Neuronal damage and calcium accumulation following transient cerebral ischemia in the rat

The purpose of this study was to examine the distribution of neuronal damage following transient cerebral ischemia in the rat model of four-vessel occlusion utilizing light microscopy as well as⁴⁵Ca-autoradiography. Transient ischemia was induced for 30 min. The animals were allowed to survive for 7 d after ischemia. In the animals subjected to ischemia, the most frequently and seriously damaged areas were the paramedian region of hippocampus, the hippocampal CA1 sector, and the dorsolateral part of striatum, followed by the inferior colliculus, the substantia nigra, the frontal cortex, and the thalamus, which were moderate damaged. Furthermore, the cerebellar Purkinje neurons, the hippocampal CA4 sector, the medial geniculate body, and the hippocampal CA3 sector were slightly affected.⁴⁵Ca-autoradiographyic study also revealed calcium accumulation in the identical sites of ischemic neuronal damage, except for the frontal cortex. Regional cerebral blood flow during 10 min of ischemia was severely decreased in selectively vulnerable areas. The blood flow in the medial geniculate body, the substantia nigra, the inferior colliculus, and the cerebellum was less pronounced than that in the selectively vulnerable areas. The present study demonstrates that transient cerebral ischemia can produce significant neuronal damage not only in the selectively vulnerable regions, but also in the brainstem.     

Selective neuronal vulnerability following transient cerebral ischemia in the gerbil: distribution and time course

An important feature of ischemic brain damage is the selective vulnerability of specific neuronal populations. We studied the distribution and time course of neuronal damage following transient cerebral ischemia in the gerbil, using light microscopy and 45Ca autoradiography. Following 5 min of ischemia, selective neuronal damage determined by abnormal 45Ca accumulation was recognized only in the hippocampal CA1 subfield and part of the inferior colliculus. Ischemia for 10 to 15 min caused extensive neuronal injury in the 3rd and 5th layers of neocortex, the striatum, the septum, the whole hippocampus, the thalamus, the medial geniculate body, the substantia nigra, and the inferior colliculus. Progression of the damage was rapid in the medial geniculate body and the inferior colliculus, moderate in the neocortex, striatum, septum, thalamus, and the substantia nigra, and was delayed in the hippocampal CA1 sector. However, the delayed damage of the hippocampus occurred earlier when the ischemia period was prolonged. Histological observation revealed neuronal loss in the identical sites of the 45Ca accumulation. This study revealed that the distribution and time course of selective neuronal damage by ischemia proceeded with different order of susceptibility and different speed of progression.     

Neuronal damage and calcium accumulation following repeated brief cerebral ischemia in the gerbil

We investigated the distribution of neuronal damage following brief cerebral transient ischemia and repeated ischemia at 1-h intervals in the gerbil, using light microscopy and 45Ca autoradiography as a marker for detection of ischemic damage. The animals were allowed to survive for 7 days after ischemia induced by bilateral carotid artery occlusion. Following 2-min ischemia, neuronal damage determined by abnormal calcium accumulation was not observed in the forebrain regions. Following 3-min ischemia, however, abnormal calcium accumulation was recognized only in the hippocampal CA1 sector and part of the striatum. Two 2-min ischemic insults caused extensive abnormal calcium accumulation in the dorsolateral part of striatum, the hippocampal CA1 sector, the thalamus, the substantia nigra and the inferior colliculus. The ischemic insults were more severe than that of a single 3-min ischemia. However, three 1-min ischemic insults caused abnormal calcium accumulation only in the striatum. On the other hand, three 2-min ischemic insults caused severe abnormal calcium accumulation in the brain. The abnormal calcium accumulation was found in the dorsolateral part of striatum, the hippocampal CA1 sector, the thalamus, the medial geniculate body, the substantia nigra and the inferior colliculus. Gerbils subjected to three 3-min ischemic insults revealed most severe abnormal calcium accumulation. Marked calcium accumulation was seen not only in the above sites, but also spread in the neocortex, the septum and the hippocampal CA3 sector. Morphological study after transient or repeated ischemia indicated that the distribution and frequency of the neuronal damage was found in the sites corresponding to most of the regions of abnormal calcium accumulation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Regional neuroprotective effects of pentobarbital on ischemia-induced brain damage

