- Email: [email protected]
Extended therapeutic time window after focal cerebral ischemia by non-competitive inhibition of AMPA receptors
BR A I N R ES E A RC H 1 0 8 5 ( 2 00 6 ) 1 8 9 –1 94
a v a i l a b l e a t w w w. s c i e n c e d i r e c t . c o m
w w w. e l s e v i e r. c o m / l o c a t e / b r a i n r e s
Short Communication
Extended therapeutic time window after focal cerebral ischemia by non-competitive inhibition of AMPA receptors Bernd Elger ⁎, Martin Gieseler, Oliver Schmuecker, Ingrid Schumann, Astrid Seltz, Andreas Huth Schering AG, D-13342 Berlin, Germany
A R T I C LE I N FO
AB S T R A C T
Article history:
In acute stroke, the therapeutic time window is a critical factor which may have contributed
Accepted 9 February 2006
to the failure of several phase III clinical trials with so-called neuroprotective agents. Since
Available online 3 April 2006
cerebral glutamate levels are elevated for many hours in progressing stroke, we investigated the novel AMPA glutamate receptor antagonist ZK 187638 in rodent models of stroke using
Keywords:
up to 12 h delays in the start of therapy after permanent occlusion of the middle cerebral
Stroke
artery (MCA). In rats, ZK 187638 reduced total infarct volume by 43% and 33% when therapy
Excitotoxicity
was started immediately or with a delay of 6 h, respectively, but no effect was observed after
Brain infarction
a 12 h delay. Dose-dependent decreases of total infarct volume (up to 42%) were measured in
Neuroprotection
mice given the first injection of ZK 187638 6 h after permanent MCA occlusion. In conclusion,
Delayed treatment
the AMPA receptor antagonist ZK 187638 has a therapeutic time window of at least 6 h after
Focal cerebral ischemia
permanent focal cerebral ischemia in rodents. © 2006 Elsevier B.V. All rights reserved.
Abbreviations: AMPA, alpha-amino-3-hydroxy-5methyl-4-isoxazolepropionate CBF, cerebral blood flow FDA, Food and drug administration IL-1β, interleukin-1β MCA, middle cerebral artery NBQX, 2,3-dihydroxy-6-nitro-7sulfamoyl-benzol[f]quinoxaline NMDA, N-methyl-D-aspartate t-PA, tissue-type plasminogen activator TNF-α, tumor necrosis factor-α TTC, 2,3,5-triphenyltetrazolium chloride
⁎ Corresponding author. Fax: +49 30 468 97253. E-mail address: [email protected] (B. Elger). 0006-8993/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.brainres.2006.02.080
190
BR A I N R ES E A RC H 1 0 8 5 ( 2 00 6 ) 1 8 9 –19 4
Stroke is the leading cause of adult disability in industrialized countries. The medical need of efficient therapy is largely unmet because so far only one agent, t-PA, has been approved by the FDA for the indication ischemic stroke. However, the therapeutic time window of t-PA is limited to about 3 h after the insult. Since most stroke patients are amenable to therapy later than 3 h, thrombolysis with t-PA can be performed only in few stroke patients (Fisher, 2003). As an alternative to this vascular strategy of stroke therapy, a cytoprotective strategy which prevents the progression of ischemic brain lesions may have a wider time window. A prime factor for ischemic neuronal cell death is glutamate-induced excitotoxicity. Glutamate levels are significantly elevated in brains of patients with progressing stroke for up to 24 h (Davalos et al., 1997) and similarly, persisting increases in cerebral glutamate concentrations have been found in rats 24 h after permanent middle cerebral artery (MCA) occlusion (Newcomb et al., 1998). Glutamate receptors of the alpha-amino-3-hydroxy-5methyl-4-isoxazolepropionate (AMPA) type were potently blocked by the novel 2,3-dimethyl-6-phenyl-12 H-[1,3]dioxolo [4,5-h]imidazo[1,2-c][2,3] benzodiazepine (ZK 187638, Fig. 1) in an in vitro assay using cultured rat hippocampal neurons (Elger et al., 2005). When tested in vivo, the compound was neuroprotective in mice and rats after pretreatment and early post-treatment (1 h), respectively, of focal cerebral ischemia. Therefore, the aim of the present study was to test the efficacy of ZK 187638 using further delays in the start of therapy in rodents. The rat model of permanent MCA occlusion was chosen for the experiments because of the abovementioned pathophysiological similarities to the human situation. Moreover, spontaneous recanalization occurs in only less than 19% of stroke patients within 6 h after the insult (Molina et al., 2001) and the MCA territory is most frequently affected. The predictive value of the permanent MCA occlusion model regarding the therapeutic time window of drug efficacy in stroke patients has been shown previously with the agent ancrod. Significant cerebroprotection was observed when treatment with the defibrinogenating agent ancrod was initiated within 3 h after permanent MCA occlusion in rats but not after 6 h (Elger et al., 1997). Likewise, a clinical phase III trial was positive using a 3 h time window but efficacy was lost when start of ancrod
Fig. 1 – Chemical structure of 2,3-dimethyl-6-phenyl-12 H-[1,3]dioxolo[4,5-h]imidazo[1,2-c][2,3]benzodiazepine (ZK 187638).
treatment was delayed up to 6 h after stroke (Sherman et al., 2000; Sherman, 2002; Orgogozo et al., 2000). In addition to the studies of ZK 187638 in rats, the therapeutic time window was also investigated in mice as a second species in order to evaluate the robustness of the therapeutic effects. All in vivo experiments on ZK 187638 were performed in accordance to the requirements of the German laws for the protection of animals (Deutsches Tierschutzgesetz) and in compliance with the European Communities Council Directive of 24 November 1986 (86/609/EEC). The animals were maintained under standard conditions (12 h day/night cycle, 22 °C, 50% humidity) with free access to food and tap water. Before use for the experiments, the animals were allowed to recover from transportation for about 1 week. The surgical procedure of permanent MCA occlusion did not exceed 10 min and was performed as described elsewhere (Elger et al., 2005). Briefly, male Fischer-344 rats weighing 250–300 g were anaesthetized with 4% halothane for induction and 1.5% halothane for maintenance in 30% O2/70% N2O via a face mask. After a vertical 2 cm skin incision was made between the left eye and the left ear, the temporalis muscle was partly removed in order to expose the zygoma and the squamosal bone. The left MCA was exposed through a burr hole craniectomy (2 mm diameter) drilled in close proximity to the foramen ovale. After opening the dura, the proximal portion of the middle cerebral artery was electrocauterized with bipolar forceps (Erbotom T130, Erbe, Elektromedizin GmbH, Tübingen, Germany) and cut through with scissors. The burr hole was covered with Lyostypt (Braun Dexon) and the skin was sutured. During surgery, the rectal temperature of the anesthetized animals was maintained at 37 ± 0.5 °C by a feedback regulated heating pad. Male mice (NMRI strain) weighing 23–30 g were anesthetized with 4% halothane for induction and 1.5% halothane for maintenance in 30% O2/70% N2O via a face mask. Under an operating microscope (Wild AG, Heerbrugg, Switzerland) with low power magnification, a 5–10 mm incision of the skin was made vertically on the left side between the ear and the orbit. The parotid gland and surrounding soft tissue were removed by electrocoagulation. Parts of the underlying temporal muscle were removed until the MCA became visible through the surface of the skull. A small burr hole (1 mm) was made using a high-speed microdrill through the outer surface of the semitranslucent skull just over the visibly identified MCA. The inner layer of the skull was removed with fine forceps. The MCA was electrocoagulated with a bipolar diathermy above the level of the olfactory tract, thus lenticulostriate arteries were left intact. Afterwards, the wound was sutured. The animals did not sustain blood loss, and all surgeries were completed within 7–10 min. MCA-occluded rats and mice received 4 i.p. injections of a solution of ZK 187638 containing 10% cremophor EL (Sigma). The injections were spaced by 1 h intervals. To study the efficacy of delayed therapy in rats, the highest dose (30 mg/kg per injection) was chosen from a previous dose–response investigation in MCA-occluded rats (Elger et al., 2005). Since no dose–response information was available from previous experiments with ZK 187638 in MCA-occluded mice, a known efficacious dosage (10 mg/kg per injection) was selected from an earlier study (Elger et al., 2005) and in addition, 30 mg/kg per injection was chosen comparable to the dosage in rats. For
