雌激素通过调节Gα_s-cAMP通路减轻异丙肾上腺素导致的大鼠心肌损伤

本研究旨在通过给予去卵巢大鼠异丙肾上腺素制作心肌损伤及心功能异常模型,探讨雌激素通过调节兴奋性G(Gαs)蛋白-环磷酸腺苷(cAMP)信号通路纠正儿茶酚胺导致的心功能异常的机制。观察雌激素对大鼠血流动力学参数:左心室收缩峰压(LVSP)、左心室舒张末压(LVEDP)、左心室内压上升的最大变化速率(+dp/dtmax)、左心室内压下降的最大变化速率(-dp/dtmax),血浆脑尿钠肽(brain natriuretic peptide,BNP),cAMP浓度和心肌中Gαs蛋白表达的影响。结果显示:与假手术组相比,去卵巢大鼠的血流动力学参数、血浆BNP水平、血浆cAMP水平没有显著改变;但给予去卵巢大鼠异丙肾上腺素后,血流动力学参数LVSP、+dp/dtmax降低(P0.01),LVEDP、-dp/dtmax升高(P0.01),血浆BNP水平升高(P0.01),血浆cAMP水平降低(P0.01);而进一步的雌激素补充则改善了心功能:LVSP、+dp/dtmax升高(P0.01),LVEDP、-dp/dtmax降低(P0.05,P0.01),血浆BNP水平降低(P0.01),cAMP水平升高(P0.01);雌激素对Gαs蛋白表达没有显著影响。结果提示:雌激素对心肌损伤具有保护作用,升高cAMP水平,改善心肌收缩过度抑制,调节心脏的功能状态。     

大鼠下丘脑微量注射TRH对心功能的作用及其机制

目的：探讨下丘脑促甲状腺激素释放激素（TRH）对心功能活动的调节作用及其作用机制。方法：在SD大鼠下丘脑促垂体区埋管,微量注射TRH或预先注射一氧化氮合酶抑制剂L—NAME及M型乙酰胆碱受体阻断剂阿托品,记录给药前后左心室内压峰值（LVSP）、心率（HR）、室内压瞬时上升速率峰值（dp／dtmax）和瞬时下降速率峰值（-dp／dtmax）。结果：①与对照组相比,下丘脑促垂体区注射TRH可引起LVSP、HR、dp／dtmax及-dp／dtmax显著升高（P〈0．05或P〈0．01）。②单独注射L—NAME后只引起LVSP显著升高（P〈0．05或P〈0.01）,L-NAME预处理可抑制TRH引起的正向调节效应。③单独注射阿托品引起LVSP及dp／dtmax的显著升高（P〈0．05）,HR显著下降（P〈0．05）,阿托品预处理减弱了TRH加快心率和提高-dp／dtmax的效应。结论：①下丘脑TRH对心脏有正性变时、变力作用。②下丘脑内源性NO能降低LVSP,但对HR、dp／dtmax及-dp／dtmax明显影响,TRH的作用是经NO依赖通路的。③下丘脑内源性胆碱能递质对心脏有正性变时但负性变力的作用,下丘脑TRH调节心功能可能部分通过胆碱能M受体通路。     

丹酚酸B对大鼠离体工作心脏血流动力学的影响

目的 研究丹酚酸B对离体大鼠工作心脏血流动力学的影响.方法 采用Langendorff离体心脏灌流的方法,以左室内压( LVSP)、左室舒末压(LVEDP)、室内压最大上升速率(+dp/dtmax)、室内压最大下降速率(- dp/dtmax)、心率(HR)等血流动力学参数为指标,观察丹酚酸B对心肌收缩性能的影响.结果 不同剂量(10、5、2.5 mg/L)的丹酚酸B可使LVSP、±dp/dtmax明显升高,同时使HR减慢,并呈剂量依赖性,但对LVEDP无明显作用.结论 丹酚酸B对离体工作心脏有剂量依赖性正性肌力作用.     

