fluid infusion on lethal neurogenic pulmonary edema in rats

In patients who experience sudden death from spontaneous subarachnoid hemorrhage, more than 90% present with acute pulmonary edema. The underlying pathogenesis of this complication is poorly understood. In addition, the specific role of the extravasated blood products and the associated elevation in intracranial pressure leading to the systemic and pulmonary effects during subarachnoid hemorrhage are not well established. The authors tested a new model of acute and severe subarachnoid hemorrhage comparing fresh whole autologous blood (n = 20) with 5% albumin (n = 19) injected at two different rates (35 seconds versus 24 minutes) into the cisterna magna of anesthetized, mechanically ventilated rats. Cerebral and systemic hemodynamics and the corresponding pulmonary function were evaluated. The type of fluid injected had no influence on survival or hemodynamic and respiratory parameters. Rapid infusion of either blood or albumin (n = 14) produced an acute and transient rise in intracranial pressure (37.9 +/- 3.5 mm Hg) associated with systemic hypertension and increased cerebral perfusion pressure that was sustained in survivors but not in nonsurvivors. Slow infusion (n = 23) produced a more progressive increase in intracranial pressure to 31.2 +/- 7.1 mm Hg with a parallel and sustained increase of systemic blood pressure and preserved cerebral perfusion pressure in survivors, but produced a pattern of more severe hypertension followed by hypotension in nonsurvivors. Sixty-four percent of animals (rapid infusion) and 48% of animals (slow infusion) survived the challenge and presented no pulmonary alterations. In contrast, nonsurviving rats developed reduced lung compliance and gas exchange, an increased alveolar-arterial protein concentration ratio (0.36 +/- 0.02 versus 0.17 +/- 0.03 in survivors; P <.0001), and increased lung weight (5.7 +/- 0.3 g versus 2.0 +/- 0.1 g; P <.0001), demonstrating a fulminant increased permeability pulmonary edema, leading to death within one hour. These results indicate that the chosen rapid- and slow-injection rates resulted in a similar death rate of 50%. Mortality was similar for blood and albumin administration, pulmonary edema occurred in nonsurvivors in both the rapid- and slow-injection groups, and pulmonary edema is associated with more severe hypertension in the slow-injection group. Furthermore, these results suggest that the development of neurogenic pulmonary edema that is characterized by an acutely increased capillary permeability to proteins is independent of the degree of intracranial pressure increase or the type of fluid administrated.

5-Hydroxytryptamine(1B/1D) and 5-hydroxytryptamine1F receptors inhibit capsaicin-induced c-fos immunoreactivity within mouse trigeminal nucleus caudalis

In order to investigate the c-fos response within the trigeminal nucleus caudalis (Sp5C) after noxious meningeal stimulation, capsaicin (0.25, 0.5, 1 and 5 nmol) was administered intracisternally in urethane (1 g/kg) and alpha-chloralose (20 mg/kg) anaesthetized male mice. Capsaicin induced a robust and dose-dependent c-fos-like immunoreactivity (c-fos LI) within Sp5C. C-fos LI was observed within laminae I and II of the entire brain stem from the area postrema to C2 level, being maximum at the decussatio pyramidum level. The area postrema, solitary tract, medullary and lateral reticular nuclei were also labelled. The 5-hydroxytryptamine(1B/1D/1F) receptor agonist sumatriptan (0.01, 0.1, 1 and 10 mg/kg), administered intraperitoneally 15 min before capsaicin stimulation (1 nmol), decreased the c-fos response within Sp5C, but not within solitary tract. The novel specific 5-hydroxytryptamine1F agonist LY 344864 (0.1 and 1 mg/kg, i.p.) significantly decreased the c-fos LI within the Sp5C as well. These findings suggest that intracisternally administered capsaicin activates the trigeminovascular system and that the pain neurotransmission can be modulated by 5-hydroxytryptamine(1B/1D/1F) receptors in mice. Thus, the availability of this model in mice, taken together with the possibility of altering the expression of specific genes in this species, may help to investigate further the importance of distinct proteins in the neurotransmission of cephalic pain.

Three-dimensional MR visualization of the intracisternal course of the cranial nerves V-VIII by virtual cisternoscopy

PURPOSE

A post-processing protocol for 3D visualization of the cranial nerves V-VIII along their intracisternal course is presented.