We investigated the neuroprotective effect of pentobarbital, a GABAA receptor-effector, on ischemic neuronal damage in the gerbils. The animals were allowed to survive for 7 days after 10-min ischemia induced by bilateral occlusion of the common carotid arteries. Morphological changes and abnormal calcium accumulation were evaluated in selectively vulnerable areas after ischemia. Pentobarbital (40 mg/kg, IP), administered 30 min prior to ischemia, significantly reduced neuronal cell loss in the neocortex, the striatum, and the hippocampal CA3 sector. However, pentobarbital failed to prevent the damage to the hippocampal CA1 sector and the thalamus. 45Ca autoradiographic study also revealed that a marked calcium accumulation was found in the selectively vulnerable regions after ischemia, which was consistent with the extent of histological neuronal damage. The abnormal calcium accumulation was reduced in the sites corresponding to most of the regions in which the protective effect of pentobarbital was found. The results suggest that ischemia-induced neuronal damage may be partly caused by an imbalance between excitatory and inhibitory input.     

Emphasized selective vulnerability after repeated nonlethal cerebral ischemic insults in rats.

BACKGROUND AND PURPOSE: We examined the density and distribution of brain damage after repeated periods of nonlethal ischemic insult in rats in comparison with damage after single lethal periods of ischemic insult. METHODS: Transient cerebral ischemia was induced by four-vessel occlusion for 3, 10, 20, and 30 minutes, and 3-minute periods of ischemia were repeated two, three, or five times at 1-hour intervals, followed by 7 days of survival. RESULTS: Three minutes of ischemia produced no brain damage, but 10-30 minutes of ischemia produced neuronal damage, depending on the length of ischemia, to the selectively vulnerable forebrain regions such as hippocampal CA1 and CA4 subfields, neocortex, striatum, and ventral thalamus, as well as to the brain stem structures (medial geniculate body, substantia nigra, and inferior colliculus) and cerebellar Purkinje cells. Two 3-minute periods of ischemic insult produced neuronal damage to the hippocampal CA1 subfield. Three and five 3-minute insults produced neuronal damage extensively to the selectively vulnerable forebrain areas. An intense cumulative effect of damage was observed in the ventral thalamus, whereas the substantia nigra and the inferior colliculus were resistant to repeated ischemic insults. CONCLUSIONS: Our data indicate that the density and distribution of neuronal damage after repeated ischemic insults are altered as compared with after single ischemia.     

Prevention of abnormal calcium accumulation in postischemic gerbil brain by vinconate

We investigated the effect of vinconate on ischemia-induced calcium accumulation in the gerbil brain. The animals were allowed to survive for 7 days after 10 min of ischemia. Abnormal calcium accumulation was evaluated in the gerbil brain after ischemia. Following 10 min ischemia, abnormal calcium accumulation was found in the neocortex, the striatum, the hippocampus, the thalamus, the substantia nigra and the inferior colliculus. Intraperitoneal administration of vinconate (100 mg/kg) immediately after 10 min of ischemia significantly reduced the areas of abnormal calcium accumulation only in the striatum. However, the application of vinconate (100 and 300 mg/kg) 10 min before ischemia dose-dependently decreased the areas of abnormal calcium accumulation in the striatum, the thalamus and the substantia nigra. Morphological observation revealed neuronal damage in the identical sites of the abnormal calcium accumulation. Furthermore, a autoradiographic study using 14C-vinconate showed that this drug easily penetrates the blood-brain barrier and especially localizes in the striatum and the thalamus after 5 min ischemia. The result suggests that vinconate reduces the areas of abnormal calcium accumulation in the postischemic gerbil brain. This effect seems to be mediated via the height distribution in the brain following ischemia.     

反复性脑缺血神经元选择性易损性的实验研究

目的　研究反复性脑缺血神经元选择性易损性。方法应用４５Ｃａ放射自显影及光镜对比观察大鼠反复性与单次性脑缺血神经元损害的密度和分布。结果　单次缺血易损部位主要为海马、新皮层、纹状体、丘脑、小脑、脑干等;反复缺血易损区的分布与单次缺血基本相似,但下丘和小脑对反复缺血抵抗,而丘脑腹侧和海马呈现显著的累积性损害。结论　反复性脑缺血神经元选择性易损性及其机制均有别于单次性脑缺血。     

Postischemic changes of [3H]nimodipine and [3H]ryanodine binding in the gerbil striatum and hippocampus

