Bilateral Carotid Ligation Research Articles

Combined swimming with melatonin protects against behavioural deficit in cerebral ischemia-reperfusion injury induced rats associated with modulation of Mst1– MAPK ‐ERK signalling pathway

Background The inconvenience of social and behavioural deficits after cerebral ischaemia reperfusion (I/R) injury is still not well documented. Aim We aimed to study the protective effect of preconditioning swimming exercise combined with melatonin against cerebral I/R induced injury. Methodology Sixty rats were allocated into 6 groups; groups I and II served as control. Groups 3,4,5,6 subjected to bilateral carotid ligation for 30 minutes (min.) followed by reperfusion. Group 3 left untreated while groups 4 and 6; underwent swimming exercise 30 min/day, five days a week for three weeks before the surgery. Groups 5 and 6 treated with melatonin 30 minutes before the operation, then, all rats in groups 4, 5,6 were subjected to I/R. After that, groups 5 and 6 treated with 2nd dose of melatonin 30 minutes after reperfusion. Results Combined strategy exhibited the most neuroprotective effect through prevention of cerebral I/R induced inflammation, oxidative stress and apoptosis with subsequent improvement in socio behaviour deficits and enhanced Glial cell proliferative capacity. Conclusion The protective contribution of combined strategy is associated with modulation in Macrophage‐stimulating 1/mitogen-activated protein kinase/extracellular signal-regulated kinase (MST1/MAPK/ERK) pathway which may explain, at least in part, its protective potential.

Identification of intima-to-media signals for flow-induced vascular remodeling using correlative gene expression analysis

Changes in blood flow can induce arterial remodeling. Intimal cells sense flow and send signals to the media to initiate remodeling. However, the nature of such intima-media signaling is not fully understood. To identify potential signals, New Zealand white rabbits underwent bilateral carotid ligation to increase flow in the basilar artery or sham surgery (n = 2 ligated, n = 2 sham). Flow was measured by transcranial Doppler ultrasonography, vessel geometry was determined by 3D angiography, and hemodynamics were quantified by computational fluid dynamics. 24 h post-surgery, the basilar artery and terminus were embedded for sectioning. Intima and media were separately microdissected from the sections, and whole transcriptomes were obtained by RNA-seq. Correlation analysis of expression across all possible intima-media gene pairs revealed potential remodeling signals. Carotid ligation increased flow in the basilar artery and terminus and caused differential expression of 194 intimal genes and 529 medial genes. 29,777 intima-media gene pairs exhibited correlated expression. 18 intimal genes had > 200 medial correlates and coded for extracellular products. Gene ontology of the medial correlates showed enrichment of organonitrogen metabolism, leukocyte activation/immune response, and secretion/exocytosis processes. This demonstrates correlative expression analysis of intimal and medial genes can reveal novel signals that may regulate flow-induced arterial remodeling.

The First Postlesion Minutes: An In Vivo Study of Extravasation and Perivascular Astrocytes Following Cerebral Lesions in Various Experimental Mouse Models.

The immediate alterations following lesions cannot be investigated by using fixed tissues. Here, we employed two-photon microscopy to study the alterations to the permeability of blood-brain barrier and to glio-vascular connections in vivo during the first minutes following cortical lesions in mice. Four models were used: (1) cryogenic lesion, (2) photodisruption using laser pulses, (3) photothrombosis, and (4) bilateral carotid ligation. Sulforhodamine101 was used for supravital labeling of astrocytes and dextran-bound fluorescein isothiocyanate for the assessment of extravasation. Transgenic mice, in which the endothelium and astrocytes expressed a yellow fluorescent protein, were also used. Astrocytic labeling in vivo was verified with postmortem immunostaining against glial fibrillary acidic protein (GFAP). Summary of results: (1) the glio-vascular connections were stable in the intact brain with no sign of spontaneous dynamic attachment/detachment of glial end-feet; (2) only direct vascular damage (photodisruption or cryogenic) resulted in prompt extravasation; (3) even direct damage failed to provoke a prompt astroglial response. In conclusion, the results indicate that a detachment of the astrocytic end-feet does not precede the breakdown of blood-brain barrier following lesions. Whereas vasogenic edema develops immediately after the lesions, this is not the case with cytotoxic edemas. Time-lapse recordings and three-dimensional reconstructions are presented as supplemental materials.

