Ischemia-reperfusion Injury In Rat Brain Research Articles

Cannabinoid CB1 receptor agonist ACEA alleviates brain ischemia/reperfusion injury via CB1\u2013Drp1 pathway

Activation of the cannabinoid CB1 receptor induces neuroprotection against brain ischemia/reperfusion injury (IRI); however, the mechanism is still unknown. In this study, we used oxygen-glucose deprivation/reoxygenation (OGD/R)-induced injury in neuronal cells and middle cerebral artery occlusion (MCAO)-induced brain IRI in rats to mimic ischemic brain injury, and hypothesized that the CB1 receptor agonist arachidonyl-2-chloroethylamide (ACEA) would protect ischemic neurons by inhibiting mitochondrial fission via dynamin-related protein 1 (Drp1). We found that OGD/R injury reduced cell viability and mitochondrial function, increased lactate dehydrogenase (LDH) release, and increased cell apoptosis, and mitochondrial fission. Notably, ACEA significantly abolished the OGD/R-induced neuronal injuries described above. Similarly, ACEA significantly reversed MCAO-induced increases in brain infarct volume, neuronal apoptosis and mitochondrial fission, leading to the recovery of neurological functions. The neuroprotective effects of ACEA were obviously blocked by coadministration of the CB1 receptor antagonist AM251 or by the upregulation of Drp1 expression, indicating that ACEA alleviates brain IRI via the CB1–Drp1 pathway. Our findings suggest that the CB1 receptor links aberrant mitochondrial fission to brain IRI, providing a new therapeutic target for brain IRI treatment.

Prolactin attenuates global cerebral ischemic injury in rat model by conferring neuroprotection

ABSTRACTPrimary Objective: Limited available therapeutics for ischemic stroke necessitate dire need of designing novel strategies for combating ischemic pathophysiological cascade among which neuroprotective strategies emerge as positive approaches. The neuropeptide prolactin is a pleiotropic hormone that affects various physiological conditions and reportedly combats neurotoxicity, neuronal stress and provides neuroprotection to hippocampal neurons in vitro.Research Design: The study explores the ability of prolactin in conferring neuroprotection in global cerebral ischemia in vivo and attempts to optimize the dose of prolactin which will be effective for the same.Methods and Procedure: Global cerebral ischemia was induced in male rats by bilateral common carotid occlusion (BCCAO) and different physiological and biochemical parameters were evaluated. Also, cerebral infarction and percentage of brain edema were measured.Results: The results revealed that prolactin significantly reduces cerebral infarct, brain water content and restores the physiological conditions like blood pressure, heart rate and cerebral blood flow. Also, prolactin markedly reduces the increased levels of the neurotransmitters (ɣ-aminobutyric acid and glutamate), cerebral calcium and nitrate in different brain compartments of ischemic rats.Conclusion: Prolactin is able to ameliorate ischemia-reperfusion injury in rat brain and might be a potent candidate for further neuro-therapeutics development.

Changes in electrolyte concentrations alter the impedance during ischemia-reperfusion injury in rat brain

Objective: Ischemic stroke is a major cause of death and disability worldwide. Nowadays, electrical impedance spectroscopy is an emerging tool to differentiate between normal and stroke conditions. Approach: In this study, changes in the bio-impedance spectroscopy using a two-electrode method with varying frequencies from 100 to 35 kHz have been assessed in a model of global cerebral ischemia in anesthetized rats during normal, occlusion and reperfusion conditions. Global cerebral ischemia was induced by bilateral common carotid artery occlusion for 40 min following 40 min of reperfusion. The concentration of sodium, potassium, calcium and chloride ions in the whole rat brain was determined by electrolyte analyzer. For the interpretation of in vivo results, changes in electrical impedance with varying concentrations of sodium, potassium and calcium ions in artificial cerebrospinal fluid (aCSF) were also observed using the bio-impedance spectroscopy method. Main results: The in vivo bio-impedance analysis suggests that the impedance is consistently increased during occlusion as compared to the normal condition. The in vitro study revealed that the impedance escalates with an increase in the concentration of potassium and calcium ions and reduces with an increase in the concentration of sodium ions in aCSF. A further electrolyte analysis suggested that the level of sodium and chloride ions is significantly decreased and the level of calcium and potassium is significantly increased during occlusion as compared to the normal condition. Significance: These findings suggest that the increase in impedance during occlusion may be due to changes in the ionic concentration of the rat brain. The above in vivo and in vitro studies successfully demonstrated and interrelated the change in impedance with corresponding changes in ionic concentration.