BR A I N R ES E A RC H 1 0 8 5 ( 2 00 6 ) 1 8 9 –1 94
histological analyses, animals were anesthetized with Nembutal® 24 h after MCA occlusion if not stated otherwise in the text. The chests were opened, and the brains were perfused by intracardiac infusion of 1 ml of a saline solution containing 10% 2,3,5-triphenyltetrazolium chloride (TTC). The brains were left in situ for 10–15 min, removed, and stored in fixative (4% paraformaldehyde and 2% sucrose in 0.1 M sodium phosphate) for 3 days. The brains were sliced into 1 mm coronal sections with a matrix (Harvard Bioscience). The slices were captured using a color camera combined with a Macintosh computer (Apple, Cupertino, CA, USA). The areas of the infarcts were measured using the NIH Image software package (freeware) and the infarct volumes were calculated as described elsewhere (Elger et al., 2005). All results are given as mean and standard deviation (SD). For each experimental group, the deviation from the Gaussian distribution was tested by the Kolmogorov–Smirnov test. All the data passed the normality test. Statistical comparisons
191
between control and treatment groups were made using analysis of variance followed by post hoc Student's t test or Dunnett's multiple comparison test. Significance was accepted at P < 0.05. The histological analyses in our studies on the effects of various delays of ZK 187638 therapy on permanent focal cerebral ischemia revealed that both cerebral cortex and striatum were affected by ischemia in vehicle-treated rats at all time points investigated (Fig. 2). Twenty-four hours following permanent MCA occlusion, total infarct volume was significantly (P = 0.002) reduced by 43% from 191 ± 72 mm3 in vehicle-treated controls (n = 15) to 109 ± 49 mm3 in rats (n = 12) given 4 injections of ZK 187638 (each injection 30 mg/kg i.p.) starting immediately after MCA occlusion. In a second set of experiments, the same dose of the first study (4 × 30 mg/kg i.p.) was used to study the efficacy of delayed therapy with ZK 187638 starting 6 h after MCA occlusion. As shown in Fig. 3, total infarct volume was significantly (P = 0.008) diminished by 33%
Fig. 2 – Representative, TTC-stained brain slices showing anterior as well as posterior ischemic territories of rats treated with (A) vehicle 0 h, (B) ZK 187638 (4 × 30 mg/kg i.p.) 0 h, (C) vehicle 6 h, and (D) ZK 187638 (4 × 30 mg/kg i.p.) 6 h after permanent MCA occlusion.
192
BR A I N R ES E A RC H 1 0 8 5 ( 2 00 6 ) 1 8 9 –19 4
Fig. 3 – Effect of ZK 187638 on total infarct volume in rats measured 24 h after permanent MCA occlusion (mean ± SD). Treatment with ZK 187638 (4 × 30 mg/kg, n = 9) or vehicle (n = 9) consisted of 4 i.p. injections spaced by 1 h intervals. The first injection was given 6 h after MCA occlusion.
from 188 ± 42 mm3 in vehicle-treated controls (n = 9) to 126 ± 46 mm3 in ZK 187638-treated rats (n = 9). However, when ZK 187638 therapy (4 × 30 mg/kg i.p.) was initiated in a third experiment 12 h after MCA occlusion, no differences of infarct volumes were observed between compound-treated rats and the corresponding vehicle-treated rats measured 48 h after vessel occlusion (data not shown). Following permanent MCA occlusion in mice, the ischemic territory was strictly ipsi-lateral (left side) and localized exclusively in the temporo-parietal cortex. Dose-dependent reductions of total infarct volume were obtained in mice after intraperitoneal injections of ZK 187638 (Fig. 4) starting 6 h after MCA occlusion. Twenty-four hours after MCA occlusion, the lesions were reduced from 36.8 ± 17.8 mm3 in vehicle-treated controls (n = 21) to 26.2 ± 11.1 mm3 (P = 0.033) and to 21.3 ± 6.6 mm3 (P = 0.035) in mice treated with 4 i.p. injections of 10 mg/kg ZK 187638 (n = 19) and 30 mg/kg ZK 187638 (n = 7), respectively. The injections were spaced by 1 h intervals. In parallel to these histological studies on acute neurodegeneration in mice, behavioural assessments were carried out with ZK 187638 in a mouse model of chronic neurodegeneration using SOD1G93A transgenic mice. Both models have been validated regarding a pivotal role of glutamate-induced excitotoxicity by previous investigations with 2,3-dihydroxy-6nitro-7-sulfamoyl-benzol[f]quinoxaline (NBQX) as gold standard for selective AMPA receptor inhibition (Elger et al., 2005; Van Damme et al., 2003). Therapy with ZK 187638 significantly reduced neurological deficits of the transgenic mice as quantitatively measured by stride length and rotarod performance. Furthermore, the life expectancy of mice was ameliorated despite delayed start of therapy after onset of disease (Tortarolo et al., 2006). The significant infarct reductions in rats and mice of the present studies with ZK 187638 add to the positive findings that have been reported from earlier studies with this compound in these species after permanent MCA occlusion (Elger et al., 2005). Total cerebral lesion volume is significantly
reduced even if therapy with ZK 187638 is commenced with a delay of 6 h after permanent MCA occlusion in mice. These results suggest that the 2,3-benzodiazepine ZK 187638 is more potent than the non-competitive AMPA receptor antagonist GYKI 53773 (talampanel) which failed to decrease the brain lesion in mice although it was given with only 15 min delay after permanent cerebral ischemia (Erdo et al., 2005). The chemical structure of ZK 187638 differs from that of GYKI 53773 in two ways: (1) the 4-methyl substitution is replaced by a nitrogen-containing heterocycle attached to the 3,4-position of the 2,3-benzodiazepine ring system and (2) the phenyl ring system lacks an amino group. It has been shown that GYKI 53405, which is the (+)-isomer of GYKI 53773, as well as the 2,3benzodiazepine EGIS-8332 which is structurally closely related to GYKI 53405, reduces infarct size in mice when administered 30 min after permanent MCA occlusion (Gressens et al., 2005). Thus, it may be concluded that modifications of substituents at the 2,3-benzodiazepine ring system critically determine the efficacy in focal cerebral ischemia. However, it remains to be clarified if the therapeutic time window of GYKI 53405 and EGIS-8332 is similar to that of ZK 187638 after permanent MCA occlusion and if these two compounds display equally favorable brain availability as ZK 187638 which reaches brain concentrations that are in general 3-fold higher than the plasma concentrations (Tortarolo et al., 2006). After ischemic stroke, the time window of opportunity is of special importance as frequently only 4% of patients are amenable to therapy within 3 h (Fisher, 2003). Most therapeutic strategies that address vascular mechanisms using e.g. agents to promote thrombolysis (Sakurama et al., 1994; Zhang et al.,
Fig. 4 – Effect of ZK 187638 on total infarct volume in mice measured 24 h after permanent MCA occlusion (mean ± SD). Treatment with ZK 187638 or vehicle (10% cremophor, CEL) consisted of 4 i.p. injections spaced by 1 h intervals. The first injection was given 6 h after MCA occlusion. Asterisks indicate statistical significance (P < 0.05) versus the vehicle-treated group (Dunnett's test).
