异氟烷和七氟烷对缺血神经元的保护及对bcl-2和ICE基因表达的影响

目的 了解吸入麻醉药异氟烷和七氟烷对缺血神经元的保护作用和其作用机制。方法 将大鼠右侧大脑中动脉和双侧颈总动脉分别结扎1h，造成脑缺血再灌模型，缺血期间分别吸收异氟烷和七氟烷。用流式细胞仪检测海马神经细胞凋亡情况；用Northern blot分析海马神经元blc-2和ICE mRNA的表达。结果 缺血1h，再灌24h异氟烷和七氟烷可使海马神经细胞凋亡分别下降54％和40％（P＜0.01），但对海马神经元bcl-2和ICE mRNA的表达没有显著影响。结论 异氟烷和七氟烷对缺血神经元的保护作用可能不是通过影响bcl-2和ICE基因表达实现的。     

Long-lasting increase in protein kinase C activity in the hippocampus of amygdala-kindled rat

Previous studies have demonstrated that membrane-associated protein kinase C (PKC) activities in the right and left hippocampus of rats kindled from the left hippocampus increased significantly at 4 weeks [9] and 4 months [22] after the last seizure compared with those in matched control rats. In this study, we investigated the effect of kindling from the left amygdala on PKC activities in the amygdala/pyriform cortex and hippocampus at long seizure-free intervals (4 and 16 weeks) from the last amygdala-kindled seizure. Membrane-associated PKC activity of the kindled group increased significantly only in the left hippocampus compared with the left side control (the left hippocampus of rats subjected to a sham operation) at 4 weeks (by 34%, P < 0.03) and 16 weeks (by 24%, P < 0.05) after the last seizure. There was no significant alteration in the membrane-associated PKC activity of the kindled group in the right hippocampus or amygdala/pyriform cortex in any seizure-free interval after the last amygdala seizure. Cytosolic PKC activity did not differ between the kindled and control groups in any brain region examined in any seizure-free interval. At 16 weeks after the last seizure, the PKC activity in the P₁ fraction of the kindled group increased significantly only in the left hippocampus (by 49%, P < 0.005), but not in the right hippocampus. Neither PKC activity in the P₂ fraction nor that in the cytosolic fraction was altered in the kindled group after this seizure-free interval. The prolonged increase in activity of the membrane-associated PKC and that in the P₁ fraction in the hippocampus induced by amygdala-kindling may contribute to long-lasting seizure susceptibility induced by kindling.     

Long-lasting change in the membrane-associated protein kinase C activity in the hippocampal kindled rat

The effect of hippocampal kindling on protein kinase C (PKC) activity and protein concentration was investigated in rat amygdala/pyriform cortex (AM/PC) and right (contralateral) and left (ipsilateral) hippocampus (HIPP). There was no difference in cytosolic PKC activity between control and kindled groups in any part of the brain. The membrane-associated PKC activity was altered as follows. One week after the last seizure, it was significantly increased in both right (by 26%, P less than 0.05) and left HIPP (by 30%, P less than 0.02). Four weeks after the last seizure, it was significantly increased in the AM/PC (by 14%, P less than 0.02), right HIPP (by 37%, P less than 0.01) and left HIPP (by 24%, P less than 0.05). The protein concentrations in the crude cytosolic extracts prior to elution of PKC through DE-52 columns were significantly increased in the AM/PC (by 11%, P less than 0.05) and right HIPP (by 18%, P less than 0.02) 4 weeks after the last seizure. In the membrane extracts, there was a significant increase by 23% (P less than 0.02) in the left HIPP 1 week after the last seizure. In the fraction co-eluted with PKC, a significant increase in protein concentration of the cytosolic preparation was confirmed in the AM/PC (by 12%, P less than 0.05) as well as in the left HIPP (by 15%, P less than 0.05) 4 and 1 weeks respectively after the last seizure.(ABSTRACT TRUNCATED AT 250 WORDS)     

