Effects of cannabinoid receptor agonist WIN 55,212-2 on blood-brain barrier disruption in focal cerebral ischemia in rats

This study was performed to investigate whether WIN 55,212-2 (WIN), a cannabinoid receptor agonist, could attenuate blood-brain barrier (BBB) disruption in focal cerebral ischemia in rats and whether the CB 1 receptor antagonist rimonabant could prevent this attenuation. A total of 0.3 or 1 mg/kg of WIN was injected intravenously before and after permanent middle cerebral artery (MCA) occlusion. Some animals were pretreated with rimonabant 2 mg/kg i.p. before receiving 0.3 mg/kg of WIN. At 1 h after MCA occlusion, BBB permeability was determined by measuring the transfer coefficient (K(i)) of (14)C-α-aminoisobutyric acid and the volume of dextran distribution. With MCA occlusion, K(i) increased in the ischemic cortex (IC) in all of the experimental groups. However, the K(i) of the IC of the WIN 0.3 and 1 mg/kg groups was lower (–46 and –42%, respectively, p < 0.05) than that of the control group. With rimonabant pretreatment, the K(i) of the IC became higher ((+)88%, p < 0.05) than with WIN 0.3 mg/kg alone and similar to that of the control rats. The difference in the volume of dextran distribution between the IC and the contralateral cortex was significant in the control but not in the WIN-treated rats. With rimonabant pretreatment, however, the difference became significant. Our data demonstrated that WIN could attenuate BBB disruption in focal cerebral ischemia and this attenuation could be prevented with rimonabant. Our data suggest an involvement of CB(1) receptors in the regulation of BBB disruption in the early stage of stroke.     

Effects of VEGF on the blood-brain barrier disruption caused by hyperosmolarity

This study was performed to test whether disruption of the blood-brain barrier (BBB) caused by hyperosmolarity could be related to vascular endothelial growth factor (VEGF), using anti-VEGF antibody and ciclopirox olamine (CPX), an inducer of VEGF. CPX 50 mg/kg or normal saline was given intraperitoneally to male Wistar rats 18 h before BBB disruption. Two craniotomies were made on the ipsilateral cortex (IC-1 and IC-2) where the BBB would be disrupted, and a third hole was made on the contralateral cortex (CC) to expose the cortices. We applied normal saline (to IC-1 and the CC) or anti-VEGF antibody (to IC-2) for 90 min before BBB disruption with intracarotid injection of 25% mannitol. The degree of BBB disruption was determined by measuring the transfer coefficient (K(i)) of (14)C-alpha-aminoisobutyric acid and the volume of (3)H-dextran distribution. The protein levels of VEGF were determined with Western blot analysis. In the control animals, hyperosmolar mannitol significantly increased (415%) the K(i) in IC-1. The K(i) was attenuated with anti-VEGF antibody application (-28%, p < 0.05). Even though the protein levels of VEGF were strongly increased with CPX pretreatment, this upregulation did not alter the hyperosmolar BBB disruption in the saline- or in the antibody-treated cortex. The data on the volume of dextran distribution followed the same pattern as that of the K(i) but without a statistically significant difference between IC-1 and IC-2 in either group. Our data demonstrated that hyperosmolar BBB disruption could be attenuated with anti-VEGF antibody. However, upregulation of VEGF with CPX did not alter the degree of hyperosmolar BBB disruption with or without anti-VEGF antibody treatment. This study suggests that the contribution of VEGF in hyperosmolar BBB disruption is limited.     

Effect of NXY-059 on infarct volume after transient or permanent middle cerebral artery occlusion in the rat; studies on dose, plasma concentration and therapeutic time window.