Induction of Genes Expressed in Endothelial Cells of the Corpus Callosum in the Chronic Cerebral Hypoperfusion Rat Model

Background: Cerebrovascular white matter lesions (WMLs) are associated with cognitive impairment in patients with subcortical vascular dementia. We performed a comprehensive gene expression analysis to elucidate genes associated with WML development in a chronic cerebral hypoperfusion rat model. Methods: Brains of rats with bilateral carotid ligation (2VO, n = 10) and sham-operated rats (n = 5-10/group) were removed on days 1, 7, or 28 after surgery. Total RNA isolated from the corpus callosum was evaluated by microarray analysis and quantitative reverse transcription-polymerase chain reaction. Results: On days 7 and 28, WMLs exhibited histologic changes. On day 7, 16 genes were differentially expressed between groups. mRNA levels of Ptprb, Kcnj8, Crispld2, Bcl6b, and Gja5 were differentially expressed in 2VO rats on day 7, but then returned to normal, whereas mRNA levels of Vwf and Trappc6a were upregulated after day 7. Immunohistochemistry showed that GJA5 and vWF were detected in endothelial cells, KCNJ8 in endothelial cells and astrocytes, CRISPLD2 in neurons and astrocytes, and TRAPPC6A in neurons. Conclusion: Our findings indicate novel genes that may be associated with WML development in the chronic cerebral hypoperfusion rat model, and suggest an important role of neurovascular dysfunction in the pathophysiology.

Effects of Regional Cerebral Blood Flow Perfusion on Learning and Memory Function and Its Molecular Mechanism in Rats

Objective To study the effects of regional cerebral blood flow (rCBF) perfusion on learning and memory function in special brain areas and its molecular mechanism in rat. Methods Sixty-four adult male healthy Sprague-Dawley (SD) rats were randomly divided into two groups: A false operation group and an operation group. The false operation group was randomly divided into four subgroups (A0, B0, C0, and D0) and the operation group was randomly divided into four subgroups (A, B, C, and D), with eight rats in each subgroup. The operation group underwent bilateral common carotid artery permanent ligation, while the other group only underwent a skin incision without the bilateral common carotid artery permanent ligation. Learning memory function of rats in each subgroup was measured using a Y-maze at 4 h, 8 h, 24 h, and 3 days after surgery. The rCBF in the right frontal lobe and hippocampus was detected using the Periflux PF model laser Doppler flowmetry and c-fos, c-jun, Bcl-2, and Bax protein expression in the right frontal lobe and hippocampus was measured using immunohistochemistry. Results The rCBF in the right frontal lobule division and right hippocampus division was significantly lower in the operation group than in the false operation group (P < 0.05). The error number (EN), time to reach the target, and total reaction time (TRT) for the learning index using the Y-type labyrinth test in the operation group were significantly higher than that in the false operation group (P < 0.05); however, the active avoid rate in the operation group was significantly lower than that of the false operation group. Expression of c-fos and c-jun as well as the average absorbency in the right frontal lobule division and right hippocampus division in the operation group were significantly higher than those in the false operation group (P < 0. 05). The number of Bax and Bcl-2-positive cells was significantly higher in the operation group, and the expression ratio of Bax/Bcl-2 in the operation group was significantly higher than that in the false operation group (P < 0.01). Conclusions rCBF decrease can impair learning and memory function in rats, which may be related to the increased expression of c-fos, c-jun, Bcl-2, and Bax proteins in the frontal cortex and hippocampus.

Effects of regional cerebral blood flow perfusion on learning and memory function and its molecular mechanism in rats

