Protective Effects of Adrenomedullin on Rat Cerebral Tissue After Transient Bilateral Common Carotid Artery Occlusion and Reperfusion.
ABSTRACT: OBJECTIVE:We aimed to investigate the protective effect of adrenomedullin (ADM) on cerebral tissue of rats with cerebral ischemia/reperfusion (I/R) injury. METHODS:Thirty-two Wistar rats were randomized into four groups (n=8). In the I/R Group, bilateral common carotid arteries were clamped for 30 minutes and, subsequently, reperfused for 120 minutes. In the ADM Group, rats received 12 µg/kg of ADM. In the I/R+ADM Group, bilateral common carotid arteries were clamped for 30 minutes and, subsequently, the rats received 12 µg/ kg of ADM. Then, reperfusion was performed for 120 minutes. The Control Group underwent no procedure. Blood and brain tissue samples were collected for biochemical and histopathological analysis. Serum malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GPx) were analysed. Brain tissue was evaluated histopathologically and neuronal cells were counted in five different fields, at a magnification of ×400. RESULTS:Brain MDA in I/R Group was significantly higher than in ADM Group. Brain GPx and SOD in I/R+ADM Group were significantly higher than in I/R Group. The number of neurons was decreased in I/R Group compared to the Control Group. The number of neurons in I/R+ADM Group was significantly higher than in I/R Group, and lower than in Control Group. Apoptotic changes decreased significantly in I/R+ADM Group and the cell structure was similar in morphology compared to the Control Group. CONCLUSION:We demonstrated the cerebral protective effect of ADM in the rat model of cerebral I/R injury after bilateral carotid artery occlusion.
Project description:Objective:Currently, most models of vascular cognitive impairment are established by occluding the carotid arteries uni- or bilaterally to reduce the cerebral blood flow mimicking chronic cerebral hypoxia. Due to the sudden blood flow interruption, a gradual narrowing of the carotid artery cannot be completely imitated. This paper aims to establish a bilateral carotid stenosis model with mild cognitive dysfunction and mild white matter changes to simulate patients with vascular predementia. Methods:Aged Wistar rats (18 months old) underwent either bilateral common carotid artery stenosis (BCAS) or occlusion (BCAO) surgery or a sham operation (control group). The cerebral blood flow in the frontal cortex was measured using Doppler flowmetry. Thirty days after surgery, cognitive function impairments were determined with the Morris water maze; cerebral magnetic resonance imaging was performed to detect changes in fractional anisotropy to assess white matter injuries, and histological studies were performed. Results:The aged rats in the BCAS group showed a more gradual cerebral blood flow reduction and a lower mortality rate (11%) compared to rats in the BCAO group. The water maze test revealed a more marginal impairment affecting spatial learning and memory in rats with BCAS than in rats with BCAO. Diffusion tensor imaging detected white matter injuries in the hippocampus and cerebral cortex of BCAS rats. Particularly, a small portion of nerve fibers of the lateral somatosensory cortex was significantly different between rats of the BCAO and BCAS groups. In the BCAS group, the microscopic structure of the hippocampal CA1 region changed slightly after 30 days and sustained a slight mitochondrial crista crack. Fluorescence staining indicated that the number of GFAP-positive cells was increased in rat brains of the BCAS group, and this phenomenon was even more pronounced in the BCAO group. The hnRNPA2/B1 and GABAAR-?1 expression levels were significantly decreased in the hippocampus of rats with BCAS compared to those of controls. Conclusion:Severe bilateral carotid stenosis induced mild cognitive dysfunction and slight structural changes in the brains of aged rats. Thus, a chronic cerebral hypoperfusion model was successfully established.
Project description:Current study was designed multiple occlusions and reperfusion of bilateral carotid arteries induced cerebral injury model and evaluated the protective effect of gallic acid on it. <i>In silico</i> study was involved to study gallic acid binding affinity on cerebrotonic proteins compared with standard drugs using <i>Autodoc vina tool</i>. Cerebral ischemia was induced by occlusion of bilateral common carotid arteries for 10 mins followed by 10 reperfusions (1 cycle), cycle was continued to 3 cycles (MO/RCA), then pathological changes were observed by estimation of brain antioxidants as superoxide dismutase, glutathione, catalase, oxidants like malonaldehyde, cerebral infarction area, histopathology, and study gallic acid treatment against cerebral injury. Gallic acid exhibited a strong binding affinity on targeted cerebrotoxic proteins. MO/RCA rat brain antioxidant levels were significantly decreased and increased MDA levels (p < 0.0001), Infarction size compared to sham rats. Gallic acid treatment rat brain MDA levels significantly decreased (p < 0.4476) and increased SOD (p < 0.0001), CAT (p < 0.0001), GSH (p < 0.0001), cerebral infarction area when compared to MO/RCA group. Developed model showed significant cerebral ischemic injury in rats, injury was ameliorated by Gallic acid treatment and in silico approaches also inhibit the cerebrotoxic protein function by targeting on active sites.
