Transient Bilateral Common Carotid Artery Research Articles

Combined nimodipine and citicoline reduce infarct size, attenuate apoptosis and increase bcl-2 expression after focal cerebral ischemia

Cerebral ischemia triggers a multitude of pathophysiological and biochemical events that separately affect the evolution of focal ischemia and, therefore, stroke treatment should logically employ all known neuroprotective agents. We hypothesized that a treatment combining nimodipine and citicoline might have a potential neuroprotective effect. To assess this idea, Sprague–Dawley rats underwent transient bilateral common carotid artery ligation with simultaneous middle cerebral artery occlusion for 60 min. Four treatment groups were established. Animals received either: a) saline (control group); b) intracarotid nimodipine infusion during 30 min in the ischemia-reperfusion (nimodipine group); c) i.p. postischemic citicoline injections once daily for 7 days (citicoline group); or d) intracarotid nimodipine bolus during ischemia-reperfusion plus i.p. postichemic citicoline injections (combination group). They were killed after either 7 or 3 days after reperfusion. In the first case, the volume of the infarcted tissue was studied by a stereological procedure and in the second case, in situ end-labeling of nuclear DNA fragmentation (TUNEL) and Bcl-2 expression were employed to determine the level of apoptosis. The infarct volume was significantly reduced in both the nimodipine and the citicoline treatment groups after 7 days of reperfusion; combination of both drugs produced an additive effect. After 3 days of reperfusion, the number of Bcl-2-positive neurons was significantly increased while that of TUNEL-positive cells significantly decreased at the infarct border in the combined-treatment animals. Our findings demonstrate a neuroprotective effect from an acute single dose of nimodipine during ischemia-reperfusion and prolonged post-ischemic treatment with citicoline in a model of focal cerebral ischemia. These results suggest that a possible mechanism of neuroprotective action would be mediated by increased Bcl-2 expression and decreased apoptosis within the boundary zone of the infarct together with neutralization of the ischemia-reperfusion injury.

Transplantation of human fetal brain cells into ischemic lesions of adult gerbil hippocampus.

The goal of this study was to establish whether transplanted cells derived from fetal human brain can survive in an ischemic lesion. Sixteen adult male Mongolian gerbils underwent transient bilateral common carotid artery occlusion. One week later, cell suspensions prepared from fetal human brain were injected using stereotactic guidance into the CA1 region of the hippocampus on one side. On the contralateral side injection of the cell suspension medium only was performed. One week after transplantation, the animals were perfusion fixed and their brains were processed for histological studies as well as expression of neuron and glia-specific antigens. Data from ischemic animals were compared with eight nonischemic gerbils that served as sham-operated controls. Last, the in vivo data were correlated with observations made from matching in vitro cultures of the fetal brain cell suspension. The in vivo data indicated that transplanted human fetus-derived brain cells survived in ischemic lesions of gerbil hippocampus after 1 week, provided that the host animal underwent adequate immunosuppression and the transplanted cells were not incorporated into the scar caused by the transplantation procedure. Unlike their in vivo counterparts, after 1 week, most cultured fetal brain cells expressed either neuron- or astrocyte-specific antigens. This work demonstrates that xenotransplanted fetal human brain cells are able to survive in an ischemic lesion in a rodent model. These data might be useful for future neural transplantation studies of treatments for cerebrovascular ischemia in humans.

Recombinant Adeno-Associated Virus Vector Expressing Glial Cell Line-Derived Neurotrophic Factor Reduces Ischemia-Induced Damage

To explore the potential of using the recombinant adeno-associated viral (rAAV) vector, expressing glial cell line-derived neurotrophic factor (GDNF) as the gene therapy for stroke, we injected rAAV vectors expressing GDNF (rAAV-GDNF) into the cortex of rats which had been experiencing transient bilateral common carotid artery ligation and right middle cerebral artery ligation for 90 min. GDNF levels in cortical tissues of rAAV-GDNF-injected animals were significantly higher than in the control animals injected with rAAV-expressing lacZ (rAAV-lacZ), indicating that rAAV can deliver and express the GDNF gene in cortical tissues. Triphenyltetrazolium chloride tissue stain analysis revealed that the rAAV-delivered GDNF gene could rescue the brain tissues from ischemia-induced injury. Cortical tissues which received rAAV-GDNF injections had both significantly smaller total volumes of infarction and smaller areas of infarction on each brain slice than those which were injected with rAAV-lacZ. An in situ labeling analysis demonstrated significantly less apoptotic cells in cortical tissues rescued by rAAV-GDNF, indicating prevention of apoptosis as the mechanism of cortical cell protection. Moreover, immunohistochemistry staining of Neu-N indicated that the rescued brain tissues contained the same number of Neu-N-positive neuronal cells as contralateral undamaged brain tissues. This provides strong evidence that cortical neuronal cells can be rescued by GDNF gene therapy. Indeed, these findings show that the rAAV is a potential delivery vector of GDNF gene for the therapy of stroke.

