Involvement of adenylate cyclase and protein kinase C in the α2-adrenoceptor-mediated inhibition of noradrenaline and 5-hydroxytryptamine release in rat hypothalamic slices

Summary In superfused rat hypothalamic slices prelabelled with [³H]-noradrenaline, the ₂-adrenoceptor agonist UK 14304 inhibited in a concentration-dependent manner the electrically-evoked release of tritium. This inhibition was antagonized by the ₂-adrenoceptor blocking agent idazoxan, which by itself increased the electrically-evoked tritium overflow. Exposure to forskolin, an adenylate cyclase activator, increased the electrically-evoked release of [³H]-noradrenaline. In the presence of forskolin (1 mol/l), both the inhibitory effect of UK 14304 and the increasing effect of idazoxan on the electrically-evoked release of [³H]-noradrenaline were less pronounced than in the absence of the adenylate cyclase activator. Exposure to forskolin and to the phosphodiesterase inhibitor 3-isobutyl-l-methylxanthine shifted to the right the concentration-effect curve for UK 14304 in a similar manner as that observed in the presence of forskolin alone. Exposure to phorbol-12,13-dibutyrate (0.01–10 mol/l), a drug which activates protein kinase C, increased the electrically-evoked release of [³H]-noradrenaline. In the presence of phorbol-12,13-dibutyrate (0.1 and 1 mol/l), the concentration effect curve for UK 14304 on tritium overflow was significantly shifted to the right. The increasing effect of idazoxan on tritium overflow was significantly less pronounced in the presence of 1 mol/l phorbol-12,13-dibutyrate.In superfused rat hypothalamic slices prelabelled with [³H]-5-hydroxytryptamine, the ₂-adrenoceptor agonist UK 14304 significantly inhibited the electrically-evoked release of tritium. Exposure to forskolin increased in a concentration-dependent manner [³H]-5-hydroxytryptamine overflow, but did not modify the UK 14304-mediated inhibition. Exposure to 3-isobutyl-1-methylxanthine enhanced the electrically-evoked release of [³H]-5-hydroxytryptamine. In the presence of both forskolin (1 mol/l) and 3-isobutyl-l-methylxanthine (1 mmol/l), the concentration-response curve for UK 14304 was significantly shifted to the right. Exposure to phorbol-12,13-dibutyrate (0.01–10 mol/l) enhanced in a concentration-dependent manner the electrically-evoked overflow of [³H]-5-hydroxytryptamine. In the presence of phorbol-12,13-dibutyrate (0.1 and 1 mol/l), UK 14304 was significantly less potent to inhibit tritium release than in the absence of the protein kinase C activator.It is concluded that both cyclic AMP and phosphoinositide turnover are involved in the modulation of noradrenaline and 5-hydroxytryptamine release by presynaptic ₂-adrenoceptors in rat hypothalamic slices. However, these interactions do not represent definitive proof for a cause-effect relationship for the second messengers mediating the ₂-adrenoceptor induced inhibition of transmitter release either as autoreceptor or as heteroreceptor.Send offprint requests to S. Z. Langer at the above address     

熊果酸诱导胃癌细胞BGC-823凋亡机制的研究

目的:探讨熊果酸(UA)对胃癌细胞BGC-823增殖抑制和诱导凋亡的作用机制。方法:采用MTT法检测UA对BGC-823细胞的增殖抑制效应;用琼脂糖凝胶电泳观察DNA凋亡片段;流式细胞仪检测UA作用后BGC-823细胞的周期分布和凋亡率;用Fas单克隆抗体检测BGC-823细胞表面Fas的表达;Western blot检测BGC-823细胞Bcl-2的表达及caspase-3和caspase-8的活性。结果:UA对BGC-823细胞具有增殖抑制效应,并呈浓度和时间依赖性。UA作用24 h时半数抑制浓度(IC50)为43.10μmol/L。当UA浓度为50和60μmol/L时,琼脂糖凝胶电泳可呈现DNA凋亡梯带。随着UA浓度从20μmol/L递增到60μmol/L,周期检测发现BGC-823细胞出现亚G1峰逐步增高,S期阻滞增加,G1期下降。细胞内Bcl-2表达下降,caspase-3和caspase-8活性增加。BGC-823细胞表面未发现Fas的表达。结论:UA对BGC-823细胞有较强的增殖抑制和诱导凋亡作用,下调Bcl-2的表达及激活caspase-3、caspase-8可能是其诱导凋亡的机制。     

