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(Stroke. 1997;28:387-391.)
© 1997 American Heart Association, Inc.

Articles

Medical Therapy for Intracerebral Hematoma With the -Aminobutyric Acid-A Agonist Muscimol

Patrick D. Lyden, MD; Catherine Jackson-Friedman, BS Lisa Lonzo-Doktor, BS

the Neurology and Research Services of the San Diego Veterans Administration Medical Center and the Department of Neurosciences, University of California, San Diego.

Correspondence to Dr Patrick D. Lyden, Neurology Service (127), 3350 La Jolla Village Dr, San Diego, CA 92161.

	Abstract

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Background and Purpose No therapy has been rigorously proven effective for intracerebral hematoma, although surgery is frequently used for some types of lobar hemorrhages. Since intracerebral mass causes significant ischemia in surrounding brain, we reasoned that anti-ischemia therapy might improve outcome after experimental hematoma.

Methods We stereotaxically injected varying doses of bacterial collagenase into the caudate nucleus of rats. Four hours later we administered intravenously 2 mg/kg muscimol, a potent agonist of the -aminobutyric acid-A receptor (n=20); 1 mg/kg MK-801, an antagonist of the N-methyl-D-aspartate receptor (n=17); or saline (n=28). Forty-eight hours after collagenase injection we rated each animal using a standard rodent neurological examination. The ratings were compared with the amounts of injected collagenase by the quantal bioassay procedure. Brains were then prepared for histomorphometry and brain volumes estimated.

Results We found that the ED₅₀ for collagenase (amount of enzyme that renders 50% of the subjects abnormal) was 0.77±0.09 U in saline-treated subjects. Treatment with muscimol significantly increased the ED₅₀ to 1.2±0.21 U, for a potency ratio of 1.55±0.34 (t=1.7, P<.05). MK-801 did not affect outcome. Volume of hematoma was significantly correlated with amount of injected collagenase (n=33, r=.64, P<.001). Volumes of basal ganglia and white matter were significantly reduced by hemorrhage, and muscimol partially ameliorated this.

Conclusions We conclude that muscimol significantly improves neurological outcome after intracerebral hematoma.

Key Words: intracerebral hemorrhage • GABA • hematoma • rats

	Introduction

Top Abstract Introduction Materials and Methods Results Discussion References Introduction  References

 
Cerebral hemorrhage accounts for approximately 12% of all strokes, yields a much higher mortality and morbidity than ischemic stroke, and may be responsible for a disproportionate share of the neurological disability attributed to stroke.^{1 2 3 4 5} There is no known medical treatment for hematoma, and surgical evacuation has not been proven effective in a prospective, randomized, properly blinded trial, although large case series support its use in some circumstances.^{2 3 4} The majority of cerebral hematomas are found in subcortical structures, usually the basal ganglia, a site that is technically difficult to reach at operation.⁴ A need exists, therefore, to find nonsurgical therapy for intracerebral hematoma.

Although the pathophysiology of acute cerebral hematoma is poorly understood, it is now clear that significant ischemia surrounds intracerebral hematoma.^{6 7 8 9} This observation led us to consider using therapy for acute cerebral hematoma that has proven effective in animal models of focal cerebral ischemia. We have shown considerable neuroprotective effects of two drugs, muscimol (a -aminobutyric acid-A [GABA-A] agonist) and MK-801 (an N-methyl-D-aspartate [NMDA] antagonist) in such models.^{10 11 12} Both of these agents interrupt the excitotoxic cascade that follows the ischemic release of glutamate. To test these agents efficiently, we adapted the collagenase-hemorrhage model described by Rosenberg et al.¹³ We used an efficient and reliable statistical method, the quantal bioassay, to evaluate behavioral outcome and applied the stereological brain morphometry method we previously devised for measuring cerebral infarction.^{11 14 15 16}