Objective: To study the effects of regional cerebral blood flow (rCBF) perfusion on learning and memory function in special brain areas and its molecular mechanism in rat. Methods: Sixty-four adult male healthy Sprague-Dawley (SD) rats were randomly divided into two groups: A false operation group and an operation group. The false operation group was randomly divided into four subgroups (A0, B0, C0, and D0) and the operation group was randomly divided into four subgroups (A, B, C, and D), with eight rats in each subgroup. The operation group underwent bilateral common carotid artery permanent ligation, while the other group only underwent a skin incision without the bilateral common carotid artery permanent ligation. Learning memory function of rats in each subgroup was measured using a Y-maze at 4 h, 8 h, 24 h, and 3 days after surgery. The rCBF in the right frontal lobe and hippocampus was detected using the Periflux PF model laser Doppler flowmetry and c-fos, c-jun, Bcl-2, and Bax protein expression in the right frontal lobe and hippocampus was measured using immunohistochemistry. Results: The rCBF in the right frontal lobule division and right hippocampus division was significantly lower in the operation group than in the false operation group (P < 0.05). The error number (EN), time to reach the target, and total reaction time (TRT) for the learning index using the Y-type labyrinth test in the operation group were significantly higher than that in the false operation group (P < 0.05); however, the active avoid rate in the operation group was significantly lower than that of the false operation group. Expression of c-fos and c-jun as well as the average absorbency in the right frontal lobule division and right hippocampus division in the operation group were significantly higher than those in the false operation group (P < 0. 05). The number of Bax and Bcl-2-positive cells was significantly higher in the operation group, and the expression ratio of Bax/Bcl-2 in the operation group was significantly higher than that in the false operation group (P < 0.01). Conclusions: rCBF decrease can impair learning and memory function in rats, which may be related to the increased expression of c-fos, c-jun, Bcl-2, and Bax proteins in the frontal cortex and hippocampus. Citation Xu CL, Wu WH, Kong LB. Effects of regional cerebral blood flow perfusion on learning and memory function

Aneurysmal Remodeling in the Circle of Willis after Carotid Occlusion in an Experimental Model

Carotid occlusions are associated with de novo intracranial aneurysm formation in clinical case reports, but this phenomenon is not widely studied. We performed bilateral carotid ligation (n=9) in rabbits to simulate carotid occlusion, and sham surgery (n=3) for control. Upon euthanasia (n=3 at 5 days, n=6 at 6 months post ligation, and n=3 at 5 days after sham operation), vascular corrosion casts of the circle of Willis (CoW) were created. Using scanning electron microscopy, we quantified gross morphologic, macroscopic, and microscopic changes on the endocasts and compared findings with histologic data. At 5 days, CoW arteries of ligated animals increased caliber. The posterior communicating artery (PCom) increased length and tortuosity, and the ophthalmic artery (OA) origin presented preaneurysmal bulges. At 6 months, calibers were unchanged from 5 days, PComs further increased tortuosity while presenting segmental dilations, and the OA origin and basilar terminus presented preaneurysmal bulges. This exploratory study provides evidence that flow increase after carotid occlusion produces both compensatory arterial augmentation and pathologic remodeling such as tortuosity and saccular/fusiform aneurysm. Our findings may have considerable clinical implications, as these lesser-known consequences should be considered when managing patients with carotid artery disease or choosing carotid ligation as a therapeutic option.

Effect of rehabilitation training on insulin-resistance and hippocampus amyloid-beta peptide in rats with vascular dementia

To investigate the effect of rehabilitation training on insulin-resistance and insulin degrading enzyme (IDE) in the hippocampus in rats with vascular dementia. A total of 45 female Sprague-Dawley rats were randomly assigned into a rehabilitation group (n=15), an immobilization group (n=15), and a sham-operation group (n=15). The rats in the former 2 groups were operated on to establish the experimental vascular dementia model by bilateral common carotid artery permanent ligation. The rats' learning and memory were assessed 4 weeks after the operation. The plasma level of insulin was determined by ELISA at different time points after the operation. Immunohistochemical staining was used to detect the IDE expression in the hippocampus area. The rats in the rehabilitation group showed significantly better learning ability than that in the immobilization group (P<0.05). The plasma level of insulin in the rehabilitation group was lower than that in the immobilization group (P<0.05), IDE expression in the rehabilitation group was higher than that in the immobilization group (P<0.05) at 7 d and 28 d after the operation. Rehabilitation can accelerate the recovery of learning and memory in rats with vascular dementia, and the mechanism is possibly related to the amelioration of insulin resistance and increase of IDE expression in the hippocampus.

