In vivo modulation of the firing activity of putative slow- and fast-spiking interneurons in the medial prefrontal cortex by 5-HT3 receptors in 6-hydroxydopamine-induced Parkinsonian rats

In the present study, we examined changes in the firing rate and firing pattern of putative slow-spiking (SS) and fast-spiking (FS) interneurons in medial prefrontal cortex (mPFC) and the effect of 5-hydroxytryptamine-3 (5-HT₃) receptor agonist SR 57227A on the neuronal firing in rats with 6-hydroxydopamine lesions of the substantia nigra pars compacta (SNc) by using extracellular recording. The lesion of the SNc in rats decreased the firing rate of FS interneurons and the firing pattern of both SS and FS interneurons changed towards a more burst-firing. Systemic administration of SR 57227A (40–640 μg/kg, i.v.) increased the firing rate of SS interneurons, and decreased FS interneurons in sham-operated and the lesioned rats, respectively. The doses producing excitation or inhibition in the lesioned rats were higher than sham-operated rats. The local application of SR 57227A (0.01 μg) in mPFC excited SS interneurons, and inhibited FS interneurons in sham-operated rats, while having no effects on firing rate in the lesioned rats. Systemic administration of GABA_A receptor antagonist bicuculline (2 mg/kg, i.v.) excited FS interneurons in sham-operated rats, whereas bicuculline did not change the activity of FS interneurons in the lesioned rats. Our findings indicate that the putative SS and FS interneurons activity is modulated through activation of 5-HT₃ receptor by direct or indirect action, and the lesion of the SNc leads to changes in firing activity of the SS and FS interneurons and decreased response of these interneurons to SR 57227A, suggesting dysfunction and/or down-regulation of 5-HT₃ receptor on interneurons in the 6-hydroxydopamine-lesioned rats.     

蝎毒抗帕金森病小鼠多巴胺能神经元凋亡

研究蝎毒对帕金森病 (PD)小鼠脑内多巴胺能神经元的抗凋亡作用及其机制。用C5 7BL/ 6 品系小鼠 ,每日于颈部皮下注入 1 甲基 4 苯基 1,2 ,3,6 四氢吡啶 (MPTP ,2 0mg/kg)复制帕金森病模型 ,随机分为模型组及蝎毒 (SV)提取液高 (2 0 0mg/kg)、低剂量 (2 0mg/kg)治疗组 ;另设对照组 (NS)和空白给SV高、低剂量组。各组均为 8只。采用爬杆、游泳行为学检测小鼠的运动功能障碍 ;应用DNA断裂点标记法 (TUNEL)检测黑质致密部 (SNc)多巴胺 (DA)能神经元的凋亡 ;利用免疫细胞化学法检测Bcl 2 /Bax基因的表达。结果表明 :SV能改善PD小鼠运动功能障碍 ;模型组SNc部可见大量TUNEL阳性细胞 (P <0 0 1) ,治疗组TUNEL阳性细胞数均明显减少 (P <0 0 1) ;模型组SNcBcl 2免疫反应活性 (IR)阳性神经元数明显减少 (P <0 0 1) ,Bax IR阳性神经元数明显增多 (P <0 0 1) ,治疗药组未见Bcl 2 IR阳性神经元数明显减少或Bax IR阳性神经元数明显增多。提示 :SV可能通过上调Bcl 2、下调Bax基因表达抑制DA能神经元凋亡。     

Neurogenesis in the striatum of the quinolinic acid lesion model of Huntington's disease