	Materials and Methods

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This study was approved in advance by the Animal Use Committee at the Veterans Affairs Medical Center, San Diego, according to all local, state, and federal regulations. Male Sprague-Dawley rats (weight, 250 to 300 g) were anesthetized with 1% halothane in oxygen/nitrous oxide (40:60) by face mask. The head was placed into a stereotaxic frame; after infiltration with 0.3 mL lidocaine (1%, no epinephrine), the scalp was incised over the midline. Through a small burr hole, a calibrated syringe (Hamilton Co) was inserted into the anterior portion of the caudoputamen (1.0 mm anterior to bregma, 3.0 mm right of midline, and 4.0 mm below dura).¹⁷ A total of 2.0 µL of solution containing collagenase (type 7, Sigma Chemical Co) was infused over 10 minutes with low pressure. Variable amounts of collagenase were used, ranging from 0.1 to 3.0 U, but the volume was always made constant with saline. After withdrawal of the syringe, the burr hole was filled with paraffin, and the scalp incision was closed with steel surgical staples. Body temperature was not measured and the animal was not heated during surgery because the total anesthetic period was only approximately 12 minutes. Rosenberg et al¹⁸ have shown that hematoma begins to form over the ensuing few hours, and therefore temperature autoregulation would be intact. Four hours later, each subject was rated normal or abnormal by an examiner who was unaware of the treatment received by each subject. An abnormal rating was given for any of the following signs: reduced exploration in the cage, circling, asymmetrical forepaw flexion when lifted by the tail, and asymmetrical forepaw grasping. Death was given the abnormal rating. The subjects were also rated at 24, 48, and 72 hours. We determined to use the behavioral rating at 72 hours as the primary outcome variable in this study to avoid confounding sedative effects of the study drugs. If any subject exhibited signs that were equivocal, another blinded rater was asked to evaluate that subject. The subject received the abnormal rating if any doubt remained. We have used this scale for 5 years, and the interrater agreement is approximately 95%.^{10 11 19} Forty-eight to 72 hours after collagenase injection, each subject was anesthetized with halothane and perfused transcardially with 100 mL saline and 100 mL 4% buffered paraformaldehyde. The brain was removed and placed in 4% paraformaldehyde (24 to 48 hours) followed by 30% sucrose (24 hours). Each brain was mounted whole on a freezing microtome stage to cut serial 45-µm sections every 400 µm, which were stained with cresyl violet and eosin and covered. Each slide was examined under a microscope with semiautomated image analysis and point counting, a method we have described in detail elsewhere.¹¹ Briefly, to simplify volumetric measurements and allow morphometry of several cerebral structures simultaneously, we derived a stereological point-counting system.²⁰ A grid of defined dimension is digitally superimposed over each section image, and the grid intersections that fall on tissue compartments of interest are tallied. One can calculate a ratio for the structure of interest compared with the total cerebral volume. In stereological practice, these ratios are called densities, so that the average "volume density" of a structure is equal to the number of points falling on one structure divided by the number of points falling on all cerebral structures.

We computed volume densities after collecting point counts of cortex, white matter, thalamus, hippocampus, basal ganglia, ventricle, cerebellum/brain stem, and hematoma.²⁰ This method corrects for artifacts due to tissue shrinkage or misalignment of the section plane and is unbiased in that no assumptions about lesion shape are needed.²⁰ To compare cerebral volumes among treatment groups, we used a one-way ANOVA and Newman-Keuls procedure for post hoc comparisons.²¹

A total of 119 subjects were used in this investigation. In a pilot study, 28 subjects were used to find the most appropriate collagenase infusion parameters (volume, concentration, rate, and duration). Next, we studied the effect of neuroprotection on outcome; we chose drugs and dosages that have been proven effective in previous studies of focal cerebral ischemia.^{10 11 19} Through the tail vein we administered saline (n=28) or 2 mg/kg muscimol (n=20) 4 hours after collagenase injection. Four hours was chosen for therapy because Rosenberg et al¹⁸ have shown that the hematoma is well developed by this time. Also, the effect of the inhaled anesthetic wears off over 1 hour and therefore does not interact with the neuroprotectant drug. For morphometric comparisons, 7 subjects received the identical preparation except that saline was injected instead of collagenase ("no collagenase" group) into the caudate. In the final experiment, an additional 20 subjects were given saline and 16 subjects received 1 mg/kg MK-801 by tail vein 4 hours after collagenase. These subjects were not included in the morphometry studies. In all experiments collagenase doses and drug treatments for each subject were chosen at random, although progressively higher doses of collagenase were used until a dose was found that rendered all animals abnormal.