富硒板党对大鼠心肌缺血/再灌注损伤的保护作用及其机制

目的:研究富硒板党对大鼠心肌缺血/再灌注损伤的保护作用及其作用机制。方法:将32只大鼠随机分为假手术组、模型组、实验组和阳性对照组(n=8)。实验组术前按5.0 g/(kg·d)灌服富硒板党水溶液,阳性对照组按300 mg/(kg·d)灌服通心络胶囊,假手术组和模型组按5 ml/(kg·d)灌服生理盐水,连续给药14 d,参考Jonassen方法制作心肌缺血/再灌注模型,记录再灌注30 min内发生的的心律失常,并对室性心律失常(VA)进行量化评分,监测再灌注30 min时左室收缩压(LVSP)、左室舒张末压(LVEDP)、左室内压力上升最大速率(LV+dp/dtmax)及左室压力下降最大速率(LV-dp/dtmax),检测各组大鼠血清乳酸脱氢酶(LDH)、肌酸磷酸激酶(CK)、超氧化物歧化酶(SOD)的活性与丙二醛(MDA)的含量。结果:与与假手术组比,模型组大鼠LVSP、+dp/dtmax、-dp/dtmax显著降低,VA和LVEDP明显升高,血清LDH、CK活性显著增强,SOD活性显著降低,MDA含量明显增加(P0.01);与模型组比,实验组及阳性对照组大鼠LVSP、+dp/dtmax、-dp/dtmax显著升高,VA和LVEDP明显降低,血清LDH、CK活性显著降低,SOD活性显著增强,MDA含量明显减少(P0.01);与阳性对照组比,实验组大鼠VA、LVSP、+dp/dtmax、LVEDP-dp/dtmax和血清LDH、CK、SOD活性与MDA含量无显著性差异(P0.05)。结论:富硒板党对大鼠心肌缺血/再灌注损伤具有明显的保护作用,其作用机制与抗氧化损伤有一定关系。     

大鼠肢体缺血/再灌注后的心肌损伤和NO的保护效应

目的:探讨大鼠肢体缺血/再灌注(LI/R)后心肌的损伤性变化及NO的保护效应。方法:制备LI/R动物模型,将Wistar大鼠随机分为4组(n=10):C(control)组、I/R组、L-Arg组和L-NAME组。用生物化学方法测定大鼠血浆CK、CK-MB及NO水平,测定心肌组织XOD、SOD、MDA含量。用BL-420生物机能实验系统监测大鼠MAP、LVSP、±dp/dtmax等。结果:LI/R后,血浆CK、CK-MB水平均明显升高(P<0.01);心肌组织SOD活性降低而MDA、XOD含量增加(P<0.01或P<0.05);MAP、LVSP、dp/dtmax、-dp/dtmax均降低(P<0.01或P<0.05);血浆NO水平在L-Arg组明显升高(P<0.01),在L-NAME组显著降低(P<0.05)。结论:大鼠LI/R可引起心肌损伤,机体的氧化应激状态可能是其发生机制之一;提高体内NO水平可在一定程度上减轻LI/R后心肌损伤的程度。     

脊髓苯环立啶受体的心血管效应与去甲肾上腺素能系统

本文应用受体阻断、高效液相,6-OHDA 化学损毁神经末梢和放射自显影等多学科技术方法,探讨脊髓苯环立啶受体的心血管效应与去甲肾上腺素能神经系统的关系。结果表明,哌唑嗪、育亨宾均可对抗 ith PCP 的降压和减慢心率作用,ith PCP 产生降压和减慢心率作用时,脊髓脑脊液内 MHPG 的含量升高;用6-OHDA 损毁脊髓 NA 能神经末梢后,ith PCP的降压和减慢心率作用大为减弱,脊髓 PCP 受体密度亦同时大为降低。可以认为,脊髓内有 PCP 受体分布于 NA 能神经末梢上,促进 NA 释放或抑制 NA 重摄取,可能是脊髓 PCP 受体产生心血管抑制效应的重要机理。     

