licostinel and Brain-Ischemia

Licostinel (ACEA 1021; 5-nitro-6, 7-dichloro-2,3-quinoxalinedione), a competitive antagonist of glycine at the N-methyl-D-aspartate (NMDA) receptor, is an effective neuroprotective agent in animal models of cerebral ischemia. The purpose of this study was to assess the safety, tolerability, and pharmacokinetics of licostinel in patients with acute stroke.. In this 5-center dose escalation trial, patients were enrolled within 48 hours of an ischemic stroke and treated with ascending doses of a short infusion of licostinel or a placebo. Adverse effects were assessed with clinical and laboratory measurements, and patient outcome was determined with the National Institutes of Health Stroke Scale.. Sixty-four patients (44 treated with escalating doses of licostinel and 20 who received placebo) were treated. Lower doses of licostinel (0.03 to 0.60 mg/kg) were not associated with any significant adverse effects. Higher doses of licostinel (1.2 to 3.0 mg/kg) were associated with a variety of mild-to-moderate adverse effects including neurological and gastrointestinal complaints. No major psychotomimetic effects or significant safety concerns occurred. At the higher dose levels, peak plasma concentrations of licostinel were substantially higher than those required for neuroprotection in animal stroke models. A similar improvement in National Institutes of Health Stroke Scale scores over time was seen in both the placebo group and the licostinel-treated patients.. A short infusion of licostinel in doses up to 3.0 mg/kg is safe and tolerable in acute stroke patients. Licostinel may be a safer and better tolerated neuroprotective agent than many of the previously evaluated NMDA antagonists.

Topics: Acute Disease; Adult; Aged; Aged, 80 and over; Brain Ischemia; Dose-Response Relationship, Drug; Excitatory Amino Acid Antagonists; Female; Humans; Male; Middle Aged; Quinoxalines

The neuroprotective activity of ACEA 1021 (5-nitro-6,7-dichloro-1,4-dihydro-2,3-quinoxalinedione; licostinel), a selective antagonist at the strychnine-insensitive glycine site associated with the NMDA receptor complex, has been investigated in various models of focal cerebral ischemia. In isoflurane-anaesthesised Wistar rats with permanent ipsilateral carotid artery ligation and transient middle cerebral artery occlusion (duration of occlusion, 2 h) followed by reperfusion (24 h), intravenous administration of ACEA 1021 (bolus: 10 mg/kg, 15 min after the onset of middle cerebral artery occlusion; infusion: 7 mg/kg/h for 6 h beginning 30 min after occlusion of the artery) produced a 32% reduction in infarct volume. Similarly, in Sprague-Dawley rats with transient middle cerebral artery occlusion (2 h) followed by 24 h of reperfusion, identical treatment with ACEA 1021 decreased infarct size by 39%. Magnetic resonance imaging (MRI) confirmed these effects in the transient model, in that infarct volume observed using apparent diffusion coefficient (ADC) maps was significantly smaller after 24 h in the ACEA 1021-treated rats compared with Tris-treated controls. Furthermore, the increase in perfusion signal intensity after reperfusion was more pronounced in the ACEA 1021-treated rats than in controls. In Fisher 344 rats with permanent occlusion of the middle cerebral artery, ACEA 1021 induced a dose-related decrease in infarct volume, which was associated with an improvement in neurological outcome as measured by the rope suspension procedure. Administration of the same dose regimen, as above, in Fisher rats with permanent middle cerebral artery occlusion reduced infarct volume by 68%. This dose was as effective when administration was delayed for 2 h. In mice with permanent middle cerebral artery occlusion, ACEA 1021 (5 mg/kg, i.v., 5 min after occlusion; 30 mg/kg, s.c., 1 and 4 h post-middle cerebral artery occlusion) decreased infarct size by 42%. The consistent anti-ischemic effects of ACEA 1021 make it a valuable compound for exploratory stroke research.