MATERIAL AND METHODS

Six healthy volunteers underwent MR imaging (1.5 T) to obtain high-resolution heavily T2-weighted data sets (3DFT CISS) with isotropic voxels (0.5 mm3). The data sets were post-processed by using volume rendering software in order to visualize the intracisternal courses of the cranial nerves V-VIII as well as their root entry zones. The data acquisition and post-processing protocol was then applied in 14 patients with a suspected neural compression syndrome according to the clinical findings as well as cross-sectional images and evaluated with respect to image quality and diagnostic value by two neuroradiologists, using a five-point scale.

RESULTS

Virtual cisternoscopy allowed a comprehensive intracisternal 3D visualization of the affected cranial nerves in 12/14 patients. The mean post-processing time amounted to 13.1/5.6/13.7 min for the cranial nerves V/VI/VII and VIII. The mean score for image quality was 4.2, that for diagnostic value 4.1. 2D and/or 3D reference images were indispensable for appreciating the spatial information provided by virtual cisternoscopy.

CONCLUSION

The data acquisition and post-processing protocol presented here allows comprehensive and standardized intracisternal 3D visualization of the cranial nerves V-VIII in a routine setting as a complementary imaging procedure.

Serial cerebrospinal fluid sampling in a rat model to study drug uptake from the nasal cavity

Drug transport from the nasal cavity to the brain has gained much interest in the last decade. In the present study, a model was developed to determine the uptake of drugs into the cerebrospinal fluid (CSF) after nasal delivery in rats. CSF samples were taken using a cisternal puncture method. In this method, a needle is advanced through the skin and muscles overlying the atlanto-occipital membrane into the cisterna magna, while the rat is fixed in a stereotaxic frame. This method appears to be superior over cannulation of the atlanto-occipital membrane for CSF sampling. The major advantages of the puncture method is the ability of serial and simultaneous CSF and blood sampling for over 2 h in the same rat. To obtain maximal drug absorption from the nasal cavity and uptake into CSF, different positions of the rat's head (upright-90 degrees, supine-90 degrees, supine-45 degrees and supine-70 degrees angles) were tested in nasal delivery studies using hydrocortisone (HC) as a model drug. Putting the rat in the supine-90 degrees angle position increased the absorption of HC into plasma and CSF 2-fold compared to the upright-90 degrees angle position. The supine-70 degrees angle position did not change the HC plasma and CSF levels compared to the supine-90 degrees angle position. However, the supine-70 degrees angle position showed the fastest CSF sampling rate, enabling more accurate CSF sampling and therefore preferred for further studies. In conclusion, the cisternal puncture method using the supine-70 degrees and 90 degrees angle position is a suitable method to study drug transport from the nasal cavity into the CSF, with the ability of multiple CSF sampling.

Influence of imaging parameters on high-intensity cerebrospinal fluid artifacts in fast-FLAIR MR imaging

BACKGROUND AND PURPOSE

High-intensity CSF artifacts at the basal cisterns on MR images are often seen when a fast fluid-attenuated inversion recovery (FLAIR) technique is used. We investigated the influences of four optional fast-FLAIR sequence parameters on the high-intensity CSF artifacts.

METHODS

A total of 377 patients (age range, 1 week to 91 years; mean 40.6 years; 186 female, 191 male) were examined with axial fast-FLAIR images obtained (TR/TE(eff)/TI, 8800/133/2200) with a 1.5-T system during 6 months. The effects of the optional addition of inferior inflow saturation (thickness, 80 mm), section flow compensation, and tailored radiofrequency (TRF) pulses, plus the choice of interleaving acquisition factors of 2 or 3, were evaluated for the presence of high-intensity CSF artifacts on the fast-FLAIR images. Two radiologists independently reviewed the fast-FLAIR images in 76 patients; afterward, a single observer reviewed the remainder of the images.

RESULTS

The interobserver agreement rate in 76 cases was more than 90%. The use of TRF and/or three interleaving acquisitions resulted in a substantial reduction in the incidence of high-intensity CSF artifacts from about 80% to 40% (P <.05, two-sample two-sided Z test). Inferior inflow saturation and section flow compensation did not significantly improve image quality (P >.05). The results were consistent with the image quality ranking obtained in five healthy volunteers.

CONCLUSION

The appropriate choice of sequence parameters in fast-FLAIR imaging reduces the incidence of high-intensity CSF artifacts that are frequently encountered in the presence of rapid CSF flow.