实验性糖尿病心肌病大鼠模型建立及心脏功能和结构相关性分析

目的建立实验性糖尿病心肌病大鼠模型,观察心功能和结构变化,初步分析心脏功能和结构指标相关性。方法雄性Wistar大鼠随机分为正常对照组、高糖高脂膳食组和糖尿病心肌病模型组,采用高糖高脂膳食12周负荷一次性小剂量STZ腹腔注射建立糖尿病心肌病模型,观察各组动物心脏功能、心脏重量和心重指数、左心室形态和胶原含量等的变化。结果 (1)与正常对照组比较,糖尿病心肌病模型组大鼠左心室舒张末压(LVEDP)和最大舒张速率(-dp/dtmax)值显著升高(P0.05),心率(HR)、左心室收缩压(LVSP)、左心室最大收缩速率(+dp/dtmax)、每搏输出量(SV)和心排量(CO)明显降低(P0.05);全心重指数(HW/BW)和左心室重量指数(LVW/BW)明显升高(P0.01);常规HE染色显示心肌细胞排列紊乱,心肌细胞肥大,细胞核边缘不清等,室间隔和左心室壁厚度明显增加(P0.001,P0.05);心肌胶原含量明显增加(P0.05)。(2)大鼠心脏功能参数±dp/dtmax和CO值分别与结构参数HW/BW和LVW/BW呈现明显的相关性(P0.01或P0.05)。结论大鼠高糖高脂膳食喂养负荷小剂量STZ一次性腹腔注射,可造成心脏舒张和收缩功能紊乱以及心肌结构重塑,心脏功能与结构变化呈显著相关性,可复制实验性糖尿病心肌病模型。     

家兔第四脑室注射P物质对肺动脉压和颈动脉压的影响

本工作将P物质(SP)注入麻醉家兔第四脑室,观察其对肺动脉压和颈动脉压的影响。结果观察到:(1)脑室注射SP后,肺动脉压升高或降低,颈动脉压上升,心率减慢。(2)切断肺动脉压下降组家兔的两侧颈部迷走神经,再ivt.SP,则引起肺动脉压的升高,降心率反应则明显减弱。(3)预先用酚妥拉明或α_1受体阻断剂哌唑嗪均可阻断SP引起的肺动脉和颈动脉升压反应。(4)α_2受体阻断剂育亨宾或纳洛酮均可增强这二个升压反应。(5)心得安对这二个升压反应无明显影响。(6)SP的心血管效应可被SP受体拮抗剂[D-pro~2.D-Trp~(7.9)]-SP阻断。 实验结果表明:脑中SP升高可通过SP受体引起肺动脉压和颈动脉压上升,心率减慢;在SP引起的加压反应的中枢环节中有肾上腺素能α_1受体活动参与;中枢肾上腺素能α_2受体系统和内啡肽系统对传递SP中枢加压作用的路径有抑制性的调制作用。看来,SP与儿茶酚胺及阿片样物质一起参与脑干对血压的调节。     

侧脑室注射Orexin-1受体拮抗剂对大鼠心血管效应的影响

目的:用侧脑室微量注射和免疫组化方法研究食欲素-1受体(OX1R)拮抗剂SB408124对麻醉大鼠的心血管效应及其作用机制。方法:雄性SD大鼠,侧脑室微量注射SB408124,及甲硝阿托品、六甲溴铵静脉注射预处理后侧脑室注射SB408124,观测动脉血压(MAP)和心率(HR)的变化。然后,用免疫组化方法检测侧脑室注射SB408124对大鼠脑延髓头端腹外侧区(RVLM)内酪氨酸羟化酶(TH)阳性神经元的影响。结果:侧脑室注射SB408124可显著降低麻醉大鼠的MAP和HR,但是HR变化不如MAP变化明显。应用六甲溴铵可完全阻断SB408124的心血管效应,但甲硝阿托品不能阻断SB408124的心血管效应。侧脑室注射SB408124可使鼠脑延髓头端腹外侧区内酪氨酸羟化酶阳性神经元的数量显著降低。结论:侧脑室注射OX1R拮抗剂SB408124可显著降低麻醉大鼠的MAP和HR,其作用主要是通过抑制交感神经系统的活性而实现的。     

