Nefiracetam improves the impairment of local cerebral blood flow and glucose utilization after chronic focal cerebral ischemia in rats

In this study we investigated the effects of nefiracetam (DM-9384) on local cerebral blood flow (LCBF) and local cerebral glucose utilization (LCMR(glc)) in the chronic phase after middle cerebral artery (MCA) occlusion in rats. Nefiracetam (10 mg/kg) was administered orally once a day for 2 weeks from day 15 after MCA occlusion. On day 28 after MCA occlusion, LCBF and LCMR(glc) were measured by an autoradiographic image-processing method. In MCA-occluded rats, LCBF and LCMR(glc) in the ischemic side of seven regions including the frontal cortex were significant decreased compared with those of the nonischemic side. Nefiracetam significantly improved the impairment of LCBF in the frontal cortex, parietal cortex, caudate putamen, ventral thalamus, amygdaloid nucleus and hippocampus. It also improved the decrease of LCMR(glc) in the frontal cortex, ventral thalamus and hippocampus. These results suggested that nefiracetam has ameliorating effects on chronic disorders of LCBF and LCMR(glc) induced by MCA occlusion.     

(S)-emopamil, a novel calcium and serotonin antagonist for the treatment of cerebrovascular disorders. 3rd communication: effect on postischemic cerebral blood flow and metabolism, and ischemic neuronal cell death

The effect of (S)-emopamil ((2S)-2-isopropyl-5-(methylphenethylamino)-2-phenylvaleronitril e hydrochloride) treatment on postischemic cerebral blood flow and metabolism was investigated in nitrous oxide anesthetized, artificially ventilated rats. Forebrain ischemia was induced and maintained for 20 min by lowering arterial blood pressure to approximately 40 mmHg and clamping both carotid arteries. Local cerebral blood flow and glucose utilization were evaluated autoradiographically in 34 cerebral regions. In the cerebral blood flow studies intravenous infusion of 0.1 mg/(kg min) (S)-emopamil was begun 5 min after the end of ischemia. Local cerebral blood flow was determined 60 min later using [14C]iodoantipyrine. When the animals were treated with saline only, postischemic blood flow of 22 affected forebrain areas fell on average to 42 +/- 13% of nonischemic control. Treatment with (S)-emopamil increased perfusion of the same areas in a region-dependent fashion by an average of 54 +/- 19%, resulting in 63 +/- 17% of control values. The rise of blood flow in structures not directly affected by ischemia amounted to 52 +/- 27% (134 +/- 23% of control). In the studies on cerebral metabolism, the experimental animals received a total of 6 mg/kg (S)-emopamil by slow intravenous infusion before and during the ischemic episode. Determination of local cerebral glucose utilization was initiated after 50 min of postischemic recirculation using [14C]deoxyglucose. In the placebo-treated experimental group average glucose utilization of 14 forebrain areas was significantly lower (74 +/- 9% of control) than in the nonischemic control group.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of buflomedil on survival rate, local cerebral blood flow and glucose utilization after cerebral ischemia in spontaneously hypertensive rats

Cerebral protective effects of oral Buflomedil administration for 7 days were studied in spontaneously hypertensive rats (SHR). After permanent bilateral carotid artery occlusion (BCAO), the survival rates at 24 hr were 38% and 44% in groups treated with Buflomedil at the doses of 30 mg/kg (n = 16) and 90 mg/kg (n = 15), respectively, which were significantly higher than that in the control group (orally given saline for 7 days), 6%. In rats that survived and given Buflomedil, carbon filling of the brain after BCAO was extended to the territories of the internal carotid artery, while it was restricted to the brainstem and cerebellum in rats died within 3 hr and given either saline or Buflomedil. Local cerebral blood flow (LCBF), monitored by [14C]-Iodoantipyrine autoradiography, was determined at 3 hr after the start of BCAO or at 2 hr after reperfusion in rats orally given either saline or Buflomedil 30 mg/kg for 7 days. Local cerebral glucose utilization (LCGU), monitored by [14C]-Deoxyglucose autoradiography, was determined at 2 hr after reperfusion. At 3 hr after the start of BCAO, the LCBF in the Buflomedil group was higher by 71-128% in the cerebral cortex, 61-150% in the amygdala, caudate-putamen, nucleous accumbens and globus pallidus, and 82% in the internal capsule. At 2 hr after reperfusion, LCBF did not differ between groups, but LCGU in the Buflomedil group was significantly higher by 26-49% in the cerebral cortex, cochlear nuclei and vestibular nuclei than that in the control group. From these results, it is concluded that Buflomedil improved survival rate after permanent BCAO and have beneficial effect on local cerebral blood flow distribution after BCAO in SHR.     