Consistent injury in the striatum of C57BL/6 mice after transient bilateral common carotid artery occlusion.

The recent availability of transgenic mice enables us to study the functional role of single gene products in cerebral ischemia. To establish an experimental murine model of transient forebrain ischemia, this study examined the temporal profile of ischemic neuronal damage in the striatum after bilateral common carotid artery occlusion. C57BL/6 mice, which are frequently used for genetic manipulations, were subjected to 15-minute bilateral common carotid artery occlusion. Ischemic injury was examined (4, 8, 24, 48, and 96 h after reperfusion) by Nissl staining, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick-end-labeling, and nuclear staining with Hoechst 33258 dye. Regional cerebral blood flow was decreased to 11 +/- 6% of control values during the ischemic insult. Striatal injury was observed in 95% of animals examined after 15-minute bilateral common carotid artery occlusion. The number of small and medium-size neurons in the striatum was significantly (P < 0.05) decreased 8 hours after reperfusion and continued to decrease until 96 hours, whereas the number of large neurons remained constant. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick-end-labeling-positive cells appeared in the dorsomedial region of the striatum 48 hours after the ischemic insult and throughout the striatum 96 hours after the ischemic insult. Brain sections stained with Hoechst 33258 dye also demonstrated apoptotic nuclei 96 hours after the ischemic insult. Striatal injury after transient forebrain ischemia is reproducible in C57BL/6 mice and is a good model to study the molecular mechanisms of ischemic injury, including delayed neuronal death, using transgenic mice.

Consistent Injury in the Striatum of C57BL/6 Mice after Transient Bilateral Common Carotid Artery Occlusion

Consistent Injury in the Striatum of C57BL/6 Mice after Transient Bilateral Common Carotid Artery Occlusion

Consistent Injury in the Striatum of C57BL/6 Mice after Transient Bilateral Common Carotid Artery Occlusion

Consistent Injury in the Striatum of C57BL/6 Mice after Transient Bilateral Common Carotid Artery Occlusion

Consistent Injury in the Striatum of C57BL/6 Mice after Transient Bilateral Common Carotid Artery Occlusion

Consistent Injury in the Striatum of C57BL/6 Mice after Transient Bilateral Common Carotid Artery Occlusion

Consistent Injury in the Striatum of C57BL/6 Mice after Transient Bilateral Common Carotid Artery Occlusion

Consistent Injury in the Striatum of C57BL/6 Mice after Transient Bilateral Common Carotid Artery Occlusion

Failure of an endothelin antagonist to modify hypoperfusion after transient global ischaemia in the rat.

The role of endogenous endothelins in mediating postischaemic hypoperfusion after transient global ischaemia was investigated in halothane-anaesthetised rats. Pretreatment with the broad-spectrum (ET (A) and ET (B)) endothelin antagonist. Bosentan (17 micromol/kg) had minimal effect on postischaemic hypoperfusion, measured by hydrogen clearance, in the caudate nucleus and the parietal cortex in the 3 h after bilateral common carotid artery occlusion with concomitant haemorrhagic hypotension (transient global ischaemia). In a separate series of rats with CBF measured by [14C]iodoantipyrine autoradiography at 90 min after carotid occlusion with concomitant haemorrhagic hypotension, Bosentan treatment failed to significantly alter CBF in any of the 35 brain regions examined. No significant alterations in CBF, measured by hydrogen clearance, were observed after transient bilateral common carotid artery occlusion. [14C]Iodoantipyrine autoradiography at 90 min after occlusion failed to demonstrate any significant increases in CBF after transient bilateral common carotid artery occlusion in any of the 35 brain regions examined in anaesthetised rats. The failure of the broad-spectrum endothelin antagonist Bosentan, at concentrations known to inhibit the cerebrovascular effects of exogenous ET-1, provide no support for the view that endothelins have a major role in mediating acute postischaemic hypoperfusion.

Reduction of infarct size by intra-arterial nimodipine administered at reperfusion in a rat model of partially reversible brain focal ischemia.

