丙泊酚麻醉对老龄大鼠认知功能和海马神经元γ-氨基丁酸A受体表达的影响

目的观察丙泊酚麻醉对老龄大鼠认知功能及海马神经元γ-氨基丁酸A(GABA)受体表达的影响。方法50只SD老年大鼠随机分为丙泊酚组和对照组,每组25只。丙泊酚组大鼠腹腔注射1%丙泊酚中/长链脂肪乳注射液6 mL/kg,对照组腹腔注射等体积的生理盐水。麻醉后1 d进行Morris水迷宫实验,分别采用HE染色和尼氏体染色观察海马区神经细胞及尼氏体(Nissl体)形态学变化,Western Blot检测GABA蛋白量表达。结果麻醉后,2组大鼠肛温、心率、呼吸频率、血氧饱和度比较,差异均无统计学意义(P>0.05)。随着实验时间的延长,2组大鼠逃逸潜伏期、总里程数逐渐减小,丙泊酚组大鼠各时间点逃逸潜伏期、总里程均高于对照组,差异有统计学意义(P<0.05)。丙泊酚组大鼠穿越平台区域次数、时间小于、短于对照组,差异有统计学意义(P<0.05)。对照组海马区Nissl体存在于细胞浆及树突,染色较深,神经细胞排列整齐,形态规则;丙泊酚组Nissl体消失,神经细胞数量减少,细胞核破裂、丢失。丙泊酚组大鼠海马GABA蛋白表达量低于对照组,差异有统计学意义(P<0.05)。结论丙泊酚对大鼠认知功能有影响,并与海马区GABA的表达相关。     

Interaction of nicotinic acetylcholine receptors with dopamine receptors in synaptic plasticity of the mouse insular cortex

The insular cortex plays essential roles in nicotine addiction. However, much is still unknown about its cellular and synaptic mechanisms responsible for nicotine addiction. We have previously shown that in layer 5 pyramidal neurons of the mouse insular cortex, activation of the nicotinic acetylcholine receptors (nAChRs) suppresses synaptic potentiation through enhancing GABAergic synaptic transmission, although it enhances both glutamatergic and GABAergic synaptic transmission. In the present study, we examined whether dopamine receptors might contribute to the nicotine‐induced inhibition of synaptic potentiation. The nicotine‐induced inhibition of synaptic potentiation was decreased in the presence of a D1 dopamine receptor antagonist SCH23390 irrespective of the presence of a D2 dopamine receptor antagonist sulpiride, suggesting that D1 dopamine receptors are involved in nicotine‐induced inhibition. We also investigated how dopamine receptors might contribute to the nAChR‐induced enhancement of glutamatergic and GABAergic synaptic transmission. The nAChR‐induced enhancement of GABAergic synaptic transmission was decreased in the presence of SCH23390 irrespective of the presence of sulpiride, whereas that of glutamatergic synaptic transmission was not altered in the presence of SCH23390 and sulpiride. These results suggest that D1 dopamine receptors are involved in the nAChR‐induced enhancement of GABAergic synaptic transmission while dopamine receptors are not involved in that of glutamatergic synaptic transmission. These observations indicate that the interaction between nAChRs and D1 dopamine receptors plays critical roles in synaptic activities in layer 5 pyramidal neurons of the mouse insular cortex. These insular synaptic changes might be associated with nicotine addiction.     

New insights into Wnt signaling alterations in amyotrophic lateral sclerosis: a potential therapeutic target?

Amyotrophic lateral sclerosis is a fatal neurodegenerative disorder characterized by upper and lower motor neuron degeneration, which leads to progressive paralysis of skeletal muscles and, ultimately, respiratory failure between 2–5 years after symptom onset. Unfortunately, currently accepted treatments for amyotrophic lateral sclerosis are extremely scarce and only provide modest benefit. As a consequence, a great effort is being done by the scientific community in order to achieve a better understanding of the different molecular and cellular processes that influence the progression and/or outcome of this neuropathological condition and, therefore, unravel new potential targets for therapeutic intervention. Interestingly, a growing number of experimental evidences have recently shown that, besides its well-known physiological roles in the developing and adult central nervous system, the Wnt family of proteins is involved in different neuropathologica conditions, including amyotrophic lateral sclerosis. These proteins are able to modulate, at least, three different signaling pathways, usually known as canonical(β-catenin dependent) and non-canonical(β-catenin independent) signaling pathways. In the present review, we aim to provide a general overview of the current knowledge that supports the relationship between the Wnt family of proteins and its associated signaling pathways and amyotrophic lateral sclerosis pathology, as well as their possible mechanisms of action. Altogether, the currently available knowledge suggests that Wnt signaling modulation might be a promising therapeutic approach to ameliorate the histopathological and functional deficits associated to amyotrophic lateral sclerosis, and thus improve the progression and outcome of this neuropathology.     