Effects of the indirect dopaminomimetic diethylpemoline on local cerebral glucose utilization and local cerebral blood flow in the conscious rat

The changes in local cerebral glucose utilization (LCGU) and local cerebral blood flow (LCBF) following the systemic application of the indirect dopaminomimetic diethylpemoline (50 mg/kg i.v.) were measured in conscious rats using the autoradiographic [14C]2-deoxyglucose and the [14C] iodoantipyrine technique. Increased rates of glucose utilization were observed in the sensorimotor cortex, parafascicular nucleus, ventrolateral nucleus of the thalamus, substantia nigra, caudate nucleus, globus pallidus, red nucleus, subthalamic nucleus, cerebellar cortex and vermis. Cingulate cortex, anteromedial, anteroventral nucleus of the thalamus, habenula and nucleus accumbens showed a decreased LCGU. The determination of LCBF revealed a similar pattern of altered blood flow values. Statistical evaluation of the relationship between glucose utilization and blood flow by regression analysis did not reveal any distinguishable difference between diethylpemoline-treated rats and controls. The data suggest that it is mainly the altered neuronal activity and metabolic demand after dopaminergic stimulation that effect the changes in blood flow rather than a direct dopaminergic effect on brain vasculature.     

Delayed administration of JTP-2942, a novel thyrotropin-releasing hormone analogue, improves cerebral blood flow and metabolism in rat postischaemic brain

1. The aim of the present study was to examine the central nervous system action of JTP-2942, a novel thyrotropin-releasing hormone (TRH) analogue, from the point of view of cerebral blood flow (CBF) and metabolism in the postischaemic brain. 2. Left middle cerebral artery ischaemia was induced for 90 min followed by reperfusion. 3. Animals were separated into four groups: (i) low-dose (0.003 mg/kg) JTP-2942; (ii) high-dose (0.03 mg/kg) JTP-2942; (iii) cystidine diphosphate choline (500 mg/kg); and (iv) saline. The test drug or saline was administered intravenously 1 week after ischaemia. 4. Local CBF and local cerebral glucose utilization were measured autoradiographically, adjacent sections were stained with haematoxylin-eosin and infarction size was measured. 5. JTP-2942 ameliorated the reduction of local CBF and glucose utilization except in the ischaemic core. In particular, the higher dose (0.03 mg/kg) of JTP-2942 significantly increased local CBF and glucose utilization not only in peri-infarcted areas, but also in distal and contralateral areas. 6. These results suggest that JTP-2942 treatment may be beneficial for improving cerebral circulation and metabolism in the postischaemic brain.     

阿魏酸对脑梗死大鼠的神经功能、GLUT蛋白与神经元葡萄糖代谢的影响

目的 探究阿魏酸在减轻大鼠脑梗死过程中对葡萄糖转运蛋白（GLUTs）和神经元葡萄糖代谢的影响。方法 72只SD大鼠随机分为假手术组、模型组、尼莫地平组以及阿魏酸25、50、100 mg/kg组。采用Longa线栓法构建脑梗死模型，梗死期间，模型组尾iv生理盐水，阿魏酸组分别尾iv 25、50、100 mg/kg的阿魏酸治疗，尼莫地平组尾iv 20 mg/kg尼莫地平，给药3 d。完成给药后24 h，对各组大鼠开展神经功能评分，完成后取大鼠血液检测外周血糖值，再通过PET/CT实验检测缺血区葡萄糖摄取水平。将大鼠处死后全脑组织进行TTC染色，取缺血核心区组织，通过比色法检测ATP含量，采用Western blotting法检测GLUT蛋白表达水平。结果 与假手术组比较，模型组大鼠神经功能评分增加，出现明显梗死区域，缺血核心区葡萄糖摄取量减少，ATP含量降低，GLUT1、GLUT3、PFKFB3蛋白表达降低（P＜0.05）。与模型组比较，阿魏酸50、100 mg/kg组大鼠神经功能评分减少，梗死区域面积占比减少，缺血核心区葡萄糖摄取量增加，ATP含量升高，GLUT1、GLUT3、PFKFB3蛋白表达升高（P＜0.05）。结论 阿魏酸对脑梗死大鼠的治疗效果与尼莫地平相似，其机制可能与提高GLUT1和GLUT3蛋白表达，促进葡萄糖向中枢神经元转运，提高葡萄糖代谢相关。     

HA1077, a novel calcium antagonistic antivasospasm drug, increases both cerebral blood flow and glucose metabolism in conscious rats.

