应激对大鼠海马谷氨酸、天冬氨酸和γ-氨基丁酸含量的影响

目的　探讨应激对大鼠海马谷氨酸、天冬氨酸和γ 氨基丁酸 (GABA)含量的动态影响。方法　将 72只健康雄性大鼠随机分为 5个应激暴露不同时间组和对照组 ,每组 12只。利用高效液相色谱仪 紫外检测法 ,分别于应激第 1,3,7,14和 2 8天观察应激对大鼠海马谷氨酸、天冬氨酸及GABA含量的影响。结果　应激第 1天组大鼠海马谷氨酸和天冬氨酸含量与对照组相比 ,差异无显著性 ;但GABA含量 [(2 74 7± 0 339) μmol/g]低于对照组 [(3 719± 0 5 2 8) μmol/g;P <0 0 5 ]。应激第 3,7,14和 2 8天组谷氨酸含量 [分别为 (7 818± 0 799) μmol/g ,(9 0 0 7± 0 5 2 0 ) μmol/g,(8 0 4 9± 0 733) μmol/g和 (8 12 9± 1 5 5 6 ) μmol/g]高于对照组 [(6 4 11± 0 6 38) μmol/g];天冬氨酸含量 [分别为 (2 717± 0 2 5 8)μmol/g,(2 6 96± 0 317) μmol/g,(2 82 8± 0 4 6 8) μmol/g和 (4 6 4 9± 0 6 37) μmol/g]也高于对照组 [(2 0 0 3± 0 2 71) μmol/g];均P <0 0 1。应激第 14天组和 2 8天组GABA含量 [分别为 (4 4 6 2± 0 883) μmol/g和(4 4 97± 0 85 7) μmol/g]高于对照组 (P <0 0 5～0 .0 0 1) ,应激第 3天组和 7天组的GABA含量与对照组间的差异无显著性。结论　应激第 3天开始     

癫痫患者脑脊液γ—氨基丁酸,谷氨酸的研究

应用高效液相色法检测了３２例痫患者及２０例对照组脑脊γ－氨基丁酸、谷氨酸的变化。     

γ—氨基丁酸和癫痫

早在１９５３年，Ｆｌｏｒｅｙ从哺乳动物组织中就提取到一种可以阻断神经传导的物质，称之为“抑制因子”。后来，Ｂａｚｅｗｏｒｅ等证明“抑制因子”起主要作用的组分就是γ－氨基丁酸（ＧＡＢＡ），其对中枢神经系统具有普遍抑制作用，是中枢神经系统主要的抑制性神经...     

马桑内酯致痫大鼠大脑皮层,海马谷氨酸、门冬氨酸、甘氨酸及γ-氨基丁酸含量的测定

为了探讨氨基酸类神经递质在癫痫发病中的作用,我们采用高效液相色谱仪（HPLC）结合紫外分光光度仪分析检测了马桑内脂（CL）致病大鼠大脑皮层、海马Glu、Asp、Gly、GABA的含量变化。结果显示：CL致痫组与正常对照组相比,Glu、Asp、Gly含量增加（P<0.01,P<0.05）;GABA含量减少,但差异无显著性（P＞0．05）。这些结果提示兴奋性和抑制性氨基酸在癫痫发病中具有重要作用,可能参与了惊厥的发生、发展和惊厥后神经元损伤。     

海藻氨酸致痫大鼠海马谷氨酸转运体功能的变化

目的研究腹腔注射海藻氨酸致癫痫发作后海马谷氨酸转运体功能的动态变化,以探讨谷氨酸转运体在癫痫发生中的作用机制。方法60只健康成年雄性Wistar大鼠,随机分为海藻氨酸组和对照组。海藻氨酸组30只大鼠均腹腔注射海藻氨酸10mg/kg,分别于注射后4h、24h、48h、5d和7d依据Racine制定的行为学标准观察大鼠的行为学改变。同时还分别测定不同时间点海马突触膜颗粒和海马组织切片对3氢-左旋-谷氨酸(3H-L-Glu)的摄取量,以反映谷氨酸转运体于点燃后不同时间点的活性。结果与对照组相比,海藻氨酸组大鼠海马突触膜颗粒谷氨酸转运体功能于点燃后4h减弱,对3氢-左旋-谷氨酸的摄取量减少(P<0.05),并持续至注射后第5～7天(P<0.01);海马组织切片检查显示谷氨酸转运体功能在点燃后4～48h增强,于注射后第5～7天减弱(P<0.05)。结论谷氨酸转运体功能的变化与海藻氨酸致痫大鼠模型癫痫的发生及易感性有关。     