Comparison of the peripheral and central effects of the opioid agonists loperamide and morphine in the formalin test in rats

The effects of the peripherally restricted opioid agonist loperamide were compared to those of morphine in the formalin test in rats. Both loperamide and morphine were efficacious in producing antihyperalgesia after both subcutaneous and intracisternal administration. The antihyperalgesic effects of peripherally administered loperamide and morphine were antagonized by both naloxone and its quaternary derivative naloxone methiodide. The effects of intracisternally administered loperamide and morphine were antagonized by naloxone SC. However, quaternary naloxone SC did not block the effects of intracisternally administered loperamide, and, quaternary naloxone blocked intracisternally morphine only at a dose approximately 10-fold higher than that required to block peripherally administered morphine. In addition, approximately 10-fold higher doses of naloxone administered SC were required to antagonize loperamide compared to doses required to antagonize morphine when the agonists were administered subcutaneously, suggesting that the effects of loperamide might be mediated by opioid receptors different from those which mediated the effects of morphine. However, neither the kappa-receptor selective antagonist nor-binaltorphimine nor the delta-receptor selective antagonist naltrindole blocked the effects of either opioid agonist. The present results are consistent with the interpretation that the antihyperalgesic effects of opioid agonists can have both a peripheral and a central component of action, and that the peripheral component of action is sufficient to produce antihyperalgesia in the formalin test after peripheral administration. The present results provide further evidence that peripherally restricted opioid agonists might provide clinically useful treatment of some pain states, in particular pain states that might involve sensitization of peripheral nociceptors.

Microdialysis in cisterna magna during cerebral air embolism in swine

Arterial gas embolism may occur as a consequence of lung rupture, decompression sickness, following operative procedures or as accidental infusion of gas during various diagnostic procedures. It can lead to severe morbidity or even death. Microdialysis is a technique that has been extensively used for evaluating localized changes in the brain. The microdialysis probe is only capable of measuring changes in the immediate adjacent tissue. In arterial gas embolism the changes are multifocal. Thus a probe located in the cerebral cortex will not detect the total amount of damage. We used microdialysis in the cisterna magna of 9 anaesthetized pigs to study the diffuse injury following arterial gas embolism. After injection of 5.0 mL of air in the internal carotid artery, we found a significantly increased lactate-pyruvate ratio in the cerebrospinal fluid, lasting for 2 hours. This indicates anaerobic metabolism. Mean levels of glycerol were significantly increased, indicating membrane disruption. Glutamate levels were also elevated, although not significantly. The injection of air affected carotid flow. Flow in the carotid artery of the side of injection decreased significantly, but returned to baseline in 1 hour. Flow in the contralateral carotid was increased, but not significantly. We conclude that massive air embolism causes ischemia and reduced blood flow in the brain that can be detected in the cisterna magna.

Cisternal MHPG level inversely correlates with Glasgow coma scale after aneurysmal subarachnoid hemorrhage

We measured the concentrations of monoamines and amino acids in the cisternal cerebrospinal fluid obtained from 15 patients after aneurysmal subarachnoid hemorrhage. Based on the Glasgow Coma Scale (GCS), the patients were divided into two conscious (GCS always 14 or better from the third post-operative day to Day 12; n = 8) and unconscious groups (n = 7). We examined the concentrations of monoamines and amino acids between the two groups and evaluated the correlation between the concentrations and the GCS at CSF sampling. The concentration of MHPG was significantly higher in the unconscious than in the conscious group from Days 4 to 12. A significant inverse correlation was observed between the MHPG concentration and the GCS (r = approximately 0.635, p < 0.0001). Measuring the cisternal MHPG concentration may be useful for estimating convalescence after subarachnoid hemorrhage.

GDNF protects against aluminum-induced apoptosis in rabbits by upregulating Bcl-2 and Bcl-XL and inhibiting mitochondrial Bax translocation

Direct (intracisternal) injection of aluminum complexes into rabbit brain results in a number of similarities with the neuropathological and biochemical changes observed in Alzheimer's disease and provides the opportunity to assess early events in neurodegeneration. This mode of administration induces cytochrome c release from mitochondria, a decrease in Bcl-2 in both mitochondria and endoplasmic reticulum, Bax translocation into mitochondria, activation of caspase-3, and DNA fragmentation. Coadministration of glial cell neuronal-derived factor (GDNF) inhibits these Bcl-2 and Bax changes, upregulates Bcl-XL, and abolishes the caspase-3 activity. Furthermore, treatment with GDNF dramatically inhibits apoptosis, as assessed by the TUNEL technique for detecting DNA damage. Treatment with GDNF may represent a therapeutic strategy to reverse the neuronal death associated with Alzheimer's disease and may exert its effect on apoptosis-regulatory proteins.