BR A I N R ES E A RC H 1 0 8 5 ( 2 00 6 ) 1 8 9 –1 94
1999) or to decrease blood viscosity (Elger et al., 1997) reduced cerebral lesion volume in rats only when given within 3 h after MCA occlusion. The so-called neuroprotective agents, however, that interfere with the biochemical cascade of events which leads to cell death may have a wider time window if directed against glutamate-induced excitotoxicity. In vivo microdialysis studies have demonstrated elevated glutamate levels in the brain up to 15–24 h after permanent MCA occlusion in rats and cats (Matsumoto et al., 1993; Newcomb et al., 1998). In patients with progressing stroke, sustained elevation of glutamate has been observed in the cerebrospinal fluid until 24 h after the insult (Davalos et al., 1997). As a possible mechanism for sustained glutamate release after cerebral ischemia, it has been found that at later time points a particular level of cerebral blood flow (CBF) decline may be associated with much more glutamate release than at earlier time points (Matsumoto et al., 1993). It has been shown in addition that microglia activation occurs in mice as well as in rats within 12 h after permanent MCA occlusion (Davies et al., 1999; Lambertsen et al., 2002). Activated microglia release glutamate causing excitotoxic neuronal cell death (Kingham et al., 1999). Accordingly, considerable increases in cerebral lesion size have been measured between 3 h and 24 h after permanent MCA occlusion in rats and in mice (Seega and Elger, 1993; Garcia et al., 1995; Panahian et al., 1999; Matsui et al., 2002). The present study demonstrates that the glutamate-mediated progression of cerebral injury following severe focal ischemia can be effectively stopped because treatment with the non-competitive AMPA receptor antagonist ZK 187638 starting 6 h after permanent MCA occlusion yielded significant cerebral lesion reductions both in rats and mice. Interestingly, the therapeutic time window of competitive AMPA receptor antagonists such as ZK 200775 and YM872 is less than 6 h in the rat model of permanent MCA occlusion (Turski et al., 1998; Takahashi et al., 1998). Hence, a growing body of evidence is accumulating from this and previous studies (Donevan and Rogawski, 1993; Elger et al., 2005) that non-competitive AMPA receptor antagonists have an advantage under conditions such as severe cerebral ischemia in which high glutamate levels may render the competitive antagonists relatively ineffective. In contrast to AMPA receptor antagonists, N-methyl-Daspartate (NMDA) receptor antagonists have only a therapeutic time window of around 1 or 2 h after MCA occlusion (Dirnagl et al., 1999). NMDA receptor activation may play an important role in glutamate-induced excitotoxicity of neurons in the very initial phase of cerebral ischemia. AMPA receptor activation, however, may be involved not only in glutamate-induced initial neuronal cell death but also in more complex processes of acute ischemic brain damage that include other cell types such as oligodendroglia and microglia. Hence, it has been demonstrated that ischemic white matter damage can be reduced by AMPA receptor inhibition but not by NMDA receptor blockade due to the relative absence of NMDA receptors in cerebral white matter (Dewar et al., 1999; McCracken et al., 2002). Functional AMPA/kainate receptors have been shown on microglia and oligodendrocytes (Noda et al., 2000; McDonald et al., 1998). Concomittant with microglia activation, increases in the expression of the cytokines tumor necrosis factor-α (TNFα) and interleukin-1β (IL-1β) have been measured with peaks at
193
about 12 h in mice as well as in rats after permanent MCA occlusion (Davies et al., 1999; Lambertsen et al., 2002). Both cytokines may contribute to early neuronal injury on the one hand and may aid in the repair processes on the other hand as reviewed recently (Allan and Stock, 2004; Pickering et al., 2005). It has been shown that TNF-α facilitates glutamate excitotoxicity of neurons directly by rapid upregulation of neuronal Ca2+ permeable AMPA channels as well as indirectly by inhibition of astrocytic glutamate uptake (Ogoshi et al., 2005; Takahashi et al., 2003). However, deleterious modulation of AMPA receptormediated excitotoxicity depends on the concentration of TNFα as well as the overall balance between endogenous antiinflammatory and pro-inflammatory molecules (Bernardino et al., 2005; Allan and Stock, 2004). Changes of this balance in the time course after onset of ischemia may account for the loss of neuroprotective efficacy of AMPA receptor inhibition that was observed in the present study when therapy was initiated 12 h after permanent MCA occlusion in rats. In conclusion, the non-competitive AMPA receptor antagonist ZK 187638 reduces ischemic brain lesions after permanent middle cerebral artery occlusion even if therapy is begun with a delay of 6 h in both rats and mice. This extended therapeutic time window together with the favorable brain availability of the compound after oral administration (Tortarolo et al., 2006) may enable inclusion of larger patient numbers in acute stroke therapy than currently possible because treatment could already be initiated by the ambulance system before patient admission in the hospital. Moreover, these positive results of ZK 187638 in models of acute neurodegeneration warrant further studies on the efficacy of this compound in animal models of other neurological disorders such as multiple sclerosis where AMPA receptor activation also plays a pathogenic key role (Pitt et al., 2000; Smith et al., 2000).
REFERENCES
Allan, S., Stock, C., 2004. Cytokines in stroke. In: Dirnagl, U., Elger, B. (Eds.), Neuroinflammation in Stroke. Springer Verlag, Berlin, pp. 39–66. Bernardino, L., Xapelli, S., Silva, A.P., Jakobsen, B., Poulsen, F.R., Oliveira, C.R., Vezzani, A., Malva, J.O., Zimmer, J., 2005. Modulator effects of interleukin-1beta and tumor necrosis factor-alpha on AMPA-induced excitotoxicity in mouse organotypic hippocampal slice cultures. J. Neurosci. 25, 6734–6744. Davalos, A., Castillo, J., Serena, J., Noya, M., 1997. Duration of glutamate release after acute ischemic stroke. Stroke 28, 708–710. Davies, C.A., Loddick, S.A., Toulmond, S., Stroemer, R.P., Hunt, J., Rothwell, N.J., 1999. The progression and topographic distribution of interleukin-1β expression after permanent middle cerebral artery occlusion in the rat. J. Cereb. Blood Flow Metab. 19, 87–98. Dewar, D., Yam, P., McCulloch, J., 1999. Drug development for stroke: importance of protecting cerebral white matter. Eur. J. Pharmacol. 375, 41–50. Dirnagl, U., Iadecola, C., Moskowitz, M.A., 1999. Pathobiology of ischaemic stroke: an integrated review. TINS 22, 391–397. Donevan, S.D., Rogawski, M.A., 1993. GYKI 52466, a 2,3-benzodiazepine, is a highly selective, noncompetitive
