Why are infant gerbils more resistant than adults to cerebral infarction after carotid ligation?

Endovascular treatment of traumatic intracranial aneurysm in an infant. A case report

SUMMARY

Traumatic intracranial aneurysms in children are rare and mostly related to skull fracture or rapid decelerating closed head injury.We report the case of an infant who developed intracranial aneurysm after minor head trauma and managed by endovascular treatment. A seven-month-old infant presented with delayed intracranial hemorrhage following minor head trauma. Cerebral angiography disclosed a multilobulated fusiform aneurysm involving the right anterior cerebral artery (ACA) distal to the anterior communicating artery. Endovascular treatment of the aneurysm was performed and the infant made an excellent recovery during six months clinical and radiological follow-up. Delayed presentation of intracranial hemorrhage with acute deterioration in the infant after head trauma warrants angiography for proper diagnosis and management of the traumatic aneurysm, which has a high mortality rate after rupture and rebleeding. Endovascular treatment of traumatic aneurysm is feasible in infants, and occlusion of distal intracranial arterial aneurysms can be safely and precisely achieved using current coil technology.

Administration of CD34+ cells after stroke enhances neurogenesis via angiogenesis in a mouse model

Thrombo-occlusive cerebrovascular disease resulting in stroke and permanent neuronal loss is an important cause of morbidity and mortality. Because of the unique properties of cerebral vasculature and the limited reparative capability of neuronal tissue, it has been difficult to devise effective neuroprotective therapies in cerebral ischemia. Our results demonstrate that systemic administration of human cord blood-derived CD34(+) cells to immunocompromised mice subjected to stroke 48 hours earlier induces neovascularization in the ischemic zone and provides a favorable environment for neuronal regeneration. Endogenous neurogenesis, suppressed by an antiangiogenic agent, is accelerated as a result of enhanced migration of neuronal progenitor cells to the damaged area, followed by their maturation and functional recovery. Our data suggest an essential role for CD34(+) cells in promoting directly or indirectly an environment conducive to neovascularization of ischemic brain so that neuronal regeneration can proceed.

Skin blood vessels are simultaneously innervated by sensory, sympathetic, and parasympathetic fibers

Despite the known major role of skin blood vessel innervation in blood flow control, particularly in disease, little information on the co-innervation of blood vessels by sensory and autonomic fibers and the relationships of these fibers to one another is available. To fill this gap, we performed a light and electron microscopic analysis of the innervation of skin vessels by sensory and autonomic fibers by using the rat and monkey lower lips as a model. In rats, double-labeling immunocytochemistry revealed that combinations of fibers immunoreactive for substance P (SP) and dopamine-beta-hydroxylase (DbetaH), SP and vesicular acetylcholine transporter (VAChT), as well as DbetaH and VAChT occurred only around blood vessels in the lower dermis. All fiber types travelled in parallel and in close proximity to one another. In the upper dermis, blood vessels were innervated by SP-containing fibers only. Although nerve terminals displayed synaptic vesicles, synaptic specializations were never observed, suggesting that, in this territory, these fibers do not establish synaptic contacts. Quantification of the distance between the various immunoreactive terminals and their presumptive targets (smooth muscle cells and endothelial cells) revealed that both sympathetic and parasympathetic fibers were significantly closer to the endothelial cell layer and smooth muscle cells compared with sensory fibers. In monkeys, double-labeling immunocytochemistry was performed for SP-DbetaH and SP-VAChT only. The results obtained are similar to those found in rats; however, the fiber density was greater in monkeys. Our findings suggest that the regulation of skin microcirculation might be the result of the coordinated functions of sensory and autonomic fibers.