Sequential alterations of [³H]nimodipine and [³H]ryanodine binding in gerbils were investigated in selectively vulnerable regions, such as the striatum and hippocampus, 1 h to 7 days after 10 min of transient cerebral ischemia. [³H]Nimodipine binding showed no significant changes in the striatum and hippocampus up to 48 h after ischemia. Seven days after ischemia, however, a severe reduction in [³H]nimodipine binding was observed in the dorsolateral striatum, hippocampal CA1 (stratum oriens, stratum pyramidale and stratum radiatum) and hippocampal CA3 sector. On the other hand, [³H]ryanodine binding showed a significant increase in the hippocampus 1 h after ischemia. Five hours after ischemia, a significant reduction in [³H]ryanodine binding was observed only in the hippocampal CA1 sector. Thereafter, the striatum and hippocampus showed no significant alterations in [³H]ryanodine binding up to 48 h after ischemia. After 7 days, a marked reduction in [³H]ryanodine binding was observed in the striatum and hippocampus which were particularly vulnerable to ischemia. These results demonstrate that postischemic alteration in [³H]nimodipine and [³H]ryanodine binding is produced with different processes in the hippocampus. They also suggest that the mechanism for striatal cell damage caused by transient cerebral ischemia may, at least in part, differ from that for hippocampal neuronal damage. Furthermore, our findings suggest that abnormal calcium release from intracellular stores may play a pivotal role in the development of hippocampal neuronal damage.     

反复性脑缺血丘脑神经元损害的实验研究

目的 :研究反复性脑缺血丘脑神经元的病理损害及其机制。方法 :应用45Ca放射自显影及光镜对比研究大鼠单次性和反复性脑缺血及 NMDA受体拮抗剂 MK- 80 1治疗后丘脑钙积聚和神经元损害的病理改变。结果 :反复缺血组丘脑异常钙积聚与神经元损害明显重于单次缺血组 ;MK- 80 1能显著减轻和改善丘脑钙积聚与组织病理损害。结论 :反复非致死性短暂脑缺血导致丘脑腹侧神经元显著累积性损害 ,兴奋性氨基酸及 Ca2 +可能起着重要作用。     

Brain damage in a mouse model of global cerebral ischemia. Effect of NMDA receptor blockade

The importance of particular genes in neuronal death following global cerebral ischemia can readily be studied in genetically modified mice provided a reliable model of ischemia is available. For that purpose, we developed a mouse model of global cerebral ischemia that induces consistent damage to different regions of the brain and with a low mortality rate. Twelve minutes of ischemia was induced in C57BL/6 mice by bilateral common carotid artery occlusion under halothane anesthesia and artificial ventilation. Body and brain temperature were monitored and cortical cerebral blood flow in each hemisphere was measured by laser Doppler flowmeter before, during, and for 5 min after ischemia. Extensive damage was found in the striatum and marked cell damage was observed in the CA1 and CA2 regions of hippocampus and in thalamus. Mild damage was seen in the CA3 region, dentate gyrus and cortex. Hippocampal damage in the CA1 region is delayed and developed over 48 h. Intraischemic hypothermia of 33 degrees C provided a robust neuroprotection. The non-competitive N-methyl-D-aspartate receptor blocker, MK-801, did not provide protection in the hippocampus, cortex, striatum or thalamus when administered 30 min prior to ischemia or 2 h after the end of ischemia, but selectively mitigated damage in the hippocampus, when administered immediately following ischemia. This model of global cerebral ischemia may be useful in pharmacological and genomic studies of ischemic brain damage.     

Calcium deposits in the thalamus following repeated cerebral ischemia and long-term survival in the gerbil

We investigated the long-term changes in the gerbil brain following three episodes of 2-min forebrain ischemia at 1-h intervals in comparison with a 6-min period of ischemia. The animals were sacrificed after 1 month and 6 months. Following either ischemic insult, the hippocampal CA1 region showed a loss of pyramidal neurons together with a diffuse calcium accumulation as shown by alizarin red S staining. Three 2-min ischemic insults additionally produced neuronal damage in the striatum and thalamus. The thalamic damage was accompanied by an accumulation of small calcium granules after 1 month and large calcium concretions after 6 months. Calcium staining in the striatum was weak. Thus, the thalamic neuronal damage was accompanied by an active process of calcification, which has not been described in experimental cerebral ischemia models. The observations show that repeated ischemic insults produce different long-term effects in different brain regions.     