Cationic polymer and lipids augment adenovirus-mediated gene transfer to cerebral arteries in vivo

Adenovirus-mediated gene transfer to blood vessels is relatively inefficient because binding of adenovirus to vessels is limited. The authors have reported that incorporation of cationic polymer and lipids with adenovirus augments gene transfer to blood vessels ex vivo. In this study, the authors determined whether complexes of adenovirus and cations improve efficiency of gene transfer in vivo. Poly-L-lysine, lipofectamine, or lipofectin was complexed with adenovirus encoding beta-galactosidase. Optimum ratios of the cations per adenovirus were determined by gene transfer to fibroblasts. After injection of the adenovirus into the cisterna magna of anesthetized rabbits, transgene activity was greater in the adventitia of intracranial arteries and meninges after injection of the complexes than adenovirus alone. Thirty minutes after application of adenovirus with the cations, binding of adenovirus to fibroblast cells in vitro or the basilar artery in vivo (by Southern blot analysis) was augmented, which suggests that enhanced binding of virus contributes to augmentation of transgene expression. Thus, cationic polymer and lipids improve transgene expression in intracranial arteries, primarily in the adventitia, after adenovirus-mediated gene transfer in vivo. This strategy may be applicable to studies of gene transfer and eventually for gene therapy.

Respective contributions of alpha-adrenergic and non-adrenergic mechanisms in the hypotensive effect of imidazoline-like drugs

The hypotensive effect of imidazoline-like drugs, such as clonidine, was first attributed to the exclusive stimulation of central alpha2-adrenoceptors (alpha2ARs). However, a body of evidence suggests that non-adrenergic mechanisms may also account for this hypotension. This work aims (i) to check whether imidazoline-like drugs with no alpha2-adrenergic agonist activity may alter blood pressure (BP) and (ii) to seek a possible interaction between such a drug and an alpha2ARs agonist alpha-methylnoradrenaline (alpha-MNA). We selected S23515 and S23757, two imidazoline-like drugs with negligible affinities and activities at alpha2ARs but with high affinities for non-adrenergic imidazoline binding sites (IBS). S23515 decreased BP dose-dependently (-27+/-5% maximal effect) when administered intracisternally (i.c.) to anaesthetized rabbits. The hypotension induced by S23515 (100 microg kg(-1) i.c.) was prevented by S23757 (1 mg kg(-1) i.c.) and efaroxan (10 microg kg(-1) i.c.), while these compounds, devoid of haemodynamic action by themselves, did not alter the hypotensive effect of alpha-MNA (3 and 30 microg kg(-1) i.c.). Moreover, the alpha2ARs antagonist rauwolscine (3 microg kg(-1) i.c.) did not prevent the effect of S23515. Finally, whilst 3 microg kg(-1) of S23515 or 0.5 microg kg(-1) of alpha-MNA had weak hypotensive effects, the sequential i.c. administration of these two drugs induced a marked hypotension (-23+/-2%). These results indicate that an imidazoline-like drug with no alpha2-adrenergic properties lowers BP and interacts synergistically with an alpha(ARs agonist.

Intrathecal delivery of IFN-gamma protects C57BL/6 mice from chronic-progressive experimental autoimmune encephalomyelitis by increasing apoptosis of central nervous system-infiltrating lymphocytes

The exclusive detrimental role of proinflammatory cytokines in demyelinating diseases of the CNS, such as multiple sclerosis, is controversial. Here we show that the intrathecal delivery of an HSV-1-derived vector engineered with the mouse IFN-gamma gene leads to persistent (up to 4 wk) CNS production of IFN-gamma and inhibits the course of a chronic-progressive form of experimental autoimmune encephalomyelitis (EAE) induced in C57BL/6 mice by myelin oligodendrocyte glycoprotein (MOG)(35-55). Mice treated with the IFN-gamma-containing vector before EAE onset showed an earlier onset but a milder course of the disease compared with control mice treated with the empty vector. In addition, 83% of IFN-gamma-treated mice completely recovered within 25 days post immunization, whereas control mice did not recover up to 60 days post immunization. Mice treated with the IFN-gamma-containing vector within 1 wk after EAE onset partially recovered from the disease within 25 days after vector injection, whereas control mice worsened. Recovery from EAE in mice treated with IFN-gamma was associated with a significant increase of CNS-infiltrating lymphocytes undergoing apoptosis. During the recovery phase, the mRNA level of TNFR1 was also significantly increased in CNS-infiltrating cells from IFN-gamma-treated mice compared with controls. Our results further challenge the exclusive detrimental role of IFN-gamma in the CNS during EAE/multiple sclerosis, and indicate that CNS-confined inflammation may induce protective immunological countermechanisms leading to a faster clearance of encephalitogenic T cells by apoptosis, thus restoring the immune privilege of the CNS.