1. The efficacy of the free radical trapping agent NXY-059 in reducing the infarct volume following both transient and permanent focal ischaemia has been examined in rats. 2. In the transient ischaemia model, rats were subjected to a 2 h occlusion of the middle cerebral artery (MCA). Intravenous infusion of NXY-059 (1, 10 and 30 mg kg(-1) h) for 21.75 h starting 2.25 h after the occlusion, produced a dose-dependent decrease in both neurological impairment and the histologically measured infarct volume (a mean 59% decrease at 10 mg kg(-1) h). 3. In the permanent ischaemia model, animals were injected (s.c.) with a loading dose of NXY-059 of 32.5, 53.8 or 75.4 mg kg(-1) and osmotic minipumps were implanted which had been primed to deliver respectively 30, 50 or 70 mg kg(-1) h. When treatment was initiated 5 min after MCA occlusion there was a dose dependent protection of both cortical and sub-cortical tissue (cortex: 63% at the mid-range dose). Protection was related linearly to plasma concentration (plasma unbound NXY-059 concentration at 1 h: 37+/-16 micromol l(-1) at the mid-range dose). 4. When the mid range dose was administered between 5 min - 4 h after MCA occlusion, a marked and statistically significant protection was seen at all time points (44% protection in cortex at 4 h). 5. These data demonstrate the substantial neuroprotective efficacy of NXY-059 at plasma concentrations that can be achieved clinically and indicate that NXY-059 also has a therapeutic window of opportunity that is clinically relevant.     

The effect of chlormethiazole on neuronal damage in a model of transient focal ischaemia.

1. The effect of chlormethiazole has been studied in a transient middle cerebral artery (MCA) occlusion model of cerebral ischaemia in the rat. The MCA was occluded for 1 h by use of an intraluminal suture technique, with reperfusion for 24 h following removal of the occluding filament. Neuronal damage was determined by measurement of the area of necrosis following Cresyl Violet staining of sections taken through the ischaemic region. 2. In the initial experiment, occlusion of the MCA produced a large volume of ischaemic damage in both cortex and striatum, characterized by necrosis and pyknosis (total volume of damage, 287 +/- 13 mm3, n = 9). Rats injected with chlormethiazole (1000 mumol kg-1, i.p.) 60 min before occlusion had a reduced volume of damage in both regions (104 +/- 11 mm3; n = 9; P < 0.001). 3. In a subsequent study systemic physiological parameters (heart rate, blood pressure, blood pH, blood gases and rectal temperature) were measured throughout the ischaemic period. 4. Chlormethiazole (1000 mumol kg-1) pretreatment produced little change in systemic physiology and the neuroprotective effect of the drug when given 60 min prior to the MCA occlusion was confirmed. Chlormethiazole was also neuroprotective when given 10 min following the start of reperfusion (control group: 244 +/- 52 mm3, n = 10; chlormethiazole pretreatment group: 102 +/- 23 mm3, n = 10; P < 0.001; chlormethiazole post-ischaemia group: 122 +/- 16 mm3; P < 0.001, n = 10).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of TTC-909 on cerebral infarction following permanent occlusion of the middle cerebral artery in stroke prone spontaneously hypertensive rats

We investigated the effect of TTC-909, a drug preparation of the stable prostaglandin I(2) analogue clinprost (isocarbacyclin methylester; methyl 5-[(1S,5S,6R,7R)-7-hydroxy-6-[(E)-(S)-3-hydroxy-1-octenyl] bicyclo[3.3.0]oct-2-en-3-yl] pentanoate) incorporated into lipid microspheres, on cerebral infarction 7 days after permanent occlusion of the middle cerebral artery (MCA) in stroke prone spontaneously hypertensive rats (SHRSP). Under the anesthesia, the MCA was permanently occluded above the rhinal fissure. In schedule 1, vehicle or TTC-909 was injected i.v. once daily over 7 days starting immediately after MCA occlusion. In schedule 2, vehicle or TTC-909 was infused for 3 h starting immediately after MCA occlusion. In schedule 3, vehicle or TTC-909 was infused for 3 h starting immediately after MCA occlusion followed by bolus injection once daily over 6 days. Seven days later, the infarct volume was estimated following hematoxylin and eosin staining. Cerebral infarction produced by permanent occlusion of MCA was limited to the cerebral cortex. While this volume was reduced significantly in case of schedule 3, the infarct volume was not reduced significantly in schedules 1 and 2. Ozagrel, a thromboxane A(2) synthetase inhibitor, had no effect on the infarct volume in schedule 3. These results suggest that cerebral infarction can be developed progressively not only during the first few hours but also after a permanent occlusion of MCA in SHRSP. TTC-909 inhibited cerebral infarction, maybe by improving cerebral blood flow and by protecting against neuronal damage.     

