蝗虫微孢子虫Nosema locustae对红胫戟纹蝗Dociostaurus kraussi kraussi致病性及呼吸代谢的影响

【目的】研究蝗虫微孢子虫Nosema locustae对红胫戟纹蝗Dociostaurus kraussi kraussi致病性及呼吸代谢的影响,为筛选蝗虫微孢子虫适宜的新疆本地的活体增殖寄主提供实验依据。【方法】采用逐头口服法感染红胫戟纹蝗,以镜检法检测蝗虫感染情况,并用呼吸仪测量试虫的呼吸代谢。【结果】在6.5×105个孢子/头的感染剂量下,红胫戟纹蝗的感染率和死亡率分别为41.70%和72.22%。蝗虫微孢子虫的感染剂量与其毒力高度相关(r2=0.961),LD50为1.7088×104个孢子/头;随孢子浓度增加和感染时间延长,试虫的CO2释放率显著降低(P<0.05),但耗氧率没有显著变化。【结论】红胫戟纹蝗被微孢子虫感染后表现出典型症状,高剂量组感染下死亡率达到70%以上,由此推断红胫戟纹蝗可作为微孢子虫在新疆本地的潜在增殖寄主。     

昆虫病原微生物及其在蝗灾治理中的应用

本文重点介绍了蝗虫痘病毒、蝗虫微孢子虫、蝗噬虫霉、绿僵菌、白僵菌、米曲霉等的生物学特性、侵染机制、流行病学和应用潜力。蝗虫痘病毒和蝗噬虫霉分别由于生产成本过高和分生孢子在离体条件下存活时间过短而难以开发应用;蝗虫微孢子虫和绿僵菌已广泛应用到蝗灾治理中,有关绿僵菌致病机理的研究最深入全面;白僵菌也已成功应用到蝗灾治理中;介绍了一种新病原——米曲霉对飞蝗的毒力以及产孢量和耐热性等生物学特性。最后,提出蝗虫新病原微生物资源的开发、提高生产工艺水平、研发新的制剂和延长储存时间等是今后蝗虫微生物农药的发展方向。     

莱氏绿僵菌FJMR2对草地贪夜蛾不同虫态的致病性研究

【目的】为明确莱氏绿僵菌Metarhizium rileyi FJMR2对草地贪夜蛾Spodoptera frugiperda的生物防治潜力。【方法】在室内条件下,采用浸渍法测定了莱氏绿僵菌FJMR2对草地贪夜蛾卵、幼虫和蛹的致病性。【结果】当孢子浓度为2×10⁸孢子/m L时,草地贪夜蛾1-5龄幼虫和蛹的校正死亡率分别为100%、95.78%、87.15%、64.67%、38.00%和93.93%;草地贪夜蛾1-5龄幼虫和蛹的LC_(50)分别为3.12×108孢子/m L时,草地贪夜蛾1-5龄幼虫和蛹的校正死亡率分别为100%、95.78%、87.15%、64.67%、38.00%和93.93%;草地贪夜蛾1-5龄幼虫和蛹的LC_(50)分别为3.12×10⁴、7.94×104、7.94×10⁴、2.24×104、2.24×10⁶、2.13×106、2.13×10⁷、7.46×107、7.46×10⁸和1.25×108和1.25×10⁵孢子/m L。LT_(50)随孢子浓度的增大而缩短、随幼虫虫龄的增长而延长,当孢子浓度为2×105孢子/m L。LT_(50)随孢子浓度的增大而缩短、随幼虫虫龄的增长而延长,当孢子浓度为2×10⁸孢子/m L时,草地贪夜蛾1-5龄幼虫和蛹的LT_(50)分别为3.93、4.32、5.62、7.18、9.40和4.45 d。卵期为0 h和24 h的草地贪夜蛾卵经莱氏绿僵菌FJMR2浸渍处理后,孵化率分别为84.53%和89.77%,初孵化3 d的幼虫存活率分别为1.81%和3.02%,均显著低于对照组。【结论】莱氏绿僵菌FJMR2对草地贪夜蛾1-4龄幼虫和蛹具有较强侵染致病能力,同时显著降低卵的孵化率和初孵幼虫存活率。     

