Time course of transgene expression after intrastriatal pseudotyped rAAV2/1, rAAV2/2, rAAV2/5, and rAAV2/8 transduction in the rat.

In vivo recombinant adeno-associated viral vector (rAAV)-mediated transduction of various tissues including brain has been characterized by slow onset and gradual increase in gene expression before reaching stable long-term protein levels. The early time course of transgene expression has not been quantified using newly available rAAV capsid serotypes. In this experiment, the onset of expression of green fluorescent protein (GFP) after intrastriatal injection of rAAV2-based pseudotyped vectors (rAAV1, rAAV5, and rAAV8 capsids) was quantified. Native GFP fluorescence displayed a delayed onset of expression of at least 7 days for all the pseudotyped rAAV vectors. However, GFP immunohistochemical staining revealed significant transgene expression by 4 days after transduction for all serotypes and stable GFP(+) neuronal populations mediated by all serotypes within 14 days post transduction at the latest. rAAV2/1 and rAAV2/2 displayed no time-dependent increase of GFP(+) striatal neurons; reaching maximal striatal cell GFP(+) counts at 4 days after injection. All serotypes displayed peak transgene expression by 4 weeks post injection where native GFP(+) neurons were equal to immunostained striatal GFP(+) neurons. The inflammatory response to these rAAV vectors was present up to 4 weeks after transduction but was not apparent 9 months post injection. Thus, rAAV-mediated transgene expression begins earlier than previously thought.     

Efficient Gene Transfer Into the Mouse Lung by Fetal Intratracheal Injection of rAAV2/6.2

Fetal gene therapy is one of the possible new therapeutic strategies for congenital or perinatal diseases with high mortality or morbidity. We developed a novel delivery strategy to inject directly into the fetal mouse trachea. Intratracheal (i.t.) injection at embryonic day 18 (E18) was more efficient in targeting the fetal lung than conventional intra-amniotic (i.a.) delivery. Viral vectors derived from adeno-associated virus serotype 6.2, with tropism for the airway epithelium and not earlier tested in the fetal mouse lung, were injected into the fetal trachea. Bioluminescence (BL) imaging (BLI) was combined with magnetic resonance (MR) imaging (MRI) for noninvasive and accurate localization of transgene expression in vivo. Histological analysis for β-galactosidase (β-gal) revealed 17.5% of epithelial cells transduced in the conducting airways and 1.5% in the alveolar cells. Stable gene expression was observed up to 1 month after injection. This study demonstrates that direct injection of rAAV2/6.2 in the fetal mouse trachea is superior to i.a. delivery for transducing the lung. Second, as stable gene transfer was detected up to 1 postnatal month, this approach may be useful to evaluate fetal gene therapy for pulmonary diseases such as cystic fibrosis, requiring both substantial numbers of transduced cells as well as prolonged gene expression to obtain a stable phenotypic effect.     

重组α-突触核蛋白对 SD大鼠黑质多巴胺能神经元的作用

目的 研究重组人全长α-突触核蛋白对大鼠黑质多巴胺能神经元的毒性作用. 方法 原核表达、鉴定α-突触核蛋白;雄性 SD大鼠 30只,随机分为α-突触核蛋白注射组、六羟多巴注射组及α-突触核蛋白和六羟多巴联合注射组.用立体定位的方法分别右侧黑质注射α-突触核蛋白,六羟多巴及α-突触核蛋白+六羟多巴,左侧黑质注射等量的生理盐水,测定大鼠纹状体多巴胺含量和黑质酪氨酸羟化酶阳性神经元数目. 结果 六羟多巴和α-突触核蛋白+六羟多巴注射使注射侧多巴胺分别减少到对照侧的 36.98%和 21.79%,多巴胺能神经元数减少到 30.81%和 28.05%.而α-突触核蛋白注射对纹状体多巴胺和黑质多巴胺能神经元数目无显著影响. 结论 没有发现重组α-突触核蛋白对大鼠黑质多巴胺能神经元有明显的毒性作用.     