Topics: Animals; Behavior, Animal; Brain; Brain Infarction; Brain Ischemia; Disease Models, Animal; Dose-Response Relationship, Drug; Injections, Intravenous; Injections, Subcutaneous; Magnetic Resonance Imaging; Male; Mice; Neuroprotective Agents; Psychomotor Performance; Quinoxalines; Rats; Rats, Inbred F344; Rats, Sprague-Dawley; Rats, Wistar; Receptors, N-Methyl-D-Aspartate; Reperfusion

A series of analogues of the indole-2-carboxylate GV150526, currently in clinical trials as a potential neuroprotective agent for the control of the cerebral damage after stroke onset, was designed based on previous studies dealing with the electronic features of the north-east region of the glycine binding site associated with the NMDA receptor. In particular, the substitution of the para position of the terminal phenyl ring of GV150526 with suitable hydrophilic groups resulted in the identification of a new class of glycine antagonists. These compounds exhibited nanomolar in vitro affinity to the glycine binding site, high receptor selectivity, and outstanding in vivo potency. In particular, 3-[(E)-2-[(4-ureidomethylphenyl)aminocarbonyl]ethenyl]-4, 6-dichloroindole-2-carboxylic acid was found to be highly effective in the middle cerebral artery occlusion (MCAo) model in the rat, an animal model of focal ischemia, when given both prior to and after the occlusion of the middle cerebral artery. Notably, a significant neuroprotective effect was seen in this model postischaemia, when the administration of this compound was delayed up to 6 h from the occlusion of the middle cerebral artery, further confirming the wide therapeutic window seen for GV150526A.

Topics: Animals; Anticonvulsants; Binding Sites; Brain Ischemia; Carboxylic Acids; Cerebral Infarction; Disease Models, Animal; Glycine; Glycine Agents; Indoles; Mice; Molecular Structure; Neuroprotective Agents; Protein Binding; Rats; Rats, Sprague-Dawley; Receptors, Glycine; Receptors, N-Methyl-D-Aspartate; Urea

Several lines of inquiry have indicated that glycine plays an important role in both glutamatergic neurotransmission and pathophysiology of cerebral ischemia. However, subacute outcome trials demonstrating the efficacy of glycine antagonists as neuroprotectants have not been performed with rigorous control of brain temperature. In this study, we investigated the effect of N-methyl-D-aspartate (NMDA) receptor glycine recognition site antagonism in a temperature-controlled rodent model of transient focal ischemia. Male Wistar rats underwent 75 min of intraluminal middle cerebral artery occlusion (MCAO). During MCAO and the first 24 h of reperfusion, rats (n = 10) were administered e55-nitro-6,7-dichloro-2,3-quinoxalinedione (ACEA 1021) i.v. as a bolus infusion of 5 mg/kg followed by 3.5 mg/kg/h (Low-Dose) or 10 mg/kg followed by 7 mg/kg/ h (High-Dose) for 24 h. Cortical temperature was controlled at 38.0 +/- 0.1 degrees C during MCAO and the first 6 h of reperfusion. A 7-day recovery interval was allowed. Mean total infarct volume was reduced by approximately 40% in both high- and low-dose groups (p < 0.01). The preponderance of infarct reduction occurred in the cortex (p < 0.01). Neurologic function correlated with the size of cerebral infarct (p = 0.001). Neurologic grade was similarly improved by treatment with either dose (p = 0.01). These results demonstrate that neuroprotection achieved by antagonism of the glycine recognition site persists when brain temperature is controlled, indicating a potent mechanism of action other than attenuating a hyperthermic response to ischemia.

Topics: Animals; Binding Sites; Brain Damage, Chronic; Brain Ischemia; Cerebral Infarction; Excitatory Amino Acid Antagonists; Fever; Glycine; Male; Neuroprotective Agents; Quinoxalines; Rats; Rats, Wistar; Receptors, N-Methyl-D-Aspartate; Temperature