The presence of ongoing neurogenesis in the adult mammalian brain raises the exciting possibility that endogenous progenitor cells may be able to generate new neurons to replace cells lost through brain injury or neurodegenerative disease. We have recently demonstrated increased cell proliferation and the generation of new neurons in the Huntington's disease human brain. In order to better understand the potential role of endogenous neuronal replacement in neurodegenerative disorders and extend our initial observations in the human Huntington's disease brain, we examined the effect of striatal cell loss on neurogenesis in the subventricular zone (SVZ) of the adult rodent forebrain using the quinolinic acid (QA) lesion rat model of Huntington's disease. Cell proliferation and neurogenesis were assessed with bromodeoxyuridine (BrdU) labeling and immunocytochemistry for cell type-specific markers. BrdU labeling demonstrated increased cell proliferation in the SVZ ipsilateral to the QA-lesioned striatum, resulting in expansion of the SVZ in the lesioned hemisphere. Quantification revealed that QA lesion-induced striatal cell loss produced a significant increase in the area of BrdU-immunoreactivity in the SVZ ipsilateral to the lesioned hemisphere between 1 and 14 days post-lesion compared with sham-lesioned animals, with the greatest increase observed at 7 days post-lesion. These changes were associated with an increase in cells in the anterior SVZ ipsilateral to the lesioned striatum expressing the antigenic marker for SVZ neuroblasts, doublecortin (Dcx). Importantly, we observed Dcx-positive cells extending from the SVZ into the QA-lesioned striatum where a subpopulation of newly generated cells expressed markers for immature and mature neurons. This study demonstrates that loss of GABAergic medium spiny projection neurons following QA striatal lesioning of the adult rat brain increases SVZ neurogenesis, leading to the putative migration of neuroblasts to damaged areas of the striatum and the formation of new neurons.     

去卵巢后大鼠基底前脑NOS阳性神经元的变化及雌激素的作用

目的　研究基底前脑NOS阳性神经元在大鼠去卵巢之后的时程变化 ,为雌激素类药物替代防治绝经后老年性痴呆提供理论依据。方法　将 6 9只 3月龄雌性大鼠随机分为假手术组、去卵巢对照组及雌激素替代治疗组 ,各 2 3只 ,分别在术后 3d、1周、2周、4周、8周处死 ,脑切片用NADPH d组化方法染色 ,观察并和计数基底前脑各区NOS阳性神经元 ,并进行统计分析。结果　各组大鼠基底前脑各区NOS阳性神经元数目在去卵巢后先上升 ,2周时达到高峰 ,以后假手术组及雌激素替代组NOS阳性神经元数目逐渐下降 ,8周时达正常水平。去卵巢对照组斜角带核水平支及垂直支NOS阳性神经元数目却保持较高水平 ,在 8周时与假手术组及雌激素替代治疗组之间差异有显著性 (P <0 0 1)。结论　去卵巢后基底前脑NOS阳性神经元表达增加 ,而雌激素替代治疗对其有保护作用。     

色钉菇乙酸乙酯提取物对脂多糖损伤的多巴胺能神经元的保护作用

目的 探讨不同剂量的色钉菇乙酸乙酯提取物对帕金森病（PD）模型小鼠多巴胺能神经元的保护作用。 方法 以昆明小鼠为实验材料,将脂多糖（LPS）定位注射至黑质内复制PD模型。30只小鼠随机分为假手术对照组、LPS 实验对照组、低剂量实验组（LPS+ 100mg/kg）、中剂量实验组（LPS+ 200mg/kg）和高剂量实验组（LPS+ 400mg/kg）,每组6只。用免疫荧光方法显示多巴胺能神经元和星形胶质细胞,荧光显微镜下观察、计数黑质内的阳性细胞数。结果 LPS实验对照组小鼠的黑质内,多巴胺能神经元数量少于假手术组（P<0.05）,且细胞胞体变圆,突起变短;星形胶质细胞胞体增大, 多呈激活形态。低剂量实验组与中剂量实验组小鼠黑质内的多巴胺能神经元数量多于LPS实验对照组（P<0.05）,星形胶质细胞密度降低;高剂量实验组小鼠黑质内的多巴胺能神经元数量与实验组差异无统计学意义（P>0.05）。 结论 低剂量与中剂量的色钉菇乙酸乙酯提取物能够抑制星形胶质细胞的激活,对LPS导致的多巴胺能神经元损伤有显著保护作用。     

Diet selection following area postrema/nucleus of the solitary tract lesions

Ten adult Long-Evans male rats were offered access to fat, protein and carbohydrate from separate sources. After adaptation to this diet, 5 animals received thermal lesions of the area postrema and adjacent caudal-medial portion of the nucleus of the solitary tract (AP/cmNTS). The remainder were sham-operated. AP/cmNTS lesioned rats ate significantly less and lost more weight than controls during the first postsurgery measurement period (Days 4–13 after lesioning). The decrease of food intake of AP/cmNTS lesioned rats was due to reduced fat consumption. Carbohydrate and protein intakes of lesioned animals did not differ from those of controls. Food intakes and weight changes of lesioned rats did not differ from those of controls during days 14–23 after lesioning. Intake of fat by lesioned animals remained low but was no longer significantly different from that of controls. Carbohydrate and protein intakes of lesioned rats increased slightly but did not differ significantly from those of nonlesioned controls.     