LKB1表达下调对培养海马神经元突触mEPSC的影响

目的研究离体培养的海马神经元LKB1表达下调对于神经元微小兴奋性突触后电流(mEP-SC)的影响。方法选用17d的胚胎大鼠培养海马神经元,分别用电穿孔的方法转染CAG-RE质粒和LKB1RNAi质粒,培养10~12d后进行电生理记录,选用全细胞膜片钳方式及自由记录模式,细胞外液加TTX阻断动作电位,加Bicucullin抑制GABA电流,记录神经元的mEPSC,比较2组神经元的mEPSC频率和幅度的差别。结果转染CAG-RE的神经元mEPSC幅度平均为25.6pA,频率平均为(5.21±0.25)Hz,是基线的99.8%;转染LKB1RNAi的神经元mEPSC幅度平均为35.1pA,频率平均为(5.79±0.27)Hz,是基线的127.1%;比较2组间频率、幅度变化,差别有显著性意义(P<0.05)。结论LKB1基因表达下调增强了培养海马神经元突触传递的效率。     

γ-干扰素对大鼠胚胎基底前脑及隔区核团胆碱能神经元分化的影响

为了研究γ-干扰素(IFNγ)对大鼠胚胎基底前脑及隔区核团胆碱能神经元分化的作用,采用免疫组织化学方法对胆碱能神经元的特异性标记酶-胆碱乙酰基转移酶(ChAT)进行染色,ChAT阳性细胞的数量反映了胆碱能神经元的数量,并用14C-乙酰CoA作底物来检测ChAT活性。结果显示,IFNγ处理过的实验组,ChAT阳性细胞数量显著增加,ChAT活性也增加,这种增加被大鼠抗小鼠IFNγ单克隆抗体(Ab-IFNγ)完全拮抗。采用流式细胞术对细胞周期进行分析,细胞周期及细胞百分率无明显改变。用MAP2标记神经细胞,神经细胞数基本未增加。以上结果提示:IFNγ不能促进基底前脑和隔区神经元增殖,胆碱能神经元表达增加不是因为神经元数目增加而是分化的结果。     

丹参对持续癫痫幼鼠脑损伤保护作用的实验研究

目的 探讨丹参对持续癫痫发作诱发幼鼠脑神经元损伤是否具有保护作用。方法 皮下及腹腔注射贝美格针诱发健康幼龄鼠癫痫持续状态发作。光镜下观察神经元病变情况；电镜观察海马神经元超微结构的改变。结果 持续癫痴组幼鼠脑组织光镜下可见明显的神经元病变。电镜下可见海马区神经元的超微结构病变。丹参治疗组神经元病变均轻于持续癫痴组；而正常对照组未见类似病变。结论 丹参在组织、细胞和亚细胞水平对持续癫病幼鼠脑神经元损伤具有一定的保护作用，为临床有效防治小儿惊厥性脑损伤提供了可靠的实验依据。     

l-DOPA induces concentration-dependent facilitation and inhibition of presynaptic acetylcholine release in the guinea-pig submucous plexus

Neurotransmitter- or neuromodulator-like actions ofl-DOPA were investigated with intracellular recordings from submucous plexus neurons of the guinea-pig caecum.l-DOPA at 30 nM augmented the amplitude of fast EPSPs, but did not affect depolarizations elicited by puff application of acetylcholine (ACh). The augmenting effect ofl-DOPA on the fast EPSPs was counteracted byl-DOPA methyl ester. The fast EPSPs were depressed by 10 μMl-DOPA, but transiently augmented after rinsing the drug.l-DOPA methyl ester did not affect the inhibitory action ofl-DOPA on the fast EPSPs, but antagonized the potentiation following the inhibition. The depolarization elicited by exogenously applied. ACh was inhibited by 10 μMl-DOPA. Intracellular Ca²⁺ concentrations ([Ca²⁺]_i) of the neuronal soma were measured with fura-2 microfluorophotometry. The transient increase in the [Ca²⁺]_i evoked by the somatic action potential (Δ[Ca²⁺]_AP) was facilitated by 30 nMl-DOPA, but decreased by the drug at 10 μM. It is concluded thatl-DOPA at low concentrations enhances the Δ[Ca²⁺]_AP, increasing the neurotransmitter release, but at high dose diminishes the Δ[Ca²⁺]_AP, inhibiting the neurotransmission.     

钾通道阻断剂对低氧/复氧诱导的培养海马神经元死亡的防护作用

目的研究钾通道阻断剂对单纯低氧/复氧诱导的培养海马神经元死亡的防护作用。方法培养8 d的海马神经元置于低氧环境(95% N2/5% CO2)6 h,复氧再培养直至72 h,复氧后0.5 h培养液内分别给予不同钾通道阻断剂,用细胞计数及MTT比色法检测神经元死亡情况。结果低氧/复氧诱导培养海马神经元出现迟发性死亡;四乙铵以剂量依赖性的方式防护低氧/复氧诱导的培养海马神经元免于死亡;大电导钙激活钾通道(BK通道)阻断剂iberiotoxin(IbTX)可完全消除低氧/复氧诱导的神经元死亡(P<0.001);A型钾通道阻断剂4-氨基吡啶不能防护低氧/复氧诱导的神经元免于死亡(P>0.05)。结论钾通道阻断剂四乙铵和IbTX能防护低氧/复氧诱导的培养海马神经元免于死亡,提示某些类型的钾通道尤其是BK通道活动增强可能参与了低氧/复氧诱导的培养海马神经元死亡。     

Immunocytochemical staining of cholinergic amacrine cells in rabbit retina

Cholinergic neurons of rabbit retina were labelled with an antibody against choline acetyltransferase, the synthesizing enzyme for acetylcholine. Two populations of cells are immunoreactive. Type a cell bodies lie in the inner nuclear layer (INL), their dendrites branching narrowly in sublamina a of the inner plexiform layer (IPL), while type b cell bodies lie in the ganglion cell layer (GCL) with dendrites branching in sublamina b of the IPL. The irregular networks of clustered immunoreactive dendrites are similar, but not identical, in the two sublaminae. Type b cells are more numerous than type a cells in central retina. No axons were stained. It appears that the immunoreactive neurons are normally placed and displaced starburst/cholinergic amacrine cells.