碱性成纤维细胞生长因子对脑出血大鼠神经细胞凋亡和BaX、Bcl-2基因表达的影响

目的观察碱性成纤维细胞生长因子(bFGF)对大鼠脑出血后神经细胞凋亡及血肿周围大脑皮质和出血侧海马Bax、Bcl-2基因表达的影响。方法采用脑内注射胶原酶建立大鼠脑出血模型,应用TUNEL法测定大鼠大脑皮质、海马神经细胞凋亡数目。及应用采用半定量逆转录酶聚合链反应(RT-PCR),检测脑出血后血肿周围大脑皮质和出血侧海马的Bax mRNA、Bcl-2 mRNA表达。结果(1)bFGF组的皮质和海马神经细胞凋亡数比生理盐水(NS)对照组明显减少(P<0.05)。(2)bFGF组的血肿周围大脑皮质和出血侧海马Bax mRNA表达比NS对照组明显减少(P<0.05);而Bcl-2 mRNA表达比NS对照组明显增高(P<0.05)。结论bFGF提高大鼠脑出血后大脑组织和海马Bcl-2 mRNA的表达,降低Bax mRNA的表达,抑制脑出血后神经细胞凋亡。     

The density and distribution of ischemic brain injury in the rat following 2–10 min of forebrain ischemia

Summary The density and distribution of brain damage after 2–10 min of cerebral ischemia was studied in the rat. Ischemia was produced by a combination of carotid clamping and hypotension, followed by 1 week recovery. The brains were perfusion-fixed with formaldehyde, embedded in paraffin, subserially sectioned, and stained with acid fuchsin/cresyl violet. The number of necrotic neurons in the cerebral cortex, hippocampus, and caudate nucleus was assessed by direct visual counting.Somewhat unexpectedly, mild brain damage was observed in some animals already after 2 min, and more consistently after 4 min of ischemia. This damage affected CA4 and CA1 pyramids in the hippocampus, and neurons in the subiculum. Necrosis of neocortical cells began to appear after 4 min and CA3 hippocampal damage after 6 min of ischemia, while neurons in the caudoputamen were affected first after 8–10 min.Selective neuronal necrosis of the cerebral cortex worsened into infarction after higher doses of insult. Damage was worst over the superolateral convexity of the hemisphere, in the middle laminae of the cerebral cortex. The caudate nucleus showed geographically demarcated zones of selective neuronal necrosis, damage to neurons in the dorsolateral portion showing an all-or-none pattern. Other structures involved included the amygdaloid, the thalamic reticular nucleus, the septal nuclei, the pars reticularis of the substantia nigra, and the cerebellar vermis.Supported by the Swedish Medical Research Council (projects 12X-03020, 14X-263) and the National Institutes of Health of the United States Public Health Service (grant no. 5 R01 NS07838). Dr. Auer is the recipient of a Medical Research Council of Canada Fellowship.     

Exercise increased BDNF and trkB in the contralateral hemisphere of the ischemic rat brain

Previous studies have suggested that brain-derived neurotrophic factor (BDNF) and trkB both have a role in plasticity following brain insults and exercise increases BDNF and trkB mRNA levels in the normal brain. We attempted to determine whether treadmill exercise improves motor function following experimental cerebral ischemia, and whether motor outcome is associated with BDNF and trkB expression. We subjected adult male Sprague-Dawley rats to a permanent ischemia, followed by either 12 days of treadmill exercise or non-exercise. In the exercise group, improvements in the motor behavior index were found and BDNF and trkB proteins in contralateral hemisphere were increased. This study suggests that after permanent brain ischemia, exercise improves motor performance and elevates BDNF and trkB proteins in the contralateral hemisphere.     

Expansion of receptive fields in the mouse cortical barrelfield after administration of capsaicin to neonates or local application on the infraorbital nerve in adults

A possible role fore peripheral unmyelinated fibres on the establishment and maintenance of stable receptive fields mediated by myelinated afferents has been studied in the mouse cortical barrefield. The barrels are cytoarchitectonic units consituting a visible and particularly precise somatotopic map of the facial vibrissae. Barrelfields were mapped electrophysiologically in adults using two experimental setups: (i) after destruction of unmyelinated peripheral fibres by systemic administration of capsaicin neonatally; and (ii) after inactivation of these fibres by local application of capsaicin to the nerve subserving the vibrissae in the adult. The latter procedure is known not to destroy fibres. Control animals received the vehicle used to dissolve capsaicin. The effectiveness of capsaicin on the peripheral fibres was assessed histochemically on their terminals in the substantia gelatinosa. Both methods of application of capsaicin resulted in a large expansion of cortical receptive fields: units within a particular barrel were driven by a statistically significant, larger number of vibrissae than in controls. No morphological alterations of the barrels were found in cortical tangential sections. We concluded that capsaicin treatment ‘defocusses’ the normal physiological precision without destroying the general plan of representation and without alteration of the barrel pattern.     