癫痫患者脑脊液γ—氨基丁酸,谷氨酸,催乳素的研究

目的研究神经递质的改变在癫痫发病中的作用。方法应用高效液相色谱法和放射免疫法分别检测了癫痫患者脑脊液（ＣＳＦ）中γ－氨基丁酸（ＧＡＢＡ）、谷氨酸（Ｇｌｕ）和催乳素（ＰＲＬ）含量的改变。结果癫痫患者ＣＳＦ中ＧＡＢＡ含量明显低于对照组，而Ｇｌｕ、ＰＲＬ含量明显高于对照组。相关分析发现：ＧＡＢＡ与Ｇｌｕ之间呈直线负相关，Ｇｌｕ与ＰＲＬ之间呈直线正相关。结论ＧＡＢＡ、Ｇｌｕ、ＰＲＬ与癫痫发作有关，三者之间的平衡失调可能是癫痫产生的重要原因     

戊四氮点燃大鼠中海马谷氨酸转运体的作用研究

目的 研究点燃形成过程中和点燃后谷氨酸转运体的变化,进一步探讨慢性癫痫的点燃机制。方法 将78只雄性成年Wistar 大鼠随机分为对照组（I组）和戊四氮（PTZ）组（Ⅱ组）。Ⅱ组腹腔注射阈下剂量的PTZ（35mg/kg),每日1次,直至达到点燃标准;Ⅰ组腹腔注射等量生理盐水。采用逆转录聚合酶链式反应（RT－PCR）方法检测海马区谷氨酸转运体－1（GLT－1）mRNA和兴奋性氨基酸载体－1（EAAC1）mRNA的表达。结果 GLT－1mRNA的表达在0h、48h时显著升高,随后下降;EAAC1mRNA的表达呈上升趋势。点燃后第60d时,基本恢复至对照组水平。结论 海马区GLT－1的下降和EAAC1的升高可能与癫痫敏感性的形成与维持有关。     

γ—氨基丁酸,谷氨酸能神经纤维在大鼠垂体前叶的分布

本文报告大鼠垂体前叶γ－氨基丁酸（ＧＡＢＡ），谷氨酸（Ｇｌｕ）能神经纤维的直接支配。ＧＡＢＡ和Ｇｌｕ免疫反应神经纤维呈斑片状分布在大鼠垂体前叶远侧部，虽然部分沿血管走行，但大部分神经纤维迂曲于腺细胞周，并与腺细胞接触。神经纤维可见膨体型、细和中等粗细三种类型，其上有大量的膨体。在垂体前叶也发现有ＧＡＢＡ、Ｇｌｕ免疫反应细胞分布。     

青霉素对体外培养鼠脑γ—氨基丁酸能神经元及胶质细胞的影响

经免疫细胞化学方法观察了分离培养４天，、１０天鼠大脑皮层、海马ＧＡＢＡ能神经元以及ＧＦＡＰ免疫反应阳性星形胶质细胞对大剂量致痫剂青霉素的反应。结果大剂量ＰＥＮ可引起培养海马及皮层γ－氨基丁酸能神经元数目明显减少，星形胶质细胞显著增生，且尤以海马胶质细胞增生明显。提示：（１）脑内尤其海马区星形胶南细胞增生与癫痫发生，发展有一定的关系。（２）传统致痫剂ＰＥＮ可能是通过抑制ＧＡＢＡ能神经元功能、刺激星形     

迷走神经刺激影响致痫大鼠丘脑神经递质受体活动的实验研究

目的 探讨迷走神经刺激（Vagus Nerve Stimulation,VNS)抗癫痫的机制。方法 应用原位杂交组织化学及图像分析方法研究了戊四氮（pentylenetetrazol,PTZ)致痫大鼠丘脑网状核γ-氨基丁酸A受体（GABAAR）α1亚单位mRNA的变化。结果 PTZ致痫组大鼠丘脑网状核GABAARα1mRNA表达明显低于正常对照组，而VNS抗癫痫组明显高于PTZ致癫痫组。结论 VNS可能通过增强抑制性神经递质受体α-氨基丁酸受体的活动，降低大脑皮层的兴奋性，从而抑制癫痫的形成及发展。     

依达拉奉对癫痫大鼠脑内谷氨酸的影响

目的 探讨依达拉奉对戊四氮致痫大鼠脑中谷氨酸的影响.方法 30只成年SD大鼠随机分为对照组、癫痫组和治疗组,癫痫组和治疗组大鼠腹腔注射戊四氮60mg/kg,诱导癫痫发作.治疗组于注射戊四氮之前1h经腹腔注射依达拉奉30mg,并观察1h.然后处死大鼠取脑,应用柱前衍生HPLC-荧光法测定大鼠脑皮质谷氨酸(Glu)的含量.结果 治疗组痫性发作潜伏期、平均痫性发作等级及脑内谷氨酸含量与癫痫组相比差异均有显著性(P<0.01).结论 依达拉奉可以通过拮抗氧自由基并抑制谷氨酸的释放,在癫痫发作中发挥保护作用.     