194
BR A I N R ES E A RC H 1 0 8 5 ( 2 00 6 ) 1 8 9 –19 4
antagonist of AMPA/kainate receptor responses. Neuron 10, 51–59. Elger, B., Hornberger, W., Schwarz, M., Seega, J., 1997. MRI study on delayed ancrod therapy of focal cerebral ischaemia in rats. Eur. J. Pharmacol. 336, 7–14. Elger, B., Huth, A., Neuhaus, R., Ottow, E., Schneider, H., Seilheimer, B., Turski, L., 2005. Novel alpha-amino-3-hydroxy5-methyl-4-isoxazole propionate (AMPA) receptor antagonists of 2,3-benzodiazepine type: chemical synthesis, in vitro characterization, and in vivo prevention of acute neurodegeneration. J. Med. Chem. 48, 4618–4627. Erdo, F., Berzsenyi, P., Andrasi, F., 2005. The AMPA-antagonist talampanel is neuroprotective in rodent models of focal cerebral ischemia. Brain Res. Bull. 66, 43–49. Fisher, M., 2003. Recommendations for advancing development of acute stroke therapies. Stroke therapy academic industry roundtable 3. Stroke 34, 1539–1546. Garcia, J.H., Liu, K.-F., Ho, K.-L., 1995. Neuronal necrosis after middle cerebral artery occlusion in Wistar rats progresses at different time intervals in the caudatoputamen and the cortex. Stroke 26, 636–643. Gressens, P., Spedding, M., Gigler, G., Kertesz, S., Villa, P., Medja, F., Williamson, T., Kapus, G., Levay, G., Szenasi, G., Barkoczy, J., Harsing, L.G., 2005. The effects of AMPA receptor antagonists in models of stroke and neurodegeneration. Eur. J. Pharmacol. 519, 58–67. Kingham, P.J., Cuzner, M.L., Pocock, J.M., 1999. Apoptotic pathways mobilized in microglia and neurones as a consequence of chromogranin a-induced microglial activation. J. Neurochem. 73, 538–547. Lambertsen, K.L., Gregersen, R., Finsen, B., 2002. Microglialmacrophage synthesis of tumor necrosis factor after focal cerebral ischemia in mice is strain dependent. J. Cereb. Blood Flow Metab. 22, 785–797. Matsui, T., Mori, T., Tateishi, N., Kagamiishi, Y., Satoh, S., Katsube, N., Morikawa, E., Morimoto, T., Ikuta, F., Asano, T., 2002. Astrocytic activation and delayed infarct expansion after permanent focal cerebral ischemia in rats: Part I. Enhanced astrocytic synthesis of S100β in the periinfarct area precedes delayed infarct expansion. J. Cereb. Blood Flow Metab. 22, 711–722. Matsumoto, K., Graf, R., Rosner, G., Taguchi, J., Heiss, W.-D., 1993. Elevation of neuroactive substances in the cortex of cats during prolonged focal ischemia. J. Cereb. Blood Flow Metab. 13, 586–594. McCracken, E., Fowler, J.H., Dewar, D., Morrison, S., McCulloch, J., 2002. Grey matter and white matter ischemic damage is reduced by the competitive AMPA receptor antagonist, SPD 502. J. Cereb. Blood Flow Metab. 22, 1090–1097. McDonald, J.W., Althomsons, S.P., Hyrc, K.L., Choi, D.W., Goldberg, M.P., 1998. Oligodendrocytes from forebrain are highly vulnerable to AMPA/kainate receptor-mediated excitotoxicity. Nat. Med. 4, 291–297. Molina, C.A., Montaner, J., Abilleira, S., Ibarra, B., Romero, F., Arenillas, J.F., Alvarez-Sabín, J., 2001. Timing of spontaneous recanalization and risk of hemorrhagic transformation in acute cardioembolic stroke. Stroke 32, 1079–1084. Newcomb, R., Pierce, A.R., Kano, T., Meng, W., Bosque-Hamilton, P., Taylor, L., Curthoys, N., Lo, E.H., 1998. Characterization of mitochondrial glutaminase and amino acids at prolonged times after experimental focal cerebral ischemia. Brain Res. 813, 102–111. Noda, M., Nakanishi, H., Nabekura, J., Akaike, N., 2000. AMPA-
kainate subtypes of glutamate receptor in rat cerebral microglia. J. Neurosci. 20, 251–258. Ogoshi, F., Yin, H.Z., Kuppumbatti, Y., Song, B., Amindari, S., Weiss, J.H., 2005. Tumor necrosis-factor-alpha (TNF-alpha) induces rapid insertion of Ca2+-permeable alpha-amino-3hydroxyl-5-methyl-4-isoxazole-propionate (AMPA)/kainate (Ca-A/K) channels in a subset of hippocampal pyramidal neurons. Exp. Neurol. 193, 384–393. Orgogozo, J.M., Verstrate, M., Kay, R., Hennerici, M., Lenzi, G.L., 2000. Outcomes of ancrod in acute ischemic stroke. JAMA 284, 1926–1927. Panahian, N., Huang, T., Maines, M.D., 1999. Enhanced neuronal expression of the oxidoreductase – biliverdin reductase – after permanent focal cerebral ischemia. Brain Res. 850, 1–13. Pickering, M., Cumiskey, D., O'Connor, J.J., 2005. Actions of TNF-alpha on glutamatergic synaptic transmission in the central nervous system. Exp. Physiol. 90, 663–670. Pitt, D., Werner, P., Raine, C.S., 2000. Glutamate excitotoxicity in a model of multiple sclerosis. Nat. Med. 6, 67–70. Seega, J., Elger, B., 1993. Diffusion- and T2-weighted imaging: evaluation of oedema reduction in focal cerebral ischemia by the calcium and serotonin antagonist levemopamil. Magn. Reson. Imaging 11, 401–409. Sakurama, T., Kitamura, R., Kaneko, M., 1994. Tissue-type plasminogen activator improves neurological functions in a rat model of thromboembolic stroke. Stroke 25, 451–456. Sherman, D.G., 2002. Ancrod. Curr. Med. Res. Opin. 18 (Suppl. 2), s48–s52. Sherman, D.G., Atkinson, R.P., Chippendale, T., Levin, K.A., Ng, K., Futrell, N., Hsu, C.Y., Levy, D.E., 2000. Intravenous ancrod for treatment of acute ischemic stroke. JAMA 283, 2395–2403. Smith, T., Groom, A., Zhu, B., Turski, L., 2000. Autoimmune encephalomyelitis ameliorated by AMPA antagonists. Nat. Med. 6, 62–66. Takahashi, M., Ni, J.W., Kawasaki-Yatsugi, S., Toya, T., Ichiki, C., Yatsugi, S.-I., Koshiya, K., Shimizu-Sasamata, M., Yamaguchi, T., 1998. Neuroprotective efficacy of YM872, an α-amino-3hydroxy-5-methylisoxazole-4-propionic acid receptor antagonist, after permanent middle cerebral artery occlusion in rats. JPET 287, 559–566. Takahashi, J.L., Giuliani, F., Power, C., Imai, Y., Yong, V.W., 2003. Interleukin-1β promotes oligodendrocyte death through glutamate excitotoxicity. Ann. Neurol. 53, 588–595. Tortarolo, M., Grignaschi, G., Calvaresi, N., Zennaro, E., Spaltro, G., Colovic, M., Fracasso, C., Guiso, G., Elger, B., Schneider, H., Seilheimer, B., Caccia, S., Bendotti, C., 2006. Glutamate AMPA receptors change in motor neurons of SOD1(G93A) transgenic mice and their inhibition by a noncompetitive antagonist ameliorates the progression of amytrophic lateral sclerosis-like disease. J. Neurosci. Res. 83, 134–146. Turski, L., Huth, A., Sheardon, M., McDonald, F., Neuhaus, R., Schneider, H.H., Dirnagl, U., Wiegand, F., Jacobsen, P., Ottow, E., 1998. ZK200775: a phosphonate quinoxalinedione AMPA antagonist for neuroprotection in stroke and trauma. Proc. Natl. Acad. Sci. 95, 10960–10965. Van Damme, P., Leyssen, M., Callewaert, G., Robberecht, W., Van den Bosch, L., 2003. The AMPA receptor antagonist NBQX prolongs survival in a transgenic mouse model of amyotrophic lateral sclerosis. Neurosci. Lett. 343, 81–84. Zhang, R.L., Zhang, Z.G., Chopp, M., 1999. Increased therapeutic efficacy with rt-PA and anti-CD18 antibody treatment of stroke in the rat. Neurology 52, 273–279.