Project description:BACKGROUND: We are currently investigating microglial activation and neuronal precursor cell (NPC) proliferation after transient middle cerebral artery occlusion (tMCAo) in rats. This study aimed: (1) to investigate differences in hippocampal NPC proliferation in outbred male spontaneously hypertensive rats (SHRs) and Sprague-Dawley rats (SDs) one week after tMCAo; (2) to present the practical use of the optical fractionator and 2D nucleator in stereological brain tissue analyses; and (3) to report our experiences with an intraluminal tMCAo model where the occluding filament is advanced 22 mm beyond the carotid bifurcation and the common carotid artery is clamped during tMCAo. METHODS: Twenty-three SDs and twenty SHRs were randomized into four groups subjected to 90 minutes tMCAo or sham. BrdU (50 mg/kg) was administered intraperitoneally twice daily on Day 4 to 7 after surgery. On Day 8 all animals were euthanized. NeuN-stained tissue sections were used for brain and infarct volume estimation with the 2D nucleator and Cavalieri principle. Brains were studied for the presence of activated microglia (ED-1) and hippocampal BrdU incorporation using the optical fractionator. RESULTS: We found no significant difference or increase in post-ischemic NPC proliferation between the two strains. However, the response to remote ischemia may differ between SDs and SHRs. In three animals increased post-stroke NPC proliferation was associated with hippocampal ischemic injury. The mean infarct volume was 89.2 +/- 76.1 mm3 in SHRs and 16.9 +/- 22.7 mm3 in SDs (p < 0.005). Eight out of eleven SHRs had ischemic neocortical damage in contrast to only one out of 12 SDs. We observed involvement of the anterior choroidal and hypothalamic arteries in several animals from both strains and the anterior cerebral artery in two SHRs. CONCLUSIONS: We found no evidence of an early hippocampal NPC proliferation one week after tMCAo in both strains. Infarction within the anterior choroidal artery could induce hippocampal ischemia and increase NPC proliferation profoundly. NPC proliferation was not aggravated by the presence of activated microglia. Intraluminal tMCAo in SHRs gave a more reliable infarct with neocortical involvement, but affected territories supplied by the anterior cerebral, anterior choroidal and hypothalamic arteries.
Project description:Oxidative stress is a key pathogenic factor in both neurogenerative and metabolic diseases. However, its contribution in the brain complications of insulin resistance is still not well understood. Therefore, the aim of this study was the evaluation of redox homeostasis and oxidative damage in the hypothalamus and cerebral cortex of insulin-resistant and control rats. 16 male Wistar rats were divided into two equal groups (n = 8): the control and high fat diet group (HFD). Prooxidant enzymes (xanthine oxidase and NADPH oxidase); enzymatic and nonenzymatic antioxidants [glutathione peroxidase (GPx), glutathione reductase (GR), catalase (CAT), superoxide dismutase-1 (SOD-1), and uric acid (UA)]; and oxidative damage products [advanced glycation end products (AGE), 4-hydroxynonenal (4-HNE), malondialdehyde (MDA), and 8-hydroxy-2'-deoxyguanosine (8-OHdG)] as well as the total antioxidant capacity (TAC), total oxidant status (TOS), oxidative stress index (OSI), and total ferric reducing ability of sample (FRAP) were evaluated in the hypothalamus and cerebral cortex as well as serum/plasma of HFD-fed and control rats. The activity of prooxidant enzymes was significantly increased in the cerebral cortex and hypothalamus of HFD-fed rats vs. control rats. Additionally, we have showed enhanced antioxidant efficiency in the hypothalamus (?CAT, ?UA, ?TAC, and ?FRAP) and cerebral cortex (?GPx, ?CAT, ?SOD-1, ?UA, ?TAC, and ?FRAP) of HFD-fed rats. All of the oxidative damage markers (AGE, 4-HNE, MDA, 8-OHdG, and OSI) were significantly increased in the cerebral cortex of insulin-resistant rats, while only 4-HNE and MDA were markedly higher in the hypothalamus of the HFD group. Summarizing, the results of our study indicate an adaptive brain response to the increased production of free radicals under insulin resistance conditions. Despite the increase in antioxidative defense systems, this mechanism does not protect both brain structures from oxidative damages. However, the cerebral cortex is more susceptible to oxidative stress caused by HFD.