绿僵菌MaFZ-13对橙带蓝尺蛾幼虫致病力及林间防治效果

【目的】橙带蓝尺蛾Milionia basalis近年来在我国南方地区严重危害罗汉松Podocarpusmacrophyllus和竹柏Podocarpus nagi,扩散蔓延速度快,造成了很大的损失。本研究旨在评估金龟子绿僵菌Metarhizium anisopliae MaFZ-13菌株对橙带蓝尺蛾幼虫的致病力,探寻橙带蓝尺蛾生物防治新资源。【方法】通过绿僵菌MaFZ-13不同浓度(1.0×10⁵~1.0×10⁹孢子/mL)孢子悬浮液接种橙带蓝尺蛾幼虫,运用时间-剂量-死亡率(TDM)模型对生物测定结果进行分析,同时通过林间喷施1.0×10⁸孢子/mL绿僵菌孢子悬浮液进行林间防治效果试验。【结果】橙带蓝尺蛾幼虫累计死亡率随着绿僵菌MaFZ-13孢子悬浮液孢子浓度的增加和接种时间的延长而增大。接种1.0×10⁹孢子/mL孢子悬浮液8 d后以及接种1.0×10⁸孢子/mL孢子悬浮液10 d后,幼虫死亡率均达到100%;接种1.0×10⁷孢子/mL孢子悬浮液15 d后幼虫死亡率为95.6%。应用TDM模型对生测数据进行分析,结果表明所建模型通过Hosmer-Lemeshow拟合异质性检验,并由模型估算出了该菌株对橙带蓝尺蛾幼虫的致死剂量和致死时间。绿僵菌MaFZ-13菌株接种4, 5, 6和7 d后的半致死剂量(LC₅₀)对数估计值分别为7.99, 7.12, 6.46和5.83。以1.0×10⁷, 1.0×10⁸和1.0×10⁹孢子/mL的孢子浓度接种时,绿僵菌MaFZ-13菌株对橙带蓝尺蛾幼虫的LT₅₀值分别为5.19,3.99和2.81 d。林间用1.0×10⁸孢子/mL绿僵菌孢子悬浮液喷洒9 d后橙带蓝尺蛾幼虫死亡率可达到85.8%,防治效果为85.05%。【结论】绿僵菌MaFZ-13对橙带蓝尺蛾幼虫具有较强的致病力,林间防治效果良好,具有较好的应用潜力。     

不同寄主及地理来源的16株绿僵菌对桃蚜的毒力比较

害虫生防真菌绿僵菌的不同种及变种被广泛应用于害虫微生物防治,但罕见以蚜虫等同翅目刺吸式害虫作为靶标。从两种绿僵菌的4个变种中精选16个不同寄主及地理来源的菌株,用喷塔接种桃蚜(Myzus persicae)无翅成蚜并在25±1℃和12L∶12D条件下饲养观察,所获生物测定数据进行时间-剂量-死亡率模型模拟分析。结果显示,高接种剂量(~1000个孢子/mm2)下7d内死亡率达67%~100%的10个菌株均为金龟子绿僵菌Metarhiziumanisopliae(Ma)及其金龟子变种M.anisopliaevar.anisopliae(Maa);而高剂量处理下仅感染致死个别或少数蚜虫的菌株包括金龟子绿僵菌及其金龟子变种、大孢变种M.anisopliaevar.majus和蝗变种M.anisopliaevar.acridum以及黄绿绿僵菌小孢变种M.flavoviridevar.minus。杀蚜活性优异的2个菌株分别为Ma 456和Maa 3332,接种后第4天的LC50分别为113和260个孢子/mm2,第5天为32和43个孢子/mm2,第6天为17和26个孢子/mm2,第7天仅11.4和19.9个孢子/mm2。这两个菌株具有用于蚜虫微生物防治的良好开发潜力。     