The effects of a novel calcium antagonistic antivasospasm drug, HA1077, on local cerebral blood flow (LCBF) and local cerebral glucose utilization (LCGU) were studied in 33 anatomically discrete regions of the brain in conscious rats, using the quantitative autoradiographic [14C]iodoantipyrine and [14C]2-deoxyglucose techniques. HA1077 was infused i.v. over a 30-min period (1 or 3 mg/kg). HA1077 significantly increased LCBF in 9 of 33 sites in rats given 1 mg/kg, and in 14 of 33 sites in rats given 3 mg/kg compared to the control group given vehicle. Significant increases in LCGU were also noted in 16 of 33 sites in rats given 3 mg/kg. HA1077 increased both cerebral blood flow and glucose metabolism in conscious rats.     

Effects of the acute administration of a new trimethylxanthine derivative, S 9977-2, on local cerebral blood flow and glucose utilization in the rat

S 9977-2 is a new trimethylxanthine derivative with promnesic properties. Its effects on cerebral glucose utilization and blood flow were studied by means of quantitative autoradiography. S 9977-2 was injected intravenously into adult rats at doses of 0.1, 1.0 and 10 mg/kg. At 0.1 mg/kg, S 9977-2 induced a significant increase in cerebral glucose utilization over control values in two white matter areas and in the vcstibular nucleus. At 1.0 mg/kg, glucose utilization was affected in 14 areas out of the 63 studied, mainly limbic regions such as the hippocampus, raphe nuclei and locus coeruleus, as well as some posterior areas. Conversely, after the injection of 10 mg/kg S 9977-2, cerebral glucose utilization was similar to that of control rats. At the three doses tested, S9977-2 did not induce any significant variation in local rates of cerebral blood flow compared to those of controls. Likewise, S 9977-2 did not change the level of coupling between cerebral blood flow and metabolism, except at 10 mg/kg, where a relative hypoperfusion at a constant metabolic level was recorded. These data show that, at 1.0 mg/kg, S 9977-2 increased glucose utilization in hippocampal areas, an effect which may be related to the promnesic properties of this compound at the same dose. Moreover, at low doses, the lack of change in the level of coupling between cerebral blood flow and metabolism is indicative of the rather selective action of this compound, compared to that of caffeine. Thus S9977-2 should have therapeutic effects, mainly via its promnesic properties, witheat having many side effects.     

Stimulatory effects of lisuride on local cerebral blood flow and local cerebral glucose utilization in rats

Effects of lisuride, a central dopamine agonist of the ergot type, on local cerebral blood flow (LCBF) and local cerebral glucose utilization (LCGU) were studied using the autoradiographical 14C-iodoantipyrine and 3H-deoxyglucose method, respectively, in conscious rats. Lisuride significantly stimulated LCBF in the cerebellar gray matter. LCBF in some other regions including the cerebral cortex, caudate-putamen, thalamus, geniculate body and substantia nigra were also stimulated by lisuride. No changes were observed in the hippocampus, hypothalamus and white matter. A close correlation was observed between LCBF and LCGU. Region specificity of the stimulatory effect by lisuride on LCBF and LCGU was coincident. Lisuride shortened the lethal time in the anoxia model. In conclusion, lisuride stimulated not only glucose utilization but also blood flow in local regions of the brain.     

Neuroprotective activity of the proline-containing dipeptide noopept on the model of brain ischemia induced by the middle cerebral artery occlusion

The influence of noopept (N-phenylacetyl-L-prolylglycine ethyl ester, GVS-111) on the extent of ischemic cortical stroke was investigated in experiments on white mongrel male rats with ischemia induced by a combination of the middle cerebral artery occlusion with ipsilateral common carotid artery ligation. Animals were treated with noopept (0.5 mg/kg, i.p.) according to the following schedule: 15 min and 2, 24, and 48 h after the occlusion. Test rats were decapitated 72 h after occlusion, brains were extracted and frozen, and thin brain slices were stained with 2,3,5-triphenyltetrazolium chloride. The slices were scanned and processed using Auc 1 computer program, which estimates the percentage of damaged area relative to that of the whole ipsilateral hemisphere. The conditions of coagulation the distal segment of middle cerebral artery were selected, which caused necrosis localized in the fronto-parietal and dorso-lateral regions of the brain cortex without any damage of subcortical structures. The extent of the brain damage in control group (treated by saline) was 18.6%, while that in the group treated with noopept was 12.2%, thus demonstrating a decrease in the infarction area by 34.5% (p < 05). The data on noopept efficacy on the model of the extensive ischemic injury of brain cortex show that this drug has good prospects for use in the neuroprotective treatment of stroke.     