Differential expression of HSC73 and HSP72 mRNA and proteins between young and adult gerbils after transient cerebral ischemia: relation to neuronal vulnerability

This study presents a quantitative comparison of the time courses and regional distribution of both constitutive HSC73 and inducible HSP72 mRNA expression and their respective encoded proteins between young (3-week-old) and adult (3-month-old) gerbil hippocampus after transient global ischemia. The constitutive expression of HSC73 mRNA and protein in the hippocampus of the young sham-operated gerbils was significantly higher than in the adults. The HSC73 mRNA expression after ischemia in the CA1 layer of young gerbils was greater than in adult gerbils. HSC73 immunoreactivity was not significantly changed after ischemia-reperfusion in adult hippocampus, whereas it decreased in young gerbils. Ischemia-reperfusion led to induction of HSP72 mRNA expression throughout the hippocampus of both young and adult gerbils. HSP72 mRNA induction was more intense and sustained in the CA1 subfield of young gerbils; this was associated with a marked induction of HSP72 proteins and neuronal survival. The transient expression of HSP72 mRNA in the CA1 layer of adult gerbils was not associated with a subsequent synthesis of HSP72 protein but was linked to neuronal loss. Expression of HSP72 mRNA was shifted to an earlier period of reflow in CA3 and dentate gyrus (DG) subfields of young animals. These findings suggest that the induction of both HSP72 mRNA and proteins in the CA1 pyramidal neurons of young gerbils, as well as the higher constitutive expression of HSC73, may partially contribute to higher neuronal resistance of young animals to transient cerebral ischemia.

Reduced glutathione oxidation ratio and 8 ohdG accumulation by mild ischemic pretreatment

A critical role of oxidative stress has been implicated in ischemic brain damage. Mild ischemic pretreatment and/or synthesis of heat shock proteins (HSPs) has been suggested to protect against oxidative brain damage. However, experimental support of this suggestion have proven to be difficult partly because sensitive indices to assess oxidative consequences of ischemic brain damage were few. In this study, we have attempted to establish biochemical assay systems to quantitate oxidative brain damage following ischemia. We produced experimental brain ischemia in the Mongolian gerbil (Meriones unguiculatus) and examined the hippocampus for ischemic brain damage. The results obtained from ischemic gerbil hippocampus demonstrated that oxidative brain damage can be quantitated by determining glutathione oxidation ratio together with the accumulation of the oxidative DNA damage product, 8-hydroxy-2'-deoxyguanosine (8 ohdG). Our results also demonstrated a role for mild ischemic pretreatment and synthesis of HSPs against oxidative brain damage. We showed that mild 2-min ischemic pretreatment reduced the degree of both glutathione oxidation ratio and 8 ohdG accumulation in gerbil hippocampus subsequent to 10 min ischemic challenge. We also showed that the accumulation of HSP70 was closely associated with the reduction of oxidative brain damage. To our knowledge, this is the first report to investigate glutathione redox states and oxidative DNA damage levels to evaluate a protective role of mild ischemic pretreatment and HSP synthesis following brain ischemia. Our data validate the previous suggestions and provide new additional data that argue for the protective role of mild ischemic pretreatment and HSP70 synthesis against oxidative brain damage.

Postischemic hypothermia. A critical appraisal with implications for clinical treatment

The use of hypothermia to mitigate cerebral ischemic injury is not new. From early studies, it has been clear that cooling is remarkably neuroprotective when applied during global or focal ischemia. In contrast, the value of postischemic cooling is typically viewed with skepticism because of early clinical difficulties and conflicting animal data. However, more recent rodent experiments have shown that a protracted reduction in temperature of only a few degrees Celsius can provide sustained behavioral and histological neuroprotection. Conversely, brief or very mild hypothermia may only delay neuronal damage. Accordingly, protracted hypothermia of 32-34 degrees C may be beneficial following acute clinical stroke. A thorough mechanistic understanding of postischemic hypothermia would lead to a more selective and effective therapy. Unfortunately, few studies have investigated the mechanisms by which postischemic cooling conveys its beneficial effect. The purpose of this article is to evaluate critically the effects of postischemic temperature changes with a comparison to some current drug therapies. This article will stimulate new research into the mechanisms of lengthy postischemic hypothermia and its potential as a therapy for stroke patients.