Eventual analysis of global cerebral ischemia-reperfusion injury in rat brain: a paradigm of a shift in stress and its influence on cognitive functions.

Cognitive issues in stroke arise as a result of reperfusion of a clogged artery, which is reported to exacerbate the injury in the brain leading to oxidative stress. Through the present work, we try to understand the regional variations across brain regions mainly cortex and striatum associated with the progression of ischemia-reperfusion injury (IRI). In a rat model of IRI, the influence of varying ischemia and reperfusion times on the biochemical phases across the brain regions were monitored. IRI resulted in the blood-brain barrier disruption and developed mild areas of risk. The brain's tolerance towards IRI indicated a progressive trend in the injury and apoptosis from ischemia to reperfusion that was supported by the activities of plasma lactate dehydrogenase and tissue caspase-3. Cognitive impairment in these rats was an implication of cellular oxidative stress (higher lipid peroxidation and lower antioxidant enzyme activity) that persisted by 24-h reperfusion. The oxidative stress was prominent in the cortex than the striatum and was supported by the lower ATP level. Upregulated Mn-SOD expression leading to a preserved mitochondria in the striatum could be attributed to the regional protection. Overall, a progression of IRI was observed from striatum to cortex leading to 5-day cognitive decline.

Effect of theanine pretreatment on DNA repair function in neurons during brain ischemia-reperfusion injury in rats

Objective To investigate the effect of theanine pretreatment on DNA repair function in neurons during brain ischemia-reperfusion(I/R)injury in rats. Methods One hundred and eight male Sprague-Dawley rats, weighing 290-310 g, aged 15 weeks, were randomly divided into 3 groups(n=36 each)using a random number table: sham operation group(S group), I/R group and theanine pretreatment group(T group). Global cerebral I/R was produced by 4-vessel occlusion method.Bilateral vertebral arteries were electrically cauterized, and bilateral common carotid arteries were clamped for 6 min.Theanine 1 g/kg was injected intravenously at 4 h before clamping bilateral common carotid arteries in T group, and the equal volume of normal saline was given in the other two groups.At 2, 6, 12, 24, 48 and 72 h of reperfusion, 6 rats were selected in each group and sacrificed, the brains were removed, and the hippocampus was isolated for determination of the number of viable neurons in the hippocampal CA1 region(with a light microscope), apoptosis in neurons in the hippocampal CA1 region(by TUNEL), and expression of DNA repair protein X-ray repair cross-complementing group 1(XRCC1)and Ku70(by immunohistochemistry). The apoptotic index was calculated. Results Compared with S group, the number of viable neurons was significantly decreased, and the apoptotic index was significantly increased at 6, 12, 24, 48 and 72 h of reperfusion, and the expression of XRCC1 and Ku70 was significantly down-regulated at 2, 6, 12, 24, 48 and 72 h of reperfusion in I/R group(P<0.01). Compared with I/R group, the number of viable neurons was significantly increased at 12, 24, 48 and 72 h of reperfusion, the apoptotic index was significantly decreased at 6, 12, 24, 48 and 72 h of reperfusion, and the expression of XRCC1 and Ku70 was significantly up-regulated at 2, 6, 12, 24, 48 and 72 h of reperfusion in T group(P<0.01). Conclusion The mechanism by which theanine pretreatment attenuates brain I/R injury is related to enhancement of DNA repair function and reduction of neuronal apoptosis in rats. Key words: Tea; Glutamates; Brain; Reperfusion injury; DNA Repair; Apoptosis; Neurons

