Experimental studies on pharmacologic protection of the brain against focal ischemia. 1. Focal brain ischemia model in rats

Occlusion of the middle cerebral artery (MCA) in rats is being used increasingly widely as an experimental model of focal brain ischemia. However, the incidence of infarction or the size of infarction is variable. As a preliminary study we examined the anatomical variations of branching of the middle cerebral artery (MCA) and the incidence and extent of infarction and the time course of neurologic deficits following occlusion of the MCA at various sites in Sprague-Dawley (SD) rats and spontaneously hypertensive rats (SHR). Variations of branching of the MCA were closely observed in 91 rats (49 SD rats and 42 SHR). In two-thirds, the olfactory branch was single and arose from the MCA proximal to the medial border of the olfactory tract. In a small number of rats, the olfactory branch was single, but it arose at or near the lateral border of the olfactory tract, or two olfactory branches arose at both medial and lateral borders of the olfactory tract. The lateral or the tandem occlusion group caused infarction of the pallium in only one of 7 rats. Neurologic deficit was also minimal and transient and the size of infarction was small in the lateral occlusion group. In the tandem occlusion group, neurologic deficit was more severe, but it was still transient. The branch occlusion group and the ICV group caused large infarction of the pallium with moderate neurologic deficits in 5 of 8, and 6 of 8 rats, respectively. The medial occlusion group caused infarction in the pallium and/or basal ganglia in 5 of 6 rats, and neurologic deficits were severe and persistent.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of a novel calcium antagonist, KB-2796, on neurologic outcome and size of experimental cerebral infarction in rats

Effects of a novel calcium 2+ antagonist, KB-2796, on neurologic outcome and size of infarction were studied in the rat model of focal cerebral ischemia. Neurologic deficits were examined from 1 to 24 hours after occlusion of the middle cerebral artery and size of infarction was measured at 24 hours postocclusion. When KB-2796 (10 mg/kg, IP) was given immediately after, or 1 hour after, middle cerebral artery occlusion, marked improvement in neurologic score was seen 1 to 3 hours postocclusion. When given immediately after middle cerebral artery occlusion, size of infarction was also markedly smaller when compared with the control rat. The present study suggests that the calcium 2+ antagonist KB-2796 has brain-protective effects against ischemia even with its administration after induction of ischemia.     

Effects of the calcium antagonist nilvadipine on focal cerebral ischemia in spontaneously hypertensive rats

We studied the efficacy of preischemic and postischemic systemic treatment with a new calcium antagonist nilvadipine in a permanent focal cerebral ischemia model of spontaneously hypertensive rats. Rats that underwent microsurgical middle cerebral artery occlusion were blindly assigned to a single intraperitoneal injection of nilvadipine (0.32 mg/kg) or the same amount of polyethylene glycol either 15 minutes before, immediately after, 1 hour after, or 3 hours after occlusion of the left middle cerebral artery. Neurologic conditions of rats were closely examined, and rats were killed 24 hours later. Removed brains were sliced coronally, stained with triphenyltetrazolium chloride, and the size of infarct was determined. Although no neurologic improvements were observed in the treated rats, the area of infarcts was significantly reduced in the groups treated before, immediately after, and 1 hour after occlusion of the middle cerebral artery. Treatment started 3 hours after occlusion was ineffective.     

Nitrous oxide does not alter infarct volume in rats undergoing reversible middle cerebral artery occlusion

This experiment was designed to determine if nitrous oxide alters neurologic and pathologic outcome from temporary focal cerebral ischemia in spontaneously hypertensive rats deeply anesthetized with a barbiturate. Two groups of rats were given intravenous methohexital such that a stable EEG pattern of burst suppression was achieved. In one group of rats (n = 11), the lungs were mechanically ventilated with 70% N2O/30% O2, and in the other group (n = 10), ventilation was done with 70% nitrogen/30% O2. The middle cerebral artery was then occluded for 2 h, during which time mean arterial pressure, blood gases, hematocrit, plasma glucose, and head temperature were held constant between groups. The total doses of methohexital administered were similar in both groups as were the plasma methohexital concentrations immediately prior to onset of ischemia. After reperfusion of the middle cerebral artery, the animals were allowed to awaken. Neurologic evaluations were performed prior to ischemia and at 24 and 96 h postischemia. Cerebral infarct volume was measured at 96 h postischemia using triphenyl tetrazolium chloride staining and computer imaging techniques. There were no neurologic differences between the N2O and nitrogen groups at any experimental interval although both groups exhibited deficits at both 24 and 96 h postischemia relative to preischemic values. The two groups also had nearly identical cerebral infarct volumes (N2O = 231 +/- 97 mm3; nitrogen = 226 +/- 75 mm3; mean +/- SD).(ABSTRACT TRUNCATED AT 250 WORDS)     

Fetal cortical cells survive in focal cerebral infarct after permanent occlusion of the middle cerebral artery in adult rats.

