生酮饮食对幼鼠戊四氮诱导痫性发作的影响及海马CA3区形态学观察

目的　探讨生酮饮食 (KD)对幼鼠戊四氮 (PTZ)诱导痫性发作阈值的影响及海马结构的病理改变。方法　通过尾静脉输注 PTZ,测定 KD饲料和普通饲料喂养两组 Wistar幼鼠的痫性发作阈值 ,并对其抽搐行为进行评分 ,同时对致痫后两组幼鼠海马 CA3区的病理学改变进行观察。结果　KD组幼鼠 PTZ诱导的痫性发作阈值明显高于对照组 (P <0 .0 1 ) ,但两组痫性发作的强度差异无显著性 (P >0 .0 5 )。 KD组幼鼠海马 CA3区正常锥体细胞计数较对照组明显增多 ,神经元损伤程度较轻。结论　KD可提高幼鼠 PTZ诱导的痫性发作阈值 ,但不影响发作强度 ;KD可减少痫性发作次数 ,对致痫幼鼠具有神经保护作用。     

发育期癫大鼠移植骨髓源性神经干细胞对海马BDNF和bFGF表达的影响

目的将骨髓源性神经干细胞(BMSCs)移植到发育期癫大鼠海马区,观察大鼠海马脑源性神经营养因子(BDNF)和碱性成纤维生长因子(bFGF)表达的变化。方法选择21日龄发育期大鼠,分离大鼠骨髓基质细胞,在特定条件下培养使其诱导分化为神经干细胞(NSC)。建立戊四氮(PTZ)点燃癫大鼠模型,将BMSCs经侧脑室注射移植至癫大鼠海马区;侧脑室注射磷酸缓冲液(PBS)作为对照。分为4组(均n=8):对照组(无癫发作),PTZ致组(癫造模,无治疗),假手术组(癫+PBS侧脑室注射),治疗组(癫+NSC侧脑室注射)。于3、7和14 d处理后用免疫组化法检测大鼠海马区BDNF和bFGF表达。结果致组大鼠海马区(齿状回、CA1区)BDNF和bFGF表达较对照组增加(P0.05),治疗组海马区(齿状回、CA1区)BDNF和bFGF表达较假手术组也有所增加(P0.05)。结论 BMSCs移植可以增加PTZ致大鼠海马BDNF和bFGF表达,从而发挥对癫后脑损伤的保护作用。     

癫痫大鼠海马中神经肽Y表达的动态观察及其作用探讨

目的　探讨癫痫大鼠海马中神经肽 Y( NPY)表达的动态变化及其作用 ,以及外源性 NPY对癫痫的影响。方法　将 SD大鼠随机分为 4组 ,采用匹鲁卡品 ( PILO)癫痫动物模型及外源性 NPY侧脑室注入干预法 ,并以免疫组织化学染色观察 NPY的表达。结果　癫痫模型组 PILO注射后 ,门区、CA3区、CA1 区的 NPY阳性细胞数表达增多 ,1 2 h达高峰 ,以后逐渐下降 ,60 d又达一高峰 ;海马颗粒细胞层有 NPY异位表达 ,3 d时最明显 ;NPY干预组门区 NPY阳性细胞数较其对照组表达少。结论　 ( 1 )癫痫发作后急性期海马 NPY表达增多及颗粒细胞层出现异位表达 ,与癫痫发作有关 ;( 2 )外源性 NPY有抗癫痫作用。     