a v a i l a b l e a t w w w. s c i e n c e d i r e c t . c o m
w w w. e l s e v i e r. c o m / l o c a t e / b r a i n r e s
Short Communication
Extended therapeutic time window after focal cerebral ischemia by non-competitive inhibition of AMPA receptors Bernd Elger ⁎, Martin Gieseler, Oliver Schmuecker, Ingrid Schumann, Astrid Seltz, Andreas Huth Schering AG, D-13342 Berlin, Germany
A R T I C LE I N FO
AB S T R A C T
Article history:
In acute stroke, the therapeutic time window is a critical factor which may have contributed
Accepted 9 February 2006
to the failure of several phase III clinical trials with so-called neuroprotective agents. Since
Available online 3 April 2006
cerebral glutamate levels are elevated for many hours in progressing stroke, we investigated the novel AMPA glutamate receptor antagonist ZK 187638 in rodent models of stroke using
Keywords:
up to 12 h delays in the start of therapy after permanent occlusion of the middle cerebral
Stroke
artery (MCA). In rats, ZK 187638 reduced total infarct volume by 43% and 33% when therapy
Excitotoxicity
was started immediately or with a delay of 6 h, respectively, but no effect was observed after
Brain infarction
a 12 h delay. Dose-dependent decreases of total infarct volume (up to 42%) were measured in
Neuroprotection
mice given the first injection of ZK 187638 6 h after permanent MCA occlusion. In conclusion,
Delayed treatment
the AMPA receptor antagonist ZK 187638 has a therapeutic time window of at least 6 h after
Focal cerebral ischemia
permanent focal cerebral ischemia in rodents. © 2006 Elsevier B.V. All rights reserved.
Abbreviations: AMPA, alpha-amino-3-hydroxy-5methyl-4-isoxazolepropionate CBF, cerebral blood flow FDA, Food and drug administration IL-1β, interleukin-1β MCA, middle cerebral artery NBQX, 2,3-dihydroxy-6-nitro-7sulfamoyl-benzol[f]quinoxaline NMDA, N-methyl-D-aspartate t-PA, tissue-type plasminogen activator TNF-α, tumor necrosis factor-α TTC, 2,3,5-triphenyltetrazolium chloride
⁎ Corresponding author. Fax: +49 30 468 97253. E-mail address: [email protected] (B. Elger). 0006-8993/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.brainres.2006.02.080
190
BR A I N R ES E A RC H 1 0 8 5 ( 2 00 6 ) 1 8 9 –19 4
Stroke is the leading cause of adult disability in industrialized countries. The medical need of efficient therapy is largely unmet because so far only one agent, t-PA, has been approved by the FDA for the indication ischemic stroke. However, the therapeutic time window of t-PA is limited to about 3 h after the insult. Since most stroke patients are amenable to therapy later than 3 h, thrombolysis with t-PA can be performed only in few stroke patients (Fisher, 2003). As an alternative to this vascular strategy of stroke therapy, a cytoprotective strategy which prevents the progression of ischemic brain lesions may have a wider time window. A prime factor for ischemic neuronal cell death is glutamate-induced excitotoxicity. Glutamate levels are significantly elevated in brains of patients with progressing stroke for up to 24 h (Davalos et al., 1997) and similarly, persisting increases in cerebral glutamate concentrations have been found in rats 24 h after permanent middle cerebral artery (MCA) occlusion (Newcomb et al., 1998). Glutamate receptors of the alpha-amino-3-hydroxy-5methyl-4-isoxazolepropionate (AMPA) type were potently blocked by the novel 2,3-dimethyl-6-phenyl-12 H-[1,3]dioxolo [4,5-h]imidazo[1,2-c][2,3] benzodiazepine (ZK 187638, Fig. 1) in an in vitro assay using cultured rat hippocampal neurons (Elger et al., 2005). When tested in vivo, the compound was neuroprotective in mice and rats after pretreatment and early post-treatment (1 h), respectively, of focal cerebral ischemia. Therefore, the aim of the present study was to test the efficacy of ZK 187638 using further delays in the start of therapy in rodents. The rat model of permanent MCA occlusion was chosen for the experiments because of the abovementioned pathophysiological similarities to the human situation. Moreover, spontaneous recanalization occurs in only less than 19% of stroke patients within 6 h after the insult (Molina et al., 2001) and the MCA territory is most frequently affected. The predictive value of the permanent MCA occlusion model regarding the therapeutic time window of drug efficacy in stroke patients has been shown previously with the agent ancrod. Significant cerebroprotection was observed when treatment with the defibrinogenating agent ancrod was initiated within 3 h after permanent MCA occlusion in rats but not after 6 h (Elger et al., 1997). Likewise, a clinical phase III trial was positive using a 3 h time window but efficacy was lost when start of ancrod
Fig. 1 – Chemical structure of 2,3-dimethyl-6-phenyl-12 H-[1,3]dioxolo[4,5-h]imidazo[1,2-c][2,3]benzodiazepine (ZK 187638).
treatment was delayed up to 6 h after stroke (Sherman et al., 2000; Sherman, 2002; Orgogozo et al., 2000). In addition to the studies of ZK 187638 in rats, the therapeutic time window was also investigated in mice as a second species in order to evaluate the robustness of the therapeutic effects. All in vivo experiments on ZK 187638 were performed in accordance to the requirements of the German laws for the protection of animals (Deutsches Tierschutzgesetz) and in compliance with the European Communities Council Directive of 24 November 1986 (86/609/EEC). The animals were maintained under standard conditions (12 h day/night cycle, 22 °C, 50% humidity) with free access to food and tap water. Before use for the experiments, the animals were allowed to recover from transportation for about 1 week. The surgical procedure of permanent MCA occlusion did not exceed 10 min and was performed as described elsewhere (Elger et al., 2005). Briefly, male Fischer-344 rats weighing 250–300 g were anaesthetized with 4% halothane for induction and 1.5% halothane for maintenance in 30% O2/70% N2O via a face mask. After a vertical 2 cm skin incision was made between the left eye and the left ear, the temporalis muscle was partly removed in order to expose the zygoma and the squamosal bone. The left MCA was exposed through a burr hole craniectomy (2 mm diameter) drilled in close proximity to the foramen ovale. After opening the dura, the proximal portion of the middle cerebral artery was electrocauterized with bipolar forceps (Erbotom T130, Erbe, Elektromedizin GmbH, Tübingen, Germany) and cut through with scissors. The burr hole was covered with Lyostypt (Braun Dexon) and the skin was sutured. During surgery, the rectal temperature of the anesthetized animals was maintained at 37 ± 0.5 °C by a feedback regulated heating pad. Male mice (NMRI strain) weighing 23–30 g were anesthetized with 4% halothane for induction and 1.5% halothane for maintenance in 30% O2/70% N2O via a face mask. Under an operating microscope (Wild AG, Heerbrugg, Switzerland) with low power magnification, a 5–10 mm incision of the skin was made vertically on the left side between the ear and the orbit. The parotid gland and surrounding soft tissue were removed by electrocoagulation. Parts of the underlying temporal muscle were removed until the MCA became visible through the surface of the skull. A small burr hole (1 mm) was made using a high-speed microdrill through the outer surface of the semitranslucent skull just over the visibly identified MCA. The inner layer of the skull was removed with fine forceps. The MCA was electrocoagulated with a bipolar diathermy above the level of the olfactory tract, thus lenticulostriate arteries were left intact. Afterwards, the wound was sutured. The animals did not sustain blood loss, and all surgeries were completed within 7–10 min. MCA-occluded rats and mice received 4 i.p. injections of a solution of ZK 187638 containing 10% cremophor EL (Sigma). The injections were spaced by 1 h intervals. To study the efficacy of delayed therapy in rats, the highest dose (30 mg/kg per injection) was chosen from a previous dose–response investigation in MCA-occluded rats (Elger et al., 2005). Since no dose–response information was available from previous experiments with ZK 187638 in MCA-occluded mice, a known efficacious dosage (10 mg/kg per injection) was selected from an earlier study (Elger et al., 2005) and in addition, 30 mg/kg per injection was chosen comparable to the dosage in rats. For