Protective Effects of Minocycline against Short-Term Ischemia-Reperfusion Injury in Rat Brain

The aim of this study was to assess the effects of minocycline on cerebral ischemia-reperfusion (I/R) injury in rats. The study was carried out on 24 male Wistar albino rats, weighing 200-250 g, which were divided into three groups: (i) control (n = 8), (ii) I/R (n = 8) and (iii) I/R + minocycline (n = 8). Minocycline was administrated at a dose of 90 mg/kg p.o. to the I/R group 48, 24 and 1 h before ischemia. Following bilateral exposure of the common carotid arteries by anterior cervical dissection and separation of the vagus nerve, I/R injury was performed by occlusion. Following reperfusion, malondialdehyde (MDA), superoxide dismutase, glutathione peroxidase and catalase levels in the blood and brain tissue, and creatine kinase (CK), CK-BB, lactate dehydrogenase (LDH), neuron-specific enolase (NSE) and protein S100β levels in the blood were measured and the histopathological changes were monitored. Regarding histopathological evaluation, symptoms of degeneration were significantly improved in the I/R + minocycline group compared to the I/R-only group. Statistical analysis of the biochemical parameters revealed significant differences in MDA (p < 0.001), nitric oxide (p < 0.05), CK (p < 0.05) and CK-MB (p < 0.05) levels between the I/R + minocycline group and the I/R group. According to the literature, the effect of minocycline is firstly assessed by LDH, CK-MB, NSE and S-100β analysis in addition to antioxidant status and histopathological analysis.

Imaging of rat cerebral ischemia-reperfusion injury using(99m)Tc-labeled duramycin.

Prompt identification of necrosis and apoptosis in the infarct core and penumbra region is critical in acute stroke for delineating the underlying ischemic/reperfusion molecular pathologic events and defining therapeutic alternatives. The objective of this study was to investigate the capability of (99m)Tc-labeled duramycin in detecting ischemia-reperfusion injury in rat brain after middle cerebral artery (MCA) occlusion. Ischemic cerebral injury was induced in ten rats by vascular insertion of a nylon suture in the left MCA for 3 hr followed by 21-24hr reperfusion. After i.v. injection of (99m)Tc-duramycin (1.0-3.5 mCi), dynamic cerebral images were acquired for 1 hr in six rats using a small-animal SPECT imager. Four other rats were imaged at 2 hr post-injection. Ex vivo images were obtained by autoradiography after sacrifice. Histologic analyses were performed to assess cerebral infarction and apoptosis. SPECT images showed that (99m)Tc-duramycin uptake in the left cerebral hemisphere was significantly higher than that in the right at 1 and 2 hr post-injection. The level of radioactive uptake in the ischemic brain varied based on ischemic severity. The average ratio of left cerebral hot-spot uptake to right hemisphere radioactivity, as determined by computerized ROI analysis, was 4.92±0.79. Fractional washout at 1 hr was 38.2±4.5% of peak activity for left cerebral hot-spot areas and 80.9±2.0% for remote control areas (P<0.001). Based on triphenyltetrazolium chloride staining and autoradiograph image data, the hotspot uptake may be associated primarily with the ischemic penumbra, in which high apoptotic activity was observed by cleaved caspase-3 immunocytochemical staining. (99m)Tc-duramycin SPECT imaging may be useful for detecting and quantifying ongoing apoptotic neuronal cell loss induced by ischemia-reperfusion injury.

Injectable Caltrop Fruit Saponin Protects Against Ischemia-Reperfusion Injury in Rat Brain