Brain ischemia following bilateral carotid occlusion during development of hypertension in young spontaneously hypertensive rats--importance of morphologic changes of the arteries of the circle of Willis

The present study was designed to examine the effect of morphologic changes of the arteries of the circle of Willis on cerebral blood flow (CBF) and metabolism in young spontaneously hypertensive rats (SHR). CBF in the parietal cortex was measured by the hydrogen clearance method before and during a one-hour bilateral carotid artery occlusion (BCO), and supratentorial brain metabolites were determined by standard enzymatic methods at a one-hour BCO. The internal diameters of the main arteries of the circle of Willis were estimated morphologically. With increase in age, systemic arterial pressure at rest was significantly raised, while cortical CBF tended to decrease and calculated cerebral vascular resistance increased. During BCO, CBF and supratentorial metabolism (adenosine triphosphate and lactate/pyruvate ratio) tended to be better preserved in two-month-old rats as compared with those in one- or three-month-old rats. The internal diameter of the posterior communicating artery (PcomA) was significantly smaller in the one-month-old group than in the other groups, while the diameter of the internal carotid artery was significantly smaller in rats aged three months than those in rats aged one or two months. It is indicated that cortical CBF reduction and impairment of supratentorial metabolism following occlusion of carotid arteries, at least in part, depend on the morphologic changes of the arteries of the circle of Willis associated with age and development of hypertension in young SHR.

Cerebral ischemia in young and adult gerbils: effects on cholinergic metabolism

The effect of transient cerebral ischemia on cholinergic metabolism was investigated in adult and young gerbils subjected to bilateral carotid artery occlusion (15 min) alone or with release. Ischemia decreased brain acetylcholine (ACh) and increased choline (Ch) levels, affecting the young to a lesser degree than the adult gerbils. Blood recirculation induced a rapid early restoration of brain ACh levels in young animals, whereas a tremendous rebound of ACh was observed in the adults. After 2 h of reflow, Ch levels normalized in the adult brain, whereas a decreased choline level was seen in the young brain. This is the first study demonstrating an age-dependent susceptibility of cholinergic neurotransmission to cerebral ischemia.

Resistance to cerebral ischemia in developing gerbils

Two-, three-, four-, five-, and twelve-week-old gerbils were subjected to various periods of bilateral carotid occlusion (BCO). Rectal and cranial temperatures were maintained at 37 degrees C during BCO, and only rectal temperature was monitored for 30 min of reperfusion. Seven days after ischemia, animals were perfusion-fixed and the neuronal densities in the hippocampal CA1 subfields were counted. The extent of cerebral ischemia during BCO was evaluated with [14C]iodoantipyrine autoradiography. The rectal temperature spontaneously fell to 33-34 degrees C during reperfusion in 2-week-old gerbils, although animals over 3 weeks old presented postischemic hyperthermia. Two-week-old animals therefore were divided into three experimental groups: In one group (2-week-old group I) rectal temperature was not regulated during 30 min of reperfusion, while in the other two groups (2-week-old groups II and III) rectal temperature was regulated at 37 and 38 degrees C, respectively, during reperfusion. Five-minute BCO produced almost complete destruction of the CA1 neurons in 12-week-old animals. In contrast, most CA1 neurons survived 30 min of BCO in 2-week-old group I and 15 min of BCO in 2-week-old groups II and III. [14C]Iodoantipyrine autoradiography revealed that BCO produced severe forebrain ischemia in 2-week-old gerbils as well as in 12-week-old gerbils. These findings indicate that developing gerbils have a greater tolerance to cerebral ischemia and that such ischemic tolerance is not due to a collateral network between the vertebrobasilar and the carotid circulations previously reported to develop more abundantly in developing gerbils.

Immunocytochemical and in situ hybridization approaches to the optimization of brain slice preparations

Methods are described for determining the expression of specific mRNAs and proteins in brain slices, in order to elucidate changes in gene expression during preparation of vibratome slices from hippocampus of adult rats. In situ hybridization with 35S-labeled oligonucleotides was used to evaluate the level and distribution of c-fos and hsp72 mRNAs in 15-microns frozen sections prepared from these slices. Commercially available antibodies were used to examine the distribution of induced Fos and Jun proto-oncogenes as well as expression of the neuronal cytoskeletal protein, microtubule-associated protein 2 (MAP2), in 50-microns vibratome sections from immersion-fixed slices. These studies confirm the induction of c-fos and hsp72 mRNAs during routine incubation, as previously observed in hippocampal slices obtained with a tissue chopper and incubated under somewhat different conditions, indicating that such responses are likely to be common features of many slice preparations. Accumulation of Fos and Jun immunoreactivities in neurons and glia was generally consistent with the distribution of c-fos mRNA induction observed in slices, and the neuronal component of this response was comparable to the expression of these proteins observed after transient ischemia in vivo. MAP2 immunoreactivity detected in the dendritic processes of neurons tended to show an increase in staining intensity during slice incubation, although loss of dendritic staining in specific regions was occasionally observed in association with the absence of Fos and Jun expression and histological evidence of neuron damage. These results support the use of MAP2 immunoreactivity as a sensitive indicator of neuronal integrity in slices.(ABSTRACT TRUNCATED AT 250 WORDS)