颞叶癫痫模型中黑质多巴胺能神经元变化的实验研究

目的:建立颞叶癫痫模型,探讨颞叶癫痫模型中黑质多巴胺能神经元的改变。方法:实验于2004-05/09在解放军第一军医大学珠江医院进行。取SD大鼠43只,设空白对照组,生理盐水组,红藻氨酸组。生理盐水组及红藻氨酸组大鼠于右侧侧脑室分别注射生理盐水(2mL)和红藻氨酸(5μg),于给药后第0.5,2.0,12.0,24.0和72.0h处死;取黑质部切片作免疫组织化学检测,根据记录阳性细胞数作半定量检测。结果:对照组及生理盐水组无癫痫发作。红藻氨酸组大鼠均出现癫痫发作,发作于脑室注射红藻氨酸后10min开始,1h达高峰,3～6h后停止。癫痫发作后0.5h开始伴随有黑质多巴胺能神经元阳性细胞数犤(80.00±9.15)个犦减少,与生理盐水组犤(119.02±12.02)个犦相比其差异有显著性意义(t=4.931,P=0.003),2～6h持续下降,3d后细胞数接近正常,与生理盐水组相比其差值没有统计学意义(P>0.05)。结论:一侧侧脑室注入红藻氨酸,可成功建立癫痫模型。红藻氨酸致痫后伴有黑质多巴胺阳性细胞数的改变,提示黑质多巴胺能神经元可能在颞叶癫痫活动中参与了调节作用。     

大鼠黑质多巴胺能神经元衰老性变化的多项参数测量

目的:探讨大鼠中脑黑质多巴胺能神经元的衰老性变化规律,为进一步揭示黑质病变的病因提供客观依据。方法:实验于2005-07/2006-07在贵阳医学院解剖学教研室完成。选择健康SD大鼠32只,雌雄各半,按随机数字表法分为幼年组(1～2个月龄)、青年组(4～5个月龄)、中年组(11～12个月龄)、老年组(≥24个月龄)4组,每组8只。取中脑组织常规石蜡包埋,行中脑黑质连续冠状切片,焦油紫染色、酪氨酸羟化酶免疫组织化学染色,图像分析仪测量酪氨酸羟化酶免疫阳性产物的吸光度值和酪氨酸羟化酶免疫反应阳性神经元的胞面积、体密度、数密度、圆球度。结果:32只大鼠均进入结果分析。①中脑黑质焦油紫染色形态学观察:幼年组与青年组大鼠黑质神经元胞体大,细胞排列密集,形状规则,细胞成椭圆形或锥体形,胞浆丰富,每个细胞有清晰的胞核,核仁清楚可见,尼氏体粗大而染色深,中年组和老年组大鼠神经元胞浆染色较淡,尼氏体较分散,细胞散在,数量少,可见软化灶形成。幼年组、青年组、中年组、老年组计数单位面积焦油紫染色细胞数分别为(48.00±9.10),(65.00±8.73),(20.00±4.10),(13.25±1.83)个/40倍视野,各组间比较差异有显著性意义(F=3.79,P<0.05)。②中脑黑质酪氨酸羟化酶免疫反应阳性神经元:光镜下,酪氨酸羟化酶免疫反应阳性神经元成群分布,胞浆内阳性产物以幼年组和青年组为显著,中年组和老年组胞浆内酪氨酸羟化酶阳性反应颗粒明显减少,部分神经元丧失大多角形或锥体形形状,胞体变大,排列不规则,数量减少。幼年组、青年组、中年组、老年组胞浆内酪氨酸羟化酶免疫反应阳性产物吸光度值分别为0.1993±0.0711,0.2428±0.1729,0.1978±0.0687,0.1671±0.1018,各组间比较差异有显著性意义(F=1.87,P<0.05)。中年组、老年组酪氨酸羟化酶免疫反应阳性神经元体密度、数密度低于青年组,差异有显著性意义[体密度分别为(2.57±0.02),(2.36±0.01),(3.22±0.01)×10-2μm-3,t=0.66,1.78,P<0.05;数密度分别为(0.91±0.04),(0.59±0.03),(1.20±0.09)×10-5μm-3,t=7.02,2.25,P<0.05]。幼年组平均截面积低于青年组,差异有显著性意义[分别为(27.30±5.56),(30.40±1.08)×101μm2,t=1.47,P<0.05]。幼年组、中年组、老年组平均体积低于青年组,差异有显著性意义[分别为(9.67±0.40),(5.85±0.42),(5.20±0.33),(11.53±0.90)×102μm3,t=1.60,2.93,0.18,P<0.05]。老年组神经元圆球度低于幼年组、青年组、中年组,差异有显著性意义(分别为0.74±0.18,0.91±0.01,0.92±0.05,0.90±0.03,t=0.68,0.99,1.02,P<0.05,0.001)。结论:黑质多巴胺能神经元随年龄增长而出现衰老性变化,可能是黑质病变的原因之一。     