Repeated focal cerebral ischemia in gerbils is associated with development of infarction.

We induced repeated focal cerebral ischemia in gerbils. Single 5-min ischemia produced neuronal damage limited to the ipsilateral CA1 and CA4 hippocampus. Two 5-min ischemic insults spaced at a 1-h interval caused selective neuronal damage to the CA1, CA3 and CA4 hippocampus, striatum, neocortex, and thalamus. Three 5-min ischemic insults at 1-h intervals produced infarction. Thus, repeated focal ischemia produced cumulative brain damage by conversion of sublethal damage into selective neuronal damage and of the neuronal damage into infarction.     

Calcium accumulation during the evolution of hypoxic-ischemic brain damage in the immature rat

An excessive accumulation of calcium in neuronal and other tissues has been postulated to represent a "final common pathway" for cell death arising from hypoxia-ischemia. To clarify the role of altered calcium flux into and distribution within the perinatal brain undergoing hypoxic-ischemic injury, 7-day postnatal rats underwent unilateral common carotid artery ligation followed by 3 h of hypoxia with 8% oxygen. This insult is known to produce brain damage confined to the cerebral hemisphere ipsilateral to the arterial occlusion in greater than 90% of the animals. Either before or after hypoxia-ischemia, the animals received a subcutaneous injection of [45Ca]Cl2, and their brains were subjected to 45Ca autoradiography at 0-1, 5, 24, and 72 h, 7 or 15 days thereafter. During hypoxia-ischemia, calcium flux into the ipsilateral cerebral hemisphere was prominent in 13 of 14 rat pups, especially in neocortex, hippocampus, striatum, and thalamus. Calcium accumulation also occurred to a variable degree (6 of 14 animals) in the contralateral cerebral hemisphere. During recovery, radioactivity in the contralateral cerebral hemisphere was no longer apparent, whereas in the ipsilateral hemisphere, the extent of calcium accumulation was mild in four of six at 1 h, moderate in three of six at 5 h, moderate to intense in six of seven and six of seven at 24 and 72 h, respectively, and intense in three of three and two of two animals at 7 and 15 days, respectively. As during hypoxia-ischemia, the distribution of the radioactivity was most prominent in those structures that are known to be vulnerable to hypoxic-ischemic injury.(ABSTRACT TRUNCATED AT 250 WORDS)     

Regional impairment of protein synthesis following brief cerebral ischemia in the gerbil

Summary Regional cerebral protein synthesis following brief ischemia was investigated in the Mongolian gerbil, utilizing l-[methyl-¹⁴C]methionine autoradiography. Transient ischemia was induced for 1,2 or 3 min. At various recirculation periods up to 48 h, animals received a single dose of l-[methyl-¹⁴C]-methionine and then were terminated 35 min later. Sham-operated animals showed a normal pattern of amino acid incorporation into the proteins of the brain. Following 1-min ischemia, the pattern of protein synthesis was similar to that in the sham-operated gerbils. Ischemia for 2 min, however, caused marked inhibition of protein synthesis in the neocortex, striatum, hippocampal CA1 sector and the thalamus at 1 h of recirculation. Extensive recovery of protein synthesis was found in the neocortex, the striatum, the hippocampal CA1 sector and the thalamus at 5–24 h of recirculation, but, a slight inhibition was detectable in the hippocampal CA1 sector in one of six animals. This inhibition had fully recovered at 48 h of recirculation. Following 3-min ischemia, severe impairment of protein synthesis was found in the neocortex, striatum, the whole hippocampus and the thalamus. After 5–24 h of recirculation, the protein synthesis in these regions had gradually recovered, except that complete lack of amino acid incorporation was seen in the hippocampal CA1 subfield. This impairment of protein synthesis in the hippocampal CA1 sector was not recovered at 48h of recirculation. Morphological study indicated that 2-min ischemia did not produce any significant neuronal damage in the brain, whereas gerbils subjected to 3-min ischemia revealed a mild neuronal damage in the hippocampal CA1 sector. The present study indicates that even non-lethal ischemia can produce a severe inhibition of protein synthesis in the selectively vulnerable regions during the early stage of recirculation.     