缺血性脑损害对帕金森病运动症状影响的研究

目的：探讨静止性脑梗死(SCl)和脑白质损害(WML)对帕金森病(PD)运动症状的影响。方法：选取无中风史、头颅CT检查末见异常,年龄和病程配比的PD患者,观察3年后头颅MRI显示的SCl及WML的发生率及其对PD的运动功能的影响。结果：伴随高血压、糖尿病的PD患者较无伴随疾病者SCI及WML的发生率明显增高(P＜0．05),出现SCI及WML患者的运动功能评分较无SCI及WML患者明显增加(P＜0．01)。结论：预防脑缺血损害对延缓PD病情进展、控制症状具有重要的临床意义。     

Changes in gene expression following induction of ischemic tolerance in rat brain: detection and verification.

Tolerance against ischemic insults can be elicited in the CA1 region of rat hippocampus by inducing a short ischemic period 2–3 days prior to the ischemic insult. To detect genes whose expression changes following induction of ischemic tolerance (IT), we applied a differential display technique called restriction fragment differential display‐PCR (RFDD‐PCR). RFDD‐PCR displays the coding region of mRNA and allows detection of differentially expressed mRNA. Double‐stranded cDNA generated using a T₂₅V primer is digested by the endonuclease TaqI, and adapters are ligated onto the cDNA fragments. When amplifying the adapter‐containing cDNA fragments under high‐stringency conditions, reproducible PCR profiles are obtained. By comparing these profiles from naïve and ischemia‐tolerant rat brains statistically, significant expression changes of 20 fragments were identified. To verify the observed changes, quantitative PCR and in situ hybridization were performed for three fragments representing proteins with quite different functions (GluR2‐flop, SC1, and p68 RNA helicase). Quantitative PCR displayed the same degree of regulation as RFDD‐PCR, but in situ hybridization did not display any regulation. As the applied PCR‐based techniques detect only polyadenylated mRNA, whereas in situ hybridization detects both nonadenylated and adenylated mRNA, changes in the polyadenylation state of the mRNA, rather than inconsistent changes in the total amount of mRNA, probably explain this discrepancy. Thus, our results show that the expression of genes hitherto not related to IT changes with the induction of IT and that the degree of regulation displayed by RFDD‐PCR can be verified by quantitative PCR. J. Neurosci. Res. 65:54–58, 2001. © 2001 Wiley‐Liss, Inc.     

Serotonergic sprouting is induced by dopamine-lesion in substantia nigra of adult rat brain

We have previously extracted a serotonin (5-HT) neurotrophic supernatant from the 5,7-DHT lesioned hippocampus. The current study shows that a new 5-HT neurotrophic signal was monitored in the striatum and nigra after DA-denervation. Such a signal may be involved in the heterotypic sprouting. Dopaminergic neurotoxin, 6-hydroxydopamine (6-OHDA), was injected directly into the substantia nigra of adult rats. Two months after surgery, immunocytochemical staining showed that tyrosine hydroxylase (TH)-positive cell bodies had mostly disappeared in the substantia nigra, and TH-positive terminals in the striatum were almost completely depleted. Meanwhile, the 5-HT fibers, which exist in the same areas with low density, sprouted in the nigra as well as in the striatum and became dense. Normally 5-HT fibers innervate the striatum sparsely and the globus pallidus densely with sharp delineation (in the control side), and become dense across both areas with no appreciable delineation (in the lesion side). The increase of 5-HT fibers was more prominent in the posterior than in the anterior striatum. A significant increase in 5-HT and 5-HIAA levels was also evident in the posterior striatum when the decrease in DA level exceeded 90% in the nigra and striatum. In addition, we found that induction of 5-HT sprouting requires a greater than 90% decrease of DA level. Current data support that 6-OHDA injection in the substantia nigra of adult rats triggered a trophic signal or removed an inhibition for the growth of 5-HT neurons which responded with sprouting in the nigra as well as in the striatum.     

Amplified expression of uncoupling proteins in human brain ischemic lesions

Uncoupling proteins (UCPs) are reported to regulate mitochondrial respiration and energy metabolism during hibernation. Recently, it has been reported that UCP2 and UCP5 might reduce free radical stress in the ischemic condition in in vitro models, suggesting both as potential neuroprotective agents. We therefore investigated the levels of UCP2 and UCP5 expression in the lesion of human brain infarction. Brain slice sections were prepared from pathological samples collected at our hospital. Embolic stroke brains sectioned because of the stroke (n = 5) and multiple brain infarction with several stroke episodes (n = 4) were selected for this study. We observed the amount of UCP2 and UCP5 expression in both lesioned and intact areas, and compared them between embolic stroke and multiple infarcton cases. The results showed that the expression of UCP2 and UCP5 was significantly elevated in the ischemic lesions compared to the intact area. UCP5 expression in the lesions was higher in multiple infarction cases than in embolic stroke cases. In conclusion, brains may respond to neuroprotection through the increased expression of UCP2 and UCP5 under ischemic conditions. Moreover, UCP5 may respond to repetitive ischemic stresses or have a long‐term effect.     