戊四氮致痫大鼠不同脑区神经肽Y的表达及意义

目的研究神经肽Y(neuropeptideY,NPY)在戊四氮(pentylenetetrazol,PTZ)致痫大鼠不同脑区中的变化,以探讨NPY与癫痫的关系。方法清洁级近交系雄性SD大鼠50只,分为对照组(A组,n=10)及实验组(40只)。实验组按体重50mg/kg经腹腔注射PTZ1次,对照组腹腔注射同等容量的生理盐水。根据癫痫发作分级,0~1级7只为B组,立即取脑;2级以上发作33只,随机于癫痫发作后0(C组,n=10)、6(D组,n=11)、24(E组,n=10)、72h(F组,n=2)取脑。采用放射免疫方法动态观察脑组织中海马、中脑、纹状体和额叶中NPY的改变;SP免疫组化染色法染色,观察各组大鼠海马CA1区NPY的表达。结果B组中脑、纹状体及额叶NPY含量较A组升高(P<005),而两组间海马NPY含量差异无显著性;癫痫发作组(C组、D组、E组)各部位NPY含量均明显高于A组。动态观察结果显示,癫痫发作后在中脑、海马、纹状体和额叶的NPY含量明显增高随后呈逐步下降,在癫痫发作后24h其含量与未发生惊厥的B组NPY含量差异无显著性(P>005);免疫组化染色显示癫痫大发作后海马NPY的表达明显增加,但随着时间的推移而降低。结论NPY与大鼠癫痫的发生、发展有密切关系。     

柴胡总皂甙对戊四氮慢性点燃大鼠海马谷氨酸细胞的影响

目的研究柴胡总皂甙对戊四氮(PTZ)慢性点燃癫痫模型大鼠海马区谷氨酸(Glu)阳性细胞表达的影响。方法48只健康SD大鼠被随机分为6组,即空白组(A组)、生理盐水组(B组)、丙戊酸钠(VPA)组(C组)和柴胡总皂甙高、中、低三种剂量组(D组、E组、F组),每组8只,除A组不做处理外,其他各组采用腹腔注射PTZ慢性点燃造模,造模同时给予VPA、柴胡总皂甙等不同处理因素,连续4周后取脑组织切片进行Glu免疫组化染色,从阳性细胞数、灰度值分析结果。结果在CAl区,B组海马阳性细胞数高于A、C、D、E、F组,有显著性差异(P＜0．05),B组海马各区阳性细胞灰度值低于其他各组,与A、C、D各组比较,有显著性差异(P＜0．05)；而在CA2区和DG区,B组阳性细胞数、灰度值与各组差异无统计学意义。结论柴胡总皂甙可以影响PTZ点燃大鼠海马CA1区的Glu表达水平,从而抑制PTZ慢性点燃大鼠的痫性发作。     

荧光金逆行示踪观察匹罗卡品致痫大鼠CA1区锥体细胞突触联系变化的研究

目的通过荧光金(FG)逆行示踪观察氯化锂-匹罗卡品致痫模型大鼠慢性自发发作期海马CA1区锥体细胞之间的突触联系变化。方法 SD大鼠2 0只随机分为实验组和对照组。癫痫持续状态后6 0 d左右,利用立体定位仪在活体内注射逆行性示踪剂FG至海马CA1区,术后常规喂养5~7 d后灌注取材。激光扫描共聚焦显微镜下观察FG的分布。结果 7只实验组大鼠中有5只可见有FG标记的锥体细胞,对照组未见。实验组中有2只大鼠在海马下托亦可见有FG标记的锥体细胞,而对照组未见。结论颞叶癫痫大鼠海马CA1区锥体细胞之间和下托至CA1区有异常兴奋性突触联系,其可能是构成异常兴奋性回路的解剖学基础。     

γ-氨基丁酸能神经元在新生大鼠缺氧性痫性发作中的作用

目的 通过观察新生大鼠早期发育过程中及缺氧性痫性发作后海马组织病理改变以及原癌基因c-fos蛋白、谷氨酸脱羧酶(glutamate decarboxylase,GAD)的变化,探讨γ-氨基丁酸(γ-amino butylic acid,GABA)能神经元在缺氧性痫性发作中的作用及可能的影响机制.方法 采用出生后10d的SD大鼠建立改良Jensen缺氧诱导痫性发作模型,分为痫性发作后1d、3d、7d、14d 4组,并选取相应时间点正常大鼠为对照组,采用尼氏染色方法检测海马组织的组织病理变化,免疫组织化学法检测各组海马c-fos蛋白灰度值以及GAD阳性神经元数量的改变.结果 尼氏染色结果显示,各缺氧性痫性发作组海马区形态结构正常,细胞排列略稀疏,但未见明显的细胞丢失.免疫组化结果显示,与对照组比较,c-fos蛋白灰度值在痫性发作后7d,在缺氧性痫性发作组海马CA2、CA3和DG区明显地降低(P ＜0.05);GAD阳性细胞数在痫性发作后7～ 14d,缺氧性痫性发作组海马CA1、CA3和DG区明显地减少(P＜0.05).结论 缺氧性痫性发作后14d内并没有造成大鼠海马区及时或迟发性细胞丢失,但c-fos表达在大鼠海马区有迟发性增高;缺氧性痫性发作后海马GABA神经元数量的减少可能是新生大鼠缺氧诱导痫性发作后癫痫易感性升高的原因之一.     

