氯丙烯亚慢性染毒对大鼠神经组织中ATP的含量

氯丙烯(Allyl Chloride)广泛应用于有机合成、医药、农药和合成树脂等工业,长期低浓度接触可引起对称性轴突变性型周围神经病[1-2]。动物超微神经病理观察发现神经轴浆内微管和神经丝大量堆积,单位面积内数量明显减少,线粒体明显增多,少部分可见嵴脱落呈空泡变性[3-4],这种病理     

焦亚硫酸钠对大鼠背根节神经元胞内钙离子浓度的影响

目的:探讨一种食品添加剂焦亚硫酸钠(SMB)对大鼠背根节神经元(DRG)的生理作用和毒性效应。方法:急性分离大鼠背根节神经元细胞后,应用Ca2+荧光指示剂Fura-2/AM标记细胞检测大鼠DRG神经元细胞内钙离子浓度的变化。结果:SMB可增大大鼠背根神经元胞内钙离子浓度。结论:SMB可以引起大鼠背根神经元胞内钙超载,进而可能导致一系列与钙离子浓度有关的中枢神经系统损伤。     

胞内钙离子浓度与咖啡因保护小脑颗粒神经元作用的关系

用凝胶电泳和fura-2荧光技术测定［Ca²⁺］_i方法研究咖啡因对低钾诱导的大鼠小脑颗粒神经元凋亡的保护作用与［Ca²⁺］_i升高之间的关系. 将体外培养的小脑颗粒神经元从高钾（25 mmol·L^-1 KCl）培养基中转移到低钾（5 mmol·L^-1 KCl）培养基中,神经元发生凋亡. 但低钾引起的神经元死亡可被咖啡因（5-20 mmol·L^-1）浓度依赖性地保护,且咖啡因的这种作用不受蓝尼定(ryanodine) 敏感钙释放阻断剂蓝尼定和丹曲林(dantrolene)的影响;也不被Ｌ-型钙通道阻断剂硝苯地平, 尼莫地平, 维拉帕米和NMDA受体阻断剂地佐环平抑制. 结果说明［Ca²⁺］_i的升高并不是咖啡因对小脑颗粒神经元的保护作用所必需的.     

脊神经结扎后大鼠邻近未损伤背根神经节神经元高电压激活钙电流的变化

目的 探讨脊神经结扎后大鼠邻近未损伤背根神经节神经元(DRG)高电压激活(HVA)钙电流的变化及其意义.方法 采用左侧L5脊神经结扎术(SNL)制备大鼠神经病理性痛模型.于结扎后第14天采用酶消化法急性分离结扎侧邻近未损伤L4脊神经DRG神经元(SNL组),另取正常大鼠L4 DRG神经元作为对照(C组).采用全细胞膜片钳技术记录神经元HVA钙电流.结果 与C组比较,SNL组钙峰电流密度降低(P＜0.05).两组钙电流半数激活电压和半数失活电压比较差异均无统计学意义(P＞0.05).与C组比较,SNL组L和P/Q型钙电流均降低(P＜0.05).两组L、N、P/Q三型钙电流比例比较差异均无统计学意义(P＞0.05).结论 脊神经结扎后大鼠邻近未损伤DRG神经元HVA钙峰电流密度降低主要是由L和P/Q型钙电流的减少而引起,可能是诱发SNL损伤后神经病理性痛发生的重要原因.     

腺苷及腺苷三磷酸对大鼠离体结肠平滑肌的作用

目的 比较腺苷和腺苷三磷酸对大鼠离体近端结肠纵行平滑肌活动的调节作用.方法 四导生理记录仪记录大鼠近端结肠纵行肌的等长舒张和收缩反应.结果 对于静息状态下的大鼠离体近端结肠纵行肌标本,腺苷无明显影响(P＞0.05).但是,腺苷三磷酸使静息状态下的大鼠离体近端结肠纵行肌产生微弱的舒张反应后续浓度依赖性收缩反应;腺苷三磷酸的上述作用不受神经阻断剂河豚毒素的影响.大鼠离体近端结肠纵行肌标本在五羟色胺或乙酰胆碱预收缩条件下,腺苷和腺苷三磷酸均可产生浓度依赖性舒张反应,但是腺苷引起的舒张反应明显弱于腺苷三磷酸(P＜0.01).结论 在大鼠离体近端结肠纵行肌,腺苷三磷酸可产生舒张反应和收缩反应,而腺苷仅产生舒张反应.     