蓝斑复合核区内微量注射去甲肾上腺素对刺激兔下丘脑诱发室性期前收缩的影响

在72只乌拉坦、氯醛糖麻醉兔,静脉注射三碘季铵酚后,在人工呼吸下进行实验。结果观察到,在家兔蓝斑复合核(Lo-So)区微量注射去甲肾上腺素(NE)或可乐宁(Clonidine)能减少刺激下丘脑诱发的室性期前收缩(HVE)数。而微量注射β-肾上腺素能受体阻断剂心得安、α_1肾上腺素激动剂甲氧胺(Methoxamine)或苯肾上腺素(Phenylephrine)、α肾上腺素能阻断剂育亨宾(Yohimbine)或阿片受体阻断剂纳洛酮则对 HVE 无明显影响。在 Lo-So 区微量注射 NE 对 HVE 的抑制效应不能被事先在该区注射心得安所阻断但能被事先静脉或 Lo-So 区注射育亨宾所阻断。NE 或可乐宁的抑制效应也均可被育亨宾所翻转。可乐宁的抑制效应还可被纳洛酮所翻转。电解损毁延髓中缝大核区可消除在 Lo-So 区微量注射 NE 或可乐宁对HVE 的抑制效应。上述结果提示,Lo-So 区α_2受体的兴奋可减少 HVE 数,这些作用可能依赖于延髓中缝大核区的完整。可乐宁对 HVE 的抑制作用可能有阿片受体的参与。     

Role for dopamine in malonate-induced damage in vivo in striatum and in vitro in mesencephalic cultures

Defects in mitochondrial energy metabolism have been implicated in the pathology of several neurodegenerative disorders. In addition, the reactive metabolites generated from the metabolism and oxidation of the neurotransmitter dopamine (DA) are thought to contribute to the damage to neurons of the basal ganglia. We have previously demonstrated that infusions of the metabolic inhibitor malonate into the striata of mice or rats produce degeneration of DA nerve terminals. In the present studies, we demonstrate that an intrastriatal infusion of malonate induces a substantial increase in DA efflux in awake, behaving mice as measured by in vivo microdialysis. Furthermore, pretreatment of mice with tetrabenazine (TBZ) or the TBZ analogue Ro 4-1284 (Ro-4), compounds that reversibly inhibit the vesicular storage of DA, attenuates the malonate-induced DA efflux as well as the damage to DA nerve terminals. Consistent with these findings, the damage to both DA and GABA neurons in mesencephalic cultures by malonate exposure was attenuated by pretreatment with TBZ or Ro-4. Treatment with these compounds did not affect the formation of free radicals or the inhibition of oxidative phosphorylation resulting from malonate exposure alone. Our data suggest that DA plays an important role in the neurotoxicity produced by malonate. These findings provide direct evidence that inhibition of succinate dehydrogenase causes an increase in extracellular DA levels and indicate that bioenergetic defects may contribute to the pathogenesis of chronic neurodegenerative diseases through a mechanism involving DA.     

2018年中国植物科学若干领域重要研究进展

2018年中国植物科学继续呈现快速发展的态势, 我国科学家在国际植物科学主流学术刊物发表论文数量大幅增加, 取得了多项具有重要影响的成果。调控植物生长-代谢平衡实现可持续农业发展入选2018年度中国科学十大进展; 中国被子植物区系进化历史研究入选2018年度中国生命科学十大进展。以水稻为代表的农作物和果蔬等经济作物研究在国际上已呈现出明显的优势, 若干领域已从“追赶”状态跨越到“领跑”地位。该文对2018年中国科学家在植物科学若干领域取得的重要研究成果进行了概括性评述, 旨在全面追踪和报道当前中国植物科学领域的发展前沿和热点, 展示中国科学家所取得的杰出成就。     