The present study aimed to investigate the protective effects of injectable caltrop fruit saponin preparation (ICFSP) on ischemia-reperfusion injury in rat brain. Rats were injected with ICFSP and then subjected to cerebral ischemia-reperfusion injury induced by middle cerebral artery occlusion. Then the neurological deficit score was evaluated by Bederson's method. The infarct size was assessed by TTC staining. The content of malondialdehyde (MDA) and nitric oxide (NO), and the activity of superoxide dismutase (SOD) in rat cerebrum were measured with kits, and the content of 6 K prostaglandin F1α (6-K-PGF 1α), thromboxane B2 (TXB2) and endothelin (ET) in blood plasma was measured by radioimmunoassay. The results demonstrated that ICFSP led to a decrease in infarct size (p < 0.01), neurological deficit score (p < 0.05) and plasma content of TXB2 and ET (p < 0.05), and an increase of the plasma level of 6-K-PGF 1α (p < 0.05) and SOD activity in cerebrum, where the MDA and NO content were decreased. The treatment improved forelimb function. ICFSP showed a similar potency compared to that of Ligustrazine hydrochloride parenteral solution (LHPS) and nimodipine (Nim). We concluded that ICFSP protects the brain damage caused by ischemia-reperfusion injury in rats, and this may be closely related to the regulation of reactive oxygen species (MDA and SOD activity) and NO levels in the rat cerebrum, as well as vasoactive factors in the plasma (6-K-PGF 1α, TXB2 and ET).

Neuroprotective and antioxidative effect of cactus polysaccharides in vivo and in vitro.

Cactus polysaccharides (CP), some of the active components in Opuntia dillenii Haw have been reported to display neuroprotective effects in rat brain slices. In the present study, we investigated the neuroprotective properties of CP and their potential mechanisms on brain ischemia-reperfusion injury in rats, and on oxidative stress-induced damage in PC12 cells. Male Sprague-Dawley rats with ischemia following middle cerebral artery occlusion and reperfusion were investigated. CP (200 mg/kg) significantly decreased the neurological deficit score, reduced infarct volume, decreased neuronal loss in cerebral cortex, and remarkably reduced the protein synthesis of inducible nitric oxide synthase which were induced by ischemia and reperfusion. Otherwise, the protective effect of CP was confirmed in in vitro study. CP protected PC12 cells against hydrogen peroxide (H(2)O(2)) insult. Pretreatment with CP prior to H(2)O(2) exposure significantly elevated cell viability, reduced H(2)O(2)-induced apoptosis, and decreased both intracellular and total accumulation of reactive oxygen species (ROS) production. Furthermore, CP also reversed the upregulation of Bax/Bcl-2 mRNA ratio, the downstream cascade following ROS. These results suggest that CP may be a candidate compound for the treatment of ischemia and oxidative stress-induced neurodegenerative disease.

Effects of repetitive transcranial magnetic stimulation on adenosine triphosphate content and microtubule associated protein-2 expression after cerebral ischemia-reperfusion injury in rat brain

Repetitive transcranial magnetic stimulation (rTMS) research has mainly been focused on the therapeutic effect of psychiatric disorders and Parkinson's disease. A few studies have shown that rTMS might protect against delayed neuronal death induced by transient ischemia, enhance long-term potentiation in ischemic conditions and affect regional brain blood flow and metabolism. The aim of this study was to determine the effects of repetitive transcranial magnetic stimulation (rTMS) on adenosine triphosphate (ATP) content and microtubule associated protein-2 (MAP-2) expression in rat brain after middle cerebral artery occlusion (MCAO)/reperfusion. To study the effects of different timecourses of rTMS on ATP content and MAP-2 expression, 90 rats were randomly divided into three groups (30 rats in each group). To study the effects of multiple rTMS parameters on ATP content and MAP-2 expression, the rats in each group were further divided into six subgroups (five rats each). The rats were sacrificed at 1-hour, 24-hour and 48-hour intervals after reperfusion, and the brain tissues were collected for the detection of ATP and MAP-2. rTMS could significantly increase ATP content and MAP-2 expression in the left brain following ischemic insult (P < 0.01) and different rTMS parameters had different effects on the ATP level and the MAP-2 expression in the left striatum. A high-frequency rTMS played an important role in MAP-2 expression and ATP preservation. This study revealed that rTMS induced significant increase of ATP content and MAP-2 expression in the injured area of the brain, suggesting that the regulation of both ATP and MAP-2 may be involved in the biological mechanism of the effect of rTMS on neural recovery. Therefore, rTMS may become a potential adjunctive therapy for ischemic cerebrovascular disease.