胞内钙离子浓度与咖啡因保护小脑颗粒神经元作用的关系(英文)

用凝胶电泳和 fura- 2荧光技术测定 [Ca2 + ]i方法研究咖啡因对低钾诱导的大鼠小脑颗粒神经元凋亡的保护作用与 [Ca2 + ]i 升高之间的关系 .将体外培养的小脑颗粒神经元从高钾 ( 2 5mmol· L-1KCl)培养基中转移到低钾 ( 5mmol· L-1KCl)培养基中 ,神经元发生凋亡 .但低钾引起的神经元死亡可被咖啡因 ( 5- 2 0 mmol· L-1)浓度依赖性地保护 ,且咖啡因的这种作用不受蓝尼定 ( ryanodine) -敏感钙释放阻断剂蓝尼定和丹曲林 ( dantrolene)的影响 ;也不被 L-型钙通道阻断剂硝苯地平 ,尼莫地平 ,维拉帕米和 NMDA受体阻断剂地佐环平抑制 .结果说明 [Ca2 + ]i 的升高并不是咖啡因对小脑颗粒神经元的保护作用所必需的 .     

氯丙烯对神经细胞内钙磷含量和能量合成的影响

用鸡胚脑神经细胞研究氯丙烯作用下细胞内钙 ,磷 ,ATP,ADP,AMP含量及线粒体琥珀酸脱氢酶 (SDH)活性的改变 .结果表明 ,随着氯丙烯浓度的增加 ,细胞内钙含量明显增加 ,而磷含量则明显减少 ;线粒体 SDH活性明显减低 ,并有明显的浓度 -效应关系 (r=- 0 .9957) ;细胞内 ATP,ADP,AMP含量明显减低 ,细胞外 ADP,AMP含量明显增高 .结果提示氯丙烯可引起神经细胞内钙增加和细胞内线粒体 SDH活性降低 ,ATP合成减少 .氯丙烯引起的细胞内钙增加可能与能量合成减少有关     

ATP诱导的血管内皮细胞氯电流及其与Ca~(2+)运动的关系

采用全细胞膜片钳技术和fura 2荧光测定胞浆 [Ca2 +]i 变化技术 ,在培养的牛主动脉内皮细胞上观察ATP诱导的Cl- 电流的特性及其与Ca2 +内流的关系。记录到ATP激活一外向电流 ,其反转电位为 - (2 9± 8)mV ,与Cl- 的平衡电位接近 ,降低细胞外Cl- 浓度使反转电位变化 ,证明是Cl- 电流 .ATP激活的Cl- 电流具有较强的外向整流特性 ,具有Ca2 +依赖性 ,可被Cl- 通道阻滞剂呋塞米和格列本脲分别最大抑制 (88± 8) %和 (93± 4 ) % (+ 10 0mV) .ATP又可诱导内皮细胞外Ca2 +内流 ,呋塞米和格列本脲对Ca2 +内流分别最大抑制 (36± 14) %和 (44± 12 ) % ,并且二者敏感的Ca2 +内流特性不同 .结果说明Cl- 通道开放在调节内皮细胞Ca2 +内流中起重要作用     

大鼠盆总神经节腺苷三磷酸释放的调节

用荧光素-荧光素酶方法测定大鼠盆总神经节腺苷三磷酸(ATP)释放. 钠通道阻断剂河豚毒素(1 μmol·L^-1)抑制电刺激诱发的盆总神经节ATP的释放. 灌流液中去除Ca^2＋并加入EGTA(1 mmol·L^-1)后消除ATP的释放. 腺苷(100 μmol·L^-1)，A₁腺苷受体激动剂环戊腺苷 (0.1 μmol·L^-1)，毒蕈碱性受体激动剂氧化震颤素(1 μmol·L^-1)和5-羟色胺(100 μmol·L^-1)减少ATP的释放. A₁腺苷受体拮抗剂8-环戊基-1，3-二丙基黄嘌呤(10 nmol·L^-1)，α₂肾上腺素受体拮抗剂育亨宾(3 μmol·L^-1)，D₂多巴胺受体拮抗剂舒必利(20 μmol·L^-1)和组胺(100 μmol·L^-1)增加ATP的释放.　结果提示， 在大鼠盆总神经节存在着作为神经递质参与突触传递的ATP释放. A₁腺苷受体，毒蕈碱性受体，α₂肾上腺素受体，D₂多巴胺受体，5-羟色胺受体及H₁组胺受体激动剂或拮抗剂可以通过节前机制影响ATP的释放.     