Fetal rat cortical cells have been shown previously to survive at the periphery of cerebral infarction. The present study was designed to examine the ability of fetal cells to survive at the edge of the central core of ischemia. In three groups of 8 adult Sprague-Dawley rats, fetal cortical cells from ED 16 were stereotactically transplanted at 3 h, 24 h, and 7 days after unilateral middle cerebral artery occlusion. In 6 rats, fetal cells were transplanted by using the same coordinates, without arterial occlusion, for control. In the ischemic groups, overall graft survival was 85%, and in the control group, all grafts survived. Graft survival was determined by light microscopy. No significant difference was found in the survival of grafts transplanted at different intervals after middle cerebral artery occlusion. It is concluded that fetal cortical cells can survive in cerebral tissue undergoing severe ischemic change.     

Immunohistopathologic analysis of olfactory degeneration caused by ischemia

The development of olfactory dysfunction caused by ischemia was studied in Mongolian gerbils. Mongolian gerbils frequently have an anomaly of the cerebral circulation and are susceptible to brain ischemia or infarction following ligation of a single common carotid artery. Ischemia was induced by unilateral common carotid artery ligation or temporary occlusion of both common carotid arteries, and the olfactory pathway was examined. In the olfactory pathway of the forebrain, ischemic changes were observed in the lateral olfactory tract, olfactory tubercle, olfactory ventricle, and anterior olfactory nucleus. The olfactory bulb was resistant to ischemia. Partial or complete degeneration of the ipsilateral olfactory neuroepithelium was observed in some gerbils that survived more than 14 days after the onset of ischemia. Immunohistopathologic analysis of the neuroepithelium for the olfactory marker protein revealed that functional damage of the olfactory neurons occurred in some gerbils within the first few days after the ischemic event.     

Neuroprotective effect of postischemic administration of progesterone in spontaneously hypertensive rats with focal cerebral ischemia

OBJECT: Exogenous progesterone has been shown to reduce brain edema and ischemia-induced cell damage and to improve physiological and neurological function during the early stage of focal cerebral ischemia. In the present study, the authors assessed the neuroprotective potential of progesterone during the late stage of ischemia in a transient middle cerebral artery (MCA) occlusion model in the rat. METHODS: Forty-eight male spontaneously hypertensive rats were randomly assigned to six groups. Progesterone was dissolved in dimethyl sulfoxide (DMSO). In four groups of rats, the dissolved progesterone (4 mg/kg or 8 mg/kg) was administered for 2 or 7 days after ischemia. In two control groups DMSO was administered for 2 or 7 days after ischemia. Occlusion of the MCA was induced by insertion of an intraluminal suture, and reperfusion was accomplished by withdrawal of the suture. Treatment was initiated on reperfusion, which followed 2 hours of MCA occlusion, and continued once a day. Lesion volume, neurological deficit, and body weight loss were measured 2 or 7 days after ischemia, depending on the animal group. Treatment with a high dose of progesterone (8 mg/kg) resulted in reductions in lesion size, neurological deficits, and body weight, compared with control rats. CONCLUSIONS: Administration of progesterone to male rats 2 hours after MCA occlusion reduces ischemic brain damage and improves neurological deficit even 7 days after ischemia.     