To measure the effect of treatment on clinical outcome, we adapted the quantal bioassay used in ischemia studies.^{15 22} In brief, we compared the behavioral ratings to the doses of collagenase injected in each group. At lower doses all subjects are normal, at high doses all subjects are abnormal, and with intermediate doses a fraction of the animals are abnormal. One can fit the logistic equation to these data and generate a location parameter, the ED₅₀, which is the dose of collagenase that renders 50% of the subjects abnormal. Effective medical therapy will increase the ED₅₀ by increasing the tolerance to larger hematomas. The independent samples t test was used to compare ED₅₀s among groups.

	Results

Top Abstract Introduction Materials and Methods Results Discussion References Introduction  References

 
In the pilot study we determined the volume, concentration, and quantity of collagenase to use in further studies. The behavioral ratings for 26 of these 28 subjects are shown as dark circles in Fig 1; 2 subjects were not injected properly and were excluded from further analysis. From inspection of the data it is clear that the increasing doses of collagenase resulted in larger fractions of abnormal subjects, shown graphically in Fig 1. In these subjects a variety of dosing schemes were tried, varying infusion volume, duration of infusion, and anesthetics used. Nevertheless, there is a clear relationship between enzyme dose and outcome. The figure also shows that the ED₅₀ and its standard deviation was 0.60±0.05 U of collagenase. In the main study, we first examined the neuroprotective effect of muscimol. It is clear that subjects treated with 2 mg/kg muscimol tolerated larger doses of collagenase (Fig 2): the ED₅₀ was 0.77±0.09 U for saline-treated subjects compared with 1.2±0.21 for muscimol-treated subjects. The ratio of the two ED₅₀s was 1.55±0.34, a statistically significant treatment effect (P<.05). We then administered an antagonist of the NMDA receptor, 1 mg/kg MK-801, to a similarly prepared group of rats. The resulting curves are shown in Fig 3. This dose of MK-801 is often not protective in ischemia models, and no benefit was seen in this experiment.

View larger version (15K): [in this window] [in a new window]   Figure 1. Response to varying doses of collagenase. Each subject is represented by a dark circle. Those that were normal 72 hours after treatment were placed along the bottom of the figure, and those that were abnormal were placed along the top. Higher doses of collagenase injected into the caudate nucleus produced larger fractions of abnormal subjects. To these data the logistic equation is fit with an iterative procedure. The amount of enzyme that results in one half of the subjects being abnormal is the ED50.

View larger version (24K): [in this window] [in a new window]   Figure 2. Effect of muscimol on response to varying doses of collagenase. As in Fig 1, the ED50s of the saline-treated () and muscimol-treated () groups were calculated from the data points. The ED50 of the muscimol group is significantly larger (P<.05, Student's t test), implying a neuroprotective effect of the drug.

View larger version (21K): [in this window] [in a new window]   Figure 3. Effect of MK-801 on response to varying doses of collagenase. Treatment with MK-801 did not increase the ED50, implying no protective effect. The individual data points are omitted for clarity because there was considerable overlap.

Survival was greater in the muscimol group (16/20 or 80%) than in the saline-treated group (17/28 or 60%, P<.05, ² test). We performed histomorphometry on the surviving subjects (17 saline-treated, 16 muscimol-treated, and 7 no-collagenase control subjects). The data are presented in the Table, where the mean volume density is the mean of the volume estimates for the entire group. For example, in the no-collagenase control group the mean volume of cortex was 45% of the entire cerebrum. Volumes for this unlesioned group are comparable to our previous data.¹¹ In the saline-treated group the volume of basal ganglia was significantly smaller than in the control group, while the basal ganglia volume in the muscimol-treated group was intermediate (F_2,57=3.38, P<.05), suggesting that treatment may have minimized the damage in this structure. On the other hand, white matter volume was the same in the saline group as in the control group but significantly smaller in the muscimol group (F=3.5, P<.05).