Ontogenetic development of glutamate and GABA metabolizing enzymes in cultured cerebral cortex interneurons and in cerebral cortex in vivo

The development of the enzymes phosphate activated glutaminase (PAG), glutamate dehydrogenase (GLDH), glutamic-oxaloacetic-transaminase (GOT), glutamine synthetase (GS), GABA-transaminase (GABA-T) and ornithine-δ-aminotransferase (Orn-T) was followed in mouse cerebral cortex in vivo and in cultured mouse cerebral cortex interneurons. It was found that GLDH, GOT and Orn-T exhibited an enhanced developmental pattern in the cultured neurons compared to cerebral cortex. The activities of PAG and GABA-T developed in parallel in vivo and in culture but the activity of GS remained low in the cultured neurons compared to the increasing activity of this enzyme found in vivo. Compared to cerebral cortex the cultured neurons exhibited higher activities of PAG, GLDH and Orn-T, whereas the activities of GABA-T and GOT were lower in the cultured cells. The activity of GS in the cultured neurons was only 5–10% of the activity in cerebral cortex in vivo. It is concluded that neurons from cerebral cortex represent a reliable model system by which the metabolism and function of GABAergic neurons can be conveniently studied in a physiologically meaningful way.     

Alteration of GABA transporter expression in the rat cerebral cortex following needle puncture and colchicine injection

In the adult cerebral cortex, GABA transporters (GATs) are expressed by both neurons and astrocytes. GAT-1 immunoreactivity is found in axon terminals of GABAergic neurons and astrocytes, while GAT-3 immunolabeling occurs only in the latter. The present study was designed to determine whether the expression of GAT-1 and GAT-3 in the adult rat cerebrum changes after needle lesion and colchicine infusion. Following a needle puncture or a saline injection, immunolabeling for GAT-1 and GAT-3 was slightly increased in an area around the needle track. Not only was the neuropil labeling for both GATs increased, but also a few neuronal somata were found to be immunoreactive for GAT-1. Colchicine injections induced a striking increase in immunolabeling for both GATs in the neuropil in an area adjacent to the needle path and surrounding it. A homologous region of the contralateral hemisphere also showed a moderate increase of immunoreactivity in the neuropil for both GATs. Furthermore, this contralateral site showed many neuronal somata immunolabeled for GAT-1. These changes were mainly detected during the first 5 days following intracortical lesions. These results indicate that (1) the upregulation of GAT-1 and GAT-3 in cortical interneurons and astrocytes is caused by both mechanical and chemical factors associated with the injections; (2) increased GAT-1 and GAT-3 expression contralateral to the site of colchicine injection is mediated by transcellular signaling across the corpus callosum; and (3) the lesion-induced GAT expression may play a protective role by helping to balance excitatory and inhibitory neuronal activities.     

Ultrastructure of glutamate and GABA immunoreactive axon terminals of the rat nucleus tractus solitarius, with a note on infralimbic cortex afferents

The principal fast neurotransmitters in the CNS are glutamate and GABA. Our aim was to provide a baseline account on the ultrastructure of the axon terminals immunoreactive to glutamate or GABA present in the nucleus tractus solitarius (NTS) of the rat. In addition, we wanted to complete our study of cortico-solitary afferents at the electron microscopic level, by analyzing the inputs from the infralimbic cortex. Using post-embedding immunogold, we found that nearly 61% of the axon terminals were glutamatergic, and 36% were GABAergic in the rat visceral NTS. In general, axons making asymmetric synaptic contacts were enriched in glutamate, compared to axons involved in symmetric synapses. In contrast, the vast majority of the GABAergic axon terminals made symmetric synaptic contacts. We could discern five types of glutamatergic and two types of GABAergic axon terminals that differed in their fine structure. Afferents from the infralimbic cortex were small, with clear synaptic vesicles and no dense core vesicles; they made asymmetric contacts with fine dendrites, and were glutamatergic. We conclude that most axon terminals in the NTS use glutamate or GABA as fast transmitters, in addition to being a heterogeneous population of morphological types.     

