Interleukin-6 expression in exo-focal neurons after striatal cerebral ischemia

Although anatomical and biochemical properties of the rat entopeduncular nucleus (EPN) closely resemble those of the substantia nigra pars reticulata (SNr), the present study shows that, unlike in the SNr, focal cerebral ischemia does not cause trans-synaptic degeneration of EPN neurons, despite striatal infarction and a similar delayed glial activation in both nuclei. In this study, interleukin-6 (IL-6) expression was found within EPN neurons 3 and 7 days after striatal ischemia. Since it has been reported that neuroprotective properties seem to predominate IL-6 function and that distinct SNr regions which demonstrate low trans-synaptic neuronal degeneration show high IL-6 expression and vice versa, IL-6 expression within partially deafferentiated but surviving EPN neurons could represent an intrinsic neuroprotective mechanism.     

Expression of IL-6 in the ischemic penumbra

We examined the expression of IL-6 within the ischemic penumbra at various time points after transient (3 h) middle cerebral occlusion (MCA-O) in rats. The animals were killed at 1, 3, 7 or 14 days following operation. Coronal brain sections were processed for immunohistochemistry with antibodies against GFAP, OX 42, IL-6 and Nissl-staining. Glial activation within the penumbra started on day one after ischemia and persisted up to day 14. Expression of IL-6 was not present in sham-operated controls. One day after MCA-O there were several IL-6-positive cells in the penumbra. This expression of IL-6 increased on day 3 and remained elevated up to day 14. According to the shape of the IL-6-positive cells they seem to be microglia and neurons. The present results demonstrate a longlasting expression of IL-6 in the ischemic penumbra.     

15d-PGJ2对糖尿病大鼠脑缺血再灌注损伤小胶质细胞活化及神经细胞凋亡的影响

目的 观察PPAR-γ激动剂15d-PGJ2对糖尿病脑缺血再灌注大鼠脑缺血再灌注损伤小胶质细胞活化及神经细胞凋亡的影响。方法 成年SD大鼠80只,随机分为4组:(1)假手术组;(2)正常血糖脑缺血组;(3)糖尿病脑缺血组;(4)糖尿病脑缺血+15d-PGJ2干预组。采用链脲佐菌素诱导糖尿病,应用改良的Zea-Longa法制作大鼠大脑中动脉闭塞再灌注模型。糖尿病脑缺血组+15d-PGJ2干预组在成功制备糖尿病大鼠模型后给予15d-PGJ2 200 μg·kg^-1·d^-1腹腔注射21 d后应用改良的Zea-Longa法制作大鼠大脑中动脉闭塞再灌注模型,再灌注后3 h腹腔注射15d-PGJ2 400 μg·kg^-1,以后6 d每天给予15d-PGJ2 200μg·kg^-1·d^-1腹腔注射。每组分别于24 h、7 d各处死一批大鼠,并随机分为2组:一组行免疫组化法检测小胶质细胞CD68的表达水平及ELISA检测TNF-α与IL-1β水平,另一组用TUNEL法原位标记DNA片段检测凋亡细胞计数。结果 正常血糖脑缺血组、糖尿病脑缺血组、糖尿病脑缺血+15d-PGJ2干预组与假手术组比较,再灌注24 h、再灌注7 d CD68阳性面积、TNF-α与IL-1β水平、神经细胞凋亡率均明显增加(P<0.05); 糖尿病脑缺血组在再灌注24 h、再灌注7 d CD68阳性面积、TNF-α与IL-1β水平、神经细胞凋亡率明显高于正常血糖脑缺血组(P<0.05); 糖尿病脑缺血+15d-PGJ2干预组再灌注24 h、再灌注7 d CD68阳性面积、TNF-α与IL-1β水平、神经细胞凋亡率低于未干预组(P<0.05)。结论 糖尿病脑缺血组与正常血糖脑缺血组相比较CD68阳性面积更大、TNF-α与IL-1β水平更高及神经细胞凋亡率更高; 15d-PGJ2可减少糖尿病脑缺血大鼠小胶质细胞激活、减少炎症因子分泌、降低神经细胞凋亡率。     