BR A I N R ES E A RC H 1 0 8 5 ( 2 00 6 ) 1 8 9 –1 94
histological analyses, animals were anesthetized with Nembutal® 24 h after MCA occlusion if not stated otherwise in the text. The chests were opened, and the brains were perfused by intracardiac infusion of 1 ml of a saline solution containing 10% 2,3,5-triphenyltetrazolium chloride (TTC). The brains were left in situ for 10–15 min, removed, and stored in fixative (4% paraformaldehyde and 2% sucrose in 0.1 M sodium phosphate) for 3 days. The brains were sliced into 1 mm coronal sections with a matrix (Harvard Bioscience). The slices were captured using a color camera combined with a Macintosh computer (Apple, Cupertino, CA, USA). The areas of the infarcts were measured using the NIH Image software package (freeware) and the infarct volumes were calculated as described elsewhere (Elger et al., 2005). All results are given as mean and standard deviation (SD). For each experimental group, the deviation from the Gaussian distribution was tested by the Kolmogorov–Smirnov test. All the data passed the normality test. Statistical comparisons
191
between control and treatment groups were made using analysis of variance followed by post hoc Student's t test or Dunnett's multiple comparison test. Significance was accepted at P < 0.05. The histological analyses in our studies on the effects of various delays of ZK 187638 therapy on permanent focal cerebral ischemia revealed that both cerebral cortex and striatum were affected by ischemia in vehicle-treated rats at all time points investigated (Fig. 2). Twenty-four hours following permanent MCA occlusion, total infarct volume was significantly (P = 0.002) reduced by 43% from 191 ± 72 mm3 in vehicle-treated controls (n = 15) to 109 ± 49 mm3 in rats (n = 12) given 4 injections of ZK 187638 (each injection 30 mg/kg i.p.) starting immediately after MCA occlusion. In a second set of experiments, the same dose of the first study (4 × 30 mg/kg i.p.) was used to study the efficacy of delayed therapy with ZK 187638 starting 6 h after MCA occlusion. As shown in Fig. 3, total infarct volume was significantly (P = 0.008) diminished by 33%
Fig. 2 – Representative, TTC-stained brain slices showing anterior as well as posterior ischemic territories of rats treated with (A) vehicle 0 h, (B) ZK 187638 (4 × 30 mg/kg i.p.) 0 h, (C) vehicle 6 h, and (D) ZK 187638 (4 × 30 mg/kg i.p.) 6 h after permanent MCA occlusion.
192
BR A I N R ES E A RC H 1 0 8 5 ( 2 00 6 ) 1 8 9 –19 4
Fig. 3 – Effect of ZK 187638 on total infarct volume in rats measured 24 h after permanent MCA occlusion (mean ± SD). Treatment with ZK 187638 (4 × 30 mg/kg, n = 9) or vehicle (n = 9) consisted of 4 i.p. injections spaced by 1 h intervals. The first injection was given 6 h after MCA occlusion.
from 188 ± 42 mm3 in vehicle-treated controls (n = 9) to 126 ± 46 mm3 in ZK 187638-treated rats (n = 9). However, when ZK 187638 therapy (4 × 30 mg/kg i.p.) was initiated in a third experiment 12 h after MCA occlusion, no differences of infarct volumes were observed between compound-treated rats and the corresponding vehicle-treated rats measured 48 h after vessel occlusion (data not shown). Following permanent MCA occlusion in mice, the ischemic territory was strictly ipsi-lateral (left side) and localized exclusively in the temporo-parietal cortex. Dose-dependent reductions of total infarct volume were obtained in mice after intraperitoneal injections of ZK 187638 (Fig. 4) starting 6 h after MCA occlusion. Twenty-four hours after MCA occlusion, the lesions were reduced from 36.8 ± 17.8 mm3 in vehicle-treated controls (n = 21) to 26.2 ± 11.1 mm3 (P = 0.033) and to 21.3 ± 6.6 mm3 (P = 0.035) in mice treated with 4 i.p. injections of 10 mg/kg ZK 187638 (n = 19) and 30 mg/kg ZK 187638 (n = 7), respectively. The injections were spaced by 1 h intervals. In parallel to these histological studies on acute neurodegeneration in mice, behavioural assessments were carried out with ZK 187638 in a mouse model of chronic neurodegeneration using SOD1G93A transgenic mice. Both models have been validated regarding a pivotal role of glutamate-induced excitotoxicity by previous investigations with 2,3-dihydroxy-6nitro-7-sulfamoyl-benzol[f]quinoxaline (NBQX) as gold standard for selective AMPA receptor inhibition (Elger et al., 2005; Van Damme et al., 2003). Therapy with ZK 187638 significantly reduced neurological deficits of the transgenic mice as quantitatively measured by stride length and rotarod performance. Furthermore, the life expectancy of mice was ameliorated despite delayed start of therapy after onset of disease (Tortarolo et al., 2006). The significant infarct reductions in rats and mice of the present studies with ZK 187638 add to the positive findings that have been reported from earlier studies with this compound in these species after permanent MCA occlusion (Elger et al., 2005). Total cerebral lesion volume is significantly
reduced even if therapy with ZK 187638 is commenced with a delay of 6 h after permanent MCA occlusion in mice. These results suggest that the 2,3-benzodiazepine ZK 187638 is more potent than the non-competitive AMPA receptor antagonist GYKI 53773 (talampanel) which failed to decrease the brain lesion in mice although it was given with only 15 min delay after permanent cerebral ischemia (Erdo et al., 2005). The chemical structure of ZK 187638 differs from that of GYKI 53773 in two ways: (1) the 4-methyl substitution is replaced by a nitrogen-containing heterocycle attached to the 3,4-position of the 2,3-benzodiazepine ring system and (2) the phenyl ring system lacks an amino group. It has been shown that GYKI 53405, which is the (+)-isomer of GYKI 53773, as well as the 2,3benzodiazepine EGIS-8332 which is structurally closely related to GYKI 53405, reduces infarct size in mice when administered 30 min after permanent MCA occlusion (Gressens et al., 2005). Thus, it may be concluded that modifications of substituents at the 2,3-benzodiazepine ring system critically determine the efficacy in focal cerebral ischemia. However, it remains to be clarified if the therapeutic time window of GYKI 53405 and EGIS-8332 is similar to that of ZK 187638 after permanent MCA occlusion and if these two compounds display equally favorable brain availability as ZK 187638 which reaches brain concentrations that are in general 3-fold higher than the plasma concentrations (Tortarolo et al., 2006). After ischemic stroke, the time window of opportunity is of special importance as frequently only 4% of patients are amenable to therapy within 3 h (Fisher, 2003). Most therapeutic strategies that address vascular mechanisms using e.g. agents to promote thrombolysis (Sakurama et al., 1994; Zhang et al.,
Fig. 4 – Effect of ZK 187638 on total infarct volume in mice measured 24 h after permanent MCA occlusion (mean ± SD). Treatment with ZK 187638 or vehicle (10% cremophor, CEL) consisted of 4 i.p. injections spaced by 1 h intervals. The first injection was given 6 h after MCA occlusion. Asterisks indicate statistical significance (P < 0.05) versus the vehicle-treated group (Dunnett's test).