A new gerbil model of hindbrain ischemia by extracranial occlusion of the bilateral vertebral arteries

A new gerbil model of hindbrain ischemia was induced by extracranial occlusion of the bilateral vertebral arteries just before their entry into the transverse foramen of the cervical vertebra. Carbon black studies, performed at 5 min after occlusion, revealed that the pons-medulla oblongata, and the cerebellum were quite ischemic in all animals. Cardiovascular changes in mean arterial blood pressure (MABP) and heart rate were recorded until 30 min after occlusion, and revealed that the typical cerebral ischemic response (i.e., abrupt increase in MABP, bradycardia, and apnea) was elicited in all animals (n = 10). Thirty minutes after occlusion, animals (n = 4) were decapitated and immersion-fixed. Brain sections were stained with hematoxylin-eosin (HE) and also immunostained for microtubule-associated protein 2 in order to evaluate ischemic neuronal damage from 30 min of ischemia. By HE staining, ischemic lesions were detected bilaterally in the oculomotor, the trigeminal motor, the lateral vestibular, and the cerebellar interpositus nucleus. In addition, immunostaining revealed ischemic lesions in several other hindbrain areas. In conclusion, we could successfully establish a new gerbil model of hindbrain ischemia. Carbon black perfusion and hemodynamic studies revealed that severe and reproducible hindbrain ischemia was produced. By histopathological examination, we could also clearly demonstrate symmetrical ischemic lesions in several hindbrain areas.

Sustained increase in adrenergic activity in gerbil striatum following transient ischemia

We investigated the changes in striatal monoaminergic functions, focusing on the release and metabolism, in a cerebral ischemic model induced by a 5-min bilateral occlusion of the carotid arteries (BOCA) and reperfusion in anesthetized gerbils. In the microdialysis study, the striatal extracellular level of dopamine (DA) markedly increased (144-fold) immediately after BOCA. Although norepinephrine (NE) and 5-hydroxytryptamine (5-HT) could not be detected in the dialysates throughout the baseline period, they increased to detectable levels after BOCA. On the contrary, the tissue contents of NE and 5-HT decreased or tended to decrease up to 4 hr following reperfusion. Striatal DA contents did not show any changes in the early period after ischemia-reperfusion and slightly increased at 4 hr or later. Tissue contents of 3-methoxytyramine (3-MT), a metabolite of DA by catechol-O-methyltransferase (COMT), increased 0 and 5 min after reperfusion. Normethanephrine (NMN), which is a metabolite of NE by COMT, also increased not only 5 min after but also up to 4 hr after ischemia-reperfusion, indicating a sustained increase in NE release. These results suggested that the neuronal activity of NE, which is supposed to exert a protective effect on ischemic damage, was enhanced for a longer period than that of DA after transient ischemia.

Age and cerebral infarction: a postmortem study of 77 cases of cerebral infarcts in the middle cerebral artery territory

Adverse effect of age on ischemic stroke short-term mortality was reported in some studies and attributed either to more frequent extracerebral causes of death or to an increased severity of ischemia in the aged brain. Relationship between age, size of infarcts, and causes of death were studied in 77 consecutive patients who died from infarction in the middle cerebral artery territory. Area of infarcts was assessed by planimetry, and results were expressed as an index of infarcted area. No significant relationship was found between age and the size of infarcts, the cause of death, or the interval from stroke to death. These results do not support the hypothesis of an increased severity of ischemia in the aged brain.