Acute subdural hematoma (SDH) complicates about 20% of severely head-injured patients, and death and severe disability frequently result, yet over half of these patients may have been conscious, at some time after injury, implying secondary mechanisms of brain damage. Drugs that block the "excitotoxic" effects of glutamate at the N-methyl-D-aspartate (NMDA) receptor have generally been effective in reducing ischemic brain damage associated with SDH in animal models, yet these agents all appear to be associated with major behavioral side effects, in conscious patients, at neuroprotective doses. We therefore evaluated the effects of treatment with a novel antagonist for the glycine binding site of the NMDA receptor (ACEA1021) upon ischemic brain damage, in the rat SDH model. ACEA1021 may be free of psychomotor effects, and may thus permit high dose therapy in conscious trauma and stroke patients. SDH was produced by the slow injection of 0.4 mL autologous blood into the subdural space overlying the parietal cortex. brain damage was assessed histologically at 8 coronal planes, in animals sacrificed 4 h after induction of hematoma. Both pre- and posttreatment with ACEA1021 significantly reduced hemispheric ischemic damage produced by SDH. The magnitude of neuroprotection with this compound (26 to 39% reduction in infarct size) is similar to other NMDA antagonists, and the robust posttreatment effect implies that human studies with this compound should be performed in head injured patients, subject to completion of toxicology testing.

Topics: Animals; Binding, Competitive; Blood Pressure; Brain Ischemia; Excitatory Amino Acid Antagonists; Glycine; Hematoma, Subdural; Humans; Male; Quinoxalines; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Time Factors

Ischemia-induced neuronal injury can be reduced by glutamate antagonists acting at the N-methyl-D-aspartate (NMDA) receptor. 7-Chlorokynurenic acid and the recently synthesized compound Acea 1021 block NMDA receptors by acting at the strychnine-insensitive glycine site. The anti-ischemic properties of these compounds were tested by evaluating their ability to reduce CA1 neuronal damage in hippocampal slice cultures deprived of oxygen and glucose. Acea 1021 and 7-chlorokynurenic acid significantly reduced CA1 injury produced by oxygen and glucose deprivation in a dose-dependent manner. The neuroprotective effect of these compounds was reversed by the addition of glycine. The phencyclidine site NMDA antagonist MK-801 also provided significant protection to CA1 neurons against the same insult, and this protection was not affected by the addition of glycine. These results indicate that Acea 1021 and 7-chlorokynurenic acid can provide protection to CA1 neurons against ischemia-induced injury by a glycine-sensitive mechanism.

Topics: Animals; Brain Ischemia; Cell Death; Dizocilpine Maleate; Glycine; Glycine Agents; Hippocampus; Kynurenic Acid; Neurons; Organ Culture Techniques; Quinoxalines; Rats; Rats, Sprague-Dawley; Receptors, Glycine; Receptors, N-Methyl-D-Aspartate

Both in vitro and in vivo experiments have implicated extracellular glycine in the pathogenesis of ischemic brain damage. Recently, halogenated derivatives of quinoxaline-2,3-dione have been synthesized that possess bioavailability when parenterally administered and minimal psychotomimetic properties. Such compounds have allowed investigation into the efficacy of glycine receptor antagonism as a strategy for protection against cerebral ischemic insults. Rats underwent either 90 min of middle cerebral artery filament occlusion or 10 min of forebrain ischemia with recovery while receiving intraperitoneal injections of either a glycine receptor antagonist (ACEA-1021, ACEA-1031, or ACEA-1011) or vehicle (dimethyl sulfoxide). Both ACEA-1021 and ACEA-1031 reduced cerebral infarct volumes and were associated with a reduced incidence of hemiparesis resulting from MCA occlusion. ACEA-1011, administered in a smaller dose had no effect. In the forebrain ischemia model, glycine receptor antagonism had no effect on delayed neuronal necrosis in the hippocampal CA1 sector, neocortex, or caudoputamen. We conclude that pharmacologic antagonism of glycine at the strychnine-insensitive glycine receptor presents a neuroprotective profile similar to that previously observed for antagonists of glutamate at the N-methyl-D-aspartate complex with a potential for fewer side effects.

Topics: Animals; Brain Ischemia; Male; Nervous System; Neuroprotective Agents; Quinoxalines; Rats; Rats, Wistar; Receptors, Glycine; Receptors, N-Methyl-D-Aspartate