Differential gene expression by endothelial cells under positive and negative streamwise gradients of high wall shear stress

Flow impingement at arterial bifurcations causes high frictional force [or wall shear stress (WSS)], and flow acceleration and deceleration in the branches create positive and negative streamwise gradients in WSS (WSSG), respectively. Intracranial aneurysms tend to form in regions with high WSS and positive WSSG. However, little is known about the responses of endothelial cells (ECs) to either positive or negative WSSG under high WSS conditions. We used cDNA microarrays to profile gene expression in cultured ECs exposed to positive or negative WSSG for 24 h in a flow chamber where WSS varied between 3.5 and 28.4 Pa. Gene ontology and biological pathway analysis indicated that positive WSSG favored proliferation, apoptosis, and extracellular matrix processing while decreasing expression of proinflammatory genes. To determine if similar responses occur in vivo, we examined EC proliferation and expression of the matrix metalloproteinase ADAMTS1 under high WSS and WSSG created at the basilar terminus of rabbits after bilateral carotid ligation. Precise hemodynamic conditions were determined by computational fluid dynamic simulations from three-dimensional angiography and mapped on immunofluorescence staining for the proliferation marker Ki-67 and ADAMTS1. Both proliferation and ADAMTS1 were significantly higher in ECs under positive WSSG than in adjacent regions of negative WSSG. Our results indicate that WSSG elicits distinct EC gene expression profiles and particular biological pathways including increased cell proliferation and matrix processing. Such EC responses may be important in understanding the mechanisms of intracranial aneurysm initiation at regions of high WSS and positive WSSG.

Autogenous fecal peritonitis in Wistar rats with permanent bilateral carotid occlusion: morbidity, mortality and microbiological response

To investigate morbidity, mortality and microbiological response to fecal peritonitis induced in Wistar rats with permanent bilateral carotid ligation (PBCL). Fecal peritonitis was induced in 30 rats, with 10 animals in each group: Group1 - normal young animals; Group2 - normal mature animals; and Group3 - rats with PBCL after four months postoperative follow-up. Peritonitis was induced with 10% stool suspension. Morbidity and mortality were evaluated. The survival animals after seven days were euthanized for tests. For microbiological studies blood were collected from the carotids and right ventricle; and fragments of lung and peritoneum. The morbidity and mortality of young animals were significantly lower than in mature animals with and without PBCL. There was no difference in morbidity and mortality among mature rats with and without PBCL. The diversity of microorganisms producing septicemia was similar to native micro biota of the large bowel. The immune response was more efficient in young animals, represented by significant less morbidity and no natural mortality. PBLC did not affect morbidity and mortality in mature rats. The immune response to fecal peritonitis has age as an independent predictor.

Learning and survival memory undergoing a permanent bilateral carotid ligation in rats

To evaluate the effect of cerebral hypoxia-ischemia on memory and learning survival of rats submitted to permanent bilateral carotid ligation (PBCL). Twenty-four survivors of PBCL were evaluated after 30 days with regard to memory and learning using a water survival maze. Twenty-three healthy rats were used as control group. The results were expressed by their means and standard error of the mean (SEM). p<0.05 was used for rejecting the null hypothesis. The study was approved by the Ethics Committee for animal investigation. The mortality rate for the surgery was 44.4%. The latency time to find the survival platform was higher in rats that underwent PBCL (Normal: 10.24 ± 1.85s - 25.30 ± 4.69s - Mann - Whitney p=0.0388). Additionally, the type of swimming and the spatial stability of the studied rats on the survival platform were compromised in these animals. The permanent bilateral carotid ligation induces change in the learning and survival memory.

Bone-marrow cell therapy induces differentiation of radial glia-like cells and rescues the number of oligodendrocyte progenitors in the subventricular zone after global cerebral ischemia

The subventricular zone (SVZ) is recognized as one of the neurogenic regions in the adult mammalian central nervous system and the presence of cells that share similar characteristics with developmental radial glia, the radial glia-like cells (RGLCs) has been demonstrated in this region. In this study, we investigated whether and how SVZ cells respond to global ischemia and/or to the intravenous transplant of bone-marrow mononuclear cells (BMMCs). Adult rats were subjected to bilateral common carotid ligation (BCCL) and after 1day 2×107 BMMCs or saline injection. The BMMC transplant stimulated a transitory increase in the proliferation of SVZ cells in the BCCL group. We observed a significant increase in the number of RGLCs 3days after ischemia, in both BCCL and BCCL+BMMC groups. However, this increase persisted in the subsequent days only in BCCL animals that received the transplant. BMMC transplantation also inhibits the reduction of NG2-positive oligodendrocyte progenitors in the SVZ observed in the BCCL group. Interestingly, brain-derived neurotrophic factor (BDNF) expression was up-regulated in the SVZ in the treated animals, but not in the other groups. These data thus suggest that BMMC transplantation modulates the phenotype of RGLCs/progenitors in the SVZ and could have a protective role after ischemia.