Differential vulnerability in the hindbrain neurons and local cerebral blood flow during bilateral vertebral occlusion in gerbils

Differential vulnerability in the hindbrain neurons was examined immunohistochemically during hindbrain ischemia in the gerbil. Hindbrain ischemia was produced by extracranial occlusion of the bilateral vertebral arteries just before their entry into the transverse foramen of the cervical vertebra. Local cerebral blood flow was measured by quantitative autoradiographic technique after 5 min of ischemia and was reduced to less than 5 ml/100 g per min in the cerebellum, the pons, and the medulla, indicating that severe and reproducible hindbrain ischemia was induced immediately after occlusion. For immunohistochemical investigation, four gerbils each were used for each ischemic period of 5, 10, 15, and 30 min. Immunohistochemical lesions, detected by the reaction for microtubule-associated protein 2, were visible in the lateral vestibular nucleus and the cerebellar interpositus nucleus even after 5 min of ischemia. These results suggested that these areas were more vulnerable than others, although blood flow was markedly reduced in various regions of the hindbrain. In contrast, areas related to respiratory or cardiovascular control were rather resistant to ischemia. The present study suggests that selective vulnerability during hindbrain ischemia depends mainly on different metabolic characteristics inherent to various neurons in the hindbrain.

Induced resistance and susceptibility to cerebral ischemia in gerbil hippocampal neurons by prolonged but mild hypoperfusion

Brief periods of non-lethal cerebral ischemia can induce resistance against subsequent lethal ischemia. In this study, asymptomatic gerbils after unilateral carotid artery ligation were subjected to 5 min of forebrain ischemia. The prolonged but mild hypoperfusion, by carotid occlusion, induced susceptibility at 1 day and tolerance at 30 days to lethal ischemia in the hippocampal neurons. The neuroprotective effect correlated well with induction of heat shock protein 72 in the hippocampal neurons. These results suggested that neuronal cells possess a cellular response to sublethal hypoperfusion and can survive forthcoming ischemic stress.

Influence of oxidative stress on induced tolerance to ischemia in gerbil hippocampal neurons

We investigated whether reversible oxidative stress induced by the administration of the superoxide dismutase inhibitor, diethyldithiocarbamate, could induce tolerance to subsequent cerebral ischemia in gerbil hippocampal neurons. Mature male gerbils received intraperitoneal injections of diethyldithiocarbamate (1.0 g/kg), which led to reduced superoxide dismutase activity and increases in thiobarbituric acid-reactive substance in the brain. Cerebral ischemia was produced by occluding the bilateral common carotid arteries for 5 min, either 2 or 4 days after diethyldithiocarbamate injection. One week after ischemia, samples from each brain were stained with hematoxylin-eosin to evaluate ischemic neuronal damage in the hippocampal CA1 sector. Diethyldithiocarbamate treatment 4 days before ischemia had significant protective effects against cerebral ischemia, while diethyldithiocarbamate 2-day pretreatment and vehicle treatment failed to show neuroprotection. Biochemical examinations showed a clear induction of heat shock protein 72 and a significant increase in manganese-containing superoxide dismutase in the hippocampus in animals treated with diethyldithiocarbamate 4 days prior to ischemia. These results suggested that the oxidative stress caused by diethyldithiocarbamate could induced tolerance to ischemia in the gerbil brain, and that the increase in the biosynthesis of manganese-containing superoxide dismutase and heat shock protein 72 could provide a biochemical explanation of the tolerance induced under these conditions.

Protective effect of adenosine and a novel xanthine derivative propentofylline on the cell damage after bilateral carotid occlusion in the gerbil hippocampus

The role of adenosine in the development of ischemia induced pathological changes has been examined in Mongolian gerbils. A dramatic increase in the concentrations of adenosine, inosine and hypoxanthine was detected by microdialysis in the dorsal part of hippocampus and in the striatum immediately after 5 min bilateral occlusion of the carotid arteries. From a resting value of about 0.5 microM the concentration of adenosine increased to more than 10 microM. The adenosine levels became normalized within 30 min after ischemia. Inosine and hypoxanthine levels were higher and they increased and also returned towards control somewhat later than adenosine. A second occlusion resulted in a similar but somewhat smaller increase in purine levels. Carotid occlusion for up to 12 min had no major, lasting effect on the binding to adenosine A1-receptors in the CA-regions of the hippocampus, as determined by autoradiography. Neuronal and vascular changes (degeneration of neurons, mitochondrial destruction and ribosomal disaggregation, astroglial oedema) due to ischemia (3-12 min, followed by 48 h recirculation) was studied with light and electron microscopy in the selectively vulnerable CA1 area of hippocampus. In one series of experiments the adenosine antagonist theophylline (20 mg/kg i.p.), given 15 min prior to a 5 min occlusion, significantly enhanced the ischemia induced changes. In another experiment the adenosine uptake inhibitor propentofylline (HWA 285, 10 mg/kg), injected 15 min before a 12 min carotid occlusion, reduced the neuronal (90%) and astroglial changes (84%) due to ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of cerebral ischemia on synaptosomal uptake and release of 3H-5-hydroxytryptamine in adult and young Mongolian gerbils