The effects of oxiracetam (CT-848) on local cerebral glucose utilization after focal cerebral ischemia in rats.

The effects of oxiracetam on the reduction of brain metabolism induced by focal cerebral ischemia were investigated by measuring local cerebral glucose utilization (LCGU) in rats 24 hr after left middle cerebral artery occlusion. Focal cerebral ischemia reduced LCGU in the entire ipsilateral cortex, the greatest reduction being in the lateral parts of the frontoparietal cortex. LCGU was slightly reduced in the contralateral cortex; this reduction was considered to be caused by diaschisis. Oxiracetam was administered intraperitoneally for 3 days prior to middle cerebral artery occlusion. In the ipsilateral cortex, LCGU reduction was minimized in the ischemic center areas by oxiracetam at a dose of 400 mg/kg and in more extensive areas, by a dose of 800 mg/kg. Moreover, oxiracetam at a dose of 800 mg/kg enhanced metabolism impaired by diaschisis in the caudal areas of the contralateral cortex. These findings suggest that oxiracetam minimizes the reduction of brain function induced by ischemia and may therefore be useful in the treatment of cerebrovascular disease.     

Effects of methylenedioxymethamphetamine on local cerebral glucose utilization in the rat

The effects of (+-)3,4-methylenedioxymethamphetamine (MDMA, "ecstasy") (5, 10, 15 or 30 mg/kg, i.p.) on local cerebral utilization of glucose were studied by the quantitative autoradiographic 2-deoxy-D-[1-14C]glucose method in awake adult male Fischer-344 rats. Statistically significant effects on local utilization of glucose, 5 min after the administration of MDMA were observed in 20 of 60 areas of brain sampled. Marked stimulation was seen in components of the extrapyramidal motor system (substantia nigra, globus pallidus, entopenduncular nucleus, subthalamic nucleus, cerebellar vermis). The limbic system showed decrements in the medial cortex and hippocampal dentate gyrus (outer blade) and the lateral habenula, while there was stimulation in the mammillary body and the basolateral amygdaloid nucleus. Glucose utilization in MDMA-treated rats was reduced in the superior colliculus and medial terminal nucleus of the accessory optic system, but was unchanged in the visual cortex and components of the auditory system. Some of the effects of MDMA on cerebral utilization of glucose resembled those previously reported with l-cocaine, d-amphetamine, and phencyclidine, implicating some common mechanisms in the actions of these drugs.     

Dopamine enhancement of the cerebral microcirculation in a local ischemic lesion

The effect of dopamine on the local cerebral blood flow in parietal brain cortex region of rats was studied in conditions of local ischemia induced by middle cerebral artery occlusion. Registration of the local cerebral blood flow was performed on a ALF-21 laser doppler flowmeter ("Transonic System Inc.", USA). Dopamine produces a pronounced effect on cerebral circulation in conditions of local brain ischemia thus causing a significant increase in blood flow both in ischemic and intact hemispheres. The effect is observed both in the acute stage of ischemic brain injury and in the remote period of brain ischemia.     

诱导型一氧化氮合酶在GK糖尿病大鼠心肌梗死后的表达

目的本研究通过制作GK糖尿病大鼠及非糖尿病大鼠心肌梗死模型,观察诱导型一氧化氮合酶(iNOS)的表达在糖尿病大鼠合并心肌梗死时与非糖尿病大鼠心肌梗死时的变化,为冠心病合并糖尿病的心脏病理改变提供理论基础与科学依据。方法应用体质量在200～250g的雄性GK糖尿病大鼠及其对照雄性Wistar大鼠通过开胸手术结扎麻醉大鼠冠状动脉左前降支制作大鼠在体心肌梗死模型。心肌梗死模型制作前测量血糖。手术成功后分组饲养大鼠3周。3周后,测量血糖,活体剪取心脏,进行iNOS的免疫组织化学染色及实时聚合酶链反应(RT-PCR)检测。结果①GK糖尿病大鼠血糖明显高于Wistar大鼠血糖(P<0.05);②Wistar心肌梗死组与GK心肌梗死组在缺血区可见到心肌细胞iNOS大量阳性染色,但GK心肌梗死组与Wistar心肌梗死组相比,iNOS阳性染色减少,二者吸光度测定值差异有统计学意义(P<0.05);③Wistar心肌梗死组与GK心肌梗死组iNOSmRNA表达在缺血区明显增加,但GK心肌梗死组iNOSmRNA表达减少,二者之间差异有统计学意义(P<0.05)。结论iNOS在糖尿病大鼠合并心肌梗死时其在缺血区的表达是降低的,表明高血糖可能抑制iNOS的表达,使体内一氧化氮(NO)生成减少,不利于梗死后血供的恢复。     