Decreased susceptibility to seizures induced by bicuculline after transient bilateral clamping of the carotid arteries in rats

Summary Rats were exposed for 24 min to bilateral clamping of the common carotid arteries (BCCA) in pentobarbital anaesthesia. 14 days later the animals were subjected to subcutaneous injection of (+)-bicuculline (3 or 4 mg/kg). A significantly decreased susceptibility to bicuculline-induced seizures could be observed in BCCA treated rats compared with sham operated controls. It is suggested that BCCA treatment protects animals against status epilepticus and lethal toxicity produced by bicuculline. Electrographic recordings of the BCCA animals revealed no ictal activity within 1 h after bicuculline injection. An analysis of the GABA content showed a significant increase in the hippocampus (HPC), frontal cortex (FCX), parietal cortex and substantia nigra in BCCA animals compared with controls. It is therefore possible that an increase in GABA content postsynaptically counteracts the GABA_A antagonistic effect of bicuculline in BCCA animals thus preventing the normal seizure inducing effect of this substance.Supported by Deutsche Forschungsgemeinschaft, SFB 330, Organprotektion     

GABA in the inferior colliculus plays a critical role in control of audiogenic seizures

Previous studies have implicated a decreased efficacy of GABA as an important defect subserving the audiogenic seizures of the genetically epilepsy-prone rat (GEPR-9). The inferior colliculus (IC) is a critical site for audiogenic seizure (AGS) initiation, and the pontine reticular formation (PRF) is implicated in the propagation fo AGS and in other generalized seizure models. The present study observed that microinjection of baclofen, a GABA-B receptor agonist, into Ic protects against AGS, and blockade of the breakdown of endogenous GABA by gabaculine, a GABA transaminase inhibitor, increased GABA levels and blocked AGS susceptibility in the GEPR-9. Microinjection of baclofen or gabaculine into the PRF reduced AGS severity, but the doses required were considerably greater and the degree of anticonvulsant effect was less. Uptake of [³H]GABA into GEPR-9 synaptosomes from the IC is significantly increased as compared to normal, which could contribute to the diminished effectiveness of GABA in the GEPR-9. Previous studies indicate that GABA-A receptor agonists block AGS with IC microinjection, and recent data indicate that blockade of GABA uptake in this nucleus significantly reduced AGS severity. These data taken together strongly support the critical importance of the defect in GABA function in the IC in modulating susceptibility to audiogenic seizure intiation in the GEPR-9.     

点燃鼠痫性发作对神经元凋亡的影响

目的 观察点燃大鼠痫性发作对神经元凋亡的影响。方法 用ＩＳ－Ⅱ型智能刺激仪点燃大鼠致痫性反复发作,并用原位末端标记染色法显示点燃后不同时期垢凋亡细胞,结果 发现痫性发作后海马、杏仁核、大脑皮质、丘脑、小脑神经元凋亡明显增多。其海马ＣＡ３、ＣＡ１区凋亡细胞在２４小时最多,且持续３周以上。结论 痫性发作可使痫灶局部和远隔痫灶的神经元凋亡,此可能与顽固性癫痫的成因有关。     

Endogenous GABA release from slices of rat cerebral cortex and hippocampus in vitro

Using a rapid, simple and sensitive radioreceptor assay, a Ca²⁺-dependent K⁺-evoked release of endogenous GABA was demonstrated from rat cortical and hippocampal slices in vitro. This evoked-release of endogenous GABA was similar to tha of [³H]GABA release (in its Ca²⁺ dependency) but differed from the latter in having a higher signal to noise level. Neither 5-HT nor a stable enkephalin analogue had any effect on endogenous GABA release from hippocampus slices.     

Dentate granule cell neurogenesis after seizures induced by pentylenetrazol in rats

Epileptic seizures originating from the limbic system have been shown to stimulate the proliferation rate of granule cell precursors in the adult brain, but it is not clear if other type(s) of seizures have the similar effects. This study examined the effects of pentylenetrazol (PTZ)-induced generalized clonic seizures on dentate granule cell neurogenesis in adult rats. Using systemic bromodeoxyuridine (BrdU) to label dividing cells, we studied the proliferation rate of neural precursor cells in the dentate gyrus at various time points after PTZ-induced seizures. The double-label immunofluorescence with confocal microscopy was used to determine the newborn cell phenotypes. Quantitative analysis of BrdU labeling revealed a significant increase in the proliferation rate of neural precursor cells in the dentate gyrus 3, 7, and 14 days after seizures. The number of BrdU-labeled cells in the dentate gyrus returned to baseline levels by 28 days after the initial seizures. Most of newborn cells migrated into the granule cell layer from the subgranular zone, displayed the neuronal phenotype, and developed morphological characteristics of differentiated dentate granule cells. These results indicated that neuron proliferation in the dentate gyrus was enhanced during a time window (3-14 days) after PTZ-induced seizures. Its underlying mechanism is discussed.