Cerebral ischemia induced by bilateral common carotid artery occlusion (15 min) with and without release (1 hr) served as a model for comparative regional studies of synaptosomal 3H-5-hydroxytryptamine (3H-5-HT) uptake and release in adult and young gerbils. A decreased uptake and an increased release of 5-HT was observed in the adult after ischemia alone and/or ischemia with reflow. At the same time, 5-HT uptake was not affected except in the cortex and the release was reduced in the young. These findings indicate that the same ischemic insults affect differently the synaptosomal uptake and/or release of 5-HT in adult and young brain.

Dexamethasone treatment attenuates the development of ischaemic brain oedema in gerbils

Transient global forebrain ischaemia was produced in Mongolian gerbils by occluding both common carotid arteries for 10 min followed by 48 h recirculation. Dexamethasone, 5 mg/kg i.p., was given 5 h before the occlusion and every 12 h thereafter. After occlusion an increase in water, sodium and calcium content was found in the parietal cortex and hippocampus, while the concentration of potassium decreased. Exudation of plasma albumin was not found in the brain. The activity of Na+, K(+)-ATPase decreased in the hippocampus. Morphological signs of cerebral oedema were also observed, both in the CA1 region of the hippocampus and in the cortex. Dexamethasone treatment prevented the accumulation of water, sodium and calcium in the ischaemic brain. It also attenuated the oedematous morphological changes of the blood-brain barrier. Thus dexamethasone treatment may also have therapeutic relevance in the acute, high-risk phase of patients suffering from repetitive, transitoric cerebral ischaemia.

Prediction of stroke-prone gerbils and their cerebral circulation

We attempted to predict the severity of cerebral ischemia, prior to permanent occlusion of a common carotid artery (CCA), in the gerbil by measuring the diameter of the distal CCA before and during temporary ligation and correlated the severity of cerebral ischemia and the pattern of cerebral circulation. All gerbils with reduction of the diameter over 44% after temporary occlusion developed severe neurological signs following permanent ligation. These gerbils lacked any connection between the left and right anterior cerebral arteries (ACA) and the pericallosal arteries originated from the ACA of the occluded side. No gerbils with reduction of less than 30% developed neurological signs and those gerbils possessed a definite anastomosis between the ACAs from both sides. Six of 7 gerbils without connection between the ACAs whose pericallosal arteries originated from the ACA of the non-occluded side proved to be moderately symptomatic. It was concluded that we could reliably predict severely symptomatic and moderately symptomatic gerbils with specific cerebral circulation patterns prior to permanent occlusion of the CCA. The preselected 'stroke-prone' gerbils should be useful for the investigation of cerebral ischemia and the evaluation of pharmacological agents.

Effect of ischemia on noradrenergic and energy-related metabolites in the cerebral cortex of young and adult gerbils

Relationships between ischemic changes in the cerebral cortical content of energy and noradrenergic metabolites were evaluated in young and adult gerbils. Groups of 3-week- and 3-month-old gerbils were subjected to 5 or 15 min of bilateral carotid artery occlusion alone or with 1 hr of release. Ischemia of 5 and 15 min depleted energy-related metabolites but did not affect the content of either norepinephrine or homovanillic acid in young and adult gerbils. At 1 h of reflow, after 5 and 15 min of ischemia, the levels of norepinephrine significantly decreased, while those of homovanillic acid increased in the adult but not in the young gerbils. At this time a complete recovery of energy reserves was seen in both the young and the adult gerbils. These results indicate that the ischemic change in homeostasis of energy metabolism is not directly associated with that of the noradrenergic system in young and adult cerebral cortex.