强力宁对大鼠脑缺血再灌注损伤的保护作用

目的：观察强力宁（QLN）对大鼠急性脑缺血再灌注损伤的作用。方法：采用大鼠急性不完全性脑缺血再灌注损伤模型,测定脑组织含水量,丙二醛（MDA）,超氧化物歧化酶（SOD）及三磷酸腺苷酶（ATPase)的含量,结果：QLN（20mg.kg^-1)能显著对抗缺血再灌注大鼠脑组织含水量,MDA含量的升高（P＜0．05,P＜0．012）,SOD及ATPase活性的降低（P＜0．05,P＜0．01）,结论：QLN具有保护脑缺血再灌注性损伤的作用,机制与降低脑脂质过氧化和增强氧自由基清除酶的活性,改善ATP酶的功能有关。     

Rapid inhibition of ATP-induced currents by corticosterone in rat dorsal root ganglion neurons

The effects of corticosterone (CORT), a natural glucocorticoid hormone, on ATP-induced currents in rat dorsal root ganglion (DRG) neurons and the underlying signaling mechanism were studied by using patch-clamp techniques. Three types of currents (fast, slow and mixed) were evoked by ATP in cultured DRG neurons. Pretreatment with CORT (0.01-10 mumol/l) for 30 s could inhibit the fast current and the fast component of the mixed current. In contrast, CORT had no significant effect on the slow current evoked by ATP. The inhibitory effects were concentration dependent, reversible and could be blocked by glucocorticoid receptor antagonist RU38486 (10 micromol/l), but not by GDP-beta-S (0.2 mmol/l), a blocker of G protein activation. Membrane-impermeable bovine serum albumin-conjugated corticosterone failed to mimic the effects of CORT. The inhibitory effects of CORT on ATP-induced currents diminished after adding protein kinase A inhibitor H89 (10 micromol/l), but were not influenced by protein kinase C inhibitor chelerythrine chloride (10 micromol/l). These results suggest that glucocorticoid hormones might participate in the control of pain by modulating P2X(3) receptor-mediated events in sensory neurons, and the effect is mediated by glucocorticoid receptors and the downstream activation of protein kinase A.     

Modulation of ATP-induced inward currents by docosahexaenoic acid and other fatty acids in rat nodose ganglion neurons

The effects of docosahexaenoic acid (DHA) and other fatty acids on P2X-receptor-mediated inward currents in rat nodose ganglion neurons were studied using the nystatin perforated patch-clamp technique. DHA accelerated the desensitization rate of the ATP-induced current. DHA showed use-dependent inhibition of the peak ATP-induced current. Other polyunsaturated fatty acids, such as arachidonic acid and eicosapentaenoic acid, displayed a similar use-dependent inhibition. The inhibitory effects of saturated fatty acids including palmitic acid and arachidic acid were weaker than those of polyunsaturated fatty acids. The results suggest that fatty acids may modulate the P2X receptor-mediated response when the channel is in the open-state.     