Identification of first candidate genes for creativity: a pilot study

Nitric oxide (NO) can be neuroprotective or neurotoxic during cerebral ischemia, depending on the NO synthase (NOS) isoform involved. In addition to neurotoxic effect in ischemic brain, inducible NOS (iNOS) also adversely affect ischemic outcome by blocking neurogenesis. In the present study, therefore, we studied the chronological and spatial change of the distribution of iNOS and cell proliferation in subventricular zone (SVZ) after transient focal cerebral ischemia. After 90 min of transient middle cerebral artery occlusion (tMCAO), iNOS-positive cells decreased in the ischemic core at 1 to 21 days, and increased in the ipsilateral periischemic area at 1 and 3 days. 5-Bromodeoxyuridine (BrdU)-positive cells appeared in the ischemic core at 3 to 21 days, appeared in the periischemic area at 3 and 7 days, and increased in the ipsilateral SVZ at 7 days. ED-1-positive cells appeared in the ischemic core at 3 to 21 days, and some of them were double positive with BrdU or iNOS, but the majority were BrdU-negative. The present study suggests that astrocytes are born within the periischemic area at early stage after tMCAO and migrate from SVZ into periischemic area at later stage, and that time-dependent and spatial changes of iNOS expression may be involved in the proliferation and differentiation of adult neurogenesis after focal cerebral ischemia.     

Temporal profile of serum albumin extravasation following cerebral ischemia in a newly established reproducible gerbil model for vasogenic brain edema: a combined immunohistochemical and dye tracer analysis

Summary We investigated the temporal profile of the extravasation of serum albumin in a reproducible gerbil model of unilateral cerebral ischemia, using immunohistochemical and dye-tracer techniques to evaluate albumin accumulation and the occurrence of active extravasation, respectively. After 30 min of cerebral ischemia and subsequent reperfusion, immunostaining for albumin became visible in the lateral part of the thalamus during the first 3 h, and then expanded to other brain regions up to 24 h. At both 24 h and 3 days after reperfusion, massive extravasation of albumin was noted in the whole ischemic hemisphere, and this had decreased again by 7 days after reperfusion. The extent and the degree of albumin immunopositivity were almost the same in all animals examined at each period after reperfusion. The extravasation of Evans blue, which was allowed to circulate for 30 min before death, was limited to the lateral part of the thalamus during the first 6 h of reperfusion. In the circumscribed area of massive albumin extravasation, many neurons were immunopositive for albumin; most of these neurons appeared to be intact and also showed immunostaining for microtubule-associated protein 2. The current investigation clearly demonstrated that (1) albumin extravasation was produced with reliable reproducibility in this model, (2) the lateral part of the thalamus was the region most vulnerable to ischemic blood-brain barrier damage, and (3) many apparently intact neurons in the ischemic region were positive for albumin.Supported in part by a Grant-in-aid (01570485) from the Ministry of Education, Science and Culture and by a research grant for cardiovascular diseases (2A-2) from the Ministry of Health and Welfarc in Japan     

Neuronal apolipoprotein E is not synthesized in neuron after focal ischemia in rat brain

Apolipoprotein E (ApoE) is a major apolipoprotein in the central nervous system (CNS) that plays an important role in Alzheimer's disease. It may also be involved in other CNS disorders including ischemic injury. We investigated the changes of ApoE protein and mRNA expression in the brain with middle cerebral artery occlusion (MCAO) to clarify its origin after focal ischemia in rats. Increased ApoE immunoreactivity was recognized in astrocytes 3-14 days after MCAO in the affected side of cortex, and in neurons 4-14 days after MCAO in the same area. ApoE immunoreactivity was also detected in macrophages in the ischemic core 3-14 days after MCAO. In contrast, ApoE mRNA was expressed in astrocytes and macrophages, but not in neurons. These results suggested that neuronal ApoE was not synthesized in neurons, but derived from astrocytes.     