Arecoline, but not haloperidol, induces changes in the permeability of the blood-brain barrier in the rat

The aim of the present study was to investigate the existence of alterations of the blood-brain barrier (BBB) permeability in rats injected with centrally acting drugs, by calculating a unidirectional blood-to-brain transfer constant (Ki) for the circulating tracer [14C]-alpha-aminoisobutyric acid. The intraperitoneal (i.p.) injection of the dopaminergic antagonist haloperidol (1 mg kg-1) did not modify the regional BBB permeability. When the cholinomimetic agent arecoline hydrobromide (6.25 mg kg-1) was injected i.p. into methylatropine-pretreated rats, it induced a significant decrease of Ki values within the frontal cortex, parietal cortex, striatum and brain-stem. Our findings emphasize two concepts: (1) centrally acting drugs, such as arecoline, can induce changes in the BBB permeability, through several mechanisms; (2) there is no predictable correlation of drug stimulation of specific brain neuronal pathways and changes in the permeability of the BBB.     

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.     

Beta-hydroxybutyrate,a cerebral function improving agent,protects rat brain against ischemic damage caused by permanent and transient focal cerebral ischemia

In our previous study, beta-hydroxybutyrate (BHB) was found to prolong survival time and to inhibit cerebral edema by improving energy metabolism in the hypoxia, anoxia and global cerebral ischemia models. In this study, the cerebroprotective effect of BHB was examined in rats with permanent (p)-occlusion and transient (t)-occlusion of middle cerebral artery (MCA). BHB (30 mg x kg(-1) x h(-1) was continuously administered through the femoral vein. In rats with p-MCA occlusion, BHB significantly reduced infarct area at 24 h after the occlusion, but not at 72 h after the occlusion. In rats with 2-h t-MCA occlusion followed by 22-h reperfusion, BHB significantly reduced cerebral infarct area, edema formation, lipid peroxidation and neurological deficits. Moreover, in the t-MCA occlusion model, delayed administration of BHB started at 1 h after the initiation of the MCA occlusion also significantly reduced cerebral infarct area. Taking together the results obtained in our previous study into account, these results indicate that BHB decreased cerebral edema formation and infarct area by improving of the cerebral energy metabolism during ischemia and by inhibition of lipid peroxidation after reperfusion.     

Effect of nimodipine on ischemia-induced brain edema and mortality in a novel transient middle cerebral artery occlusion model

A novel transient middle cerebral artery (MCA) occlusion model in the rat was used to evaluate the effect of nimodipine on brain edema and mortality. Nimodipine (30 micrograms/kg) administered immediately after 3 hr of transient unilateral MCA occlusion attenuated significantly the post-ischemic increase of tissue water content and partly attenuated 45Ca accumulation in the parieto-temporal cortex ipsilateral to the left MCA occlusion 3 hr after reperfusion. Nimodipine decreased the mortality rate at 6 and 9 hr after recirculation, although the survival rate at 24 hr after recirculation was not different from the control group. These results suggest that nimodipine has beneficial effects in the early phase of the reperfusion period.     

Cardioprotective effects of the vasodilator/beta-adrenoceptor blocker, carvedilol, in two models of myocardial infarction in the rat.