Orexin受体拮抗剂对睡眠剥夺的戊四氮致疒间大鼠癫疒间发作及脑组织病理学变化的影响

目的探讨orexin-1受体(OX1R)和orexin-2受体(OX2R)拮抗剂对睡眠剥夺(SD)的戊四氮(PTZ)致疒间大鼠癫疒间发作及脑组织病理学变化的影响。方法雄性Wistar大鼠48只,随机分为正常对照(NC)组、PTZ组、SD+PTZ(SD)组、SD+PTZ+二甲基亚砜(DMSO)组、SD+PTZ+OX1R拮抗剂SB334867(SB)组和SD+PTZ+OX2R拮抗剂TCS OX229(TCS)组。采用改良多平台SD法,SD前及SD 48 h分别给予相应组大鼠侧脑室注射DMSO、SB或TCS。SD 72 h给予各组腹腔注射PTZ 50 mg/kg诱导癫疒间发作;观察各组大鼠癫疒间发作的潜伏期、发作等级评分、发作持续时间及死亡率;应用常规染色法观察海马的病理学变化,免疫荧光法(BrdU标记)观察神经细胞增殖的变化。结果 (1)与PTZ组比较,SD组及DMSO组疒间性发作的潜伏期明显缩短,发作等级评分、持续时间及死亡率明显增加(均P<0.001),海马CA3区神经元损害加重,海马齿状回门区和颗粒细胞下层BrdU阳性细胞数显著增多(P<0.001);SD组与DMSO组间差异无统计学意义。(2)与SD组比较...     

Orexin受体拮抗剂对睡眠剥夺的戊四氮致(癎)大鼠癫(癎)发作及脑组织病理学变化的影响

目的 探讨orexin-1受体(OX1R)和orexin-2受体(OX2R)拮抗剂对睡眠剥夺(SD)的戊四氮(PTZ)致(癎)大鼠癫(癎)发作及脑组织病理学变化的影响.方法 雄性Wistar大鼠48只,随机分为正常对照(NC)组、PTZ组、SD+ PTZ( SD)组、SD+ PTZ+二甲基亚砜(DMSO)组、SD+ PTZ+ OX1R拮抗剂SB334867(SB)组和SD+ PTZ+ OX2R拮抗剂TCS OX229 (TCS)组.采用改良多平台SD法,SD前及SD 48 h分别给予相应组大鼠侧脑室注射DMSO、SB或TCS.SD 72 h给予各组腹腔注射PTZ 50 mg/kg诱导癫(癎)发作;观察各组大鼠癫(癎)发作的潜伏期、发作等级评分、发作持续时间及死亡率;应用常规染色法观察海马的病理学变化,免疫荧光法(BrdU标记)观察神经细胞增殖的变化.结果 (1)与PTZ组比较,SD组及DMSO组(癎)性发作的潜伏期明显缩短,发作等级评分、持续时间及死亡率明显增加(均P ＜0.001),海马CA3区神经元损害加重,海马齿状回门区和颗粒细胞下层BrdU阳性细胞数显著增多(P＜0.001);SD组与DMSO组间差异无统计学意义.(2)与SD组比较,SB组和TCS组大鼠(癎)性发作的潜伏期明显延长,发作等级评分、持续时间及死亡率明显下降(均P＜0.05),海马CA3区神经元损害明显减轻,齿状回门区和颗粒下层BrdU阳性细胞数减少(均P ＜0.05);TCS组的变化较SB组更显著(P＜0.05 ～0.01).结论 Orexin受体拮抗剂尤其是OX2R拮抗剂可通过减轻海马CA3区神经元的损害和抑制齿状回区细胞增殖减轻SD对PTZ诱导癫(癎)发作的不利影响.     