Extracellular ATP-induced calcium channel inhibition mediated by P1/P2Y purinoceptors in hamster submandibular ganglion neurons

1. The presence and profile of purinoceptors in neurons of the hamster submandibular ganglion (SMG) have been studied using the whole-cell configuration of the patch-clamp technique. 2. Extracellular application of adenosine 5'-triphosphate (ATP) reversibly inhibited voltage-dependent Ca(2+) channel (VDCC) currents (I(Ca)) via G(i/o)-protein in a voltage-dependent manner. 3. Extracellular application of uridine 5'-triphosphate (UTP), 2-methylthioATP (2-MeSATP), alpha,beta-methylene ATP (alpha,beta-MeATP) and adenosine 5'-diphosphate (ADP) also inhibited I(Ca). The rank order of potency was ATP=UTP>ADP>2-MeSATP=alpha,beta-MeATP. 4. The P2 purinoceptor antagonists, suramin and pyridoxal-5-phosphate-6-azophenyl-2', 4'-disulfonic acid (PPADS), partially antagonized the ATP-induced inhibition of I(Ca), while coapplication of suramin and the P1 purinoceptor antagonist, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), virtually abolished I(Ca) inhibition. DPCPX alone partially antagonized I(Ca) inhibition. 5. Suramin antagonized the UTP-induced inhibition of I(Ca), while DPCPX had no effect. 6. Extracellular application of adenosine (ADO) also inhibited I(Ca) in a voltage-dependent manner via G(i/o)-protein activation. 7. Mainly N- and P/Q-type VDCCs were inhibited by both ATP and ADO via G(i/o)-protein betagamma subunits in seemingly convergence pathways.     

Bradykinin-induced modulation of calcium signals in rat dorsal root ganglion neurons in vitro

We used combined patch-clamp-microfluorimetric recordings to examine the effects of bradykinin on [Ca2+]i transients and the Ca2+ current (ICa) in rat dorsal root ganglion neurons in vitro. Bradykinin increased [Ca2+]i in approximately 20% of dorsal root ganglion cells examined and inhibited the ICa in approximately 65% of dorsal root ganglion cells. Bradykinin also inhibited the ICa when [Ca2+]i was buffered with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid or when Ba2+ was the charge carrier. When ICa's of increasing duration were elicited in these neurons, [Ca2+]i transients were produced that increased in amplitude but eventually approached an asymptote at longer voltage steps. Similarly, the amplitude of the [Ca2+]i transient also approached an asymptote in current-clamp recordings when cells were induced to fire a large number of action potentials. The bradykinin-induced inhibition of the amplitude of the [Ca2+]i transient was more pronounced at shorter voltage steps. At pulse durations that produced asymptotic [Ca2+]i signals, bradykinin no longer decreased the amplitude of the rise in [Ca2+]i, although it still reduced the ICa. In current-clamp recordings, bradykinin also reduced the [Ca2+]i signal that accompanied the generation of action potentials, but again bradykinin was more effective for shorter spike trains. Bradykinin also depolarized the majority of neurons (65%). The reduction in [Ca2+]i produced by bradykinin in sensory neurons may be an important factor contributing to bradykinin-induced excitation of primary sensory afferents.     

Cytosolic calcium oscillations in signal transduction pathways

The oscillatory nature of the intracellular calcium signal has been recognized as soon as the methodological developments allowed us to record calcium fluctuations at the single cell level. While the principal mechanisms responsible for the generation of these oscillations have been partially resolved, more attention has been recently focused on signal decoding and more particularly on the role of cell structure organization in transducing this signal to the molecular targets of the calcium messenger.     