Project description:Background:Reperfusion syndrome after carotid endarterectomy is a complication associated with cerebrovascular self-regulation in a chronically hypoperfused cerebral hemisphere, leading to severe neurological damage. Vitamin C is an important antioxidant in brain metabolism that has shown some neuroprotective actions. Objective:To investigate the potential effects of vitamin C on cerebral reperfusion in comparison with placebo (saline) in rats. Methods:Male Wistar rats were divided into 3 groups: (i) Sham (n = 4), animals exposed to carotid arteries dissection without clamping; (ii) Control (n = 4), animals exposed to carotid arteries dissection without clamping; (ii) Control (n = 4), animals exposed to carotid arteries dissection without clamping; (ii) Control (. Results:Rats treated with vitamin C presented with a similar behavior as compared to the Sham group in all the three tests (p > 0.05), but it was significantly different from controls (p > 0.05), but it was significantly different from controls (p > 0.05), but it was significantly different from controls (. Conclusion:In the present study, vitamin C was associated with behavioral and motor preservation as well as decreased cerebral MDA levels after induced cerebral ischemia in rats.
Project description:Glucagon-like peptide-1 (GLP-1) receptor activation in the brain provides neuroprotection. Exendin-4 (Ex-4), a GLP-1 analog, has seen limited clinical usage because of its short half-life. We developed long-lasting Ex-4-loaded poly(D,L-lactide-co-glycolide) microspheres (PEx-4) and explored its neuroprotective potential against cerebral ischemia in diabetic rats. Compared with Ex-4, PEx-4 in the gradually degraded microspheres sustained higher Ex-4 levels in the plasma and cerebrospinal fluid for at least 2 weeks and improved diabetes-induced glycemia after a single subcutaneous administration (20 μg/day). Ten minutes of bilateral carotid artery occlusion (CAO) combined with hemorrhage-induced hypotension (around 30 mm Hg) significantly decreased cerebral blood flow and microcirculation in male Wistar rats subjected to streptozotocin-induced diabetes. CAO increased cortical O2(-) levels by chemiluminescence amplification and prefrontal cortex edema by T2-weighted magnetic resonance imaging analysis. CAO significantly increased aquaporin 4 and glial fibrillary acidic protein expression and led to cognition deficits. CAO downregulated phosphorylated Akt/endothelial nitric oxide synthase (p-Akt/p-eNOS) signaling and enhanced nuclear factor (NF)-κBp65/intercellular adhesion molecule-1 (ICAM-1) expression, endoplasmic reticulum (ER) stress, and apoptosis in the cerebral cortex. PEx-4 was more effective than Ex-4 to improve CAO-induced oxidative injury and cognitive deficits. The neuroprotection provided by PEx-4 was through p-Akt/p-eNOS pathways, which suppressed CAO-enhanced NF-κB/ICAM-1 signaling, ER stress, and apoptosis.
Project description:After carotid artery stenting, the procurement of information about blood flow redistribution among brain-feeding arteries and its time trend is essential to understanding a patient's physiological background and to determine their care regimen. Cerebral blood flow has been measured twice following carotid artery stenting in few previous studies, with some discrepancies in the results. The purpose of this study was to measure cerebral blood flow at multiple time points after carotid artery stenting, and to elucidate the time trend of cerebral blood flow and redistribution among arteries. Blood flow rates in 11 subjects were measured preoperatively, at one day, one week, and about three months, respectively after carotid artery stenting by using phase-contrast magnetic resonance imaging. The target vessels were the bilateral internal carotid arteries, the basilar artery, and the bilateral middle cerebral arteries. Lumen was semi-automatically defined using an algorithm utilizing pulsatility. The results showed that blood flow rates in the stented internal carotid artery and the ipsilateral middle cerebral artery increased following carotid artery stenting. Blood flow rates in the contralateral internal carotid artery and the basilar artery gradually declined, and they were lower than the preoperative values at three months after stenting. The sum of blood flow rates of the bilateral internal carotid arteries and the basilar artery increased after carotid artery stenting, and then decreased over the next three months. There was no significant change in the blood flow rate in the contralateral middle cerebral artery. From these results, it was concluded that redistribution among the bilateral internal carotid arteries and the basilar artery occurs after carotid artery stenting, and that it takes months thereafter to reach another equilibrium.