异丙酚及咪唑安定和硫喷妥钠对鼠局灶脑缺血/再灌注损伤的影响

目的 观察异丙酚、咪唑安定和硫喷妥钠对鼠局灶脑缺血／再灌注后的神经功能和病理结果的影响。方法 雄性SD大鼠,采用可逆性大脑中动脉内线栓法诱发局灶脑缺血。缺血3h,再灌注24h后,作神经功能缺陷评估,然后取脑,TTC染色,用Image软件系统作图像分析,计算脑梗塞和脑水肿容积,电镜下观察梗塞边缘组织的细胞超微结构。动物分五组：缺血组、再灌注组、用药组（异丙酚、咪唑定安和硫喷妥钠）结果 异丙酚和咪唑安定明显改善鼠神经功能缺陷程度,降低脑梗塞和脑水肿容积,并减少梗塞边缘组织细胞死亡。异丙酚的脑保护效应强于咪唑安定。结论 异丙酚和咪唑安定有拮抗鼠局灶脑缺血／再灌注损伤的作用。     

Ca++ antagonist and acute brain ischemia: effects of nilvadipine and nicardipine on middle cerebral artery occlusion in rats]

Effects of calcium antagonists, Nicardipine and Nilvadipine, on neurologic deficits and size of infarct were studied in the rat middle cerebral artery (MCA) occlusion model. Each drug was administered immediately after induction of ischemia, and neurologic grade was evaluated 1 to 24 hours after MCA occlusion. At 24 hours post-occlusion, size of the infarct was compared with that of the control group. In addition, evolution of cerebral infarction was studied at 6 hours and 12 hours post-occlusion by magnetic resonance imaging (MRI). In the Nilvadipine-treated group, neurologic deficits improved more rapidly and the size of infarct was significantly smaller than in the Nicardipine-treated group. MRI showed a progressive extension of cortical infarct in the untreated rat, whereas the infarct size remained unchanged in the Nilvadipine-treated rat. These results suggest the potential therapeutic usefulness of calcium antagonist for acute cerebral ischemia.     

Experimental studies on pharmacologic protection of the brain against focal ischemia. 2. Effects of KB-2796 and nicardipine on focal brain ischemia in rats

It has been proposed that calcium overload triggers neuronal cell damage in the acute stage of cerebral ischemia. In this study, the effects of calcium antagonists, KB-2796 and nicardipine, on neurologic deficits and size of the infarction were studied in the rat middle cerebral artery (MCA) occlusion model. Neurologic deficits were evaluated from 1 to 24 hours after occlusion of the MCA, using a grading system of Bederson et al. At 24 hours post-occlusion, the brain was removed, sliced coronally, and stained with triphenyltetrazolium chloride. Size of the infarction was measured by computerized image analysis system. KB-2796 (10 mg/kg) or nicardipine (1 mg/kg) was intraperitoneally administered immediately after occlusion of the MCA. In the KB-2796-treated group, the neurologic deficits were much improved and the size of infarction was significantly smaller, but in the nicardipine-treated group improvement was modest and did not reach the level of statistical significance. The neurologic improvement was observed in the group where KB-2796 was given at 3 hours post-occlusion but the size of infarction was unchanged. The results in the present study seem to indicate that the calcium antagonists could improve focal cerebral ischemia when administered in early stage of ischemia, and that such effect is more significant with KB-2796 probably because of its higher selectivity to the cerebral vessels.     

Brain tolerance to middle cerebral artery occlusion during hypotension in primates

The aim of this study was to determine the duration of middle cerebral artery occlusion required to produce significant ischemic damage when the occlusion occurs during controlled systemic hypotension. In 21 anesthetized cynomolgus monkeys, an IV infusion of sodium nitroprusside was used to lower the mean arterial blood pressure to 45-50 mmHg for 90 minutes. Middle cerebral artery occlusion for 15, 30, 45, or 60 minutes was performed during the hypotensive period. Neurological function was then evaluated every 8 hours for a total of 72 hours. At the end of the observation period, the monkeys were again anesthetized, magnetic resonance imaging was performed, and the brain was perfused with 10% buffered formalin. Neurological deficits were observed after 30 minutes, but not after 15 minutes, of middle cerebral artery occlusion, and rapidly increased in incidence and severity when the duration of occlusion was increased. After 60 minutes of occlusion, all the monkeys exhibited severe deficits. Four monkeys died during the observation period--two in each of the 45- and 60-minute occlusion groups. Histopathological examination revealed that little or no ischemic damage resulted from a 15-minute occlusion during hypotension. However, severe ischemic damage began to occur after only 30 minutes of occlusion, and all monkeys subjected to middle cerebral artery occlusion for 60 minutes developed extensive regions of infarction. The size and incidence of these infarctions correlated well with the lesions observed in the magnetic resonance images. These results demonstrate that the duration of middle cerebral artery occlusion that produces cerebral infarction in primates is drastically reduced when the occlusion occurs at hypotensive levels commonly employed during neurovascular surgical procedures.     