蝗虫微孢子虫病在草原蝗虫优势种种群及空间的分布

在采用蝗虫微孢子虫Nosema locustae防治过的草场中进行抽样调查,研究了草原蝗虫优势种类、混合种群平均密度与蝗虫微孢子虫疾病分布之关系,以及该疾病的空间分布。在防治后的当年,蝗虫微孢子虫疾病的感染率随着混合种群平均密度及靶标蝗虫亚洲小车蝗Oedaleus asiaticus的感病率的下降而降低。但是,次靶标蝗虫如宽须蚁蝗Myrmeleotettixpalpalis(一种中后期发生的种类)其感病率呈上升趋势,表明该疾病可在不同发生期种类蝗虫之间进行有效地传播。病蝗虫在防治后第7d其空间分布呈随机分布(Poisson),第28d 则是聚集分布,第40d时也呈聚集分布。于1993年、1994年对1988年(样区Ⅱ)、1989 年(样区Ⅲ)采用微孢子虫防治过的草场进行抽样调查。结果表明,在二个样区中,二年混合种群平均虫口密度与混合种群的平均感病率呈正相关(相关系数分别为r=0.289, r=0.479)。蝗虫微孢子虫病在主要优势种,如亚洲小车蝗、宽须蚁蝗、白边痂蝗Bryode maluctuosumluctuosum、皱膝蝗Angaracris /I>spp.、毛足棒角蝗Dasyhippus barbipes均有分布。二个样区中的混合蝗虫种群的平均感病率在1994年显著低于1993年。混合蝗虫种群的种类组成也有所变化,与1993年相比,1994年宽须蚁蝗及白边痂蝗的比例上升较大,而亚洲小车蝗的比例下降。经过5—7年的扩散,蝗虫微孢子虫病至少可扩散距防治区1 000m,其扩散方向可能与风及地势等有关。     

绿僵菌及其与dsRNA混合使用对褐飞虱的防治效果

褐飞虱Nilaparvata lugens Stl是我国重要的迁飞性水稻害虫,本文研究了金龟子绿僵菌Metarhizium anisopliae及其与dsRNA混合使用对褐飞虱的防治效果。绿僵菌悬浮液1.6×108孢子/m L至8×106孢子/m L对褐飞虱2龄、4龄和成虫进行喷药,发现1.6×107孢子/m L对各个虫态虫龄均有良好致死效果,并且成虫和4龄若虫均好于2龄若虫。在交配行为上来看,绿僵菌处理过的褐飞虱成虫活跃度非常低,从配对开始一直到交配结束的各个阶段都受到明显影响,处理组3 h的交配率只有3.70%,而对照组的交配率为24.44%。还把褐飞虱几丁质合成酶基因A的dsRNA与绿僵菌混合使用防治褐飞虱2龄和4龄若虫,结果表明0.5μg/μL ds CHSA与绿僵菌混合使用的防治效果最好,2龄若虫的死亡率为89.63%,4龄若虫的死亡率达到93.94%。而0.2μg/μL ds CHSA与绿僵菌的混合,对2龄和4龄若虫的致死率为65.56%-76.52%。研究结果为褐飞虱的生物防治提供了新的思路。     

黄绿绿僵菌Mf82悬乳剂对褐飞虱作用的时间-剂量-死亡率模型分析

为了寻找褐飞虱Nilaparvata lugens生物防治的新途径,用新分离出的黄绿绿僵菌Metarhiziumflavoviride(Mf82)菌株与实验室保存的黄绿绿僵菌、金龟子绿僵菌和球孢白僵菌3种菌种9个菌株作对比,测定了它们对褐飞虱成虫的毒力。结果表明:Mf82菌株对褐飞虱成虫的毒力最高,以1.0×108个孢子/mL的孢子液喷雾接种到褐飞虱成虫体表上,累积死亡率高达81.7%,LT50为4.6d,致病效果显著高于其他受测菌株。在此基础上研制了黄绿绿僵菌悬乳剂,并研究了其对褐飞虱的致病力。结果表明:随着黄绿绿僵菌浓度的增加,褐飞虱的累计死亡率增加,在浓度为1,048个孢子/mm2时,累计死亡率达到85.0%。利用时间-剂量-死亡率模型对数据进行处理,所建模型均顺利通过Hosmer-Lemeshow拟合异质性检验,表明模型拟合良好,并由模型估计出了该剂型对褐飞虱的致死剂量与致死时间。在接种后第7天和第9天,LC50值分别为2.1×103、9.9×102个孢子/mm2,LC90分别为7.8×104、3.7×104个孢子/mm2。黄绿绿僵菌悬乳剂对褐飞虱的致死时间与对数剂量相关,供试菌剂LT50值随着对数剂量的增加而递减,对数剂量由7.0增加到8.0时,LT50由8.9d降为5.7d。可见该黄绿绿僵菌悬乳剂对褐飞虱具有较强的毒力,在褐飞虱生物防治中具有广阔的应用前景。     