钾通道Kv1.2与致痫大鼠发病相关性的研究

目的通过检测戊四唑(PTZ)致痫大鼠钾通道Kv1.2蛋白表达,探讨钾通道Kv1.2与癫痫发病的相关性。方法 40只SD大鼠分成实验组30只和正常对照组10只。实验组30只大鼠通过腹腔注射PTZ建立全身强直阵挛发作大鼠癫痫模型,取成功致痫鼠24只均分成3组,分别于致痫后3个时间段(1h、24h、48h)取脑组织。用免疫组化法和Western blot法检测大鼠钾通道Kv1.2蛋白。结果实验组大鼠海马区钾通道Kv1.2蛋白表达水平在致痫后3个时间段(1h、24h、48h)均明显低于对照组(P0.05)。实验组大鼠海马区钾通道Kv1.2蛋白表达水平在致痫后3个时间段(1h、24h、48h)之间无显著性差异(P0.05)。结论大鼠海马区钾通道Kv1.2表达的减少与全身强直阵挛发作大鼠癫痫发病密切相关。     

Entorhinal axons exhibit sprouting in CA1 subfield of the adult hippocampus in a rat model of temporal lobe epilepsy

Intracerebroventricular kainic acid administration in rat, a model of temporal lobe epilepsy, results in CA3 pyramidal neuron degeneration leading to deafferentation of CA1 pyramidal neurons. Denervation in CA1 shows a near-complete recovery of synaptic density over 2-3 months, but the source of axons participating in the reinnervation is not clear. This study investigated the contribution of the entorhinal cortex in this reinnervation by comparing the distribution of the entorhinal axons in the CA1 subfield between the intact hippocampus and the CA3-lesioned hippocampus at 3 months after administration of kainic acid. Entorhinal axons were visualized by anterograde tracing using injections of the biotinylated dextran amine into the entorhinal cortex. In the CA1 subfield of the intact hippocampus, entorhinal axons were conspicuous in the alveus and the stratum lacunosum moleculare. The distribution in the strata oriens, pyramidale, and radiatum was sparse and was characterized by isolated entorhinal fibers of the alvear pathway crossing these strata to the stratum lacunosum moleculare. However, after kainic acid-induced CA3 lesion, the density of entorhinal axons increased significantly in the CA1 stratum radiatum (375% of the intact hippocampus), as a large number of axons emanating from the entorhinal fiber plexus in the stratum lacunosum moleculare invaded the stratum radiatum. The stratum radiatum also exhibited wavy entorhinal axons filled with boutons and oriented parallel to the stratum pyramidale, suggesting collateral sprouting from entorhinal axons traversing the stratum radiatum. Thus, a significant aberrant sprouting of entorhinal axons occurs into the CA1 stratum radiatum after CA3 lesion. The sprouted fibers appear to come from both entorhinal fiber plexus in the stratum lacunosum moleculare (translaminar sprouting) and entorhinal axons traversing the stratum radiatum (intralaminar sprouting). However, the major contribution appears to be from the entorhinal plexus in the stratum lacunosum moleculare. This aberrant sprouting may lead to altered afferent excitatory connectivity in the CA1 subfield and contribute to the persistent CA1 hyperexcitability that occurs after the CA3 lesion.     