Mitochondrial calcium sequestration in cortical and hippocampal neurons after prolonged ischemia of the cat brain

Summary Adult normothermic cats were submitted to 1- h complete cerebrocirculatory arrest, followed by blood recirculation for 6–8 h. Two groups of animals could be distinguished: In one group electrocorticogram and somatically evoked primary cortical potentials steadily recovered after ischemia, and in another electrophysiologic recovery was absent. At the end of the recirculation period, calcium content was measured in tissue samples taken from cerebral cortex and hippocampus, and compared with mitochondrial calcium sequestration as assessed by electron-microscopic cytochemistry. Protein content of cortex and hippocampus was also determined for evaluation of tissue swelling. The two regions were selected because previous experiments had revealed that in animals with electrophysiologic recovery cerebral cortex remains intact although hippocampus is selectively injured, whereas in animals without electrophysiologic recovery both cerebral cortex and hippocampus are damaged.In animals with functional recovery, neither calcium content nor mitochondrial calcium sequestration were significantly increased in either cerebral cortex or hippocampal subfield CA1. Only in dentate gyrus a minor degree of mitochondrial calcium sequestration was present. Calculation of tissue swelling revealed no change in cerebral cortex, but a volume increase by 18% in hippocampus, indicating development of brain edema in this region. In animals without functional recovery tissue calcium significantly increased both in cortex and hippocampus (by 49% and 73% of control, respectively), and there was significant mitochondrial calcium accumulation in both regions. Calculated brain swelling in these animals amounted to 16% and 26% in cortex and hippocampus, respectively.The results obtained do not support the hypothesis that selective vulnerability of hippocampus is the consequence of neuronal calcium overload but rather indicate that calcium accumulation is an unspecific epiphenomenon of irreversible cell injury.     

Neuronal damage following non-lethal but repeated cerebral ischemia in the gerbil

Summary Brief, non-lethal transient forebrain ischemia in the gerbil can injure selectively vulnerable neurons when such ischemia is induced repeatedly. The influence of the number and interval of the ischemic insults on neuronal damage, as well as the time course of damage, following repeated 2-min forebrain ischemia were examined. A single 2-min forebrain ischemia were examined. A single 2-min ischemic insult caused no morphological neuronal damage. A moderate number of hippocampal CA1 neurons were destroyed following two ischemic insults with a 1-h interval, and destruction of almost all CA1 neurons resulted from three or five insults at 1-h intervals. Three and five insults also resulted in moderate to severe damage to the striatum and thalamus, depending on the number of episodes. Although three ischemic insults at 1-h intervals caused severe neuronal damage, this number of insults at 5-min and 4-h intervals caused destruction of relatively few neurons, and non neurons were destroyed at 12-h intervals. Following three ischemic insults at 1-h intervals, damage to the striatum, neocortex, hippocampal CA4 subfield and thalamus was observed at 6–24 h of survival, whereas damage to the hippocampal CA1 subfield appeared at 2–4 days. The results indicate that even a brief non-lethal ischemic insult can produce severe neuronal damage in selectively vulnerable regions when it is induced repeatedly at a certain interval. The severity of neuronal damage was dependent on the number and interval of ischemic episodes.     

Functional, behavioral, and histological changes induced by transient global cerebral ischemia in rats: effects of cinnarizine and flunarizine

Temporary cerebral ischemia (15 min) produced by "four-vessel occlusion" in the rat causes neurological disorders, changes in behavior (locomotor hyperactivity), and neuronal damage in the neocortex, striatum, and especially the CA1 zone of the hippocampus. We have studied the effects of two calcium overload blockers, flunarizine (50 mg/kg p.o. twice a day) and cinnarizine (100 mg/kg p.o. twice a day), on these alterations. Cinnarizine markedly improved the functional abnormalities of ischemia but had little or no effect upon the neuronal damage. In contrast, flunarizine provided far greater neuronal protection but with less obvious effects upon behavioral parameters. However, there was evidence of sedation 2 h after treating animals with this dose of flunarizine that might have masked any positive effect of the drug on behavior. We conclude that under the present experimental conditions, there is no correlation between the early and late behavioral changes observed following a temporary cerebral ischemic episode and the histological damage observed in certain vulnerable neurons, particularly in the hippocampus, 72 h after the insult.     