成年大鼠脊髓全横断损伤后酪氨酸激酶受体C在脊髓和大脑皮层的表达

目的 研究神经营养因子3(neurotrophin-3,NT-3)的受体-酪氨酸激酶受体C(tyrosine kinase receptor C,TrkC)在脊髓损伤(spinal cord injury,SCI)后神经重塑中的作用.方法 研究脊髓全横断损伤大鼠手术后第1、3、7和14 d时,低位胸髓节段和大脑中央前回...     

Interleukin-2 promotes survival and neurite extension of cultured neurons from fetal rat brain

We investigated the effects of interleukin-2 (IL-2) on the survival and morphology of primary cultured neurons from fetal rat brain. Addition of recombinant human IL-2 significantly supported the survival of brain neurons in high cell density culture, but did not show any effect on the neuronal survival in low cell density culture. In addition, IL-2 significantly promoted the neurite elongation and branching of hippocampal neurons in low cell density culture. These results suggest that IL-2 supports neuronal survival indirectly and promotes neuritogenesis by directly acting on brain neurons.     

5-HT2C受体在癫患者脑组织的表达

目的研究5-羟色胺2C受体(5-HT2C受体)在癫患者脑组织的表达,探索其临床意义。方法用免疫组化方法检测46例癫患者术后脑组织5-HT2C受体的表达,研究比较不同部位不同病程脑组织表达。结果癫患者额叶脑组织5-HT2C受体的含量较颞叶海马明显增高,长病程组表达低于短病程组。结论 5-HT2C受体可能参与了癫的发病机制,改变5-HT2C受体的表达有望成为癫新的治疗靶点。     

Roles of GluN2C in cerebral ischemia: GluN2C expressed in different cell types plays different role in ischemic damage

Over the past decade, many studies have focused on clarifying the roles of different N-methyl-d -aspartate (NMDA) receptor subunits in cerebral ischemia, hoping to develop subunit-selective drugs. Recently, more attention was given to studying the role of GluN2C in ischemia damage, which may lead to the development of new NMDA receptor antagonists for cerebral ischemia. Results showed that GluN2C inhibition or knockout can effectively alleviate the ischemic injury caused by middle cerebral artery occlusion and, contrarily, can aggravate the damage to hippocampal CA1 circuit caused by transient global cerebral ischemia. These results indicate the complicated roles of GluN2C in cerebral ischemia. In this minireview, we focus on these findings, describe the roles of GluN2C from different cell origins in ischemic damage, and explain the above inconsistent experimental results.     

Unique expression patterns of 5-HT2A and 5-HT2C receptors in the rat brain during postnatal development: Western blot and immunohistochemical analyses

Serotonin (5-HT) is recognized as a potential regulatory factor in neuronal development. Two subtypes of receptors for it, 5-HT2A and 5-HT2C, are distributed broadly in the rat brain, suggesting their role in a variety of brain functions. Here, we investigated the expression patterns of these 5-HT2 receptors in the rat brain during postnatal development by using Western blot and immunohistochemical analyses. By Western blot analysis, the expression of the 5-HT2A receptor was at a low level at postnatal day 3 (P3) and increased greatly during the first 3 postnatal weeks; whereas the 5-HT2C receptor was already expressed at a high level at P3, and its expression increased only slightly during postnatal development. Immunohistochemical analysis showed the different expression patterns of 5-HT2A and 5-HT2C receptor subtypes during postnatal development: the transient expression of the 5-HT2C receptor was observed in layer IV of the somatosensory, visual, and auditory cortices from P10 to P28, and in the thalamus, mainly in the ventral posterolateral and ventral posteromedial nuclei, from P7 to P21; however, the immunoreactivity of the 5-HT2A receptor was detectable slightly at P3, but thereafter the intensity of immunolabeling increased with postnatal development and at P21 reached the adult level and pattern. These results suggest that 5-HT2 receptors have potential significance in brain development, with a functional difference between 5-HT2A and 5-HT2C receptor subtypes.