SSTR5 ablation in islet results in alterations in glucose homeostasis in mice

Somatostatin (SST) peptide is a potent inhibitor of insulin secretion and its effect is mediated via somatostatin receptor 5 (SSTR5) in the endocrine pancreas. To investigate the consequences of gene ablation of SSTR5 in the mouse pancreas, we have generated a mouse model in which the SSTR5 gene was specifically knocked down in the pancreatic beta cells (betaSSTR5Kd) using the Cre-lox system. Immunohistochemistry analysis showed that SSTR5 gene expression was absent in beta cells at three months of age. At the time of gene ablation, betaSSTR5Kd mice demonstrated glucose intolerance with lack of insulin response and significantly reduced serum insulin levels. Insulin tolerance test demonstrated a significant increase of insulin clearance in vivo at the same age. In vitro studies demonstrated an absence of response to SST-28 stimulation in the betaSSTR5Kd mouse islet, which was associated with a significantly reduced SST expression level in betaSSTR5Kd mice pancreata. In addition, betaSSTR5Kd mice had significantly reduced serum glucose levels and increased serum insulin levels at 12 months of age. Glucose tolerance test at an older age also indicated a persistently higher insulin level in betaSSTR5Kd mice. Further studies of betaSSTR5Kd mice had revealed elevated serum C-peptide levels at both 3 and 12 months of age, suggesting that these mice are capable of producing and releasing insulin to the periphery. These results support the hypothesis that SSTR5 plays a pivotal role in the regulation of insulin secretion in the mouse pancreas.     

我国葫芦科植物离体培养研究进展

葫芦科植物包括多种瓜类蔬菜,对其进行离体培养研究具有重要的理论和实践意义。综述了国内在葫芦科植物器官培养、体细胞胚胎发生、花药培养、原生质体培养和体细胞杂交及离体遗传转化等方面取得的研究进展,并对葫芦科植物离体培养、遗传转化与育种的前景作了展望。     

2017年中国植物科学若干领域重要研究进展

2017年中国植物科学继续保持高速发展态势, 重大成果频出, 具体表现在中国植物学家在国际顶级学术期刊发表的文章数量平稳上升。中国植物科学领域的研究工作者成果精彩纷呈, 如新型广谱抗病机制的发现、水稻广谱抗病遗传基础及机制和疫霉菌诱发病害成灾机制研究等。2017年中国生命科学领域十大进展评选中, 有两项植物科学领域的研究成果入选。水稻生物学、进化与基因组学和激素生物学等领域学科发展突出。另外, 值得一提的是, 长期从事高等植物与代谢途径调控分子网络研究和水稻品种设计育种的李家洋院士的研究成果“水稻高产优质性状形成的分子机理及品种设计”荣获2017年国家自然科学一等奖。这一具有重大国际影响的开创性贡献标志着中国植物科学在该领域的国际科学前沿居于引领和卓越地位。该文对2017年中国本土科学家在植物科学若干领域取得的重要研究成果进行了系统梳理, 旨在全面追踪和报道当前中国植物科学领域发展的最新前沿动态, 与广大读者共同分享我国科学家所取得的辉煌成就。     

2018年中国植物科学若干领域重要研究进展

2018年中国植物科学继续呈现快速发展的态势, 我国科学家在国际植物科学主流学术刊物发表论文数量大幅增加, 取得了多项具有重要影响的成果。调控植物生长-代谢平衡实现可持续农业发展入选2018年度中国科学十大进展; 中国被子植物区系进化历史研究入选2018年度中国生命科学十大进展。以水稻为代表的农作物和果蔬等经济作物研究在国际上已呈现出明显的优势, 若干领域已从“追赶”状态跨越到“领跑”地位。该文对2018年中国科学家在植物科学若干领域取得的重要研究成果进行了概括性评述, 旨在全面追踪和报道当前中国植物科学领域的发展前沿和热点, 展示中国科学家所取得的杰出成就。     

我国葫芦科植物离体培养研究进展

葫芦科植物包括多种瓜类蔬菜,对其进行离体培养研究具有重要的理论和实践意义.综述了国内在葫芦科植物器官培养、体细胞胚胎发生、花药培养、原生质体培养和体细胞杂交及离体遗传转化等方面取得的研究进展,并对葫芦科植物离体培养、遗传转化与育种的前景作了展望.     