Neuroprotection by intrathecal application of liposome-entrapped fasudil in a rat model of ischemia

Pharmacological treatment for cerebral ischemia cannot attain sufficiently high concentrations of the drugs in the cerebrospinal fluid (CSF) without precipitating systemic side effects. The objective of this study is the development of a liposomal drug delivery system that maintains effective concentrations of protein kinase inhibitors fasudil in the CSF, resulting in neuroprotection against cerebral ischemia. Focal cerebral ischemia in rats was induced by middle cerebral artery occlusion using an intraluminal suture technique. Treated rats received 0.25 mg liposome-entrapped fasudil via the cisterna magna 2 hours after ischemic insult. Control rats received drug-free liposomes. Neurological condition and the infarct size were assessed at 24 and 72 hours after ischemia. The concentration of liposome-entrapped fasudil in the CSF was measured before sacrifice. Treated animals showed significantly improved neurological outcomes after the 24-hour observation period compared to the control group (p < 0.001). Treatment with 0.25 mg liposomal fasudil resulted in a reduction in the infarct area (24 hours: 29.0 +/- 4.4%, 72 hours: 28.1 +/- 3.9% of total brain slices) compared to controls (49.6 +/- 4.6%, p < 0.001), but there was no statistical difference between 24 and 72 hours. At 24 hours post-administration, CSF concentrations of liposome-entrapped fasudil were 45.4 +/- 31.5 micrograms/ml (20% of the injected dose). A single intrathecal injection of liposomal fasudil can maintain a therapeutic drug concentration in the CSF over a period of time, significantly decreasing infarct size in a rat model of acute ischemia.

Effects of alterations in arterial CO2 tension on cerebral blood flow during acute intracranial hypertension in rats

Cerebrovascular reactivity to CO2 in clinical and experimental studies has been found to be impaired during increased intracranial pressure (ICP). However, from previous study results it has not been possible to estimate whether the impairment was caused by elevated ICP, or caused by decreased cerebral perfusion pressure (CPP). The current study was carried out in a group of unmanipulated control rats and in six investigation groups of six rats each: two groups with elevated ICP (30 and 50 mm Hg) and spontaneous arterial blood pressure (MABP), two groups with spontaneous ICP and arterial hypotension (77 and 64 mm Hg), and two groups with elevated ICP (30 and 50 mm Hg) and arterial hypertension (124 mm Hg). Intracranial hypertension was induced by continuous infusion of lactated Ringer's solution into the cisterna magna, arterial hypotension by controlled bleeding, and arterial hypertension by continuous administration of norepinephrine intravenously. Cerebral blood flow (CBF) was measured repetitively by the intraarterial 133Xe method at different levels of arterial PCO2. In each individual animal, CO2 reactivity was calculated from an exponential regression line obtained from the corresponding CBF/PaCO2 values. By plotting each individual value of CO2 reactivity against the corresponding CPP value from the seven investigation groups, CPP was significantly and directly related to CO2 reactivity of CBF (P < .001). No correlation was found by plotting CO2 reactivity values against the corresponding MABP values or the corresponding ICP values. Thus, the results show that CO2 reactivity is at least partially determined by CPP and that the impaired CO2 reactivity observed at intracranial hypertension and arterial hypotension may be caused by reduced CPP.

Broad-spectrum and selective serine protease inhibitors prevent expression of platelet-derived growth factor-BB and cerebral vasospasm after subarachnoid hemorrhage: vasospasm caused by cisternal injection of recombinant platelet-derived growth factor-BB

BACKGROUND AND PURPOSE

Plasma serine protease cascade, including the complement system and thrombin, is activated in the subarachnoid space during the acute phase after subarachnoid hemorrhage (SAH). To examine the effect of protease cascade-based inflammation and subsequent vascular repair in the development of cerebral vasospasm, we examined the effect of 2 synthetic serine protease inhibitors-FUT-175, an inhibitor of thrombin and the complement system, and argatroban, a selective inhibitor of thrombin-on the development of cerebral vasospasm in a rabbit SAH model.

METHODS

One hundred Japanese White male rabbits were used in the study. The SAH was simulated by a single injection of autologous arterial blood into the cisterna magna. To evaluate the development of cerebral vasospasm, the caliber of the basilar artery was measured on x-ray film before and at 2 days after SAH. Nine groups of rabbits (n=6 each) were treated with continuous intravenous injection of FUT-175 (2.5, 5, 10, or 20 mg/d), argatroban (1.25, 2.5, or 5 mg/d), or the same amount of saline (vehicle) for 48 hours, starting 40 minutes after SAH. Two days after SAH, the expression of homodimer of platelet-derived growth factor-BB (PDGF-BB) in the basilar artery was examined with immunohistochemical techniques. In 20 normal rabbits, 5 microg of recombinant PDGF-BB or vehicle was injected into the cisterna magna, and the basilar arteries were examined on angiograms for 48 hours.