The purpose of this study was to evaluate the cardioprotective effects of carvedilol, a beta-adrenergic blocker and vasodilator, in two models of ischemic myocardial damage in the rat. Following coronary artery occlusion for 0.5 h and reperfusion for 24 h (MI/R group), left ventricular (LV) injury was determined by planimetric analysis of triphenyltetrazolium chloride-stained tissue, and polymorphonuclear leukocyte infiltration was assessed by measuring myeloperoxidase (MPO) activity. In the vehicle-treated MI/R group, infarct size was 14.2 +/- 1.3% of the LV (n = 16), and MPO activity was increased to 2.8 +/- 0.7 from 0.14 +/- 0.03 U/g tissue in the vehicle-treated sham-occluded group (p less than 0.01). Carvedilol (1 mg/kg i.v., 15 min prior to coronary artery occlusion and at 3.5 h following reperfusion) reduced myocardial infarct size to 7.5 +/- 1.2% of the LV (n = 14; p less than 0.01) and attenuated the increase in MPO activity to 1.4 +/- 0.4 U/g tissue (p less than 0.05). A lower dose of carvedilol (i.e. 0.3 mg/kg i.v.) did not limit myocardial infarct size or the increase in MPO activity. In a model of permanent coronary artery occlusion, 24-hour survival was reduced from 85% in sham-occluded animals (n = 38) to 44% in the vehicle-treated MI group (n = 84; p less than 0.01). In comparison to the vehicle-treated MI group, carvedilol (0.3 mg/kg i.v., 15 min prior to coronary artery occlusion and 1 mg/kg 4 h after occlusion) improved survival by 55% (n = 64; p less than 0.05, compared to the vehicle-treated MI group), whereas the same dose of propranolol (n = 42) had no significant effect on survival. These results indicate that carvedilol reduces myocardial ischemia/reperfusion injury, and significantly improves survival in a permanent coronary artery occlusion model of myocardial infarction.     

Tacrolimus (FK506) limits accumulation of granulocytes and platelets and protects against brain damage after transient focal cerebral ischemia in rat

We investigated the neuroprotective effect of tacrolimus (FK506) on the ischemia-reperfusion injury caused by transient focal brain ischemia induced by middle cerebral artery (MCA) occlusion for 60 min in rats. Neuronal damage visualized as a decrease of MAP2 immunoreactivity was observed in the cerebral cortex at 9 h after MCA occlusion and further expanded at 24 h. Hypoxic areas visualized with an immunohistochemical reaction for 2-nitroimidazole, a hypoxia marker (hypoxyprobe-1), and accumulation of granulocytes and platelets were also observed at 9 h and 24 h after MCA occlusion. Tacrolimus (1 mg/kg, i.v.), administered immediately after MCA occlusion, attenuated cortical damage and decreased the hypoxyprobe-1 positive area, as well as the number of granulocytes and platelets at 24 h after MCA occlusion. Immunohistochemical analysis showed that tacrolimus reduced the number of blood vessels positively stained for ICAM-1, E-selectin and P-selection. These results suggested that tacrolimus limited attachment of granulocytes and platelets to blood vessels by inhibiting the expression of adhesion molecules and protected neuronal tissue from hypoxic insults.     

Neuroprotective effects of an AMPA receptor antagonist YM872 in a rat transient middle cerebral artery occlusion model

The neuroprotective effects of YM872 ([2,3-dioxo-7-(1H-imidazol-1-yl)6-nitro-1,2,3,4-tetrahydro-1-quinoxal inyl]acetic acid monohydrate), a novel alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptor antagonist with high water solubility, were examined in rats with transient middle cerebral artery (MCA) occlusion. The right MCA of male SD rats was occluded for 3 h using the intraluminal suture occlusion method. YM872 significantly reduced the infarct volume 24 hours after occlusion, at dosages of 20 and 40 mg/kg/h (iv infusion) when given for 4 h immediately after occlusion. Furthermore, delayed administration of YM872 (20 mg/kg/h iv infusion for 4 h, starting 2 or 3 h after the occlusion) also reduced the infarct volume and the neurological deficits measured at 24 h. Additionally, the therapeutic efficacy of YM872 persisted for at least seven days after MCA occlusion in animals treated with YM872 for 4 h starting 2 h after MCA occlusion. These data demonstrate that AMPA receptors contribute to the development of neuronal damage after reperfusion as well as during ischemia in the focal ischemia models and that the acute effect of the blockade of AMPA receptors persists over a long time period. YM872 shows promise as an effective treatment for patients suffering from acute stroke.     

