外周型苯二氮卓受体对海人酸点燃大鼠癫痫敏感性的影响

目的:探讨外周型苯二氮卓受体对海人酸点燃大鼠癫痫敏感性的影响。方法:大鼠随机分为海人酸组和对照组,海人酸组动物注射惊厥剂量海人酸(8mg.kg-1)建立化学点燃模型。注射7d后再注射阈下剂量海人酸(4mg.kg-1),将癫痫敏感性形成的动物作为癫痫敏感性形成组,未形成的动物作为癫痫敏感性未形成组。对照组分别经皮下注射阈下剂量的海人酸及生理盐水作为单独阈下剂量组和空白对照组。观察120min内动物癫痫发作情况,然后动物断头取脑,采用梯度离心技术制备大脑皮质线粒体,利用放射性配基结合实验测定外周型苯二氮卓受体特异结合量。结果:癫痫敏感性形成组大脑皮质线粒体外周型苯二氮卓受体水平显著高于其他3组(P<0.001)。癫痫敏感性形成组大脑皮质线粒体外周型苯二氮卓受体特异结合量与注射阈下剂量海人酸后动物湿狗样抖动次数、癫痫发作潜伏期、癫痫发作最大强度均具有显著相关性(P<0.001)。结论:大脑皮质线粒体外周型苯二氮卓受体水平与海人酸点燃大鼠癫痫敏感性有关。     

Alterations in long-term seizure susceptibility and the complex of PSD-95 with NMDA receptor from animals previously exposed to perinatal hypoxia

PURPOSE: Perinatal hypoxia is an important cause of brain injury in the newborn and has consequences that are potentially devastating and life-long, such as an increased risk of epilepsy in later life. The postsynaptic density (PSD) is a cytoskeletal specialization involved in the anchoring of neurotransmitter receptors and in regulating the response of postsynaptic neurons to synaptic stimulation. The postsynaptic protein PSD-95 binds to the N-methyl-D-aspartate receptor (NMDAR) subunit, and hence activates cascades of NMDAR-mediated events, such as cyclic adenosine monophosphate (cAMP)-responsive element binding protein phosphorylation at serine-133 (pCREB(Serine-133)). Here we studied the effect of perinatal hypoxia on protein interactions involving PSD-95 and the NMDAR, as well as pCREB(Ser-133) expression at an age when the animals show increased seizure susceptibility. METHODS: Rats were assigned randomly to the control rats or the rats exposed to transient global hypoxia at postnatal day 10 (P10). At P45, some rats from both groups were treated with pentylenetetrazol (PTZ) intraperitoneally to test the seizure threshold, and others were studied for neuronal loss, pCREB(Serine-133), PSD-95, and NMDAR expressions in the midbrain, temporal cortex, and hippocampal CA1 subfield by using immunohistochemistry, co-immunoprecipitation, and immunoblotting techniques, respectively. RESULTS: The rats with prior exposure to perinatal hypoxia exhibited increased seizure susceptibility to PTZ, compared with the control rats. Associated with this long-term change in seizure susceptibility, selective neuronal loss was observed in the midbrain region while pCREB(Ser-133) expression was reduced in the midbrain, temporal cortex, and hippocampal CA1 subfield. Perinatal hypoxia led to a decrease in PSD-95 expression in the both midbrain and hippocampal CA1 subfield, with the exception of temporal cortex. Furthermore, the association between PSD-95 and NMDAR subunits (NR1, NR2A, and NR2B) in the hippocampal CA1 was also markedly altered by perinatal hypoxia. CONCLUSIONS: This study demonstrates that the decrease in several protein complexes that are essential components of the postsynaptic apparatus is associated with the observed increase in seizure susceptibility in adult rats with prior exposure to perinatal hypoxia. The results indicate that reductions in PSD-95 expression, PSD-95 binding of NMDAR subunits, and subsequent NMDAR-mediated CREB phosphorylation, particularly in hippocampal CA1, are long-term consequences of perinatal hypoxia and may, at least in part, contribute to perinatal hypoxia-induced reduction in seizure threshold.     