RESULTS

Significant differences were observed in the caliber of the basilar arteries between the vehicle group and the groups with the 3 larger doses of FUT-175 (vehicle, 52+/-5.0%; 5 mg, 79+/-5.7%; 10 mg, 80+/-2.5%; 20 mg, 80+/-3.7%) and between the vehicle group and the groups with the 2 larger doses of argatroban (vehicle, 52+/-6.4%; 2.5 mg, 81+/-9.0%; 5 mg, 85+/-4.1%) (P<0.05). In the histological examination, administration of effective doses of FUT-175 or argatroban suppressed the expression of PDGF-BB in the endothelial and medial smooth muscle cell layers. Exogenous PDGF-BB caused delayed and prolonged vasoconstriction on normal basilar arteries.

CONCLUSIONS

Activation of the serine protease cascade and/or thrombin after SAH was demonstrated to play an essential role in the development of cerebral vasospasm. The expression of PDGF-BB-like protein in the arterial walls correlated with the development of cerebral vasospasm. Elevated PDGF-BB level in the subarachnoid space was found to induce delayed and chronic vasoconstriction.

Intracisternal TRH analog induces Fos expression in gastric myenteric neurons and glia in conscious rats

Activation of gastric myenteric cells by intracisternal injection of the stable thyrotropin-releasing hormone (TRH) analog RX-77368, at a dose inducing near maximal vagal cholinergic stimulation of gastric functions, was investigated in conscious rats. Fos immunoreactivity was assessed in gastric longitudinal muscle-myenteric plexus whole mount preparations 90 min after intracisternal injection. Fos-immunoreactive cells were rare in controls (~1 cell/ganglion), whereas intracisternal RX-77368 (50 ng) increased the number to 24.8 +/- 1.8 and 26.8 +/- 2.2 cells/ganglion in the corpus and antrum, respectively. Hexamethonium (20 mg/kg sc) prevented Fos expression by 90%, whereas atropine (2 mg/kg sc) had no effect. The neuronal marker protein gene product 9.5 and the glial markers S-100 and glial fibrillary acidic proteins showed that RX-77368 induced Fos in both myenteric neurons and glia. Vesicular ACh transporter and calretinin were detected around the activated myenteric neurons. These results indicated that central vagal efferent stimulation by intracisternal RX-77368 activates gastric myenteric neurons as well as glial cells mainly through nicotinic ACh receptors in conscious rats.

Changes in CSF hypocretin-1 (orexin A) levels in rats across 24 hours and in response to food deprivation

Hypocretin-1 is consistently detectable in the CSF of healthy human subjects, but is absent in narcoleptics. However, functional roles of CSF hypocretin are largely unknown. We examined fluctuation of CSF hypocretin-1 across 24 h and in response to food restriction in rats. Hypocretin-1 levels were high during the dark period when animals were active, but decreased by 40% toward the end of the light (rest) period. After 72 h food deprivation hypocretin-1 levels during the rest phase increased to concentrations similar to those seen during the baseline active phase; however, no increase in response to food deprivation was observed during the active phase. These results indicate an important link between circadian control of sleep and energy homeostasis via the hypocretin system.

Central GABAergic mechanisms are involved in apnea induced by SLN stimulation in piglets

Stimulation of the superior laryngeal nerve (SLN) results in apnea in animals of different species, the mechanism of which is not known. We studied the effect of the GABA(A) receptor blocker bicuculline, given intravenously and intracisternally, on apnea induced by SLN stimulation. Eighteen 5- to 10-day-old piglets were studied: bicuculline was administered intravenously to nine animals and intracisternally to nine animals. The animals were anesthetized and then decerebrated, vagotomized, ventilated, and paralyzed. The phrenic nerve responses to four levels of electrical SLN stimulation were measured before and after bicuculline. SLN stimulation caused a significant decrease in phrenic nerve amplitude, phrenic nerve frequency, minute phrenic activity, and inspiratory time (P < 0.01) that was proportional to the level of electrical stimulation. Increased levels of stimulation were more likely to induce apnea during stimulation that often persisted beyond cessation of the stimulus. Bicuculline, administered intravenously or intracisternally, decreased the SLN stimulation-induced decrease in phrenic nerve amplitude, minute phrenic activity, and phrenic nerve frequency (P < 0.05). Bicuculline also reduced SLN-induced apnea and duration of poststimulation apnea (P < 0.05). We conclude that centrally mediated GABAergic pathways are involved in laryngeal stimulation-induced apnea.