Rosiglitazone, a peroxisome proliferator-activated receptor-gamma ligand, reduces infarction volume and neurological deficits in an embolic model of stroke

1. Stroke is accompanied by a robust inflammatory response, glutamate-mediated excitotoxicity, release of reactive oxygen species and apoptosis. Thiazolidinediones, which target the nuclear receptor peroxisome proliferator-activated receptor (PPAR)-g, have been reported recently to exhibit potent anti-inflammatory and anti-oxidant actions and inhibit both neural excitotoxicity and apoptosis. 2. The present study was conducted to determine whether rosiglitazone, a potent thiazolidinedione for PPAR-g, would show efficacy against the cerebral infarction and neurological dysfunctions induced by embolic middle cerebral artery (MCA) occlusion in the rat. 3. Focal ischaemic injury was induced by embolizing a preformed clot into the MCA. Rosiglitazone was dissolved in dimethyl sulphoxide and injected i.p. 1 h before MCA occlusion at doses of 0.33, 0.1, 0.3 or 1 mg/kg. In addition, 1 mg/kg rosiglitazone was used immediately or 4 h after embolization. Forty-eight hours after MCA occlusion, brains were removed, sectioned and stained with a 2% solution of 2,3,5-triphenyltetrazolum chloride and analysed using a commercial image-processing software program. 4. When rosiglitazone was administered 1 h before embolization, it significantly reduced infarct volume by 48.2, 68.4% and 70.3% at doses of 0.1, 0.3 and 1 mg/kg, respectively (P < 0.001). Administration of rosiglitazone (1 mg/kg) immediately or 4 h after stroke also reduced infarct volume by 67 and 50.8%, respectively (P < 0.001). Rosiglitazone-treated rats also demonstrated improved neurological functions. However, there were no statistically significant differences between control and treated groups in terms of brain oedema at 48 h after ischaemic injury. 5. The findings of the present study may support the idea of a potential benefit of thiazolidinediones in the management of ischaemic stroke.     

Protective effect of adenosine against neuronal injury induced by middle cerebral artery occlusion in rats as evidenced by diffusion-weighted imaging

In the present study, adenosine, an inhibitory neuromodulator, was studied in male Wistar rats subjected to 2 h of transient middle cerebral artery (MCA) occlusion. Adenosine (500 mg/kg ip) was administered twice-once at the time of MCA occlusion and again at the time of reperfusion-and evaluated for its protective effect by using diffusion-weighted imaging (DWI) (30 min after reperfusion). After the DWI experiments, one group of animals was euthanized 2 h after reperfusion for the estimation of oxidative stress markers, while in another group, neurological deficit was assessed 24 h after MCA occlusion. In the adenosine-treated group, percent hemispheric lesion area (%HLA) in DWI was significantly attenuated (11.7+/-5.2) as compared to vehicle-treated group (21.4+/-4.7). The level of malondialdehyde (MDA) (301.8+/-22 nmol/g wet tissue) in the adenosine-treated group was significantly decreased as compared to that in the vehicle-treated MCA-occluded rats (420+/-20 nmol/g wet tissue). An insignificant change was observed in the levels of glutathione in both the vehicle-treated MCA-occluded and the adenosine-treated groups. The neurological deficit was significantly improved in the adenosine-treated group (1.8+/-0.06) as compared to the vehicle-treated (2.9+/-0.38) group. This is the first study to demonstrate the effectiveness of adenosine using DWI in the MCA-occluded rats.     

Increased leptin permeation across the blood-brain barrier after chronic alcohol ingestion.

Leptin, a polypeptide mainly produced in the periphery, crosses the blood-brain barrier (BBB) by receptor-mediated transport to exert multiple central nervous system actions including decreased food intake. The reciprocal interactions between leptin transport and alcohol drinking are not clear. In this study, we tested whether alcohol increases leptin entry into brain and, if this occurs, whether it is a consequence of a generalized increase in the permeability of the BBB. BBB permeability to albumin, the increased permeation of which indicates BBB disruption, as well as to leptin was measured after alcohol ingestion. CD1 and B6 mice ingested a 5% liquid alcohol diet or its isocaloric control for 2 weeks. Alcohol ingestion resulted in increased blood-alcohol levels, decreased blood-leptin concentrations, and increased permeation of radioactively labeled leptin across the BBB as shown by in situ perfusion. Although the increased influx of the vascular marker albumin into brain showed partial disruption of the BBB, the influx of (125)I-leptin still could be suppressed by excess unlabeled leptin, indicating persistence of its saturable transport system. When given a choice of either alcohol or control diet, even the alcohol-preferring B6 mice showed a significantly greater preference for the control liquid diet, and there was no evidence of BBB disruption or alterated leptin transport. Furthermore, acute alcohol intoxication induced by intraperitoneal injection of 20% alcohol did not result in BBB disruption or increased leptin permeation 4 h later. Thus, partial disruption of the BBB and increased permeation of leptin in both CD1 and B6 mice were only induced by chronic alcohol ingestion. The results showing increased leptin permeation across the BBB lead to the speculation that leptin may serve as a homeostatic feeding signal in these mice.     