Spatial distribution of long-term potentiation in the surround of visual cortex lesions in vitro

Focal visual cortex lesions lead to functional changes in the surrounding cortical network, possibly mediated through synaptic long-term potentiation (LTP). Although a post-lesional facilitation of LTP has been observed, nothing is known about the spatial profile of LTP in the normal and focally lesioned visual cortex of rats. We used a 64-multielectrode array to characterise the spread of LTP induced by theta-burst stimulation in layer IV. Measurements were made at comparable distances from the midline in the visual cortex of controls, sham-operated and lesioned animals. In control rats, LTP was elicited in projections to all visual cortex layers. However, we completely failed to observe LTP in sham-operated animals 1–4 days after surgery. At comparable survival times, no LTP could be elicited in the lesion-treated rats in direct vicinity of the border of the injury, while LTP was successfully induced at larger distances from the lesion. The maximal reach of this restored post-lesion LTP was spatially more limited than in controls and equal in all directions, accordingly absolute distance and not maximal length or density of connections seems to rule local lesion-induced functional remodelling.     

电刺激对背根节神经元/Schwann细胞联合培养体系髓鞘蛋白P0表达的影响

目的:建立体外背根节神经元与Schwann细胞联合培养模型,观察短时低频电刺激对Schwann细胞髓鞘蛋白表达的影响。方法:培养和纯化背根节神经元与Schwann细胞,制成背根节神经元/Schwann细胞联合培养体系。于L-ascorbic acid诱导的同时,施予低频电刺激(20Hz,100μs,3V),持续作用1h,分别于L-ascorbicacid诱导后第0,2,4,8和10d取各组培养基上清以ELISA测定其中脑衍生物神经生长因子(BDNF)的水平。另外,于诱导后第7d和14d检测培养体系中髓鞘蛋白P0的表达。结果:电刺激组各时间点BDNF的浓度较对照组显著升高(P0.01)。经电刺激作用后,联合培养体系中P0表达上调(P0.05)。然而,电刺激结束后在培养液中加入TrkB-Fc,P0的表达水平则显著降低(P0.05)。结论:在神经元存在的条件下,短时低频电刺激可促进离体Schwann细胞合成P0,初步认为该作用通过刺激神经元分泌BDNF增多所致。     

Unilateral lesion of the nigrostriatal pathway induces a transient decrease of firing rate with no change in the firing pattern of neurons of the parafascicular nucleus in the rat

Electrophysiological recordings of thalamic parafascicular nucleus neurons were done in normal rats and in three groups of rats at different time intervals after injection of 6-hydroxydopamine into the pars compacta of substantia nigra. In normal rats, parafascicular neurons exhibited low firing rates (3.88+/-0.80 spikes/s). Concerning the pattern, 59% of the units discharged irregularly and 41% exhibited bursty pattern. In rats with 6-hydroxydopamine lesions, the firing rate decreased significantly during the first week post-lesion (1.15+/-0.36 spikes/s, P<0.01). During the second week, the firing rate was slightly, but not significantly, lower (2.59+/-0.41 spikes/s, P>0.05) than that of normal rats to return to the basal level three weeks post-lesion (3. 66+/-0.41 spikes/s, P>0.05). In these three groups of 6-hydroxydopamine-lesioned rats, the firing pattern showed no change when compared to control animals. These results show that the lesion of nigral dopaminergic neurons induced a transient decrease of the firing rate of parafascicular neurons with no change in the firing pattern demonstrating the absence of a stable influence of the dopaminergic system on the spontaneous activity of parafascicular neurons.     