Altered expression of P(2) receptor mRNAs in the basilar artery in a rat double hemorrhage model

BACKGROUND AND PURPOSE

Extracellular ATP might induce cerebral vasospasm after subarachnoid hemorrhage through P(2) receptor. To investigate the roles of P(2) receptor subtypes in vasospasm, we examined the changes in mRNA expression of P(2) receptor subtypes in basilar arteries from double cisternal blood injection rat models.

METHODS

One hundred male Sprague-Dawley rats, each weighing 350 to 400 g, were divided into 2 groups of 50. In the first group (n=50), the autologous arterial blood (0.2 to 0.3 mL) was injected into the cisterna magna on days 0 and 2. The rats were killed on day 3, 5, or 7 (n=10 in each group). In the sham group (n=10), the rats were injected with saline (0.3 mL) instead of blood. Ten rats were killed without blood or saline injection and served as control. The basilar arteries from rats in each group were used for reverse transcription and polymerase chain reaction. In another group of 50 rats, the same experiment was conducted, and the basilar arteries were collected for transmission electron microscopic study.

RESULTS

In the subarachnoid hemorrhage groups, transmission electron microscopy showed the reduction in vessel perimeter on days 5 and 7 to be approximately 30% to 40%. The P(2X1) mRNA level was significantly decreased on day 3 and recovered on days 5 and 7. The P(2Y1) mRNA level was transiently increased on day 5, and the P(2Y2) mRNA level was elevated from day 5 to day 7 (P:<0.05).

CONCLUSIONS

The differential expression of the P(2) receptors indicates that P(2X1) subtype might not play an important role in vasospasm. The upregulation of P(2Y1) and P(2Y2) receptors might enable ATP to produce contraction at low levels of concentration.

Gene transfer of extracellular superoxide dismutase increases superoxide dismutase activity in cerebrospinal fluid

BACKGROUND AND PURPOSE

Copper-zinc superoxide dismutase (CuZnSOD) is expressed intracellularly, while extracellular SOD (EC-SOD) is released from cells. The purpose of this study was to determine whether gene transfer of CuZnSOD increases SOD activity predominantly in tissues, and gene transfer of EC-SOD increases SOD activity in cerebrospinal fluid (CSF). We also determined whether heparin or dextran sulfate releases EC-SOD into CSF.

METHODS

We injected recombinant adenoviruses expressing EC-SOD (AdEC-SOD), CuZnSOD (AdCuZnSOD), or beta-galactosidase (Adbeta-gal) into the cisterna magna of rabbits.

RESULTS

Total SOD activity in CSF was 39+/-11 U/mL (mean+/-SE) before virus injection. Three days later, total SOD activity in CSF increased to 148+/-22 U/mL after AdEC-SOD and 92+/-10 U/mL after AdCuZnSOD (P:<0.05 versus AdEC-SOD), with no change after Adbeta-gal (49+/-5 U/mL). EC-SOD protein was detected in CSF after AdEC-SOD but not AdCuZnSOD or Adbeta-gal. Injection of heparin or dextran sulfate into the cisterna magna increased total SOD activity 27-fold and 32-fold over basal values, respectively, in CSF of rabbits that received AdEC-SOD. In contrast to effects in CSF, total SOD activity in basilar artery and meninges was significantly higher after AdCuZnSOD and tended to be higher after AdEC-SOD than after Adbeta-gal.

CONCLUSIONS

-We have developed a method for intracranial gene transfer of CuZnSOD and EC-SOD. After gene transfer, CuZnSOD was expressed mainly in tissues, and EC-SOD was released into the CSF, especially after injection of heparin or dextran sulfate. Gene transfer of different isoforms of SOD may be useful in studies of cerebral vascular physiology and pathophysiology.

Central nervous system gene therapy with interleukin-4 inhibits progression of ongoing relapsing-remitting autoimmune encephalomyelitis in Biozzi AB/H mice