Sensory signal transduction in the vagal primary afferent neurons

The vagal nerve conveys primary afferent information from the intestinal mucosa to the brain stem. Activation of vagal afferent fibers results in inhibition of food intake, gastric emptying, and stimulation of pancreatic secretion. Afferents nerves terminating near to the mucosa are in a position to monitor the composition of the luminal contents. As afferents do not project directly into the lumen, their activation depends on an intermediary step, i.e. neuronal activation by a secondary substance released from within the mucosal epithelium. This review addresses the role for both cholecytokinin (CCK) and serotonin (5-HT) released from enteroendocrine cells and acting as paracrine agents on the terminals of vagal afferents in responses to a number of luminal signals. CCK acted on both high- and low-affinity CCK-A receptors present on distinct vagal primary afferent neurons. Neurons of the nodose ganglia respond to intraduodenal perfusions of maltose, glucose, and hypertonic saline. These neurons were also sensitive to exogenous luminally applied 5-HT at concentrations that mimic physiologic levels. Intravenous administration of a 5-HT3 antagonist blocked these responses suggesting that nodose neuronal responses to luminal osmolarity and to the digestion products of carbohydrates are dependent on the release of endogenous 5-HT from the mucosal enterochromaffin (EC) cells, which acts on the 5-HT3 receptors on vagal afferent fibers to stimulate vagal afferent neurons. Double-labeling studies revealed that nodose neurons responded to 5-HT-dependent luminal stimuli contain mainly glutamate and substance P. Over the past year or so it has become clear that there are multiple possible excitatory inputs to a common vagal afferent route with synergistic interactions being common. The nodose ganglion contains neurons that may possess only high- or low-affinity CCK-A receptors or 5-HT3 receptors. Some neurons that express high-affinity CCK-A receptors also express 5-HT3 receptors and (or) secretin receptors. Pre-exposure to luminal 5-HT may augment the subsequent response to a subthreshold dose of CCK. Synergistic interaction between CCK and secretin also occurs at the nodose ganglia; this is mediated by high affinity CCK-A receptor. This may explain the robust postprandial secretion of enzyme, bicarbonate, and fluid despite the modest increase in CCK after a meal. Some neurons that possess low-affinity CCK-A receptor colocalize with leptin receptors (OB-Rs). These neurons also respond to mechanical distention. Interaction between CCK-A receptor and OB-Rs in these neurons likely facilitates leptin mediation of short-term satiety.     

Cholecystokinin-8S-induced intracellular calcium signaling in acutely isolated periaqueductal gray neurons of the rat

Many behavior studies indicate that cholecystokinin (CCK) is related to nociception and anxiety/panic actions in the midbrain periaqueductal gray (PAG). We previously reported that a sulfated form of CCK octapeptide (CCK-8S) produced excitatory effects at both pre- and postsynaptic loci in PAG neurons using slice preparations and whole-cell patch-clamp recordings. Here, we further examined the detailed mechanism of CCK-8S in acutely isolated PAG neurons of the rat using fura-2-based imaging of intracellular Ca2+ concentration ([Ca2+]i) and whole-cell patch-clamp recordings. Application of 1 microM CCK-8S produced an increase of [Ca2+]i, and its effect did not desensitize. This CCK-8S-induced [Ca2+]i increase was inhibited by the CCK2 receptor antagonist L-365260 but not by the CCK1 receptor antagonist L-364718. In addition, the effect of CCK-8S was eliminated by removing extracellular Ca2+, but not by an addition of the intracellular Ca2+ reuptake inhibitor thapsigargin. When simultaneous recordings of [Ca2+]i imaging and whole-cell patch-clamp were performed, CCK-8S-induced [Ca2+]i increase was significantly reduced at a membrane holding potential of -60 mV while CCK-8S-induced inward current was still observed. Current-voltage plots revealed that CCK-8S-induced inward current reversed near the equilibrium potential for K+ ions with a decreased membrane conductance. However, CCK-8S produced a significant inhibition on high-voltage-activated Ca2+ channel currents. These results suggest that CCK-8S can excite PAG neurons by inhibiting K+ channels, and CCK-8S-induced [Ca2+]i increase occurs secondary to depolarization. The evidence presented here expands our understanding of cellular mechanisms for CCK-mediated anti-analgesic and anxiogenic actions in the PAG.     

虎杖苷对VSMC内钙信号的调节机制初探

目的　观察虎杖苷对大鼠主动脉平滑肌细胞(VSMC)内游离钙浓度的变化 ,以探讨虎杖苷对血管平滑肌细胞的调节机制。方法　用荧光染料Fluo 3 AM标记细胞 ,在粘附式细胞仪上测定细胞内游离钙的变化。结果　给予虎杖苷 5min后 ,VSMC内游离钙浓度升高。当虎杖苷加入前 10min用河豚毒素和优降糖分别预处理后 ,其VSMC内游离钙都不再明显升高 ;而给予普萘洛尔、甲氰咪胍及亚甲蓝分别预处理时 ,细胞内钙浓度反而升得更高 ,与单纯虎杖苷作用相比差异都有显著性。结论　虎杖苷可增加细胞内游离钙浓度 ,其作用可能与钠、钾通道开放有关 ,并且受 β肾上腺素能受体、H2 受体系统及鸟苷酸环化酶系统的反向调节。