金龟子绿僵菌及其粗毒素对樟巢螟幼虫的致病性

【目的】为了筛选感染樟巢螟Orthaga achatina幼虫的高致病力金龟子绿僵菌Metarhizium anisopliae菌株,并研究绿僵菌粗毒素对幼虫的毒力和取食粗毒素后幼虫的血淋巴细胞免疫反应。【方法】以死亡率 时间几率值法和TDM模型分析绿僵菌及其粗毒素对樟巢螟幼虫的致病力,并显微观察处理幼虫的血淋巴细胞的变化。【结果】绿僵菌菌株Ma1291-2对樟巢螟幼虫有较强的致病力,以浓度(1.0±0.5)×108个孢子/mL的孢子悬液接菌11 d后,幼虫的校正死亡率和僵虫率分别为99.8%±2.6%和86.9%±1.3%,LT₅₀为6.29 d。各菌株产粗毒素水平与其对幼虫的校正死亡率和LT₅₀呈显著相关。通过时间-剂量-死亡率模型参数估算,Ma1291-2菌株及其粗毒素对幼虫致死效应较强的时间段分别为接菌后6-7 d和3-4.5 d。幼虫取食绿僵菌粗毒素后2 d,总血细胞、浆血细胞、珠血细胞和类绛血细胞浓度上升到最高值,而后下降;粒血细胞浓度2 d后开始极显著上升,第3天达到最高值后急速下降;原血细胞前3 d未发现有明显的数量变化,第4天显著下降。幼虫取食粗毒素3~4 d后,浆血细胞和粒血细胞有破裂,珠血细胞和类绛血细胞有黑化现象,原血细胞病态变化不明显。【结论】樟巢螟幼虫取食绿僵菌粗毒素后2-3 d,幼虫血淋巴细胞对粗毒素的免疫反应最强烈,且粗毒素对血细胞有毒害和破坏作用。本研究为该害虫的生物防治提供了一定的理论与应用基础。     

草地贪夜蛾高致病力绿僵菌菌株的筛选与鉴定

为获取对草地贪夜蛾Spodoptera frugiperda具有高致病力的生防真菌,从福建省不同地区分离得到8株寄主为鳞翅目和半翅目幼虫僵虫的绿僵菌Metarhizium,采用浸渍法测定了其对草地贪夜蛾2龄幼虫和蛹的致病力,并根据形态学和分子生物学方法对高致病力菌株进行种类鉴定。结果表明,8株绿僵菌菌株对草地贪夜蛾2龄幼虫和蛹均表现出不同程度的致病力,其中菌株FJMR2和FJXY7表现出较强的致病力。在5×107个/mL孢子浓度下,FJMR2和FJXY7对草地贪夜蛾2龄幼虫的致死率分别为88.76%和82.13%,对蛹的致死率分别为86.57%和84.00%;对草地贪夜蛾2龄幼虫的LT50分别为4.81 d和4.93 d,对蛹的LT50分别为4.94 d和4.83 d。经鉴定菌株FJMR2和FJXY7均为莱氏绿僵菌Metarhizium rileyi。本研究获得2株对草地贪夜蛾2龄幼虫和蛹具有高致病力的莱氏绿僵菌菌株,在草地贪夜蛾的生物防治中具有较大应用潜力。     

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。     

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。     

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.     

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.