View this table: [in this window] [in a new window]   Table 1. Cerebral Compartment Volume Densities in Surviving Subjects

To gain further insight into the role that muscimol might play in preserving basal ganglia, we correlated the volume of hematoma with that of the other cerebral compartments. In the saline group, hematoma volume correlated with volume of the basal ganglia (r=-.61, P<.001) and white matter (r=-.70, P<.001). These correlations are consistent with the subcortical location of the hematomas. In the muscimol group, hematoma volume was not related to basal ganglia volume (n=16), but the association with white matter was present (n=16, r=-.91, P<.01). No other compartment volumes correlated with hematoma volume in any group.

The saline group received an average dose of 0.9±0.3 U collagenase, and the muscimol group was given on average 1.2±0.5 U (mean±SD values) (P=.05, t test). This imbalance occurred because we used progressively higher doses in the treated subjects to find the ED₅₀ in the quantal bioassay. The amount of infused collagenase was correlated with the volume of hematoma (r=.64, P<.001, n=33), confirming that the collagenase dose is a reasonable surrogate variable for the volume of hematoma. This confirms the essential assumption underlying the use of the quantal bioassay, that the dose of the injected enzymes serves a reasonable estimate of the amount of damage rendered in the brain.

	Discussion

Top Abstract Introduction Materials and Methods Results Discussion References Introduction  References

 
Our study shows neuroprotection after intracerebral hematoma with the use of a GABA-A agonist. Survival after hematoma was significantly improved with treatment. Seventy-two hours after hematoma, the ED₅₀ for muscimol treatment was 1.5 times that for saline (Fig 2). The mechanism of this protection cannot be deduced from our data, but muscimol and other GABA agonists have proven highly effective in several models of cerebral ischemia.^{10 11 23 24 25} The mechanism of neuroprotection after ischemia is similar to that of antagonists of the glutamate receptor. GABA causes increased chloride flux, resulting in hyperpolarization of the neuronal cell membrane.^{10 11 12 23 24} Hyperpolarization blocks most of the voltage-gated cation entry into the postsynaptic cell, and muscimol was shown to protect brain even if therapy was delayed up to 1 hour after the onset of ischemia.^{11 12} Its synaptic inhibitory action is likely the main reason for the neuroprotective effects of muscimol, but there are also blood flow effects. Muscimol decreases local glucose utilization and cerebral blood flow in awake rats^{26 27} and increases cerebral blood flow somewhat if the animals are anesthetized.²⁸ MK-801 was not protective in this study, probably because of our choice of a relatively low dose; further studies with higher doses are under way. To our knowledge this is the first demonstration of pharmacological neuroprotection after intracerebral hematoma using a clinical rating of neurological function as an end point. Rosenberg and Navratil²⁹ showed a protective effect of S-emopamil after hematoma on measures of cerebral edema. In that study, however, the anti-edema effect was seen if the drug was given early, but if a second treatment was given 5 hours later an increase in cerebral edema was noted.

Morphometry confirmed that muscimol partially preserved the volume of basal ganglia after hematoma but had no effect on white matter (Table). The basal ganglia contain glutamate and GABA receptors, and we presume that cell damage here results partly from direct injury from the expanding hematoma and partly from ischemia and excitotoxicity. Thus, it is consistent with the excitotoxic mechanism of ischemic cell damage that basal ganglia would be preserved but white matter would not. On the other hand, it has been shown that white matter may contain an autoprotective mechanism that depends on GABA-mediated effects.³⁰ Thus, considerable further work will be needed to clarify the mechanism of protective effects in white matter, cortex, and subcortical gray matter.

The volume density method we used is unbiased and independent of the effects of tissue swelling and/or shrinkage.^{16 31} The volume of each cerebral compartment is adjusted to the volume of the entire cerebrum to correct for such artifacts. Since morphometry can only be performed on surviving subjects, however, there is a potential bias in the data. Muscimol therapy promoted survival after relatively larger infusions of collagenase, and subjects with relatively larger lesions survived to undergo morphometry (Table). There are statistical approaches to this problem, such as ANCOVA, but for this small study such detailed analysis was deemed inappropriate. The morphometry results should be viewed with this caveat in mind, however.