Calcium in the mitochondria following brief ischemia of gerbil brain

Calcium was localized in neurons and glial cells of the CA1 region of hippocampus and in neurons of parietal cortex with the oxalate-pyroantimonate electron cytochemical method following recovery from 5-min ischemia of gerbil brain. During the early postischemic recirculation phase a maximum amount of calcium deposits was detected in mitochondria of all investigated cells. A second rise in mitochondrial calcium deposits was observed in parallel with the onset of ultrastructural degeneration of mitochondria and the loss of cellular integrity beginning 6 h postischemia.

The effect of the calcium antagonist nimodipine on the gerbil model of experimental cerebral ischemia

The gerbil model was used to assess the therapeutic effects of the calcium antagonist nimodipine on cerebral ischemia. Transient cerebral ischemia was produced in each gerbil by bilateral common carotid occlusion of 10-, 15- or 20-min duration. Nimodipine (0.01 or 0.1 mg/kg) was administered intraperitoneally just before the carotid occlusion or 10-30 min after the removal of the arterial clips. Morbidity of each animal was evaluated using the stroke index, and the sum of stroke indices was calculated for evaluating the overall morbidity during a particular period of reperfusion. Mortality was observed for 24 hours after clip removal. Although, depending on the timing of the drug administration, the low-dose (0.01 mg/kg) nimodipine worsened the morbidity in the gerbils with 10-min ischemia, the high-dose (0.1 mg/kg) of the drug had a clear beneficial effect on the mortality associated with cerebral ischemia. These results are considered worthwhile for further trials to assess the usefulness of nimodipine as a therapeutic agent in the management of the acute ischemic stroke.

Regional cerebral ischemia in the gerbil: measurement of regional cerebral blood flow by quantitative autoradiography

Alterations in the regional CBF after occlusion of the posterior communicating, middle cerebral, or common carotid artery were investigated in the gerbil with a quantitative autoradiographic technique using [14C]iodoantipyrine. Occlusion of the posterior communicating artery produced severe ischemia in the ipsilateral hippocampus, thalamus, and dorsal mesencephalon. Occlusion of the middle cerebral artery produced severe ischemia in the ipsilateral rostral and central cerebral cortex and lateral caudate-putamen. Occlusion of the common carotid artery produced ipsilateral hemispheric ischemia of variable degrees. The distribution and degree of cerebral ischemia produced by occlusion of one of these arteries correlated closely to the arterial territory and the extent of collateral blood supply. Since the areas affected after occlusion of the posterior communicating or middle cerebral artery differ, those models will be useful for the comparative investigation of the ischemia-related cerebral pathophysiology associated with different sites of primary lesion.

Hypoxic-ischemic brain damage and cerebral blood flow changes in young rabbits

Hypoxic-ischemic cerebral damage was demonstrated in the cerebral cortex of 2-week-old rabbits at 3 to 5 days after bilateral carotid artery ligation and reperfusion during hypoxemia. Carotid ligation and reperfusion had little effect on cortical blood flow during normoxemia, but the former suppressed a blood flow increase to hypoxemia and the latter suppressed a blood flow decrease to hyperoxemia. These results suggest a relative ischemia or vascular dysfunction which may play a part in the pathogenesis of the hypoxic-ischemic cortical necrosis.

Cell proliferation after ischemic infarction in gerbil brain

In order to study cell proliferation after ischemic infarction, a model of bilateral common carotid artery occlusion in the gerbil was developed. A comparison of survival rates after 15, 30, 45 and 60 min of occlusion revealed that 45 min was the maximum duration of ischemia after which most (72%) of the gerbils were alive at 1 week. The administration of pentobarbital (single dose, 30 mg/kg) postoperatively to badly seizing animals increased survival to 100%. Large, well-demarcated infarcts were present in posterior thalamus or midbrain in 62% of gerbils subjected to 45 min bilateral occlusion. In 60% of these animals the infarcts were unilateral; in 40% they were bilateral. To quantitate cell proliferation in the infarcts from 12 h to 25 days after ischemia, gerbils were injected with [3H]thymidine 4 h prior to sacrifice, and autoradiographs were prepared from sectioned brains. Proliferation took place from 2 to 7 days after occlusion, with a maximum of 24% labeled cells at 6 days.