Effects of quisqualic acid and glutamate on subsequent learning, emotionality, and seizure susceptibility in the immature and mature animal

To compare the long-term behavioral effects of chronic administration of excitatory amino acids in the mature and immature brain quisqualic acid (QA) and glutamate (GLU) were administered intraventricularly by osmotic pumps over 7 days in 20- and 60-day-old rats. Both age groups received identical dosages of QA or GLU. At age 90 days, all animals were assessed for abnormalities of learning and memory using the Morris water maze, emotionality using the handling test, and seizure threshold using flurothyl inhalation. No significant differences were found in either the water maze or handling test. However, 60-day-old rats receiving QA or GLU had more spontaneous seizures than the 20-day-old rats. In both age groups histological damage following QA and GLU was limited to the ipsilateral hippocampus, was maximum at the site of the catheter tube, and was similar in the two age groups studied. The adverse effects of long-term effects of chronic exposure to excitatory amino acids are similar in the immature and mature brain.     

促红细胞生成素治疗大鼠急性脊髓损伤的Meta分析

目的 探讨促红细胞生成素（EPO）对急性脊髓损伤大鼠运动功能恢复的影响。方法 计算机检索PubMed、Embase、Cochrane及中国生物医学数据库、维普信息数据库、中国知网及万方数据库,检索时限为数据库建库至2018年2月。采用Stata12.0软件进行Meta分析。结果 共纳入16个随机对照研究,包含303只大鼠,其中EPO组152只,对照组151只。Meta分析结果表明,EPO治疗后1、2、3、4、8周,大鼠BBB评分明显高于对照组（P<0.05）,6周时差异无统计学意义（P>0.05）。结论 EPO能促进脊髓损伤大鼠的运动功能恢复。     

Prenatal morphine exposure enhances seizure susceptibility but suppresses long-term potentiation in the limbic system of adult male rats

The present study examined the effects of prenatal morphine exposure on NMDA-dependent seizure susceptibility in the entorhinal cortex (EC), and on activity-dependent synaptic plasticity at Schaffer collateral and perforant path synapses in the hippocampus. During perfusion with Mg(2+)-free ACSF, an enhancement of epileptiform discharges was found in the EC of slices from prenatally morphine-exposed male rats. A submaximal tetanic stimulation (2x50 Hz/1 s) in control slices elicited LTP at the Schaffer collateral-CA1 synapses, but neither LTP nor LTD was evoked at the perforant path-DG synapses. In slices from prenatally morphine-exposed adult male rats, long-term potentiation of synaptic transmission was not observed at Schaffer collateral-CA1 synapses, while the submaximal tetanus now elicited frank LTD of synaptic EPSPs at perforant path synapses. These data suggest that prenatal morphine exposure enhances the susceptibility of entorhinal cortex to the induction of epileptiform activity, but shifts long-term plasticity of hippocampal synapses in favor of LTD.     

不同疗程促红细胞生成素对大鼠脑缺血再灌注损伤后神经细胞凋亡的影响

目的探讨不同疗程的促红细胞生成素（EPO）对局灶性脑缺血再灌注损伤大鼠神经细胞凋亡的影响。方法36只雄性SD大鼠随机分成EPO治疗组和生理盐水治疗组，每组分成短、中、长三个疗程，两组大鼠均制成局灶性脑缺血再灌注损伤模型。EPO治疗组短、中、长疗程相应时间点分别腹腔注射EPO3000U／kg；生理盐水治疗组各时间点注射等量生理盐水。疗程24h后进行神经功能评分，断头取脑制作石蜡切片，免疫组化染色检测caspase-3，流式细胞仪检测神经细胞凋亡。结果与生理盐水组比较，EPO各疗程组神经功能相应地改善，而凋亡细胞与caspase-3表达均相应地减少，其中长疗程组减少最为显著，较中、短疗程有统计学差异（氏0．05）。结论不同疗程的EPO对缺血再灌注损伤后神经细胞凋亡的影响不完全相同，长疗程接近最佳疗程。     