BR A I N R ES E A RC H 1 0 8 5 ( 2 00 6 ) 1 8 9 –1 94
1999) or to decrease blood viscosity (Elger et al., 1997) reduced cerebral lesion volume in rats only when given within 3 h after MCA occlusion. The so-called neuroprotective agents, however, that interfere with the biochemical cascade of events which leads to cell death may have a wider time window if directed against glutamate-induced excitotoxicity. In vivo microdialysis studies have demonstrated elevated glutamate levels in the brain up to 15–24 h after permanent MCA occlusion in rats and cats (Matsumoto et al., 1993; Newcomb et al., 1998). In patients with progressing stroke, sustained elevation of glutamate has been observed in the cerebrospinal fluid until 24 h after the insult (Davalos et al., 1997). As a possible mechanism for sustained glutamate release after cerebral ischemia, it has been found that at later time points a particular level of cerebral blood flow (CBF) decline may be associated with much more glutamate release than at earlier time points (Matsumoto et al., 1993). It has been shown in addition that microglia activation occurs in mice as well as in rats within 12 h after permanent MCA occlusion (Davies et al., 1999; Lambertsen et al., 2002). Activated microglia release glutamate causing excitotoxic neuronal cell death (Kingham et al., 1999). Accordingly, considerable increases in cerebral lesion size have been measured between 3 h and 24 h after permanent MCA occlusion in rats and in mice (Seega and Elger, 1993; Garcia et al., 1995; Panahian et al., 1999; Matsui et al., 2002). The present study demonstrates that the glutamate-mediated progression of cerebral injury following severe focal ischemia can be effectively stopped because treatment with the non-competitive AMPA receptor antagonist ZK 187638 starting 6 h after permanent MCA occlusion yielded significant cerebral lesion reductions both in rats and mice. Interestingly, the therapeutic time window of competitive AMPA receptor antagonists such as ZK 200775 and YM872 is less than 6 h in the rat model of permanent MCA occlusion (Turski et al., 1998; Takahashi et al., 1998). Hence, a growing body of evidence is accumulating from this and previous studies (Donevan and Rogawski, 1993; Elger et al., 2005) that non-competitive AMPA receptor antagonists have an advantage under conditions such as severe cerebral ischemia in which high glutamate levels may render the competitive antagonists relatively ineffective. In contrast to AMPA receptor antagonists, N-methyl-Daspartate (NMDA) receptor antagonists have only a therapeutic time window of around 1 or 2 h after MCA occlusion (Dirnagl et al., 1999). NMDA receptor activation may play an important role in glutamate-induced excitotoxicity of neurons in the very initial phase of cerebral ischemia. AMPA receptor activation, however, may be involved not only in glutamate-induced initial neuronal cell death but also in more complex processes of acute ischemic brain damage that include other cell types such as oligodendroglia and microglia. Hence, it has been demonstrated that ischemic white matter damage can be reduced by AMPA receptor inhibition but not by NMDA receptor blockade due to the relative absence of NMDA receptors in cerebral white matter (Dewar et al., 1999; McCracken et al., 2002). Functional AMPA/kainate receptors have been shown on microglia and oligodendrocytes (Noda et al., 2000; McDonald et al., 1998). Concomittant with microglia activation, increases in the expression of the cytokines tumor necrosis factor-α (TNFα) and interleukin-1β (IL-1β) have been measured with peaks at
193
about 12 h in mice as well as in rats after permanent MCA occlusion (Davies et al., 1999; Lambertsen et al., 2002). Both cytokines may contribute to early neuronal injury on the one hand and may aid in the repair processes on the other hand as reviewed recently (Allan and Stock, 2004; Pickering et al., 2005). It has been shown that TNF-α facilitates glutamate excitotoxicity of neurons directly by rapid upregulation of neuronal Ca2+ permeable AMPA channels as well as indirectly by inhibition of astrocytic glutamate uptake (Ogoshi et al., 2005; Takahashi et al., 2003). However, deleterious modulation of AMPA receptormediated excitotoxicity depends on the concentration of TNFα as well as the overall balance between endogenous antiinflammatory and pro-inflammatory molecules (Bernardino et al., 2005; Allan and Stock, 2004). Changes of this balance in the time course after onset of ischemia may account for the loss of neuroprotective efficacy of AMPA receptor inhibition that was observed in the present study when therapy was initiated 12 h after permanent MCA occlusion in rats. In conclusion, the non-competitive AMPA receptor antagonist ZK 187638 reduces ischemic brain lesions after permanent middle cerebral artery occlusion even if therapy is begun with a delay of 6 h in both rats and mice. This extended therapeutic time window together with the favorable brain availability of the compound after oral administration (Tortarolo et al., 2006) may enable inclusion of larger patient numbers in acute stroke therapy than currently possible because treatment could already be initiated by the ambulance system before patient admission in the hospital. Moreover, these positive results of ZK 187638 in models of acute neurodegeneration warrant further studies on the efficacy of this compound in animal models of other neurological disorders such as multiple sclerosis where AMPA receptor activation also plays a pathogenic key role (Pitt et al., 2000; Smith et al., 2000).
REFERENCES
Allan, S., Stock, C., 2004. Cytokines in stroke. In: Dirnagl, U., Elger, B. (Eds.), Neuroinflammation in Stroke. Springer Verlag, Berlin, pp. 39–66. Bernardino, L., Xapelli, S., Silva, A.P., Jakobsen, B., Poulsen, F.R., Oliveira, C.R., Vezzani, A., Malva, J.O., Zimmer, J., 2005. Modulator effects of interleukin-1beta and tumor necrosis factor-alpha on AMPA-induced excitotoxicity in mouse organotypic hippocampal slice cultures. J. Neurosci. 25, 6734–6744. Davalos, A., Castillo, J., Serena, J., Noya, M., 1997. Duration of glutamate release after acute ischemic stroke. Stroke 28, 708–710. Davies, C.A., Loddick, S.A., Toulmond, S., Stroemer, R.P., Hunt, J., Rothwell, N.J., 1999. The progression and topographic distribution of interleukin-1β expression after permanent middle cerebral artery occlusion in the rat. J. Cereb. Blood Flow Metab. 19, 87–98. Dewar, D., Yam, P., McCulloch, J., 1999. Drug development for stroke: importance of protecting cerebral white matter. Eur. J. Pharmacol. 375, 41–50. Dirnagl, U., Iadecola, C., Moskowitz, M.A., 1999. Pathobiology of ischaemic stroke: an integrated review. TINS 22, 391–397. Donevan, S.D., Rogawski, M.A., 1993. GYKI 52466, a 2,3-benzodiazepine, is a highly selective, noncompetitive