小牛血清去蛋白注射液对2型糖尿病合并脑梗死模型大鼠胰岛素抵抗的影响

目的:观察小牛血清去蛋白注射液(DCBI)对2型糖尿病合并脑梗死模型大鼠血糖、血脂代谢的影响及其对胰岛素抵抗(IR)的改善作用。方法:大鼠用高脂高糖饮食伴尾静脉注射链脲佐菌素复制2型糖尿病模型,成功后再建立大鼠大脑中动脉栓塞模型,分为模型组、假手术组、DCBI(低、高剂量,30、60mg·kg-1·d-1,腹腔注射)组和对照药罗格列酮组;并设立正常组。各组给予相应试药5周后,测定空腹血糖(FBG)、血清胰岛素(FI NS)、糖耐量(OGTT)水平,并计算胰岛素抵抗指数(IRI)、胰岛素敏感指数(ISI),测定总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)、游离脂肪酸(NEFA)水平。结果:与模型组比较,DCBI治疗后可显著降低2型糖尿病合并脑梗死模型大鼠FBG水平及增强糖耐量(P<0.01),对FI NS水平的改变不明显(P>0.05);改善机体对胰岛素的抵抗性(P<0.01或P<0.05);并明显降低TC、TG、LDL-C、NEFA水平及升高HDL-C水平(P<0.01),改善高脂状态。结论:DCBI可降低2型糖尿病合并脑梗死模型大鼠血糖,调节血脂代谢紊乱,具有改善IR的作用。     

Chronic therapy with citalopram decreases regional cerebral glucose utilization in OBX, and not sham-operated, rats: an autoradiographic study

Rationale

Chronic treatment with the selective serotonin reuptake inhibitor, citalopram, normalizes several behavioral and neurochemical abnormalities in the olfactory bulbectomized (OBX) rat model of depression.

Objective

To assess the changes in regional cerebral glucose utilization (rCGU) following chronic treatment with citalopram in OBX and sham-operated rats.

Methods

Male Sprague Dawley rats (160–190 g) were used. Two weeks following the surgeries, the rats were implanted with osmotic minipumps which delivered 10 mg/kg/day of citalopram (the sham-CTP and OBX-CTP groups) or saline (to the sham-SAL and OBX-SAL groups) for 2 weeks. Following the treatment, the rates of rCGU were determined in 43 brain regions using 2-[¹⁴C]deoxyglucose (2-[¹⁴C]DG) autoradiography.

Results

The general linear model statistical analysis revealed significantly lower rCGU in the OBX-SAL group compared to the sham-SAL group in the medial prefrontal cortex and the median forebrain bundle. The sham-CTP group had significantly lower rCGU relative to the sham-SAL group in the medial prefrontal cortex. The OBX-CTP group had significantly lower rCGU than the OBX-SAL group in the anterior olfactory nucleus, orbitofrontal cortex, frontal cortex, anterior cingulate cortex, visual cortex, and substantia nigra—pars reticulata. The rCGU in the OBX-CTP group was significantly lower than that in the sham-CTP group in the anterior olfactory nucleus, orbitofrontal cortex, visual cortex, and substantia nigra—pars reticulata.

Conclusion

The results imply that chronic citalopram treatment, shown previously to result in behavioral normalization in OBX rats, establishes a new pattern of rCGU, rather than normalizing it to the pattern of the sham-CTP rats.     

Effects of naftidrofuryl on the time course of the regional cerebral blood flow in acute ischemic stroke

The effects of naftidrofuryl (LS-121), which is known as an activator of the cerebral glucose metabolism in addition to acting as a cerebral vasodilator on the regional cerebral blood flow (rCBF), were investigated in acute and subacute ischemic stroke patients. Six acute patients and 5 subacute patients were treated with 100-200 mg/day of naftidrofuryl for 7-14 days, and the rCBF was measured before and after the treatment by the 133Xe inhalation method. The hemispheric rCBF was significantly increased by 24% for the acute stage and 22% for the subacute stage in the affected side, compared with the stage-matched control group. Naftidrofuryl may accelerate the recovery of the rCBF of the affected hemisphere even in the acute stage.     