Abstract 121: Modulation of Apoptosis, Matrix Degradation and Matrix Synthesis Are the Primary Determinants for Intimal Hyperplasia in Response to Altered Shear

Introduction: The quantity of high throughput microarray data leads to unique challenges in understanding its biological significance. We have developed a novel statistical method of clustering dynamics to elucidate for the mapping of gene expression arcs. In the current study, we applied these techniques to the multifactorial process of vein graft intimal hyperplasia, where direct correlation of these patterns was integrated with detailed morphologic data to identify those pathways central to the disease process. Methods: NZW rabbits underwent bilateral carotid vein grafting and unilateral distal branch ligation to create high and low shear environments. Vein grafts were harvested at 2h, 1 d, 7 ds, 28 d, 90 d, and 180 d (n=4 per group), and mRNA expression analyzed using a rabbit Agilent microarray platform. Parallel experiments were used to determine wall morphology, cell proliferation, apoptosis, and matrix content at each time point. Results: Compared to high shear grafts, exposure to a low shear resulted in a 5-fold greater intimal thickness at 180 d. Although 3365 (out of 14,958) genes varied with either time or shear, no single gene was significantly different (at a false discovery rate &lt;0.001) as a function of shear only. To analyze the broad-based modulation of gene expression, a novel clustering technique was used to identify temporal patterns of genes expression. Eight clusters (A through H) were identified, with five of these clusters demonstrating significant variation between high and low shear grafts (Table; A &lt;0.0001, D &lt;0.0001, F &lt; 0.0001, G &lt;0.001, H &lt;0.0001). Ingenuity pathway analysis was used to map gene ontology groups within the clusters to the dominant biologic process observed on histologic analysis. Cell death (cluster D), matrix degradation (cluster G), and matrix synthesis (cluster H), and the associated gene network pathways, were identified being significantly different in the high and low shear grafts (Figure). Conclusions: Using high throughput genomics and detailed morphologic data, we identify cell death, matrix degradation, and matrix synthesis, and the specific pathways associated with these process, as the most critical components in the development of the intimal hyperplastic lesion.

Effects of special brain area regional cerebral blood flow abnormal perfusion on learning and memory function and its molecular mechanism in rats

To study the effect of special brain area regional cerebral blood flow (rCBF) abnormal perfusion on learning and memory function and its molecular mechanism, 64 adult male healthy Sprague-Dawley (SD) rats were randomly divided into two groups, the false operation group (control group) and the operation group (model group). After surgical operation, the operation group undertook bilateral common carotid artery permanent ligation, while the other group did not. Learning and memory function were measured by Y-maze at 4 h, 8 h, 24 h and 3 d after surgical operation, respectively. The rCBF of the right frontal lobe and hippocampus was also detected by the PerifluxPF model laser Doppler flowmetry, and the expressions of c-fos or c-jun or Bcl-2 and Bax were also measured by immune histochemistry S-P method accordingly. Results showed that the rCBF of the right frontal lobe and hippocampus in the operation group was significantly lower than that in the false operation group (P < 0.05). The learning indexes, error number (EN), day of reach standard and total reaction time (TRT) in the operation group, were significantly higher than that in the false operation group (P < 0.05). However, the initiative evasion rate in the operation group was significantly lower than that in the false operation group. The study also found that the rCBF was relatively more, the indexes (EN, the day of reach standard and TRT) relatively fewer, but the initiative evasion rate and the memory keeping rate were relatively more. The positive expression and the average absorbency of Fos and Jun in the operation group were significantly higher than that in the false operation group (P < 0.05). Furthermore, Bax and Bcl-2 positive cells were all increased over time in the operation group, and the expression ratio of Bax/Bcl-2 in the operation group was significantly higher than that in the false operation group (P < 0.01). In conclusion, rCBF decrease can impair the learning and memory function in rats, which may be related to the increase of the expression ratio of c-fos or c-jun or Bcl-2 or Bax in the frontal cortex and hippocampus.