Management of carotid artery trauma

We have treated 45 patients with carotid artery injuries--33 caused by penetrating wounds and 12 secondary to blunt trauma. Preoperative angiography is useful in stable patients to rule out associated vascular injuries, and it is crucial for operative planning in cases of blunt trauma. Not unexpectedly, the results of carotid artery repair in neurologically stable patients have been excellent, as have been the results of revascularization in patients with equivocal or less-severe neurologic deficits. This has led us to be aggressive in repair of carotid artery injuries in patients with questionable neurologic deficits. In the eight patients with severe preoperative deficits, one death each followed both ligation and repair, but neurologic improvement was noted in several patients. Distal internal carotid injuries at the base of the skull that were not amenable to direct repair were observed with serial angiograms in four patients with either stabilization or improvement in the intimal injury.     

Effects of adenosine triphosphate dependent potassium channel opener on bladder overactivity in rats with cerebral infarction

PURPOSE: We evaluated the effect of the adenosine triphosphate dependent K channel opener KRN2391 (N-cyano-N' -(2-nitroxyethyl)-3-pyridinecarboximidamide methanesulfonate) (Kirin Brewery Co., Gunma, Japan) on bladder overactivity induced by middle cerebral artery occlusion. MATERIALS AND METHODS: At 7 days after implantation of a bladder catheter in male Sprague-Dawley rats a cannula for intracerebroventricular administration was implanted and the left middle cerebral artery was occluded with 4-zero monofilament nylon thread. At 22 hours after the induction of cerebral ischemia saline was infused into the bladder at a constant rate (200 microl. per minute) and a cystometrogram was obtained with the rat in the conscious state. KRN2391 (5 microl.) was administered in intracerebroventricular fashion at graded doses (0.15 to 15 microg.). RESULTS: Bladder capacity in conscious rats was significantly reduced after left middle cerebral artery occlusion. Intracerebroventricular administration of KRN2391 significantly increased bladder capacity in cerebral infarcted but not in sham operated rats. CONCLUSIONS: These results show that a adenosine triphosphate dependent K channel opener may be useful for neurogenic bladder overactivity after cerebral infarction via action on the central nervous system.     

Carotid artery injuries caused by blunt trauma.

Carotid artery injuries caused by blunt trauma often cause thrombosis and delayed neurologic deficits, and are associated with mortality rates of up to 40%. In this series of 17 patients with blunt trauma of the carotid, three had no symptoms, ten patients had limb paresis and four had severe neuroligic deficits. The wounds were identified by arteriography; repair was attempted in 15 patients, and successful in eight. All eight patients with successful repair were improved or normal after surgery, but only two out of nine patients without repair improved, and four died. The mortality rate for the series was 23%, but only 14% in the patients who had carotid surgery. This experience suggests that repair is safe and effective in patients with carotid injuries in whom prograde flow continues and only mild neurologic deficits are present. In contrast, patients with complete occlusion, severe neurologic problems, and altered consciousness are not likely to be helped by attempts at revascularization.     

Anatomic pathways facilitating middle cerebral artery bypass

Occlusion of the middle cerebral artery by thrombi is a relatively common occurrence resulting in stroke. Prompt intervention by dissolution or bypassing the thrombi could reduce the severity of the effects. Here, the anatomic pathways facilitating a bypass are explored. Four possible arteries, the two superficial temporals, left and right, and two middle meningeals, left and right, are in positions adjacent to branches of the middle cerebral arteries, the trunks of which are located in the lateral fissures of the brain. The first possibility is anastomosing a branch of the superficial temporal artery with the middle cerebral artery segment in the lateral fissure where this segment is usually clear of thrombi. The second possibility is anastomosing a branch of the middle meningeal artery with the postthrombotic segment of the middle cerebral artery. These anastomoses are to be done with donor and recipient arteries of the same side. In the unlikely event that these two possibilities are lost, it is still possible to anastomose the affected middle cerebral artery with the superficial temporal or middle meningeal artery of the opposite side using several inches of saphenous vein.     