Effects of nicotine and chlorisondamine on cerebral glucose utilization in immobilized and freely-moving rats

Chlorisondamine blocks central nicotinic receptors for many weeks via an unknown mechanism. Intracerebroventricular administration of [(3)H]-chlorisondamine in rats results in an anatomically restricted and persistent intracellular accumulation of radioactivity. The initial aim of the present study was to test whether nicotinic receptor antagonism by chlorisondamine is also anatomically restricted. Male adult rats were pretreated several times with nicotine to avoid the disruptive effects of the drug seen in drug-na?ve animals. They then received chlorisondamine (10 microg i. c.v.) or saline, and local cerebral glucose utilization (LCGU) was measured 4 weeks later after acute nicotine (0.4 mg kg(-1) s.c.) or saline administration. During testing, rats were partially immobilized. Nicotine significantly increased LCGU in the anteroventral thalamus and in superior colliculus. Chlorisondamine completely blocked the first of these effects. Chlorisondamine significantly reduced LCGU in the lateral habenula, substantia nigra pars compacta, ventral tegmental area, and cerebellar granular layer. The second experiment was of similar design, but the rats were not pre-exposed to nicotine, and were tested whilst freely-moving. Acute nicotine significantly increased LCGU in anteroventral thalamus, superior colliculus, medial habenula and dorsal lateral geniculate. Overall, however, nicotine significantly decreased LCGU. Most or all of the central effects of nicotine on LCGU were reversed by chlorisondamine given 4 weeks beforehand. These findings suggest that chlorisondamine blocks nicotinic effects widely within the brain. They also indicate that in freely-moving rats, nicotine can reduce or stimulate cerebral glucose utilization, depending on the brain area. British Journal of Pharmacology (2000) 129, 147 - 155     

Cocaine abstinence following chronic treatment alters cerebral metabolism in dopaminergic reward regions. Bromocriptine enhances recovery

2-[14C]deoxyglucose autoradiography was used to determine local cerebral glucose utilization (lCGU) in rats following chronic cocaine treatment and subsequent abstinence. lCGU was examined in 43 discrete brain regions in animals which had received daily injections of cocaine for 14 days (10 mg/kg) followed by 3 days of saline or bromocriptine (10 mg/kg) treatment. Cocaine abstinence following chronic treatment significantly reduced lCGU in several regions including mesocorticolimbic structures such as ventral tegmental area, medial prefrontal cortex, and nucleus accumbens (NAc). Within the NAc, however, only the rostral pole showed significant reduction. In contrast, when bromocriptine treatment accompanied abstinence, lCGU was no longer reduced in mesocorticolimbic and most other regions, implying that metabolic recovery was enhanced by bromocriptine treatment during early abstinence following chronic cocaine treatment. These data suggest that cerebral metabolism is decreased during cocaine abstinence following chronic treatment in critical brain regions, and that this alteration can be prevented by treatment with direct-acting dopamine agonists such as bromocriptine.     

The model of stroke induced by microsphere embolism in rats

Cerebral infarction is induced by injecting 700-900 microspheres with a diameter of 50 microm into the right internal carotid artery of the rat. Approximately 82% of the rats with typical symptoms of stroke survived at fifteen hours after the injection of microspheres. Microsphere-induced cerebral embolism elicits the widespread formation of small emboli in the ipsilateral hemisphere and subsequent neuronal loss and/or the development of multiple infarct areas in the brain, particularly in the cortex, striatum, and hippocampus. Thus, this model is considered to mimic focal ischemia-induced human stroke or multi-infarct dementia. We have found that this model showed sustained decreases in cerebral blood flow and cerebral high-energy phosphates; accumulation of tissue lactate, glucose, and glycogen; changes in the activity of several enzymes in the tricarboxylic acid cycle; loss of mitochondrial phosphorylation activity; and decreases in neurotransmitters, acetylcholine, monoamines, and amino acids in the ipsilateral hemisphere. Accordingly, microsphere embolism is capable of inducing severe and sustained cerebral ischemia resulting in disturbances of the energy and neurotransmitter metabolism in the brain. Such ischemic damage leads to learning and memory dysfunction. This model provides useful information about the pathogenesis, prophylaxis, and therapeutics of cerebral ischemic diseases.