Inhibitory effect of vasopressin receptor antagonist OPC-31260 on experimental brain oedema induced by global cerebral ischaemia

The effects of the non-peptide vasopressin V(2) receptor antagonist 5-dimethylamino-1-[4-(2-methylbenzoylamino)benzoyl]-2,3,4,5-tetrahydro-1H-benzazepine hydrochloride (OPC-31260) on the cerebral oedema induced by general cerebral hypoxia were studied in rats. The general cerebral hypoxia was produced by bilateral common carotid ligation in Sprague-Dawley rats of the CFY strain. By 6 h after the ligation, half of the rats had died, but the survival rate was significantly higher following OPC-31260 administration. Electron microscopic examinations revealed typical ischaemic changes after the carotid ligation. The carotid ligation increased the brain contents of water and Na(+) and enhanced the plasma vasopressin level. The increased brain water and Na(+) accumulation was prevented by OPC-31260 administration, but the plasma vasopressin level was further enhanced by OPC-31260. These results demonstrate the important role of vasopressin in the development of the disturbances in brain water and electrolyte balance in response to general cerebral hypoxia. The carotid ligation-induced cerebral oedema was significantly reduced following oral OPC-31260 administration. The protective mechanism exerted by OPC-31260 stems from its influence on the renal vasopressin V(2) receptors. These observations might suggest an effective approach to the treatment of global hypoxia-induced cerebral oedema in humans.

Effects of chronic brain hypoperfusion on cerebrbral free radical metabolism and learning-memory function

目的 探讨双侧颈总动脉结扎所致的慢性脑低灌注状态下大鼠学习记忆功能及脑组织自由基代谢的时程改变.方法雄性SD大鼠,行双侧颈总动脉结扎术,术后4h、24h、3d、7 d、2周、4周、8周分别取脑组织进行超氧化物歧化酶(SOD)活性及丙二醛(MDA)含量的检测,在脑缺血2周、4周、8周时进行Morris水迷宫实验.结果 Morris水迷宫实验结果表明,各缺血组大鼠在学习记忆功能上较对照组有显著减退,表现在逃避潜伏期[从(8.68±1.32)s延长至(23.95±4.76)s,P＜0.05]和游泳路径[从(171.99±23.12)cm延长至(573.68±124.22)cm,P＜0.01]均明显延长,缺血8周时仍不能恢复,表明双侧颈总动脉结扎所致的慢性脑低灌注状态可引起大鼠学习记忆功能明显下降.自由基代谢相关检测结果表明,缺血4h起,大鼠皮层SOD活性显著降低[从(257.97±10.79)Nu/mg蛋白降至(152.68±38.26)Nu/mg,P＜0.01],MDA含量明显升高[从(2.95±0.34)nmol/mg蛋白升至(5.31±1.68)nmol/mg,P＜0.05],缺血8周时仍不能完全恢复.结论双侧颈总动脉永久结扎后形成的脑部慢性低灌注状态可导致脑组织自由基代谢紊乱,并进一步引起学习记忆功能减退。

Effects of postnatal hypoxia on NMDA receptor binding and gene expression of subunits as an animal model for obstetric complications in the pathophysiology of schizophrenia

Introduction: In schizophrenia, a NMDA receptor hypotunction has been hypothesized and related to early developmental processes as well as obstetric complications, but to date the etiology of this dysfunction still remains unclear. Periand postnatal repeated hypoxia and short ischemia/hypoxia may be of major importance for alterations of NMDA receptor binding and gene expression of subunits. Method: In an animal model we imposed mild hypoxia (11%O2, 89%N2) from postnatal day 4 to 8 to 10 male SD-rats and their mothers by housing them in an air-tight plastic chamber for 6 hours per each day. A control group received normal air in the same environment. Additionally, at PND 8, 10 male rats were treated with 2 repeated bilateral carotid ligations (8%02, 92%N2) lasting 8 minutes each (ischemia/hypoxia). Control rats (n=10) were sham-operated at normoxia. At PND 11, brains were removed and frozen in isopentane. In-situ-hybridization of NMDA receptor sabunits NR1, NR2A and NR2B was performed in adjacent brain sections of ventral hippocampus, striatum and prefrontal cortex. Results: Repeated, mild hypoxia induced downregulation of NR2A mRNA in bippocampal subregions (CA1 (by 15,7%), CA3 (by 25,3%) and dentate gyrus (by 15%)). Ischemia/hypoxia decreased NR2A mRNA only in the dentate gyrus (by 25,7%). In the prefrontal cortex (gyrus cinguli (by 34,0%), infralimbic cortex (by 36,0%) and frontal cortex (by 30,6%)), chronic hypoxia increased NR1 subunit expression, while ischemia/hypoxia showed no effects. NMDA receptor binding was decreased by chronic, repeated hypoxia in both regions of the limbic cortex, the anterior cingulate cortex (by 21%) and infralimbic cortex (by 21,8%). In the frontal cortex, NMDA receptor binding was also downregulated (byq!8 2~%) Discussion: Hippoeampal and cortacal subreglons are vulnerable to hypokaa, Thggeeondary NR2A mRNA downregulation in the hippocampus may protect the tissue against glutamate exeitotoxicity. In the prefrontal cortex, decreased NMDA receptor binding and NR 1 subunit upregulation may be due to NMDA receptor hypofunction. Our investigation of this animal model helps to elucidate the role of obstetric complications and provides new insights into the development of NMDA receptor dysfunction in schizophrenia.