Changes in aquatic vegetation in Rhine floodplain streams in Alsace in relation to disturbance

Abstract. Changes are described in aquatic vegetation in oligotrophic, groundwater-fed Rhine floodplain streams in Alsace (eastern France), resulting from disturbance. Disturbance factors include changes in nutrients, either permanent ones - effluent from a waste water treatment plant or trout hatcheries - or periodic ones: flooding. Regular inputs of high levels of phosphate and ammonia modified the macrophyte vegetation in these streams. The floristic composition, which was characteristic of oligotrophic waters upstream of the eutrophicated sector, changed to that of a eutrophic situation as originally found downstream. Periodic disturbance by floods which normally occur once a year, irregularly eutrophicates the small streams, causing the development of a mixture of eutrophic and oligotrophic species. Six macrophyte communities are distinguished, indicating different trophic levels. The aquatic vegetation is adapted to the variations of phosphate and ammonia levels. Hence, aquatic macrophytes can be used as bio-indicators of fluctuations in water nutrient levels in relation to the type of disturbance.     

Apoptosis in experimental myocardial infarction in situ and in the perfused heart in vitro

We report the appearance of apoptotic cells in experimental myocardial infarction (rabbit heart) in in situ and in vitro preparations. Apoptosis was recognized by intravital staining with Hoechst 33342 (Ho342), by nick-end labeling (TUNEL) and by DNA laddering. A steady rise in the relative number of apoptotic cardiomyocytes (apoptotic index) was noted in in situ preparations. Apoptosis was first noted 6 h after the onset of ischemia with its highest value occurring after 72 h. Apoptotic nuclei were absent in remote areas of the left and right ventricles. Apoptotic nuclei within the infarcted area showed diminished intensity of Ho342 fluorescence. Three days after ischemia, a border zone adjacent to the infarcted area consisting of apoptotic macrophages was recognized. A novel finding was the appearance of apoptotic cardiomyocytes in the isolated perfused ischemic heart. Occurring as early as 50 min after the onset of ischemia, a high apoptotic index was present adjacent to the ligature placed around the coronary artery. This observation provides the opportunity to selectively examine factors leading to apoptosis in the ischemic heart under controlled experimental conditions.     

Morphine-potentiated platelet aggregation in in vitro and platelet plug formation in in vivo experiments

The detailed mechanisms underlying morphine-signaling pathways in platelets remain obscure. Therefore, we systematically examined the influence of morphine on washed human platelets. In this study, washed human platelet suspensions were used for in vitro studies. Furthermore, platelet thrombus formation induced by irradiation of mesenteric venules with filtered light in mice pretreated with fluorescein sodium was used for an in vivo thrombotic study. Morphine concentration dependently (0.6, 1, and 5 microM) potentiated platelet aggregation and the ATP release reaction stimulated by agonists (i.e., collagen and U46619) in washed human platelets. Yohimbine (0.1 microM), a specific alpha(2)-adrenoceptor antagonist, markedly abolished the potentiation of morphine in platelet aggregation stimulated by agonists. Morphine also potentiated phosphoinositide breakdown and intracellular Ca(2+) mobilization in human platelets stimulated by collagen (1 microg/ml). Moreover, morphine (0.6-5 microM) markedly inhibited prostaglandin E(1) (10 microM)-induced cyclic AMP formation in human platelets, while yohimbine (0.1 microM) significantly reversed the inhibition of cyclic AMP by morphine (0.6 and 1 microM) in this study. The thrombin-evoked increase in pH(i) was markedly potentiated in the presence of morphine (1 and 5 microM). Morphine (2 and 5 mg/g) significantly shortened the time require to induce platelet plug formation in mesenteric venules. We concluded that morphine may exert its potentiation in platelet aggregation by binding to alpha(2)-adrenoceptors in human platelets, with a resulting inhibition of adenylate cyclase, thereby reducing intracellular cyclic AMP formation followed by increased activation of phospholipase C and the Na(+)/H(+) exchanger. This leads to increased intracellular Ca(2+) mobilization, and finally potentiation of platelet aggregation and of the ATP release reaction.