Acute neurovascular unit protective action of pinocembrin against permanent cerebral ischemia in rats

Acute vascular- and neuroprotective effects of pinocembrin (1) were evaluated in a rat model of focal cerebral ischemia. Focal cerebral ischemia was induced by the middle cerebral artery occlusion (MCAO) for 24 h. 5,7-Dihydroxyflavanone (compound 1; at 3, 10, or 30 mg/kg), intravenously injected at 0, 8, and 16 h after MCAO, reduced the cerebral infarct volumes by 47, 39, and 37%, respectively, as visualized by 2,3,5-triphenyltetrazolium chloride staining (P < 0.01). Treatment with 1 also reduced brain swelling and improved behavioral deficits significantly (P < 0.01 and 0.05, respectively). To evaluate the effect of 1 on blood-brain barrier (BBB) disruption, mixture of Evans Blue (EB) and sodium fluorescein (NF) was intravenously injected immediately after MCAO. Global NF/EB uptake and fluorescence imaging of local BBB disruption were measured. Treatment with compound 1 reduced the leakage of both dyes, manifesting a preventive action in BBB integrity. This is the first time to demonstrate that 1 has acute neurovascular protective action against permanent focal cerebral ischemia. The mechanism of neurovascular protective action of 1 is under investigation.     

促红细胞生成素对低出生体质量新生大鼠缺氧缺血后脑神经细胞凋亡的影响

目的 探究促红细胞生成素(Erythropoietin,EPO)对低出生体质量(low birth weight,LBW)新生大鼠缺氧缺血后脑神经细胞凋亡的影响.方法 2019年1—8月,选取自广东省医学实验动物中心购买的80只LBW新生大鼠以随机数字表法分为空白对照组、模型组、低剂量EPO组、高剂量EPO组,每组各20只;除空白对照组外,各组大鼠均采用结扎左侧颈总动脉并吸入80 mL/L氧气2 h制作为新生大鼠制成缺氧缺血性脑损伤(hypoxic ischemic brain damage,HIBD)动物模型;低剂量EPO组和高剂量EPO组于造模前、造模后7 d连续腹腔注射EPO(2500 IU·kg-1·d-1和5000 IU·kg-1·d-1),空白对照组和模型组腹腔注射等量的生理盐水;完成给药后24 h处死大鼠,使用HE染色法检测大鼠大脑皮层改变情况;使用TUNEL法检测大鼠神经细胞凋亡情况;使用蛋白质印迹法检测半胱氨酸天冬氨酸蛋白酶-3(Caspase-3)、半胱氨酸天冬氨酸蛋白酶-9(Caspase-9)、B淋巴细胞瘤-2(Bcl-2)、Bcl-2相关X(Bax)蛋白表达情况;使用流式细胞仪检测大鼠脑神经细胞凋亡情况.结果 HE染色结果显示,空白对照组大鼠大脑皮层细胞密集、排列有序,层次清晰、分明;模型组大鼠大脑皮层细胞明显肿胀坏死、空化、间隙增宽;低剂量EPO组大鼠大脑皮层细胞轻度水肿、排列较为稀疏;高剂量EPO组大鼠大脑皮层洗白间隙增宽不明显、细胞层次较为分明、有序;TUNEL法结果显示,空白对照组、模型组、低剂量EPO组、高剂量EPO组大鼠神经细胞凋亡率分别为(10.21±2.00)％、(65.85±10.48)％、(40.32±5.22)％、(20.79±2.33)％,相比空白对照组,模型组神经细胞凋亡率、Bax、Caspase-3、Caspase-9蛋白相对表达量显著升高,Bcl-2蛋白相对表达量显著降低(P<0.05);相比模型组使用EPO处理各组神经细胞凋亡率、Bax、Caspase-3、Cas-pase-9蛋白相对表达量显著降低,且高剂量EPO组低于低剂量EPO组(P<0.05),Bcl-2蛋白相对表达量显著升高,且高剂量EPO组高于低剂量EPO组(P<0.05).结论 EPO可以通过抑制凋亡蛋白的表达并促进抑凋亡蛋白的表达,保护LBW新生大鼠缺氧缺血后脑神经细胞.     