人参皂甙Rb3对大鼠缺氧性损伤的脑组织神经递质γ-氨基丁酸的影响

目的观察人参皂甙Rb3对缺氧及缺氧复氧的大鼠脑组织神经递质γ氨基丁酸(GABA)的影响。方法将大鼠随机分为A、B、C、D、E5组,A、C组以低压低氧暴露制作大鼠脑缺氧模型,B、D组为缺氧复氧模型。C、D组动物分别于制模前24h、1h2次腹腔注射人参皂甙Rb3溶液;采用免疫组化法,观察各组大鼠在缺氧及缺氧复氧处理后海马CA1区GABA免疫反应阳性细胞形态及数量的变化,并与正常对照组(E组)比较。结果(1)与E组相比,A、B组大鼠海马CA1区锥体细胞层GABA阳性细胞密度下降,染色较淡,突起缺如;C、D组大鼠海马CA1区锥体细胞层GABA阳性细胞密度分别较A、B组明显升高,形态与E组相似。(2)A、B、C、D、E组大鼠海马CA1区GABA免疫反应阳性细胞数分别为7.7±2.83、10.1±2.08、30.9±2.02、33.1±4.2、16.9±1.05,A、B组明显低于E组,C、D组明显高于E组(均P<0.01)。结论人参皂甙Rb3能抑制缺氧时大鼠脑组织GABA的耗竭,促进抑制性神经递质作用,对缺氧性脑损伤具有保护作用。     

Preconditioning enhances the expression of mitochondrial antioxidant thioredoxin-2 in the forebrain of rats exposed to severe hypobaric hypoxia

The impact of severe hypoxia and preconditioning on the expression of the mitochondrial antioxidant thioredoxin-2 (Trx-2) in rat hippocampus (CA1, CA2, CA3 fields, and dentate gyrus) and neocortex was studied by immunocytochemistry. The preconditioning consisted of three trials of mild hypobaric hypoxia (360 Torr, 2 hr) spaced at 24 hr. The last trial was followed by severe hypobaric hypoxia (180 Torr, 3 hr) 24 hr later. Both in hippocampus and in neocortex, severe hypobaric hypoxia resulted in enhanced Trx-2 expression at 3 hr, followed by a slight decline in Trx-2 levels, which nevertheless remained increased at 24 hr elsewhere except for the CA1 region. The preconditioning considerably augmented severe hypoxia-induced Trx-2 immunoreactivity, affecting both the number of immunoreactive cells and the intensity of immunostaining. The findings suggest a role for Trx-2 in the formation of brain hypoxic/ischemic tolerance accomplished by the preconditioning.     

Influence of acute progressive hypoxia on cardiovascular variability in conscious spontaneously hypertensive rats

The purpose of this study is to examine the influence of acute progressive hypoxia on cardiovascular variability and striatal dopamine (DA) levels in conscious, spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY). After preparation for measurement, the inspired oxygen concentration of rats was decreased to 10% within 5 min (descent stage), maintained at 10% for 10 min (fixed stage), and then elevated back to 20% over 5 min (recovery stage). The systolic blood pressure (SBP) and heart rate (HR) variability at each stage was calculated to evaluate the autonomic nervous system response using the wavelet method. Striatal DA during each stage was measured using in vivo microdialysis. We found that SHR showed a more profound hemodynamic response to progressive hypoxia as compared to WKY. Cardiac parasympathetic activity in SHR was significantly inhibited by acute progressive hypoxia during all stages, as shown by the decrease in the high frequency band of HR variability (HR-HF), along with transient increase in sympathetic activity during the early hypoxic phase. This decrease in the HR-HF continued even when SBP was elevated. Striatal DA levels showed the transient similar elevation in both groups. These findings suggest that acute progressive hypoxic stress in SHR inhibits cardiac parasympathetic activity through reduction of baroreceptor reflex sensitivity, with potentially severe deleterious effects on circulation, in particular on HR and circulatory control. Furthermore, it is thought that the influence of acute progressive hypoxia on striatal DA levels is similar in SHR and WKY.