Repetitive transient forebrain ischemia in gerbils: delayed neuronal damage in the substantia nigra reticulata.

Repetitive cerebral ischemia results in severe neuronal damage in multiple regions of the brain including the hippocampus, striatum, thalamus, medial geniculate nucleus and the substantia nigra reticulata (SNr). We postulated that the damage in the SNr was delayed, resulting from a loss of striatal inhibitory input. We used the gerbil model of repetitive ischemia (3 min times 2 and 3 min times 3) to evaluate the extent of neuronal damage at 2, 3, 5 and 7 days after the ischemic insult. Silver degeneration stain was used for histological evaluation. Our results indicate that damage in the SNr begins after 48 h and is maximum at 7 days. This delay in onset of damage offers a window for pharmacological protection.     

Neuronal apolipoprotein E is not synthesized in neuron after focal ischemia in rat brain

Abstract

Apolipoprotein E (ApoE) is a major apolipoprotein in the central nervous system (CNS) that plays an important role in Alzheimer's disease. It may also be involved in other CNS disorders including ischemic injury. We investigated the changes of ApoE protein and mRNA expression in the brain with middle cerebral artery occlusion (MCAO) to clarify its origin after focal ischemia in rats. Increased ApoE immunoreactivity was recognized in astrocytes 3-14 days after MCAO in the affected side of cortex, and in neurons 4-14 days after MCAO in the same area. ApoE immunoreactivity was also detected in macrophages in the ischemic core 3-14 days after MCAO. In contrast, ApoE mRNA was expressed in astrocytes and macrophages, but not in neurons. These results suggested that neuronal ApoE was not synthesized in neurons, but derived from astrocytes.     

Time dependent changes of striatal interneurons after focal cerebral ischemia in rats

Summary. The cellular damage over time and the alterations of neuronal subtypes was characterized in the striatum after 90-min middle cerebral artery occlusion and reperfusion in rats. We investigated the immunohistochemical alterations of choline acetyltransferase (ChAT)-positive (cholinergic-positive), γ-aminobutyric acid (GABA)ergic parvalbumin (PV)-positive, GABAergic nNOS (neuronal nitric oxide synthase)-positive interneurons, neuronal nuclei (NeuN)-positive spiny projection neurons, glial fibrillary acidic protein (GFAP)-positive strocytes and microglial response factor-1 (MRF-1)-positive microglia in the striatum after focal cerebral ischemia in rats. In the present study, transient focal cerebral ischemia in rats caused severe damage against interneurons as well as spiny projection neurons in the striatum. In contrast, a significant increase in the number of GFAP-immunopositive astrocytes was observed in the ipsilateral striatum 15 days after focal cerebral ischemia. Furthermore, a significant increase of MRF-1 immunoreactivity was observed in microglia of the ipsilateral striatum 7 days and 15 days after focal cerebral ischemia. Among three types of cholinergic interneurons, GABAergic PV-positive interneurons and GABAergic nNOS-positive interneurons, the severe damage of cholinergic and GABAergic PV-positive interneurons was more pronounced than that of GABAergic nNOS-positive interneurons after transient focal cerebral ischemia in rats. Furthermore, the present results suggest that GABAergic nNOS-positive interneurons in the striatum after focal cerebral ischemia undergo cellular death in a delayed manner. Correspondence: Tsutomu Araki, Department of Neurobiology and Therapeutics, Graduate School and Faculty of Pharmaceutical Sciences, The University of Tokushima, 1-78 Sho-machi, Tokushima 770-8505, Japan     

Enriched environment delays the onset of hippocampal damage after global cerebral ischemia in rats