When blood flow to a brain region that has undergone an ischemic attack is reestablished, additional injury is to be expected from the reperfusion. The purpose of the study was to determine the effect of the intra-arterial injection of nimodipine at reperfusion on infarct volume in rats subjected to partially reversible focal neocortical ischemia. Two groups of Long-Evans rats with transient bilateral common carotid artery occlusion and permanent middle cerebral artery occlusion were subjected to retrograde cannulation of the external carotid artery close to the carotid bifurcation to allow the administration of isotonic saline (group 1) or nimodipine solution (group 2) just before and during reperfusion. The estimate for the actual amount of infarcted cortex was calculated by the volume ratio between the spared cortex in the infarcted hemisphere and the total cortex of the contralateral hemisphere by means of a serological method based on the Cavalieri principle. The percentage of cortex that was infarcted in control rats was 63.8 +/- 3.1%, whereas nimodipine-treated rats exhibited a significantly smaller (P < .005) percentage of infarct volume (31.3 +/- 12.7%). Our data show that the intra-arterial injection of nimodipine just before and during reperfusion reduced neocortical infarct volume in rats subjected to partially reversible focal cerebral ischemia.

Postischemic Hypoperfusion in Transient Global Ischemia

The role of endogenous endothelins (ETs) in mediating postischemic hypoperfusion after transient global ischemia was investigated in halothane-anesthetized rats. Pretreatment with the broad spectrum ETA and ETB antagonist bosentan (17 mumol/kg) had minimal effect on postischemic hypoperfusion, as measured by hydrogen clearance, in the caudate nucleus and the parietal cortex during 3 h after bilateral common carotid artery occlusion with concomitant hemorrhagic hypotension (transient global ischemia). In cerebral blood flow (CBF) measured by [14C]iodoantipyrine autoradiography at 90 min after carotid occlusion with concomitant hemorrhagic hypotension, bosentan treatment failed to alter CBF in any of the cerebral cortical regions examined. No changes in CBF, as measured by hydrogen clearance, were observed after transient bilateral common carotid artery occlusion. [14C]Iodoantipyrine autoradiography at 90 min post occlusion failed to demonstrate any increases in cerebral blood flow after transient bilateral common carotid artery occlusion in any of the 35 brain regions examined in anesthetized rats.

Cerebroprotective effect of BW619C89 after focal or global cerebral ischaemia in the rat.

BW619C89 (4-amino-2-(4-methylpiperazin-l-yl)-5-(2,3,5-trichlorophenyl) pyrimidine) was evaluated for cerebroprotection after focal or global ischaemia. BW619C89, as the mesylate dihydrate salt, 20 mg kg-1, i.v. for 10 min immediately, or with a 1 h delay after permanent middle cerebral artery occlusion in Fischer rats reduces cortical infarct volume (visualized with (2,3,5-triphenyltetrazolium) by 49% (p < 0.05) or by 61% (p < 0.001) and improves neurological deficit. Administration of BW619C89 with a 2 h delay is ineffective. BW619C89, given i.p. 0 and 4 h after 20 min of transient bilateral common carotid artery occlusion in vertebral artery-occluded Wistar rats reduces glutamate release and neuronal cell loss in the hippocampal CA1 sector (p < 0.01) and striatum (p < 0.05). BW619C89 resembles BW1003C87 (5-(2,3,5-trichlorophenyl)-2,4-diaminopyrimidine) in inhibiting veratrine-induced glutamate release and protecting against ischaemic brain damage.

Modulatory actions of the gigantocellular reticular nucleus on baroreceptor reflexes in the cat

In chloralose-urethane anesthetized cats, bilateral destruction of the gigantocellular reticular nucleus (GRN) in the medulla oblongata resulted in no discernible alteration of the basal arterial blood pressure and heart rate, as well as no significant influence on the degree of induced reflex bradycardia (by phenylephrine) and reflex tachycardia (by nitroglycerin). Furthermore, prolonged relfex hypertension elicited by a continuous bilateral common carotid artery occlusion was still feasible. Apart from directly promoting cardioinhibition, stimuation of the GRN was capable of interacting synergistically with reflex bradycardia (induced by phenylephrine or angio-transient and antagonistically with reflex tachycardia (induced by nitroglycerin or transient bilateral common carotid artery occlusion). The degree of potentiatioon of reflex bradycardia or suppression of reflex tachycardia by GRN-induced cardio-inhibition was, in most cases, larger than the sum of the individually produced responses. It was also directly related to the dose of the drugs and the intensity of the reticular stimulating train pulses. At the same time, bilateral vagotomy greatly diminished, but did not abolish, these interactions. It is concluded that the GRN may not be a primary component of the neural loop(s) subserving of baroreceptor reflexs. Instead, it may assume a modulatory role on the baroreceptor reflexes, possibly via an action on the autonomic preganglionic neurons.