Project description:Neonatal hypoxic-ischemic (HI) encephalopathy can lead to severe brain damage and is a common cause of neurological handicaps in adulthood. To elucidate the molecular events occurring in cerebral cortices of mature rats (8 weeks old) after neonatal HI brain insult, we performed comprehensive gene expression and gene network analyses using a DNA microarray system (Agilent 4x44K). A rat model of neonatal HI encephalopathy (Rice model) was obtained by unilateral ligation of the common carotid artery of 7-day-old rats with hypoxia (exposure to 8% oxygen). Due to the HI insult-related breakdown of the ipsilateral hemisphere in the brain, RNAs were prepared from the contralateral cerebral cortices of 8-week-old rats and analyzed by DNA microarray. Biofunctional analysis of differentially regulated genes revealed that many upregulated genes were related to cell death signaling, such as the arachidonic acid cascade. In contrast, many downregulated genes were related to gene expression, reflecting progressive damage by the HI insult, even within the contralateral cerebral hemisphere. Seven-day-old Wistar rats were assigned to two groups: the control group and the Rice group (four pups in each group). HI brain insult was not induced in the control group rats. The Rice group rats were subjected to a modified Levine’s procedure to induce HI brain injury. The Rice group rats were anesthetized with ether, and the left carotid artery was sectioned between double ligatures with 4-0 surgical silk. The rats were allowed to recover for 1–2 h and then exposed to 1 h of hypoxia in a plastic chamber that was perfused with a mixture of humidified 8% oxygen balanced with nitrogen. The temperature inside the chamber was maintained at 33 °C, the usual temperature generated when pups huddle with the mother. The cerebral cortexes contralateral to the HI brain insult and those of the same side of the control animals were used for the experiment.
Project description:Neonatal hypoxic-ischemic (HI) encephalopathy can lead to severe brain damage and is a common cause of neurological handicaps in adulthood. To elucidate the molecular events occurring in cerebral cortices of mature rats (8 weeks old) after neonatal HI brain insult, we performed comprehensive gene expression and gene network analyses using a DNA microarray system (Agilent 4x44K). A rat model of neonatal HI encephalopathy (Rice model) was obtained by unilateral ligation of the common carotid artery of 7-day-old rats with hypoxia (exposure to 8% oxygen). Due to the HI insult-related breakdown of the ipsilateral hemisphere in the brain, RNAs were prepared from the contralateral cerebral cortices of 8-week-old rats and analyzed by DNA microarray. Biofunctional analysis of differentially regulated genes revealed that many upregulated genes were related to cell death signaling, such as the arachidonic acid cascade. In contrast, many downregulated genes were related to gene expression, reflecting progressive damage by the HI insult, even within the contralateral cerebral hemisphere. Seven-day-old Wistar rats were assigned to two groups: the control group and the Rice group (four pups in each group). HI brain insult was not induced in the control group rats. The Rice group rats were subjected to a modified LevineM-bM-^@M-^Ys procedure to induce HI brain injury. The Rice group rats were anesthetized with ether, and the left carotid artery was sectioned between double ligatures with 4-0 surgical silk. The rats were allowed to recover for 1M-bM-^@M-^S2 h and then exposed to 1 h of hypoxia in a plastic chamber that was perfused with a mixture of humidified 8% oxygen balanced with nitrogen. The temperature inside the chamber was maintained at 33 M-BM-0C, the usual temperature generated when pups huddle with the mother. The cerebral cortexes contralateral to the HI brain insult and those of the same side of the control animals were used for the experiment.
Project description:Electroacupuncture (EA) has been shown to reduce blood lipid level and improve cerebral ischemia in rats with hyperlipemia complicated by cerebral ischemia. However, there are few studies on the results and mechanism of the effect of EA in reducing blood lipid level or promoting neural repair after stroke in hyperlipidemic subjects. In this study, EA was applied to a rat model of hyperlipidemia and middle cerebral artery thrombosis and the condition of neurons and astrocytes after hippocampal injury was assessed. Except for the normal group, rats in other groups were fed a high-fat diet throughout the whole experiment. Hyperlipidemia models were established in rats fed a high-fat diet for 6 weeks. Middle cerebral artery thrombus models were induced by pasting 50% FeCl<sub>3</sub> filter paper on the left middle cerebral artery for 20 minutes on day 50 as the model group. EA1 group rats received EA at bilateral ST40 (Fenglong) for 7 days before the thrombosis. Rats in the EA1 and EA2 groups received EA at GV20 (Baihui) and bilateral ST40 for 14 days after model establishment. Neuronal health was assessed by hematoxylin-eosin staining in the brain. Hyperlipidemia was assessed by biochemical methods that measured total cholesterol, triglyceride, low-density lipoprotein and high-density lipoprotein in blood sera. Behavioral analysis was used to confirm the establishment of the model. Immunohistochemical methods were used to detect the expression of glial fibrillary acidic protein and nerve growth factor in the hippocampal CA1 region. The results demonstrated that, compared with the model group, blood lipid levels significantly decreased, glial fibrillary acidic protein immunoreactivity was significantly weakened and nerve growth factor immunoreactivity was significantly enhanced in the EA1 and EA2 groups. The repair effect was superior in the EA1 group than in the EA2 group. These findings confirm that EA can reduce blood lipid, inhibit glial fibrillary acidic protein expression and promote nerve growth factor expression in the hippocampal CA1 region after hyperlipidemia and middle cerebral artery thrombosis. All experimental procedures and protocols were approved by the Animal Use and Management Committee of Beijing University of Chinese Medicine, China (approval No. BUCM-3-2018022802-1002) on April 12, 2018.