An enriched environment has been shown to improve cognitive, behavioral and histopathological outcome after focal cerebral ischemia and head trauma. The purpose of this study was to determine the effect of an enriched environment on histopathology following global cerebral ischemia. Wistar rats (21 weeks of age) were placed in different environments [standard cages (SC) or enriched environment (EE) cages] for 2 months before and either 6 days or 2 months after ischemia. Rats underwent 10 min of global ischemia by bilateral carotid artery occlusions plus hypotension. Five groups (n=4-5 in each group) were studied: (1) rats kept in SC before and 2 months after ischemia; (2) rats kept in SC before ischemia but transferred to an EE for 2 months after ischemia; (3) rats kept in EE before and after ischemia for 2 months; (4) rats kept in SC before and 6 days after ischemia; (5) rats kept in EE before and 6 days after ischemia. At 7 days or 2 months after ischemia, brains were perfusion-fixed, and ischemic injury was assessed by counting numbers of normal neurons in the hippocampal CA1 sector. Physiological variables showed no inter-group differences. Rats housed in EE for 2 months before and for 6 days (but not 2 months) after global ischemia showed significantly better preservation of pyramidal neurons in the hippocampal CA1 area when compared to control animals (middle CA1, 20.5+/-5.4 vs. 2.8+/-0.6; lateral CA1, 31.5+/-7.2 vs. 2.6+/-0.6, respectively). The present data suggest that housing in EE for 2 months before and 6 days after ischemia can delay the onset of damage to hippocampal pyramidal neurons, which eventually occurs despite 2-month EE.     

Postischemic changes in the immunophilin FKBP12 in the rat brain

An immunosuppressant tacrolimus (FK506) protects against neuronal damage following cerebral ischemia. On the other hand, the major physiological role of the immunophilin FK506-binding protein-12 (FKBP12) is a modulation of intracellular calcium flux. Since an increase in intracellular calcium concentration is a major mediator of ischemic neuronal death, we investigated the changes in FKBP12 following cerebral ischemia in the rat. We induced focal cerebral ischemia by intraluminal occlusion of the middle cerebral artery for 1 h, and global cerebral ischemia for 10 min by bilateral carotid artery occlusion combined with hypotension. The animals were killed at 4 h to 7 days after reperfusion. Immunohistochemistry was performed on paraffin sections using a monoclonal antibody raised against recombinant FKBP12. Immunoreactivity to FKBP12 in control brains was most pronounced in the CA1 subfield of the hippocampus and the striatum, the localization being primarily neuronal. Following focal ischemia, FKBP12 immunoreactivity decreased rapidly in the ischemic core by 4 h, but increased in surviving neurons in penumbra areas (4 h-7 days). Within an area of infarction, invading leukocytes and macrophages exhibited immunoreactivity to FKBP12 (3-7 days). Following global ischemia, FKBP12 immunoreactivity in CA1 neurons decreased after 1 day, and then it was lost between 2 and 7 days, although many CA1 neurons showed a transient increase in FKBP12 at 2 days. No FKBP12 immunoreactivity was observed in reactive glial cells. Thus, FKBP12 declined in dying neurons, whereas FKBP12 was upregulated in less severely injured neurons. The findings suggest that (1) FKBP12 plays an important role in the process of neuronal survival and death following cerebral ischemia, and (2) FKBP12 is involved in inflammatory reactions that occur within an area of infarction.     