Fimbria-fornix lesions compromise the induction of long-term potentiation at the Schaffer collateral-CA1 synapse in the rat in vivo

Although bilateral fimbria-fornix (FF) lesioning impairs spatial performance in animals, the literature is equivocal regarding its effects on hippocampal long-term potentiation (LTP). We examined the effects of FF lesioning on LTP induction in the Schaffer collateral-CA1 pathway in vivo with a protocol that delivered theta burst stimulation (TBS) trains of increasing length until a sufficient length was reached to induce LTP of the monosynaptic field excitatory postsynaptic potential (fEPSP). Experiments were performed in urethan-anesthetized Long-Evans rats either 4 or 12-16 wk after lesioning. In sham-operated controls, TBS trains ranging from 4 to 12 bursts were sufficient to induce robust LTP [170 +/- 10% (mean +/- SF) of control fEPSP slope; n = 8]. Four-week post -FF-lesioned animals also displayed clear LTP (167 +/- 12% of control fEPSP slope; n = 4) that did not differ from the shams (P > 0.05). In contrast, animals in the 12- to 16-wk post-lesion group showed a highly significant deficit in LTP induction (95 +/- 3% of control fEPSP slope; n = 8; < or =28 burst TBS trains tested; P < 0.001 vs. sham- and 4-wk post-FF-lesion groups). Other quantitative measures of synaptic excitability (i.e., baseline fEPSP slope and input-output relation) did not differ between the sham- and the 12- to 16-wk post-FF-lesion groups. These results indicate that the FF lesion leads to an enduring defect in hippocampal long-term synaptic plasticity that may relate mechanistically to the cognitive deficits characterized in this model.     

银杏叶提取物对拟血管性痴呆大鼠海马CA1区的保护作用

为了观察银杏叶提取物(EGb761)对拟血管性痴呆(vascular dementia,VD)大鼠海马CA1区神经细胞的保护作用,本研究通过反复夹闭再通大鼠双侧颈总动脉,同时腹膜腔内注射硝普钠制作拟血管性痴呆大鼠模型,选出造模成功者随机分为模型组及用药组,各为30只。另以条件匹配的30只大鼠为假手术组。采用Morris水迷宫和尼氏染色方法分别观察大鼠空间学习记忆能力及海马CA1区细胞形态学改变和细胞数目。结果显示:模型组大鼠在1、2和4月不同时间点测得的Morris水迷宫逃避潜伏期(EL)均较假手术组明显延长(P<0.01),药物组EL均显著短于模型组,但仍长于假手术组(P<0.05或P<0.01);各时间点模型组海马CA1区锥体细胞及其树突丢失,但药物组锥体细胞数多于模型组。上述结果说明EGb761对海马CA1区的保护作用可能是其改善VD大鼠学习记忆障碍的重要机制。     

The firing activity of pyramidal neurons in medial prefrontal cortex and their response to 5-hydroxytryptamine-1A receptor stimulation in a rat model of Parkinson's disease

The changes in the firing rate and firing pattern of pyramidal neurons in medial prefrontal cortex (mPFC) and the effects of selective 5-hydroxytryptamine-_1A (5-HT_1A) receptor agonist (R)-(+)-8-hydroxy-2-(dipropylamino)tetralin hydrobromide (8-OH-DPAT) and antagonist N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-2-pyridylcyclohexane carboxamide maleate salt (WAY-100635) on the firing activity of the neurons were studied in sham-lesioned rats and rats with 6-hydroxydopamine lesions of the substantia nigra pars compacta (SNc). The lesion of the SNc increased the firing rate of pyramidal neurons significantly compared to sham-lesioned rats, and the firing pattern of these neurons also changed significantly towards a more burst-firing. The systemic administration of 8-OH-DPAT at doses in the range of 0.5–128 μg/kg showed an excitatory-inhibitory effect on the firing rate of pyramidal neurons in mPFC of sham-lesioned rats. At lower doses, 0.5–32 μg/kg, it evoked excitation of the neurons, and at a high dose, i.e. 128 μg/kg, inhibited the activity of the neurons. In contrast to sham-lesioned rats, 8-OH-DPAT, at the same doses, showed no excitatory effect in the lesioned rats although the inhibitory phase of the effect of 8-OH-DPAT on the firing rate of pyramidal neurons in mPFC was still present. Furthermore, the local application of 8-OH-DPAT, 5 μg, in mPFC inhibited the firing rate of pyramidal neurons in sham-lesioned rats, while having no effect on firing rate in the lesioned rats. The excitatory or inhibitory effects of 8-OH-DPAT were reversed by WAY-100635, indicating that these effects are mediated by 5-HT_1A receptor. Altogether, these results indicate that the lesion of the SNc leads to hyperactivity of pyramidal neurons in mPFC and the abnormality of response of these neurons to 5-HT_1A receptor stimulation, suggesting that mPFC may be involved in the pathophysiology of the psychiatric disturbance of Parkinson's disease.     