Exo-focal postischemic neuronal death in the rat brain

We describe delayed neuronal damage in ipsilateral areas remote from the ischemic area of rat brain after transient focal ischemia induced by embolization of the right middle cerebral artery (MCA). After 15, 30, 60 and 90 min of MCA occlusion, recirculation was achieved by removal of the embolus. Chronological changes in the distribution of the neuronal damage were determined by using the 45Ca autoradiographic technique and the histological method, and the mechanism involved was investigated by measuring local cerebral glucose metabolism. Depending on the duration of ischemia, 45Ca accumulation extended to the lateral segment of the caudate putamen and to the cerebral cortex, both supplied by the occluded MCA. Moreover, 3 days after ischemic insult, 45Ca had accumulated in the ipsilateral substantia nigra and ventral posterior nucleus of the thalamus. Histological examination revealed that the neurons in both areas suffered damage and were selectively reduced in number. Cerebral glucose utilization decreased in the thalamus, but increased approximately 30% (P less than 0.01) in the substantia nigra compared with the value in the corresponding contralateral area. Both areas lie outside the ischemic area, but have transsynaptic connections with the ischemic focus. Based on the present study, we suggest that the mechanisms of delayed neuronal death in these two remote areas may not be identical, but that this phenomenon may be caused by a transsynaptic process associated with the ischemic focus.     

Prevention of delayed neuronal death in gerbil hippocampus by a novel vinca alkaloid derivative (Vinconate)

We investigated the effect of vinconate, a novel vinca alkaloid derivative, on delayed neuronal death using Mongolian gerbils. The animals were allowed to survive for 7 d after 3 or 5 min of forebrain ischemia induced by bilateral occlusion of the common carotid arteries. Morphological changes and calcium (⁴⁵Ca) accumulation were evaluated in the CA1 sector of the hippocampus after ischemia. Vinconate (50, 100, and 300 mg/kg) showed protective effects against neuronal death in a dose-dependent manner when administered intraperitoneally (ip) 10 min before 5 min of ischemia. However, the administration of vinconate (100 and 300 mg/kg, ip) immediately after 5 min of ischemia showed no therapeutic effect, whereas a marked therapeutic effect of vinconate (50 and 100 mg/kg, ip) was observed when administered immediately after 3 min of ischemia. An anesthetic dose of pentobarbital (40 mg/kg, ip) also produced significant protection against neuronal death. Furthermore, a⁴⁵Ca autoradiographic study indicated that a marked calcium accumulation was found in the CA1 sector at 7 d after 5 min of ischemia, which was consistent with the extent of histological neuronal damage. When vinconate (100 and 300 mg/kg, ip) was administered 10 min before 5 min of ischemia, the abnormal calcium accumulation was not detected in the CA1 sector. These data indicate that suppression of abnormal neuronal activity may be owing to the antagonistic action of vinconate on calcium accumulation.     

Postischemic alteration of muscarinic acetylcholine, adenosine A1 and calcium antagonist binding sites in selectively vulnerable areas: an autoradiographic study of gerbil brain.

We performed receptor autoradiography to determine sequential alterations in the binding of muscarinic cholinergic and adenosine A1 receptors and of a voltage dependent L-type calcium channel blocker 1 h-1 month after transient cerebral ischemia in the gerbil brain. [3H]Quinuclidinyl benzilate (QNB), [3H]cyclohexyladenosine (CHA) and [3H]PN200-110 were used to label muscarinic and adenosine A1 receptors and L-type calcium channels, respectively. Transient ischemia was induced for 10 min. [3H]QNB and [3H]CHA binding showed no significant alteration in selectively vulnerable areas at an early stage (1-24 h) of recirculation. However, the dentate molecular layer which was resistant to ischemia revealed a significant decrease in the [3H]CHA binding sites 24 h after ischemia. Thereafter, the [3H]QNB and [3H]CHA binding showed significant reduction in most of selectively vulnerable areas. Marked reduction was especially found in the dorsolateral part of striatum and the hippocampal CA1 sector which was the most vulnerable to ischemia. In contrast, [3H]PN200-110 binding showed a transient elevation in the hippocampal CA1 sector, the dentate molecular layer and the thalamus 1 h of recirculation. However, the striatum and neocortex revealed no alteration in the [3H]PN200-110 binding. Thereafter, the reduction in the [3H]PN200-110 binding was seen only in the dorsolateral part of the striatum and the hippocampal CA1 sector. The results suggest that transient cerebral ischemia can cause the alterations in the binding of muscarinic cholinergic and adenosine A1 receptors and of L-type calcium channel blocker in most of selectively vulnerable areas.(ABSTRACT TRUNCATED AT 250 WORDS)