It is possible that muscimol could protect the brain by blocking a toxic effect of the collagenase. This is very unlikely for several reasons. The volume of collagenase is very small; the area of diffusion when Evans blue injection is used with the collagenase is less than 1 mm (data not presented). In contrast, the hematoma is very large, subsuming the entire volume of the caudate nucleus in most cases. Furthermore, others have shown that the volume of ischemic brain surrounding an injected hematoma or inflated balloon contains most of the overlying cortex and even a portion of the contralateral hemisphere.^{7 8 9} Hematoma in humans is generally subcortical in location, and experimental hematoma is often induced in this location. The overlying cortex is then rendered severely ischemic.⁶ Although we did not measure regional cerebral blood flow in this experiment, the volume of ischemia around an experimental hematoma can be larger than the volume of the hematoma itself.⁸ Depression of blood flow has been measured in remote areas of the brain as well, including the cortex of the contralateral hemisphere.^{6 7 9} The usual explanation for this is that the expanding mass compresses adjacent brain, closing off capillaries and arterioles. Other speculative mechanisms include vasoconstrictive toxins released by the clot and diaschesis.⁶ After 24 to 36 hours, the brain around the hematoma becomes edematous, which results in further mass effect and ischemia.⁶ Finally, collagenase is a large metalloproteinase for which several inhibitors are known. These compounds do not resemble muscimol in their structure or activity. Thus, the mechanism of muscimol's protective effect remains speculative until further work is completed.

Brain temperature is an important determinant of outcome after ischemia because 1°C of hypothermia may be neuroprotective.^{32 33} We did not attempt to measure or manipulate brain temperature in this study because of the extremely short duration of anesthesia (12 minutes). Although brain temperature could conceivably fall, it would return to normal by the time the hematoma began to cause ischemia and well before the time treatment was administered, 4 hours after collagenase injection. This is the principal advantage of the model, in that the hematoma and surrounding ischemia develop at a time when the awake subject can properly regulate physiological variables such as temperature, pulse, and blood pressure. Hypothermia induced by 1 mg/kg MK-801 is generally more pronounced than that by muscimol, yet MK-801 did not appear to protect brain in the dose used in this study. Nevertheless, we cannot rule out a confounding effect of hypothermia due to muscimol until brain temperatures are measured.

The quantal bioassay is ideally suited to pharmacological screening for neuroprotective drugs.^{22 34} The groups receive a range of injuries, from mild to moderate to severe. The result of the assay is therefore more generalizable to the range of strokes seen in humans. Most other model systems use only a single injury, such as a fixed duration of ischemia, in an attempt to standardize the insult and resulting deficit. The single injury chosen is usually rather mild to ensure that sufficient numbers survive to undergo morphometry. This limits the generalizability of the results. Furthermore, there may be considerable variability in the response of groups to a standard insult. Such variability increases the sample size needed to screen drugs for neuroprotective benefit. Our data show that the dose of collagenase injected is highly correlated with the resulting volume of hematoma. This confirms that the dose of collagenase can be used as a surrogate for the injury in the bioassay procedure. However, we have not documented the size or time course of the ischemia that surrounds the hematoma. Such studies will be necessary to be certain of the mechanism of protection in this model.

	Acknowledgments

 
This study was supported by the US Department of Veterans Affairs Medical Research Service.

Received August 19, 1996; revision received October 14, 1996; accepted October 14, 1996.

	References

Top Abstract Introduction Materials and Methods Results Discussion References Introduction  References

 
1. Feldmann E. Intracerebral hemorrhage. Curr Concept Cerebrovasc Dis. 1990;25:31-35.

2. Kanno T, Sano H, Shinomiyo Y, Katada K, Nagata J, Hoshino M, Mitsuyama F. Role of surgery in hypertensive intracerebral hematoma. J Neurosurg. 1985;61:1091-1099.