P2X7 receptor expression after ischemia in the cerebral cortex of rats

Large amounts of adenosine 5'-triphosphate (ATP) released from cellular sources under pathological conditions such as ischemia may activate purinoceptors of the P2X and P2Y types. In the present study, the expression of the P2X7 receptor-subtype in the brain cortex of spontaneously hypertensive rats was investigated using a permanent focal cerebral ischemia model. Immunocytochemistry with antibodies raised against the intracellular C-terminus of the P2X7 receptor showed a time-dependent upregulation of labeled cells in the peri-infarct region after right middle cerebral artery occlusion (MCAO) in comparison to controls. Double immunofluorescence visualized with confooal laser scanning microscopy indicated the localization of the P2X7 receptor after ischemia on microglial cells (after 1 and 4 days), on tubulin betaIII-labeled neurons (after 4 and 7 days), and on glial fibrillary acidic protein (GFAP)-positive astrocytes (after 4 days). In the following experiments, changes occurring 4 days after MCAO were investigated in detail. Western blot analysis of the cortical tissue around the area of necrosis indicated an increase in the P2X7 receptor protein. Immunoelectron microscopy revealed the receptor localization on synapses (presynaptically), on dendrites, as well as on the nuclear membrane of neurons (postsynaptically) and glial cells. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling in combination with P2X7 receptor immunocytochemistry indicated a co-expression on the apoptotic cells. Active caspase 3 was especially observed on GFAP-positive astrocytes. In conclusion, the present data demonstrate a postischemic, time-dependent upregulation of the P2X7 receptor-subtype on neurons and glial cells and suggest a role for this receptor in the pathophysiology of cerebral ischemia in vivo.     

Neuronal survival is associated with 72-kDa heat shock protein expression after transient middle cerebral artery occlusion in the rat

Induction of the 72-kDa heat shock protein expression is thought to protect neurons against the subsequent effects of ischemia. However, it is not clear whether the induction of 72-kDa heat shock protein expression by an ischemic event improves neuronal survival. To address this question, we outlined the temporal profile of neuronal induction and expression of the 72-kDa heat shock protein in a model of transient focal ischemia in the rat. Fifty two adult Wistar rats were subjected to middle cerebral artery occlusion of 2 h duration. At 0.5, 3, 6, 9, 12, 24, 48, 96 and 168 h after reopening the artery, coronal brain sections were analyzed using both immunohistochemical methods and hematoxylin and eosin staining to determine the topographic and cellular distribution of the 72-kDa heat shock protein, as well as the extent of neuronal damage. Immunoreactivity to the 72-kDa heat shock protein was not detected in neurons that were destined to become necrotic, and were located in the ischemic core of the brain lesions. However, 72-kDa heat shock protein expression was evident in morphologically intact neurons located in the peripheral zone. The earliest neuronal expression of 72-kDa heat shock protein was detected in animals in which the 2 h occlusion of the middle cerebral artery was followed by 6 h recirculation; the intensity of the 72-kDa heat shock protein immunoreactivity peaked at 48 h, and progressively disappeared 7 days after the ischemic reperfusion event. These studies suggest that (1) 72-kDa heat shock protein is not expressed in morphologically intact neurons destined to become necrotic after 2 h of focal ischemia; (2) the 72-kDa heat shock protein is expressed only in morphologically intact neurons located at the periphery of the ischemic territory where they may be subjected to only sublethal stress; these neurons preserved their integrity 7 days after the ischemic episode. These data support the hypothesis that the expression of 72-kDa heat shock protein in ischemic brain may confer “protection” to the neurons.     

Enhanced protein synthesis in the ipsilateral substantia nigra following middle cerebral artery occlusion in the rat

Following focal cerebral ischemia, neuronal cell death is detected in remote areas of the brain, including the ipsilateral thalamus and substantia nigra (SN), as well as in the ischemic core. We have investigated protein synthesis in the remote areas of rats exposed to focal ischemia using autoradiography. The proximal portion of the left middle cerebral artery (MCA) was permanently occluded, and at various periods (6 h, 2, 4 and 7 days and 2 and 4 weeks following ischemia) animals received a single dose of l-[2,3-³H]valine (6.7 mCi/kg). Brain sections containing the thalamus and SN were processed for autoradiography. In the ipsilateral cerebral cortex and striatum, marked impairment of protein synthesis was observed and was never completely recovered during the experiment. No changes in protein synthesis in the ipsilateral thalamus were detected during the experiment. However, a change in protein synthesis was demonstrated in the ipsilateral SN. At 2 days after MCA occlusion, incorporation of [³H]valine into the whole zona reticulata of the ipsilateral SN was slightly enhanced and the increase became evident at 4 days after ischemia. Increased incorporation of [³H]valine began to be localized in the lateral portion of the zona reticulata after 7 days and continued up to 4 weeks following ischemia. Enhanced protein synthesis during the early stage (2 and 4 days after ischemia) may be due to the activated function of the neurons in the zona reticulata and that during the late stage (7 days and 2 and 4 weeks) after ischemia to astroglial proliferation Received: 22 July 1997 / Revised, accepted: 13 November 1997     