雷公藤红素抑制MGC - 823细胞增殖和迁移及诱导凋亡

目的 探索雷公藤红素对MGC - 823细胞的增殖，迁移及诱导凋亡的作用，并探讨其作用机制。方法 0、1、2、4、6、8、12 μM雷公藤红素作用于MGC - 823细胞，采用MTT法检测增殖比率。0、1、2和4 μM雷公藤红素作用于MGC - 823细胞0、24、48和72 h，显微镜下观察细胞形态，采用细胞划痕实验检测细胞迁移能力，流式细胞术检测细胞凋亡，western blot法检测细胞中凋亡相关蛋白Bcl - 2、Bax、Akt、p - Akt等的表达水平。结果 经雷公藤红素作用后，MGC - 823细胞的增殖率均下降（P＜0.05）；细胞数量减少，体积缩小，皱缩变圆，部分不再贴壁，细胞核缩小；细胞迁移率减小（P＜0.05）；早期凋亡率增加（P＜0.05）；MGC - 823细胞中Bax表达升高，Bcl - 2和p - Akt表达降低（P＜0.05）。结论 雷公藤红素对MGC - 823细胞的增殖和迁移有抑制作用，并诱导其凋亡。     

DADS通过Rac1/LIMK1/cofilin1通路增强沉默LIMK1抑制人胃癌BGC823细胞迁移侵袭

探讨二烯丙基二硫(DADS)通过Rac1/LIMK1/cofilin1通路对沉默LIMK1抑制BGC823细胞迁移侵袭的影响。划痕实验和侵袭实验观察迁移和侵袭能力;RT-PCR、Western blot、免疫组化检测LIMK1、Rac1、Rock1、Pak1与Cofilin1和p-Cofilin1表达。结果显示,DADS处理沉默组疤痕距离较对照组和沉默组增加(P<0.05)。DADS处理沉默组穿膜细胞低于对照组、空载体组与沉默组(P<0.05) 。沉默组LIMK1表达低于对照组和空载体组,DADS后,各处理组低于处理前各组(P<0.05)。并且,沉默组、对照组和空载体组的Rac1、Rock1、Pak1与p-cofilin1表达下调 (P<0.05)。表明DADS可增强沉默LIMK1抑制BGC823细胞迁移侵袭,机制可能与阻断Rac1/LIMK1/cofilin1通路有关。     

Differential Expression and Significance of Endoplasmic Reticulum Golgi Intermediate Compartment 1 in Precancerous Gastric Lesions and Gastric Cancer

Background

We investigated the expression of endoplasmic reticulum Golgi intermediate compartment 1 (ERGIC1) in precancerous gastric lesions and gastric cancer and the function of ERGIC in human gastric cancer cell lines.

胃泌素及其受体拮抗剂对BGC－823细胞系生长的调节

本文用液闪测定和细胞计数观察了胃泌素及其受体拮抗剂丙谷胺和Ｌ－３６５２６０对体外培养的人胃腺癌ＢＧＣ－８２３细胞系的生长调节作用。结果表明不同浓度胃泌素对ＢＧＣ－８２３细胞系的生长均有显著促进作用，而这种作用可被其受体拮抗剂丙谷胺和Ｌ－３６５２６０所抑制，且发现在胃泌素浓度衡定时，Ｌ－３６５２６０对ＢＧＧ－８２３细胞系的生长抑制作用明显强于丙谷胺。这一结果也提示，Ｌ－３６５２６０对胃泌素受体的亲合力可能明显高于丙谷胺。