3. Lisk DR, Pasteur W, Rhoades H, Putnam RD, Grotta JC. Early presentation of hemispheric intracerebral hemorrhage: prediction of outcome and guidelines for treatment allocation. Neurology. 1994;44:133-139.[Abstract/Free Full Text]

4. Broderick J, Brott T, Tomsick T, Tew J, Duldner J, Huster G. Management of intracerebral hemorrhage in a large metropolitan population. Neurosurgery. 1994;34:882-887.[Medline] [Order article via Infotrieve]

5. Jorgensen HS, Nakayama H, Raaschou HO, Olsen TS. Intracerebral hemorrhage versus infarction: stroke severity, risk factors, and prognosis. Ann Neurol. 1995;38:45-50.[Medline] [Order article via Infotrieve]

6. Yang G, Betz AL, Chenevert TL, Brunberg JA, Hoff JT. Experimental intracerebral hemorrhage: relationship between brain edema, blood flow, and blood-brain barrier permeability in rats. J Neurosurg. 1994;81:93-102.[Medline] [Order article via Infotrieve]

7. Sinar EJ, Mendelow AD, Graham DI, Teasdale GM. Experimental intracerebral hemorrhage: effects of a temporary mass lesion. J Neurosurg. 1987;66:568-576.[Medline] [Order article via Infotrieve]

8. Kobari M, Gotoh F, Tomita M, Tanahashi N, Shinohara T, Terayama Y, Mihara B. Bilateral hemispheric reduction of cerebral blood volume and blood flow immediately after experimental cerebral hemorrhage in cats. Stroke. 1988;19:991-996.[Abstract/Free Full Text]

9. Nath FP, Kelly PT, Jenkins A, Mendelow AD, Graham DI, Teasdale GM. Effects of experimental intracerebral hemorrhage on blood flow, capillary permeability, and histochemistry. J Neurosurg. 1987;66:555-562.[Medline] [Order article via Infotrieve]

10. Lyden PD, Hedges B. Protective effect of synaptic inhibition during cerebral ischemia. Stroke. 1992;23:1463-1470.[Abstract/Free Full Text]

11. Lyden PD, Lonzo L. Combination therapy protects ischemic brain in rats. Stroke. 1994;25:189-196.[Abstract]

12. Lyden P, Lonzo L, Nunez S. Combination chemotherapy extends the therapeutic window to 60 minutes after stroke. J Neurotrauma. 1995;12:223-230.[Medline] [Order article via Infotrieve]

13. Rosenberg GA, Estrada E, Kelley RO, Kornfeld M. Bacterial collagenase disrupts extracellular matrix and opens blood-brain barrier in rat. Neurosci Lett. 1993;160:117-119.[Medline] [Order article via Infotrieve]

14. Kochhar A, Zivin JA, Lyden PD, Mazzarella V. Glutamate antagonist therapy reduces neurologic deficits produced by focal central nervous system ischemia. Arch Neurol. 1988;45:148-153.[Abstract/Free Full Text]

15. Zivin JA, DeGirolami U, Kochhar A, Lyden PD, Mazzarella V, Hemenway CC, Henry ME. A model for quantitative evaluation of embolic stroke therapy. Brain Res. 1987;435:305-309.[Medline] [Order article via Infotrieve]

16. Lyden PD, Zweifler R, Mahdavi Z, Lonzo L. A rapid, reliable, and valid method for measuring infarct and brain compartment volumes from computed tomographic scans. Stroke. 1994;25:2421-2428.[Abstract]

17. Paxinos G, Watson C. The Rat Brain in Stereotaxic Coordinates. 2nd ed. San Diego, Calif: Academic Press, Inc; 1986.

18. Rosenberg GA, Mun-Bryce S, Wesley M, Kornfeld M. Collagenase-induced intracerebral hemorrhage in rats. Stroke. 1990;21:801-807.[Abstract/Free Full Text]

19. Lyden PD, Lonzo L, Nunez S. Combination chemotherapy extends the therapeutic window to 60 minutes after stroke. J Neurotrauma. 1995;12:223-230.

20. Weibel ER. Stereological Methods: Practical Methods for Biological Morphometry. 3rd ed. San Diego, Calif: Academic Press; 1989:vol 1.