Comparative analysis of cholinergic innervation in the dorsal hippocampus of adult mouse and rat: a quantitative immunocytochemical study

To obtain quantitative data on the distribution of the acetylcholine (ACh) innervation in the dorsal hippocampus of adult mouse (C57/B6) and rat (Sprague-Dawley), a semicomputerized method was used to measure the length of immunostained axons in hippocampal sections processed for light microscopic immunocytochemistry with a highly sensitive antibody against choline acetyltransferase (ChAT). The results could be expressed in density of axons (meters per mm3) for the different layers and regions of dorsal hippocampus (CA1, CA3, DG), and also in density of axon varicosities (millions per mm3), after having determined the average number of varicosities per unit length of ChAT-immunostained axon (4 varicosities/10 microm). In mouse, the mean regional densities of ACh innervation were thus measured at 13.9, 16.1, and 15.8 m of axons, for 5.6, 6.4, and 6.3 million varicosities per mm3 of tissue, in CA1, CA3, and DG, respectively. The values were comparable in rat, except for CA1, in which the densities were lower than in mouse by 40% in the stratum lacunosum, and 20% in the stratum radiatum. Otherwise, the laminar patterns of innervation were similar in the two species, the highest densities being found in the stratum lacunosum moleculare of CA3, pyramidale of both CA1 and CA3, and moleculare of DG. These quantitative data will be of particular interest to evaluate changes in mutant mice, or mice and rats subjected to experimental conditions affecting the cholinergic phenotype.     

The distribution of adenosine A1 receptors and 5'-nucleotidase in the hippocampal formation of several mammalian species

The distributions of adenosine A1 receptors, as demonstrated by 3H-cyclohexyladenosine (3H-CHA) binding, and the adenosine-producing enzyme 5'-nucleotidase were examined in the hippocampal formation of the rat, mouse, gerbil, cat, hamster, rabbit, and guinea pig. The enzyme and binding sites were restricted to subregions and often individual layers of this structure. The distribution of 3H-CHA binding was consistent among the species with the strata radiatum and oriens of fields CA1 and CA3 exhibiting the highest levels of binding. A distinct band of 3H-CHA binding was observed in the stratum moleculare of the dentate gyrus; and in most species, this band was restricted to the inner one-third of the stratum moleculare (i.e., proximal to the stratum granulosum). The strata pyramidale, granulosum, and lucidum were in general only weakly positive for 3H-CHA binding. The binding to the stratum lacunosum/moleculare (or the distinct strata lacunosum and moleculare in the rabbit and cat) was moderate. In contrast to the relative consistency of the patterns of 3H-CHA binding in these species, 5'-nucleotidase exhibited wide variations in both the absolute amount of activity and its localization. In all species, the strata granulosum and pyramidale appeared devoid of 5'-nucleotidase activity. The only clear exception to this rule was the CA3 region of the cat where activity was seen between the cell bodies of stratum pyramidale. The strata radiatum and oriens of CA1 were strongly positive in the rat and hamster but only low to moderately stained in the other species examined.(ABSTRACT TRUNCATED AT 250 WORDS)     

Smaller hippocampal subfield volumes predict verbal associative memory in pediatric brain tumor survivors

The developing hippocampus is highly sensitive to chemotherapy and cranial radiation treatments for pediatric cancers, yet little is known about the effects that cancer treatents have on specific hippocampal subfields. Here, we examined hippocampal subfield volumes in 29 pediatric brain tumor survivors treated with cranial radiation and chemotherapy, and 30 healthy developing children and adolescents. We also examined associations between hippocampal subfield volumes and short‐term verbal memory. Hippocampal subfields (Cornus Ammonis (CA) 1, CA2‐3, dentate gyrus (DG)‐CA4, stratum radiatum—lacunosum—moleculare, and subiculum) were segmented using the Multiple Automatically Generated Templates for Different Brains automated segmentation algorithm. Neuropsychological assessment of short‐term verbal associative memory was performed in a subset of brain tumor survivors (N = 11) and typically developing children (N = 16), using the Children's Memory Scale or Wechsler's Memory Scale—third edition. Repeated measures analysis of variance showed that pediatric brain tumor survivors had significantly smaller DG‐CA4, CA1, CA2‐3, and stratum radiatum‐lacunosum‐moleculare volumes compared with typically developing children. Verbal memory performance was positively related to DG‐CA4, CA1, and stratum radiatum‐lacunosum‐moleculare volumes in pediatric brain tumor survivors. Unlike the brain tumor survivors, there were no associations between subfield volumes and memory in typically developing children and adolescents. These data suggest that specific subfields of the hippocampus may be vulnerable to brain cancer treatments, and may contribute to impaired episodic memory following brain cancer treatment in childhood.     