Fine structure of peptidergic and catecholaminergic nerve fibers in the anterior cerebral artery and their interrelationship: an immunoelectron microscopic study

This study shows (1) the ultrastructure of vasoactive intestinal polypeptide (VIP)-, substance P (SP)-, and neuropeptide Y (NPY)-containing nerve fibers in the walls of the cerebral arteries and (2) the relationship between these peptidergic (VIP, SP, and NPY) and catecholaminergic (CA) nerve terminals by immunohistochemistry combined with false transmitter (5-hydroxydopamine) histochemistry under the electron microscope. VIP-, SP-, and NPY-like immunoreactivity (VIPI, SPI, and NPYI) were found diffusely in the axoplasm and around the small clear vesicles in the nerve terminals. In a few cases, SPI was found within the large vesicles. Most of the VIPI terminals were ensheathed by the cytoplasm of the Schwann cells together with CA terminals, identified as those with a number of small granulated vesicles. In some cases, they were directly apposed to the smooth muscle cells at a distance of about 100 nm. SPI terminals were frequently solitary but about 30% were located together with CA and other (neither SPI nor CA) terminals ensheathed by Schwann cells, directly apposed to the smooth muscle cells at a distance of about 100 nm. On the other hand, NPYI terminals were also identified as CA terminals, indicating the coexistence of these two substances. These findings suggest a close interrelationship between peptidergic and CA nerve terminals in the neurogenic control of cerebral blood vessel function.

Dual innervation of substance P-containing neuron system in the wall of the cerebral arteries

The present study has shown the presence of substance P-like immunoreactive (SPI) fiber plexuses both in the carotid and vertebrobasilar systems in the Mongolian gerbil, suggesting that the origins of SPI fibers in these two systems differ. The present study further demonstrated in the guinea pig, using experimental manipulations, the dual origin of SPI fibers in the cerebral arteries; one from the trigeminal ganglion (TG) that mainly innervates the carotid system, and the other that separates from the TG and mainly innervates the vertebrobasilar system.

Immunoreactive glucagon in the smooth muscle cells of the rat cerebral artery: an immunohistochemical analysis

The presence of immunoreactive glucagon (IRG) in a smooth muscle of the cerebral arteries of rats was demonstrated immunohistochemically using two antisera against pancreatic glucagon, OAL -123 and Unger 's 30K . Based on the results and on our previous radioimmunoassay and gel filtration study, the smooth muscle cells of the blood vessels may be one of the extrapancreatic sources of IRG in the plasma.

Cerebral ischemic response-like hemodynamic changes induced by telencephalic ischemia in Mongolian gerbils (Meriones unguiculatus)

The effect of bilateral common carotid occlusion on systemic hemodynamics was investigated in the gerbil with and without bilateral carotid sinus denervation. Irrespective of the sinus denervation, telencephalic, severe ischemia produced significant changes in the heart rate and systemic arterial blood pressure, similar to those observed in cerebral ischemic response. These hemodynamic changes, associated with cerebral ischemia, may play an important role in affecting the pathophysiology of cerebral ischemia itself.

Differential effect of cerebral ischemia on monoamine content of discrete brain regions of the Mongolian gerbil (Meriones unguiculatus)

The effect of bilateral cerebral ischemia on noradrenaline, dopamine, and serotonin concentrations in six brain regions (i.e., the cerebral cortex, striatum, hippocampus, midbrain-diencephalon, cerebellum, and pons-medulla oblongata) was examined in the gerbil stroke model. The relative changes in regional cerebral blood flow after bilateral common carotid occlusion were also assessed using the radioactive microsphere technique. At 1 h after bilateral carotid occlusion, a significant decrease of monoamine concentration was observed in the cerebral cortex, striatum, hippocampus, and midbrain-diencephalon whereas no significant change was detected in the cerebellum and pons-medulla oblongata. The fall in NA content was most prominent in the cerebral cortex and hippocampus and percentage reductions of dopamine and serotonin were greatest in the striatum and cerebral cortex, respectively. These results suggest that the monoamine neurons in various brain regions might have different vulnerabilities to ischemic insult and show no evidence of transtentorial diaschisis.