21. Winer BJ. Statistical Principles in Experimental Design. 2nd ed. New York, NY: McGraw-Hill Publishing Co; 1971.

22. Zivin JA, Waud DR. Quantal bioassay and stroke. Stroke. 1992;23:767-773.[Abstract/Free Full Text]

23. Shuaib A, Mazagri R, Ijaz S. GABA agonist `muscimol' is neuroprotective in repetitive transient forebrain ischemia in gerbils. Exp Neurol. 1993;123:284-288.[Medline] [Order article via Infotrieve]

24. Madden K. Effect of -aminobutyric acid modulation on neuronal ischemia in rabbits. Stroke. 1994;25:2271-2275.[Abstract]

25. Shuaib A, Ijaz S, Kanthan R. Clomethiazole protects the brain in transient forebrain ischemia when used up to 4 h after the insult. Neurosci Lett.. 1995;197:1-4.[Medline] [Order article via Infotrieve]

26. Kelly PAT, Faulkner AJ, Burrow AP. The effects of the GABA agonist muscimol upon blood flow in different vascular territories of the rat cortex. J Cereb Blood Flow Metab. 1989;9:754-758.[Medline] [Order article via Infotrieve]

27. Kelly PAT, McCulloch J. Effects of the putative GABAergic agonists, muscimol and THIP, upon local cerebral glucose utilisation. J Neurochem. 1982;39:613-624.[Medline] [Order article via Infotrieve]

28. Edvinsson L, Larsson B, Skarby T. Effect of the GABA receptor agonist muscimol on regional cerebral blood flow in the rat. Brain Res. 1980;185:445-448.[Medline] [Order article via Infotrieve]

29. Rosenberg GA, Navratil MJ. (S)-Emopamil reduces brain edema from collagenase-induced hemorrhage in rats. Stroke. 1994;25:2067-2071.[Abstract]

30. Fern R, Ransom BR, Waxman SG. White matter stroke: autoprotective mechanisms with therapeutic implications. Cerebrovasc Dis. 1996;6:59-65.

31. Mathieu O, Cruz-Orive LM, Hoppeler H, Weibel ER. Measuring error and sampling variation in stereology: comparison of the efficiency of various methods for planar image analysis. J Microsc. 1981;121:75-88.[Medline] [Order article via Infotrieve]

32. Busto R, Dietrich WD, Globus MY-T, Ginsberg MD. Postischemic moderate hypothermia inhibits CA1 hippocampal ischemic neuronal injury. Neurosci Lett. 1989;101:299-304.[Medline] [Order article via Infotrieve]

33. Zhang R-L, Chopp M, Chen H, Garcia JH, Zhang ZG. Postischemic (1 hour) hypothermia significantly reduces ischemic cell damage in rats subjected to 2 hours of middle cerebral artery occlusion. Stroke. 1993;24:1235-1240.[Abstract/Free Full Text]

34. Hsu CY. Criteria for valid preclinical trials using animal stroke models. Stroke. 1993;24:633-636.[Free Full Text]

Editorial Comment

J. Paul Muizelaar, MD, PhD, Guest Editor

Department of NeurosurgeryWayne State UniversityDetroit, Mich

	Introduction

Top Abstract Introduction Materials and Methods Results Discussion References Introduction  References

 
The accompanying article is one of the very few to study the effect of neuroprotective agents on outcome after experimental intracerebral hemorrhage.

The mechanisms leading to poor outcome with intracerebral hemorrhage are not completely understood and may be somewhat different than thought previously.^1R Therefore, it is encouraging that pharmacological treatment can improve the one outcome measure that counts most, which is clinical improvement.

Although the quantal bioassay method has been discussed twice in Stroke (References 22²² and 24²⁴ in the accompanying article), one does not see it used very often. The article convincingly shows the usefulness of the method for testing of neuroprotective agents, but of course it does not help to establish dose-response or time window–response curves.

	References

Top Abstract Introduction Materials and Methods Results Discussion References Introduction  References

 
1R. Wagner KR, Xi G, Hua Y, Kleinholz M, deCourten Meyers GM, Meyers RE, Broderick JP, Brott TG. Local intracerebral hemorrhage model in pigs: rapid edema development in perihematomal white matter. Stroke.. 1996;27:490-497.[Abstract/Free Full Text]

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