Difference in time course of modulation of synaptic transmission by group II versus group III metabotropic glutamate receptors in region CA1 of the hippocampus

We investigated the time course of modulation of synaptic transmission by group II and group III metabotropic glutamate receptors in region CA1 of the hippocampus. In the presence of 50 microM picrotoxin, pressure pulse application of 1 mM glutamate resulted in a fast onset of suppression of synaptic transmission in stratum lacunosum moleculare and a slower onset of suppression in stratum radiatum, with both effects returning to baseline over the course of several minutes. Application of 50 microM of the group II agonist (2R,4R)-APDC in stratum lacunosum moleculare resulted in the same fast onset of suppression while having no effect in stratum radiatum. Pressure pulse application of 100 microM DL-AP4 in stratum lacunosum moleculare and stratum radiatum resulted in a much slower onset of suppression of synaptic transmission than (2R,4R)-APDC. Suppression by (2R,4R)-APDC was accompanied by a rapid enhancement of paired pulse facilitation, indicative of a presynaptic mechanism. This demonstrates that activation of group II mGluRs in the hippocampus causes a fast onset of suppression in stratum lacunosum moleculare, while activation of group III mGluRs causes a slower onset of suppression. The difference in time course for group II vs. group III mGluRs suggests a different functional role, with group II playing a potential role in making synapses act as low pass filters.     

Changes in expression of neuronal and glial glutamate transporters in rat hippocampus following kainate-induced seizure activity

The expression of excitatory amino acid transporters (EAATs) in rat hippocampus was studied following kainic acid-induced seizure activity in vivo and in hippocampal slice cultures. Protein and mRNA levels of the glial (EAAT2) and neuronal (EAAT3) transporters were determined with affinity-purified antibodies and oligonucleotide probes, respectively. Kainate treatment decreased EAAT3 immunoreactivity in stratum lacunosum moleculare within 4 h of seizure onset. Upon pyramidal cell death (5 days after kainate treatment), EAAT3 immunoreactivity in stratum pyramidale of CA1 and in stratum lacunosum moleculare was almost completely eliminated. The rapid effect of kainate on EAAT3 expression was confirmed by in situ hybridization; EAAT3 mRNA levels were decreased in CA1 and CA3 regions within 4-8 h of seizure onset. Kainate treatment had an opposite effect on levels and expression of EAAT2. Developmental studies indicated that the rapid regulation of transporter expression was not observed in rats younger than 21 days, an observation congruent with previous reports regarding the resistance of young rats to kainate. In hippocampal organotypic cultures, which lack a major excitatory input from the entorhinal cortex, kainate produced a slow decrease in [3H]d-aspartate uptake. This study indicates that an early effect of kainate treatment consists of down-regulation of the neuronal transporter EAAT3 in restricted hippocampal regions, together with a modest increase in the expression of the glial transporter EAAT2. Differential regulation of neuronal and glial glutamate transporters may thus play a role in kainate-induced seizure, neurotoxicity and neuronal plasticity.     