Subclavian-external carotid bypass for symptomatic severe cerebral ischemia from common and internal carotid artery occlusion

Occlusion of the common and internal carotid arteries in a patient with symptomatic severe cerebral ischemia, with or without contralateral carotid disease, portends a poor prognosis. The present study has described our experience with subclavian and external carotid artery revascularization for symptomatic severe cerebral ischemia from common and internal carotid artery occlusion. Nine patients (five men and four women) with a mean age of 62 (range 41 to 82 years) were diagnosed as having symptomatic severe cerebral ischemia. All patients had ipsilateral hemispheric symptoms, seven had amaurosis fugax, and two had associated syncope. Four patients (three men and one woman) were hypertensive, four (two men and two women) had diabetes, eight smoked, and all had a history of coronary artery disease. All of the patients had noninvasive laboratory studies and preoperative angiography, and three had postoperative angiography. Five patients were successfully revascularized to a patent external carotid artery despite nonvisualization by angiography. Six patients had unilateral and three bilateral occlusion of the common and internal carotid arteries appropriate to their symptoms. Using regional anesthesia, four patients underwent a subclavian-external carotid bypass with polytetrafluoroethylene; saphenous vein was used in five; and three had concomitant axilloaxillary bypass grafting with polytetrafluoroethylene. Neurologic improvement (that is, no subsequent deficit and no progression of symptoms) was noted in all nine patients with a follow-up of 4 to 28 months (mean 11.2 months). Two patients died from myocardial infarction 4 and 7 months after operation. Subclavian-external carotid artery bypass is a safe addition to the options for the treatment of symptomatic severe cerebral ischemia with occlusion of the common and internal carotid arteries, visualization of a superior thyroid collateral vessel on the recipient end, and nonvisualization of the external carotid artery.     

Giant internal carotid artery aneurysm manifesting as difficulty in swallowing: case report

A 66-year-old man presented with a rare case of a giant aneurysm of the internal carotid artery manifesting as difficulty in swallowing, resulting in severe malnutrition. Initial examination found a pulsating mass protruding from the posterior wall of the pharynx in the oral cavity. The patient had left hemiplegia caused by cerebral infarction one year previously. The patient underwent surgical therapy consisting of superficial temporal artery-middle cerebral artery bypass and trapping of the internal carotid artery. The pulsation of the oral mass vanished just after surgery and his difficulty in swallowing gradually improved. The patient was discharged with no new neurological deficits. The previous cerebral infarction was probably caused by an embolus from this giant aneurysm.     

Neuroprotective effect of peroxynitrite decomposition catalyst and poly(adenosine diphosphate-ribose) polymerase inhibitor alone and in combination in rats with focal cerebral ischemia

OBJECT: The authors evaluated the neuroprotective effect of 5,10,15,20-tetrakis(N-methyl-4'-pyridyl)porphyrinato-iron(III) (FeTMPyP), a peroxynitrite decomposition catalyst, and 1,5-isoquinolinediol (ISO), a poly(adenosine diphosphate [ADP]-ribose) polymerase (PARP) inhibitor, alone and in combination in rats with focal cerebral ischemia induced by middle cerebral artery occlusion (MCAO). METHODS: Male Sprague-Dawley rats were subjected to 2 hours of MCAO followed by 22 hours of reperfusion. Cerebral infarction and neurological deficits were estimated after ischemia. Intraperitoneal injections of FeTMPyP (1 and 2 mg/kg) and ISO (0.05 and 0.1 mg/kg) were administered alone or in combination in ischemic animals. The PARP activity in vehicle- and drug-treated groups was estimated using anti-poly(ADP-ribose) antibody in immunofluorescence and immunoblotting studies. Two hours of MCAO and 22 hours of reperfusion produced significant cerebral infarction and neurological deficits. Treatment with FeTMPyP (1 and 2 mg/kg) and ISO (0.05 and 0.1 mg/kg) produced a significant reduction in cerebral infarction and neurological deficits. Combination therapy (2 mg/kg FeTMPyP and 0.1 mg/kg ISO) enhanced the inhibition of ischemic volume (77.81+/-0.86%) compared with monotherapies (FeTMPyP 54.07+/-5.6% and ISO 53.06+/-3.88%). Immunoblotting and immunofluorescence studies showed PARP activation after ischemia, which was reduced by drug treatment. CONCLUSIONS: Neuroprotection observed with FeTMPyP and ISO alone and in combination may be attributed to inhibition of the peroxynitrite-PARP cascade of cerebral ischemia/reperfusion injury.