枕大池注入促红细胞生成素在兔蛛网膜下腔出血的脑保护作用

目的研究枕大池单次注入促红细胞生成素(EPO)对蛛网膜下腔出血后脑血管痉挛和神经细胞损伤的影响。方法30只新西兰白兔随机分为3组,假手术组(Sham组)、蛛网膜下腔出血组(SAH组)和EPO组(n=10)。Sham组穿刺,其它两组行枕大池一次穿刺注血造模。30min后假手术组和出血组从枕大池注入生理盐水(0·10ml·kg-1),EPO组注入EPO(200IU·kg-1,0·10ml·kg-1)。所有动物在造模后48h处死,使用CAST体视学图像分析系统测量分析并比较不同组间基底动脉管腔面积、收缩系数以及海马CA1区正常神经元密度。结果与SAH组相比,EPO组食欲明显改善(P<0·05),体重增加(P<0·05),基底动脉管腔面积明显增加(P<0·01),收缩系数减小(P<0·01),海马CA1神经元密度值也增加(P<0·05)。结论枕大池单次小剂量注入EPO可以预防SAH后脑血管痉挛,减轻脑神经细胞损伤。     

Long-lasting neuroprotection and neurological improvement in stroke models with new, potent and brain permeable inhibitors of poly(ADP-ribose) polymerase

BACKGROUND AND PURPOSES

Thienyl-isoquinolone (TIQ-A) is a relatively potent PARP inhibitor able to reduce post-ischaemic neuronal death in vitro. Here we have studied, in different stroke models in vivo, the neuroprotective properties of DAMTIQ and HYDAMTIQ, two TIQ-A derivatives able to reach the brain and to inhibit PARP-1 and PARP-2.

EXPERIMENTAL APPROACH

Studies were carried out in (i) transient (2 h) middle cerebral artery occlusion (tMCAO), (ii) permanent MCAO (pMCAO) and (iii) electrocoagulation of the distal portion of MCA in conjunction with transient (90 min) bilateral carotid occlusion (focal cortical ischaemia).

KEY RESULTS

In male rats with tMCAO, HYDAMTIQ (0.1–10 mg·kg⁻¹) injected i.p. three times, starting 4 h after MCAO, reduced infarct volumes by up to 70%, reduced the loss of body weight by up to 60% and attenuated the neurological impairment by up to 40%. In age-matched female rats, HYDAMTIQ also reduced brain damage. Protection, however, was less pronounced than in the male rats. In animals with pMCAO, HYDAMTIQ administered 30 min after MCAO reduced infarct volumes by approximately 40%. In animals with focal cortical ischaemia, HYDAMTIQ treatment decreased post-ischaemic accumulation of PAR (the product of PARP activity) and the presence of OX42-positive inflammatory cells in the ischaemic cortex. It also reduced sensorimotor deficits for up to 90 days after MCAO.

CONCLUSION AND IMPLICATIONS

Our results show that HYDAMTIQ is a potent PARP inhibitor that conferred robust neuroprotection and long-lasting improvement of post-stroke neurological deficits.     

Intracerebroventricular injection of microglia protects against focal brain ischemia

Microglia are macrophage-like phagocytic cells in the brain parenchyma. However, microglial function after neurodegeneration is not fully understood. In this study, occlusion of the middle cerebral artery (MCA) and reperfusion caused massive neuronal loss in the rat cerebral cortex and striatum after 3 days. When exogenous microglia were microinjected into the intracerebroventricle during MCA occlusion, neurodegenerative areas significantly decreased. At that time, migrated microglia were detected in the ischemic lesion. These results suggest that exogenous microglia can migrate into brain parenchyma and then protect against neurodegeneration induced by MCA occlusion and reperfusion.