Effect of catecholamines on activity of Na +, K +-ATPase in neonatal piglet brain during posthypoxic reoxygenation

The present study examined the possible role of dopamine on the response of Na +, K +-ATPase activity in the striatum of newborn piglets to 1 h of bilateral carotid ligation with hemorrhage and 2 h of recovery. Newborn piglets, 2–4 days of age and with and without prior treatment with α-methyl- p-tyrosine (AMT), an inhibitor of catecholamines synthesis, were used for the study. The oxygen pressure in the microvasculature of the cortex (PcO 2) was measured by oxygen dependent quenching of the phosphorescence. In sham-operated animals the PcO 2 was 50±3 torr. Following ligation and hemorrhage the PcO 2 decreased to 8±0.5 torr. After release of ligation and reperfusion PcO 2 increased to 45±4 torr, a value not significantly different from controls, in approximately 30 min. There were no significant differences in PcO 2 between AMT treated and untreated animals. In sham-operated animals striatal Na +,K +-ATPase was 29.1±3 μmol/mg protein per h and decreased by 25% after 2 h of recovery. Depleting the brain of catecholamines prior to ligation and hemorrhage abolished this decrease. It is postulated that the decrease in the level of dopamine in the brain prior to ligation and hemorrhage can be at least partly responsible for the observed decrease in activity of Na +, K +-ATPase in the striatum of newborn piglets.

In Vivo Gene Transfer to Cerebral White Matter Lesions with a Recombinant Adenovirus Vector

Ischemic white matter lesions have been reported in rats after bilateral common carotid ligation (BCAL). Previously, comparing normotensive rats (WKY) with spontaneously hypertensive rats (SHR), we too found that sustained moderate ischemia with spontaneous hypertension accelerated the formation of ischemic white matter lesions. In this study, we explored the feasibility of gene therapy for lesioned white matter by means of an adenovirus vector expressing a reporter gene, LacZ. Using sham-operated and hypoperfused SHR as well as sham-operated and hypoperfused WKY, we demonstrated that (i) adenovirus vectors could deliver a foreign gene into oligodendrocytes and astrocytes in the cerebral white matter; (ii) the transduction efficiency was most effective in SHR after BCAL; and (iii) the level of αV-integrin was significantly correlated with adenoviral transduction efficiency.

Comunicación arterial carotidobasilar en gerbos (Meriones unguiculatus)

Since 1966 when Levine and Payan observed that the Mongolian gerbil (Meriones unguiculatus) was unusually susceptible to cerebral infarction following occlusion of one or both common carotid arteries, the model has been used for the experimental study of cerebral ischemia. To assess the presence of anterior-posterior arterial communication in the Mongolian gerbil (Meriones unguiculatus). 26 animals were used and divided in the following groups: 1. Bilateral carotid ligation (n = 10); 2. Unilateral left carotid ligation (n = 5); 3. Unilateral carotid right carotid ligation (n = 5); and 4. Control group without carotid ligation (n = 6). Postmortem intra-aortic dye injection demonstrated communication between anterior and posterior cerebral arteries in 30% of gerbils that previously were subjected to bilateral common carotid artery occlusion. A number of vessels, between 8.95-11.35 microns in diameter, were linking the basilar artery with the posterior cerebral artery. In the remaining animals, the absence of communication was confirmed. Communicating carotid-basilar in lower number of cases and anastomosis the smallest diameter to give the gerbil advantage on others species as model of experimental regional ischemia.