Selective cortical neuronal damage after middle cerebral artery occlusion in rats

We studied histopathologic changes in cerebral cortex of 20 rats after middle cerebral artery occlusion by using the Fink-Heimer suppressive silver impregnation method and conventional stains. At 6 hours after occlusion, Fink-Heimer-stained sections revealed abundant coarsely granular, intensely argyrophilic neurons in the ischemic cortex. These distinctive argyrophilic neurons could be clearly differentiated from neurons that suffered postmortem changes; argyrophilic neurons were present in all layers of the lateral parietal cortex but in only the superficial cortical layers II and III in the parasagittal area of the frontoparietal cortex and the temporo-occipital area. At 24 hours after occlusion as the ischemic region progressed to pannecrosis, argyrophilic neurons were still evident in peri-infarct regions, with more prominent neuritic silver deposits but no changes in number or spatial distribution. Over 2-7 days, the argyrophilic neurons gradually disappeared while many fine silver-impregnated degenerating terminals appeared in the peri-infarct regions. At 3-6 weeks after occlusion, no more argyrophilic neurons were seen in the cortex although degenerating axons were still present in the deep white matter. Our results indicate selective neuronal damage in the superficial cortical layers and massive axonal degeneration in the cerebrum surrounding infarcts. The neuronal damage does not appear to progress beyond 6 hours after middle cerebral artery occlusion. The Fink-Heimer method has many advantages over existing conventional stains for documenting selective neuronal damage in focal cerebral ischemia.     

Temporal pattern of Toll-like receptor 9 upregulation in neurons and glial cells following cerebral ischemia reperfusion in mice

Purpose: The family of Toll-like receptors (TLRs) has recently been reported to play a role in ischemic injury, but the time course and cell types of the post-stroke TLR9 upregulation remain unclear. In this study, we investigated the dynamic changes of TLR9 expression and the expression of TLR9 in neurons and glial cells after cerebral ischemia reperfusion in mice. Methods: Focal cerebral ischemia was induced by middle cerebral artery occlusion for 90 min in male C57BL/6 mice. The TLR9 expression levels in the tissue surrounding the infarct were detected by Western Blot at 6 h, 3 d, 7 d, 14 d, 21 d, and 28 d after reperfusion. The expression of TLR9 in neurons and glial cells was observed by immunofluorescence staining. Results: The expression of TLR9 protein first increased and then decreased, with the peak observed at 14 d–21 d. Only small punctate intracellular TLR9 was occasionally observed in the neurons at each time point, and the TLR9-positive rate showed no difference at different time points. By contrast, the activated microglia gathered at the margin of the infarct, and the intracellular TLR9 changed from scattered small punctate to coarse and lumpy. The TLR9-positive rate of microglia was first increased and then decreased with time, with the peak observed at 3 d. No positive TLR9 staining was found in the astrocytes and oligodendrocytes. Conclusions: TLR9 expression showed dynamic changes for a long period of time and microglias were the main brain cells to express TLR9 after cerebral ischemia and reperfusion.     