植物雌激素对去卵巢大鼠海马NOS阳性神经元及学习记忆的影响

目的 :观察植物雌激素对去卵巢大鼠海马NOS阳性神经元及学习、记忆的影响 ,对中枢神经系统的保护作用。方法 :采用NADPH d酶组化观测各组大鼠海马各功能亚区NOS阳性神经元数目和Morris水迷宫行为学方法。结果 :定位航行实验显示各组大鼠的平均逃避潜伏期无明显差异 ,而空间探索实验显示植物雌激素组平台象限的游泳距离百分比和穿台次数均高于去卵巢对照组。在海马CA1和齿状回 (DG) ,植物雌激素组NOS阳性神经元数目较去卵巢对照组明显增多 (P <0 .0 5 )。结论 :植物雌激素能增加海马神经元NOS的表达 ,改善去卵巢大鼠的学习记忆能力 ,提示对中枢神经系统退行性病变具有保护作用。     

Effects of nerve growth factor and GM1 ganglioside on the number and size of cholinergic neurons in rats with unilateral lesion of the nucleus basalis

Four groups of rats with a unilateral ibotenic acid lesion of the nucleus basalis were treated with saline, nerve growth factor (NGF) 10 micrograms administered intracerebroventricularly twice per week, sialoganglioside GM1 30 m/kg daily i.p. and NGF twice per week plus GM1 10 mg/kg i.p. daily, respectively, beginning immediately after lesioning. Twenty-one days later the rats treated with saline showed a marked impairment in negotiating a 'step through' passive avoidance conditioned response, a 32% decrease in the number of choline acetyltransferase (ChAT)-positive neurons in the lesioned nucleus basalis and a 12% decrease in their areas. The rats treated with NGF and NGF plus GM1 showed no difference from sham-operated rats. In the GM1-treated rats a 12% decrease only in the number of ChAT-positive neurons was detected while performance and neuronal areas were normal. These findings indicate that NGF and GM1 prevent the cholinergic deficit by protecting the cholinergic neurons of the nucleus basalis from ibotenic acid neurotoxicity.     

Differences in neuronal firing rates in pallidal and cerebellar receiving areas of thalamus in patients with Parkinson's disease, essential tremor, and pain

The motor symptoms of Parkinson's disease (PD) are thought to result from increased inhibitory outflow from the basal ganglia to the pallidal receiving areas of thalamus (ventral oral anterior and posterior-Voa,Vop). To test this hypothesis, we examined the firing rates of neurons in pallidal and cerebellar receiving areas of thalamus in five PD patients and compared them to those of neurons in comparable regions of motor thalamus in two other patient groups where hyperactivity of GPi is not believed to occur [essential tremor (ET), pain]. Neuronal recordings were made during microelectrode-guided functional stereotactic neurosurgery. The mean spontaneous firing rate (MSFR) of neurons classified as voluntary neurons and presumed to be in pallidal receiving areas of thalamus in PD patients [7.4 +/- 1.0 (SE) Hz] was significantly lower (P < 0.01) than in the ET (18.1 +/- 3.0 Hz) and pain (19.0 +/- 1.9Hz) groups. In contrast, the MSFR of neurons classified as kinesthetic and presumed to be primarily in the cerebellar receiving area of thalamus (ventral intermediate-Vim), although some are probably in the deep shell region of the ventrocaudal nucleus (VPLa), was significantly greater in ET patients (25.8 +/- 3.5 Hz) than in the PD (14.3 +/- 1.6 Hz; P < 0.01) and pain (16.1 +/- 1.5 Hz; P < 0.05) groups. Similar findings were obtained when the neurons were grouped according to their estimated locations in Voa/Vop and Vim of motor thalamus. These data provide support for the prediction of the classical pathophysiological model of PD and moreover suggest that pathophysiology in the cerebello-thalamo-cortical pathway may be a possible cause of tremor in ET patients.     