Substance P innervation of the rat hippocampal formation

Light and electron microscopic substance P (SP) immunostaining was performed on hippocampal sections of colchicine-pretreated, control, untreated fimbria-fornix-transected (5 days), as well as perforant path-stimulated Sprague-Dawley rats fixed in 5% acrolein. Numerous SP-immunoreactive neurons could be observed in the stratum oriens of the Ammon's horn and subiculum, fewer were seen in the dentate hilar area and stratum radiatum of CA2 and CA3, and even fewer were seen at the border between the CA1 strata radiatum and the lacunosum moleculare of CA1 subfield. A higher dose of colchicine resulted in SP immunoreactivity in a large population of granule cells and mossy axon terminals. The entire CA2 region, the stratum oriens of CA1, CA3, and the subiculum were densely innervated by SP-containing axon terminals. A homogeneous SP innervation was found in the stratum radiatum of CA1. Only a few SP fibers were seen adjacent to the granule cell layer. Symmetric axosomatic contacts were seen between SP-containing boutons and somata in the stratum oriens of the Ammon's horn. However, throughout the hippocampal formation, the majority of SP-containing axons formed axodendritic symmetric synapses. A dense population of SP-immunoreactive boutons that formed axodendritic asymmetric synapses was observed in the strata oriens and radiatum of the CA3a and CA2 regions, and a few were found in the supragranular and subgranular layers of the dentate gyrus. Fimbria-fornix transection resulted in a marked loss of SP fibers in the strata oriens, pyramidale, and radiatum of the CA3a and CA2 subfields. In perforant pathway-stimulated animals, a population of granule cells and a large number of mossy axon terminals were immunoreactive for SP. These observations suggest two sources of SP innervation to the hippocampal formation: one arising from intrinsic sources (interneurons and granule cells) and one arising from extrinsic sources, most likely the supramammillary region. J. Comp. Neurol. 384:41–58, 1997. © 1997 Wiley-Liss, Inc.     

An analysis of cholinoceptive neurons in the hippocampal formation by direct microinfusion

Microinfusions of cholinergic agents were made in various sites in the dorsal hippocampal formation of urethane anaesthetized rats. Infusions of eserine or carbachol elicited hippocampal theta activity when made in areas containing high levels of cholinergic markers: the stratum oriens and radiatum of the CA1 and CA3, the stratum moleculare and stratum granulosum of the dentate gyrus and the infragranular region of the hilus. Subsequent infusions of atropine sulfate antagonized the theta activity. Control infusions of equal volumes of saline in active sites were without effect. Infusions of eserine or carbachol in the vicinity of the hippocampal fissure, the stratum lacunosum/moleculare of the CA1 or CA3, in the deep regions of the hilus, and in the lateral ventricle and overlying neocortex, were also without effect. Furthermore, in active sites, the latency to onset of theta and subsequent theta frequency, were both directly related to the total amount of carbachol infused. Thus, areas in which theta could be elicited with a cholinergic agonist (carbachol), or an anticholinesterase (eserine) and antagonized with atropine, were found to correspond well to areas previously found to contain a high density of cholinoceptive neurons, using autoradiographic and immunohistochemical techniques. These results provide further support for the involvement of acetylcholine as a neurotransmitter in the generation of type 2 theta in the hippocampal formation.     

An in vitro autoradiographic analysis of mu and delta opioid binding in the hippocampal formation of kindled rats

Recent studies have shown that opioid peptide levels are altered in hippocampal formation of kindled animals. We therefore studied the distributions of mu and delta opioid binding sites in hippocampal formation of kindled and control rats using quantitative in vitro autoradiography. Animals received daily stimulations of the amygdala until they experienced 3 class 5 seizures. Paired control animals underwent implantation of electrodes but were not stimulated. Mu binding sites were labeled with 125I-FK-33824. Twenty-four hours after the last kindled seizure, mu binding was decreased by 32% in stratum pyramidale of CA1 and stratum radiatum of CA2 and by 17-27% throughout most of the rest of CA1, CA2, and CA3. Few, if any, differences were seen between kindled and control animals at 7 or 28 days after the last kindled seizure. Delta binding sites were labeled with 125I-[D-Ala2,D-Leu5]enkephalin in the presence of the morphiceptin analog PL-032. Twenty-four hours after the last kindled seizure, delta binding was decreased only in stratum moleculare of the dentate gyrus. Seven days after the last kindled seizure, delta binding was decreased by 11-17% throughout CA1, CA3, and the dentate gyrus. At 28 days after the last seizure, however, no differences were found between kindled and control animals. Since the decreases in mu and delta opioid binding are transient, they are unlikely to be the molecular basis of the permanent kindling phenomenon. Rather, these changes in opioid binding may represent responses to repeated seizures.