Glial Damage After Transient Focal Cerebral Ischemia in Rats

We investigated the immunohistochemical changes of 8-hydroxy-2′-deoxyguanosine (8-OHdG) immunoreactivity as a marker of DNA damage and single-strand DNA (ssDNA) immunoreactivity as a marker of apoptosis in the striatum from 1 up to 15 days after 90 min of focal cerebral ischemia caused by middle cerebral artery occlusion in rats. In the present study, marked loss of MAP2 immunostaining was observed in the ipsilateral striatum 3 days after focal cerebral ischemia. A significant increase in the number of ssDNA-immunoreactive apoptotic neurons was observed in the ipsilateral striatum 1 and 3 days after focal cerebral ischemia. In contrast, a significant increase in densities of 8-OHdG-immunopositive cells was observed in the ipsilateral striatum from 3 up to 15 days after focal cerebral ischemia. Our double-labeled immunochemical study showed that 8-OHdG immunoreactivity was observed in both isolectin B₄-positive microglia and glial fibrillary acidic protein-immunopositive astrocytes in the ipsilateral striatum 7 days after focal cerebral ischemia. These results suggest that focal cerebral ischemia can cause a marked increase in the number of microglia and astrocytes with oxidative DNA damage in the ipsilateral striatum. Furthermore, our results show that most microglia and astrocytes in the ipsilateral striatum after focal cerebral ischemia may not die by apoptosis. Thus, our findings provide novel evidence that focal cerebral ischemia can cause oxidative DNA damage in most microglia and astrocytes.     

Expression of basic fibroblast growth factor receptor messenger RNA in the periinfarcted brain tissue

The present study examined whether expression of basic fibroblast growth factor receptor (bFGFR) messenger ribonucleic acid (mRNA) was upregulated by focal ischemia. We have studied the in situ hybridization autoradiography for bFGFR mRNA in the rat model of middle cerebral artery (MCA) occlusion. Male Wistar rats were used for occlusion of the left MCA, and were sacrificed 1, 3, 7 and 14 days after MCA occlusion. In situ hybridization was performed on the brain sections of these animals and sham controls by using 35S-labeled antisense and sense (control) RNA probes for rat bFGFR. Expression of bFGFR mRNA was observed in the periinfarcted area of the rats within 1-14 days after MCA occlusion. Expression was evident in the whole hemisphere of the infarcted side, especially at 1 and 3 days after ischemia, but no expression was detected in the contralateral side. On microautoradiograms, the signals of bFGFR mRNA were detected in both neurons and non-neural cells located in the periinfarcted area. Upregulation of bFGFR mRNA detected in the periinfarcted brain tissue suggests that receptor-mediated action of bFGF may be related to preservation of neurons injured by ischemia.     

Kainic acid-induced substantia nigra seizure in rats: behavior, EEG and metabolism

RATIONALE: In order to clarify the role of substantia nigra pars reticulata (SNr) upon the development of epileptic seizure, kainic acid (KA) was injected into a unilateral SNr. MATERIALS AND METHODS: Wistar rats weighing 250-350 g were used. A stainless-steel cannula and depth electrode were inserted stereotaxically into the left substantia nigra pars reticulata (SNr). At 7 days after surgery, 1.0 microg of KA was injected into the left SNr. Experiment 1: In eight rats, behavior and electroencephalograms (EEG) were continuously recorded for about 30 h, and intermittently monitored following 1 month. Experiment 2: Two hours after KA injection into SNr, rats demonstrated status epilepticus. Then, 100 microCi/kg of [(14)C]2-deoxyglucose (2-DG) was intravenously injected in seven rats, and the rats were processed for autoradiographic study. RESULTS: Changes in behavior and EEG: On EEG, a secondary generalized seizure status was observed at about 70 min after KA injection. In video, limbic seizure manifestations such as salivation were observed as a initial symptom and followed by rolling and generalized tonic seizures. [(14)C]deoxyglucose autoradiographic study demonstrated increased local cerebral glucose metabolism in the medial and lateral septal nucleus, substantia nigra, hippocampus, parietal cortex, piriform cortex, medial and lateral geniculate nucleus, anterodorsal, lateral and ventral nucleus of the thalamus, amygdala and midbrain reticular formation. SUMMARY: The result suggested that the substantia nigra played an important role in the secondary generalization in the substantia nigra seizure model due to the decreased function of the GABAergic projection system induced by an excessive epileptic excitation of SNr.