Distribution and binding parameters of GABAA receptors in the thalamic nuclei of Macaca mulatta and changes caused by lesioning in the globus pallidus and reticular thalamic nucleus

Ascending output from the basal ganglia to the primate motor thalamus is carried by GABAergic nigro- and pallido-thalamic pathways, which interact with intrinsic thalamic GABAergic systems represented in primates by local circuit neurons and axons of the reticular thalamic nucleus. Disease-triggered pathological processes in the basal ganglia can compromise any of these pathways either directly or indirectly, yet the effects of basal ganglia lesioning on its thalamic afferent-receiving territories has not been studied in primates. Two GABA(A) receptor ligands, [(3)H]muscimol and [(3)H]flunitrazepam, were used to study the distribution and binding properties of the receptor in intact monkeys, those with kainic acid lesions in the globus pallidus, and those with ibotenic acid lesions in the reticular nucleus using quantitative autoradiographic technique on cryostat sections of fresh frozen brain tissue. In control monkeys the binding affinities for [(3)H]muscimol averaged 50 nM in the thalamic nuclei and 86 nM in the basal ganglia while the binding densities varied (maximum density of binding sites [Bmax] range of 99.4-1000.1 fmol/mg of tissue). Binding affinities and Bmax values for [(3)H]flunitrazepam averaged 2.02 nM and 81-113 fmol/mg of tissue, respectively. Addition of 100-microM GABA increased average affinity to 1.35 nM whereas Bmax values increased anywhere from 1-50% in different nuclei. Zolpidem (100 nM) decreased binding by 68-80%. Bmax values for both ligands were decreased at the two survival times in both medial and lateral globus pallidus implying involvement of both nuclei in the lesion. Statistically significant, 40% decrease (P=0.055) of Bmax for [(3)H]muscimol was observed in the ventral anterior nucleus pars densicellularis (VAdc, the main pallidal projection territory in the thalamus) 1 week after globus pallidus lesioning and a 36% decrease (P=0.017) 4 months post-lesioning. In contrast, [(3)H]flunitrazepam Bmax values in the VAdc of the same animals were increased by 23% (P=0.021) at 1 week and 28% (P=0.005) 4 months postlesion, respectively. One week after the reticular nucleus lesioning, the binding densities of [(3)H]muscimol and [(3)H]flunitrazepam were decreased in the thalamic nuclei receiving projections from the lesioned reticular nucleus sector by approximately 50% (P<0.05) and 10-33% (P<0.05), respectively. The results suggest that different GABA(A) receptor subtypes are associated with different GABAergic systems in the thalamus which react differently to deafferentation.     

6-Hydroxydopamine lesions of the nigrostriatal pathway alter the expression of glutamate decarboxylase messenger RNA in rat globus pallidus projection neurons.

In situ hybridization was used to study the effect of 6-hydroxydopamine-induced damage to the midbrain dopaminergic neurons on the level of glutamate decarboxylase mRNA in globus pallidus neurons in the rat. Some animals received an injection of Fluoro-gold in the entopeduncular nucleus or the substantia nigra prior to the 6-hydroxydopamine lesion in order to identify glutamic acid decarboxylase mRNA levels in pallidal neurons that project to one of these targets. Analysis was carried out on a sample of all pallidal neurons as well as neurons that were identified as projection neurons in control and lesioned groups. The loss of the dopamine-containing neurons in the substantia nigra resulted in significant increases in the percentage of globus pallidus neurons that expressed glutamate decarboxylase mRNA and in the amount of glutamate decarboxylase mRNA per globus pallidus neuron. These increases were noted in a sample of all pallidal neurons, as well as pallidal neurons that were identified as projecting to either the entopeduncular nucleus or the substantia nigra. In control animals, glutamate decarboxylase mRNA was clearly identified in globus pallidus neurons projecting to the entopeduncular nucleus, indicating that this recently reported projection is at least partially GABAergic. The results of this study indicate that substantia nigra dopaminergic neurons regulate globus pallidus neurons in the rat, and that removal of the dopaminergic input to the corpus striatum results in a significant increase in the amount of glutamate decarboxylase mRNA in pallidal neurons. The decreased firing rate of pallidal neurons that is seen following the loss of dopamine input appears to be accompanied by an increase in the level of glutamate decarboxylase mRNA in these neurons.     