194
BR A I N R ES E A RC H 1 0 8 5 ( 2 00 6 ) 1 8 9 –19 4
antagonist of AMPA/kainate receptor responses. Neuron 10, 51–59. Elger, B., Hornberger, W., Schwarz, M., Seega, J., 1997. MRI study on delayed ancrod therapy of focal cerebral ischaemia in rats. Eur. J. Pharmacol. 336, 7–14. Elger, B., Huth, A., Neuhaus, R., Ottow, E., Schneider, H., Seilheimer, B., Turski, L., 2005. Novel alpha-amino-3-hydroxy5-methyl-4-isoxazole propionate (AMPA) receptor antagonists of 2,3-benzodiazepine type: chemical synthesis, in vitro characterization, and in vivo prevention of acute neurodegeneration. J. Med. Chem. 48, 4618–4627. Erdo, F., Berzsenyi, P., Andrasi, F., 2005. The AMPA-antagonist talampanel is neuroprotective in rodent models of focal cerebral ischemia. Brain Res. Bull. 66, 43–49. Fisher, M., 2003. Recommendations for advancing development of acute stroke therapies. Stroke therapy academic industry roundtable 3. Stroke 34, 1539–1546. Garcia, J.H., Liu, K.-F., Ho, K.-L., 1995. Neuronal necrosis after middle cerebral artery occlusion in Wistar rats progresses at different time intervals in the caudatoputamen and the cortex. Stroke 26, 636–643. Gressens, P., Spedding, M., Gigler, G., Kertesz, S., Villa, P., Medja, F., Williamson, T., Kapus, G., Levay, G., Szenasi, G., Barkoczy, J., Harsing, L.G., 2005. The effects of AMPA receptor antagonists in models of stroke and neurodegeneration. Eur. J. Pharmacol. 519, 58–67. Kingham, P.J., Cuzner, M.L., Pocock, J.M., 1999. Apoptotic pathways mobilized in microglia and neurones as a consequence of chromogranin a-induced microglial activation. J. Neurochem. 73, 538–547. Lambertsen, K.L., Gregersen, R., Finsen, B., 2002. Microglialmacrophage synthesis of tumor necrosis factor after focal cerebral ischemia in mice is strain dependent. J. Cereb. Blood Flow Metab. 22, 785–797. Matsui, T., Mori, T., Tateishi, N., Kagamiishi, Y., Satoh, S., Katsube, N., Morikawa, E., Morimoto, T., Ikuta, F., Asano, T., 2002. Astrocytic activation and delayed infarct expansion after permanent focal cerebral ischemia in rats: Part I. Enhanced astrocytic synthesis of S100β in the periinfarct area precedes delayed infarct expansion. J. Cereb. Blood Flow Metab. 22, 711–722. Matsumoto, K., Graf, R., Rosner, G., Taguchi, J., Heiss, W.-D., 1993. Elevation of neuroactive substances in the cortex of cats during prolonged focal ischemia. J. Cereb. Blood Flow Metab. 13, 586–594. McCracken, E., Fowler, J.H., Dewar, D., Morrison, S., McCulloch, J., 2002. Grey matter and white matter ischemic damage is reduced by the competitive AMPA receptor antagonist, SPD 502. J. Cereb. Blood Flow Metab. 22, 1090–1097. McDonald, J.W., Althomsons, S.P., Hyrc, K.L., Choi, D.W., Goldberg, M.P., 1998. Oligodendrocytes from forebrain are highly vulnerable to AMPA/kainate receptor-mediated excitotoxicity. Nat. Med. 4, 291–297. Molina, C.A., Montaner, J., Abilleira, S., Ibarra, B., Romero, F., Arenillas, J.F., Alvarez-Sabín, J., 2001. Timing of spontaneous recanalization and risk of hemorrhagic transformation in acute cardioembolic stroke. Stroke 32, 1079–1084. Newcomb, R., Pierce, A.R., Kano, T., Meng, W., Bosque-Hamilton, P., Taylor, L., Curthoys, N., Lo, E.H., 1998. Characterization of mitochondrial glutaminase and amino acids at prolonged times after experimental focal cerebral ischemia. Brain Res. 813, 102–111. Noda, M., Nakanishi, H., Nabekura, J., Akaike, N., 2000. AMPA-
kainate subtypes of glutamate receptor in rat cerebral microglia. J. Neurosci. 20, 251–258. Ogoshi, F., Yin, H.Z., Kuppumbatti, Y., Song, B., Amindari, S., Weiss, J.H., 2005. Tumor necrosis-factor-alpha (TNF-alpha) induces rapid insertion of Ca2+-permeable alpha-amino-3hydroxyl-5-methyl-4-isoxazole-propionate (AMPA)/kainate (Ca-A/K) channels in a subset of hippocampal pyramidal neurons. Exp. Neurol. 193, 384–393. Orgogozo, J.M., Verstrate, M., Kay, R., Hennerici, M., Lenzi, G.L., 2000. Outcomes of ancrod in acute ischemic stroke. JAMA 284, 1926–1927. Panahian, N., Huang, T., Maines, M.D., 1999. Enhanced neuronal expression of the oxidoreductase – biliverdin reductase – after permanent focal cerebral ischemia. Brain Res. 850, 1–13. Pickering, M., Cumiskey, D., O'Connor, J.J., 2005. Actions of TNF-alpha on glutamatergic synaptic transmission in the central nervous system. Exp. Physiol. 90, 663–670. Pitt, D., Werner, P., Raine, C.S., 2000. Glutamate excitotoxicity in a model of multiple sclerosis. Nat. Med. 6, 67–70. Seega, J., Elger, B., 1993. Diffusion- and T2-weighted imaging: evaluation of oedema reduction in focal cerebral ischemia by the calcium and serotonin antagonist levemopamil. Magn. Reson. Imaging 11, 401–409. Sakurama, T., Kitamura, R., Kaneko, M., 1994. Tissue-type plasminogen activator improves neurological functions in a rat model of thromboembolic stroke. Stroke 25, 451–456. Sherman, D.G., 2002. Ancrod. Curr. Med. Res. Opin. 18 (Suppl. 2), s48–s52. Sherman, D.G., Atkinson, R.P., Chippendale, T., Levin, K.A., Ng, K., Futrell, N., Hsu, C.Y., Levy, D.E., 2000. Intravenous ancrod for treatment of acute ischemic stroke. JAMA 283, 2395–2403. Smith, T., Groom, A., Zhu, B., Turski, L., 2000. Autoimmune encephalomyelitis ameliorated by AMPA antagonists. Nat. Med. 6, 62–66. Takahashi, M., Ni, J.W., Kawasaki-Yatsugi, S., Toya, T., Ichiki, C., Yatsugi, S.-I., Koshiya, K., Shimizu-Sasamata, M., Yamaguchi, T., 1998. Neuroprotective efficacy of YM872, an α-amino-3hydroxy-5-methylisoxazole-4-propionic acid receptor antagonist, after permanent middle cerebral artery occlusion in rats. JPET 287, 559–566. Takahashi, J.L., Giuliani, F., Power, C., Imai, Y., Yong, V.W., 2003. Interleukin-1β promotes oligodendrocyte death through glutamate excitotoxicity. Ann. Neurol. 53, 588–595. Tortarolo, M., Grignaschi, G., Calvaresi, N., Zennaro, E., Spaltro, G., Colovic, M., Fracasso, C., Guiso, G., Elger, B., Schneider, H., Seilheimer, B., Caccia, S., Bendotti, C., 2006. Glutamate AMPA receptors change in motor neurons of SOD1(G93A) transgenic mice and their inhibition by a noncompetitive antagonist ameliorates the progression of amytrophic lateral sclerosis-like disease. J. Neurosci. Res. 83, 134–146. Turski, L., Huth, A., Sheardon, M., McDonald, F., Neuhaus, R., Schneider, H.H., Dirnagl, U., Wiegand, F., Jacobsen, P., Ottow, E., 1998. ZK200775: a phosphonate quinoxalinedione AMPA antagonist for neuroprotection in stroke and trauma. Proc. Natl. Acad. Sci. 95, 10960–10965. Van Damme, P., Leyssen, M., Callewaert, G., Robberecht, W., Van den Bosch, L., 2003. The AMPA receptor antagonist NBQX prolongs survival in a transgenic mouse model of amyotrophic lateral sclerosis. Neurosci. Lett. 343, 81–84. Zhang, R.L., Zhang, Z.G., Chopp, M., 1999. Increased therapeutic efficacy with rt-PA and anti-CD18 antibody treatment of stroke in the rat. Neurology 52, 273–279.