Multiple sclerosis (MS) is an immune-mediated inflammatory disease of the central nervous system (CNS) that might benefit from anti-inflammatory therapies. However, systemic delivery of anti-inflammatory drugs in MS patients has so far been disappointing, mostly due to the limited capacity of these molecules to enter the CNS. We injected into the cisterna magna (i.c.) of Biozzi AB/H mice affected by a relapsing-remitting form of experimental autoimmune encephalomyelitis (EAE), the animal model of MS, a non-replicative herpes simplex virus (HSV) type-1-derived vector containing the interleukin (IL)-4 gene (d120:LacZ:IL-4). CNS delivery of the d120:LacZ:IL-4 vector, after EAE onset, induced the in situ production of IL-4 by CNS-resident cells facing the cerebrospinal fluid (CSF) spaces and reduced by 47% (P < 0.02) the disease-related deaths. Compared with mice treated with the control d120:lacZ vector, IL-4-treated mice also showed a shorter duration of the first EAE attack, a longer inter-relapse period, and a reduction in the severity and duration of the first relapse. Protection from EAE progression in IL-4-treated mice was associated with activation of microglia in spinal cord areas where mRNA content of the pro-inflammatory chemokines, macrophage chemoattractant protein-1 (MCP-1) and Rantes, was reduced and that of the anti-inflammatory cytokine IL-4 was increased. Finally, CNS-infiltrating mononuclear cells from IL-4-treated mice produced lower levels of MCP-1 mRNA compared with control mice. Our results, showing that IL-4 gene delivery using HSV-1 vectors induces protection from EAE by in situ modulating the cytokine/chemokine-mediated circuits sustaining effector cell functions, indicate that the intrathecal 'therapeutic' use of nonreplicative HSV-1-derived vectors containing anti-inflammatory molecules might represent an alternative strategy in inflammatory diseases of the CNS.

Long-term testing of an intracranial pressure monitoring device

OBJECT

Long-term monitoring of intracranial pressure (ICP) is limited by the lack of an implantable sensor with low drift. The goal of this study was to demonstrate that a new capacitive transducer system will produce accurate and stable ICP records over extended periods.

METHODS

Intracranial pressure sensors were implanted into the frontal white matter of four dogs. In addition, a fluid-filled catheter was placed in the cisterna magna (CM) to measure cerebrospinal fluid (CSF) pressure. The animals were tested using standard physiological maneuvers such as jugular vein compression, head elevation, and CSF withdrawal from and saline injection into the CM to verify that the ICP sensor precisely matched CSF pressure changes. The mean ICP pressure and CM pressure were compared for months to demonstrate that the transducer system produced minimal drift over time. The change in the ICP sensor record closely duplicated that of the CSF waveform in the CM in response to well-known physiological stimuli. More important, mean ICP pressure remained within 3 mm Hg of CM pressure for months, with a mean difference of less than 0.3 mm Hg. Histological examination of the dog brains revealed only minimal tissue reaction to the presence of the sensor.

CONCLUSIONS

The authors demonstrate a new implantable solid-state sensor that reliably measures ICP for months, with minimal drift. The clinical application of this sensor and its telemetry is for long-term monitoring of patients with head injury, mass lesions, and hydrocephalus.

Intrathecal administration of thrombin inhibitor ameliorates cerebral vasospasm. Use of a drug delivery system releasing hirudin

The role of thrombin as a spasmogen after subarachnoid hemorrhage was evaluated using the intrathecally administered thrombin inhibitor hirudin, released from a drug delivery system (DDS) based on collagen in a canine vasospasm model. The DDS was implanted into the cisterna magna with autologous blood in the hirudin-treated group. The reduction in the angiographical diameter of the basilar artery was only 19% in the hirudin-treated group on day 7, showing a significant difference between hirudin-treated and nontreated groups (p < 0.01). These results suggest that thrombin is an important cause of vasospasm. The collagen DDS has great potential for treatment in the cerebrospinal fluid milieu.

Treatment with a monocolonal antibody to IL-8 attenuates the pleocytosis in experimental pneumococcal meningitis in rabbits when given intravenously, but not intracisternally

The role of interleukin (IL)-8 as mediator in the recruitment of leucocytes into the CSF was investigated during experimental pneumococcal meningitis. Rabbits were inoculated intracisternally with approximately 10(6) CFU Streptococcus pneumoniae, and treated (i) intravenously with 5 mg of a monoclonal antibody to IL-8 (n = 7) or 5 mg of an isotype control antibody (n = 6); (ii) intracisternally with anti-IL-8, 100 microg (n = 5), 10 microg (n = 4), 1 microg (n = 4), 0.1 microg (n = 2). Ten rabbits served as untreated control group. Intravenous treatment with anti-IL-8 attenuated the pleocytosis significantly compared to untreated rabbits (P < 0.04) or rabbits treated with an isotype control antibody (P < 0.02). In contrast, intracisternal treatment with anti-IL-8 failed to attenuate the pleocytosis (P > 0.05). These results show, that IL-8 plays an important role in the recruitment of leucocytes during experimental pneumococcal meningitis, and that the functional activity of IL-8 in this process appears to be on the bloodstream side of the microvascular endothelium of the brain.