葛根素对血管性痴呆大鼠海马锥体细胞和BDNF表达的影响

为了观察葛根素对血管性痴呆(VD)模型大鼠海马锥体细胞和BDNF表达的影响及其作用机制,本研究采用双侧颈总动脉缺血再灌注,同时腹腔注射硝普钠建立血管性痴呆大鼠模型,选出造模成功者随机分为模型组及葛根素干预组,各为24只,另以条件匹配的24只大鼠为假手术组。分别在造模术后15d,1、2和4个月等时间点,采用水迷宫检测大鼠学习记忆能力的变化,HE染色和免疫组化染色观察大鼠海马神经元的形态学改变及BDNF表达的变化。结果显示:(1)模型组大鼠的逃逸潜伏期(EL)均明显长于假手术组(P<0.01),葛根素干预组大鼠的EL较模型组明显缩短(P<0.05),但仍长于假手术组(P<0.05);(2)模型组大鼠海马CA1区锥体细胞数比假手术组明显减少(P<0.01),葛根素干预组2个月和4个月时点锥体细胞数较模型组明显增多(P<0.01),但仍少于假手术组(P<0.01);(3)模型组大鼠海马BDNF阳性细胞明显减少(P<0.01),除15d和1个月组DG区外,葛根素干预组大鼠海马BDNF阳性细胞数较模型组明显增多(P<0.05),但仍低于假手术组(P<0.05);(4)模型组大鼠海马BDNF阳性细胞平均吸光度值较假手术组明显降低(P<0.01),而葛根素干预组比模型组和假手术组均明显降低(P<0.05)。本研究结果提示,脑缺血再灌注后,海马BDNF阳性神经元和锥体细胞持续减少,在VD学习记忆障碍的发生和发展过程中起重要作用;葛根素对脑缺血再灌注损伤具有保护作用,其机制可能与葛根素上调BDNF的表达、减少锥体细胞的丢失有关。     

大鼠黑质损毁后多巴胺能神经元形态及纹状体c-fos表达的变化

目的:观察毁损黑质后,多巴胺(DA)能神经元形态学变化和纹状体内相关神经元c-fos表达情况,探讨c-fos表达与毁损程度的关系。方法:利用6羟多巴胺(6OHDA)特异毁损大鼠黑质DA能神经元,采用阿朴吗啡(APO)诱导旋转实验观察术后1、7、14和21d行为学变化;利用HE染色、Nissl染色、免疫组织化学方法和电镜,观察各时间点黑质DA能神经元形态学变化和纹状体c-fos表达。结果:毁损侧DA能神经元逐渐减少,超微结构损伤逐渐加重;DA神经元丢失比例≥80%时,纹状体毁损侧c-fos表达上调,APO诱导的旋转实验>7r/min。结论:黑质DA能神经元丢失是毁损大鼠行为改变的病理学基础;cfos的表达与DA能神经元的毁损程度、行为改变有一定的关系。     

一氧化氮对大鼠黑质致密部神经元自发放电及Glu能和GABA能传入活动的影响

目的:研究一氧化氮(NO)对大鼠黑质致密部(SNc)神经元自发放电活动及对谷氨酸(Glu)、γ-氨基丁酸(GABA)能神经纤维输入活动的影响,为进一步研究Parkinson病(PD)的发病机制奠定神经生理学基础。方法:采用微电泳技术观察NO供体硝普钠(SNP),Glu及GABA对SNc神经元自发放电活动的影响及神经递质间的相互作用。结果:微电泳SNP使81.25%(39/48)受试神经元自发放电频率加快,此兴奋性作用与微电泳电流强度正相关,随着电流强度的增加(20nA～80nA),SNc神经元自发放电频率进一步加快。在35个受试神经元上分别微电泳Glu或GABA后,可以观察到分别有31神经元兴奋或所有神经元表现为抑制作用。在已经被Glu兴奋的31个神经元上同时微电泳SNP可使SNc神经元自发放电频率进一步加快。相反,在微电泳GABA的同时应用SNP可使已经被抑制的神经元放电频率增加。结论:NO对SNc神经元产生兴奋性作用。NO与Glu、GABA能投射在SNc有汇聚作用,NO协同Glu对SNc神经元产生兴奋性作用,但拮抗GABA对SNc神经元抑制性作用。