The influence of epileptic neuropathology and prior peripheral immunity on CNS transduction by rAAV2 and rAAV5

Adeno-associated virus (AAV) provides a promising platform for clinical treatment of neurological disorders owing to its established efficacy and lack of apparent pathogenicity. To use viral vectors in treating neurological disease, however, transduction must occur under neuropathological conditions. Previous studies in rodents have shown that AAV5 more efficiently transduces cells in the hippocampus and piriform cortex than AAV2. Using the kainic acid (KA) model of temporal lobe epilepsy and AAV2 and 5 carrying a hybrid chicken β-actin promoter driving green fluorescent protein (GFP), we found that limbic seizure activity caused substantial neuropathology and resulted in a significant reduction in subsequent AAV5 transduction. Nonetheless, this reduced transduction still was greater than AAV2 transduction in control rats. Although KA seizures compromise blood-brain barrier function, potentially increasing exposure of target tissue to circulating neutralizing antibodies, we observed no interaction between KA seizure-induced damage and immunization status on AAV transduction. Finally, while we confirmed the near total neuronal-specific transgene expression for both serotypes in control rats, AAV5-GFP expression was increasingly localized to astrocytes in seizure-damaged areas. Thus, the pathological milieu of the injured brain can reduce transduction efficacy and alter viral tropism- both relevant concerns when considering viral vector gene therapy for neurological disorders.     

癌痛规范化治疗示范病房护理管理探索

【摘要】目的：通过对肿瘤病房的无痛化管理有效控制肿瘤患者疼痛,提高生活质量。 方法：对所有入院的肿瘤病人进行疼痛评估,根据评分结果采取相应护理和医疗措施,做好出院病人的随访工作。 结论：开展对肿瘤病房的无痛化管理能够及时发现,控制,处理疼痛。提高病人生活质量,增强治疗效果,使医务人员的治疗处于主动地位。     

Muscarine depolarizes rat substantia nigra zona compacta and ventral tegmental neurons in vitro through M1-like receptors

Intracellular recordings were made from presumed dopamine-containing neurons in slices of rat mesencephalon. Muscarine (3-100 microM) increased the rate of spontaneous action potentials; it also caused a membrane depolarization and, in voltage-clamp, an inward current. Concentration-effect curves to muscarine were shifted rightwards by pirenzepine (0.03-1 microM) with an estimated KD of 14 nM. The inward current caused by muscarine was voltage-dependent. Between about -50 and (-)-65 mV it was associated with a decrease in membrane conductance, but between -70 and -110 mV it was unaccompanied by any change in membrane conductance. Muscarine was without effect on the action potential afterhyperpolarization, or on a slowly developing inward current evoked by step hyperpolarizations of up to 20 mV from -45 mV. Muscarinic depolarizations or inward currents were reduced reversibly or abolished by a low calcium (0.25 mM)/high magnesium (10 mM) solution. It is concluded that muscarinic excitation of dopaminergic neurons is mediated by M1-like receptors.     

Improvement of cardiac fibrosis in dystrophic mice by rAAV9-mediated microdystrophin transduction

Duchenne muscular dystrophy (DMD) is the most common form of the progressive muscular dystrophies characterized by defects of the dystrophin gene. Although primarily characterized by degeneration of the limb muscles, cardiomyopathy is a major cause of death. Therefore, the development of curative modalities such as gene therapy is imperative. We evaluated the cardiomyopathic features of mdx mice to observe improvements in response to intravenous administration of recombinant adeno-associated virus (AAV) type 9 encoding microdystrophin. The myocardium was extensively transduced with microdystrophin to significantly prevent the development of fibrosis, and expression persisted for the duration of the study. Intraventricular conduction patterns, such as the QRS complex duration and S/R ratio in electrocardiography, were also corrected, indicating that the transduced microdystrophin has a protective effect on the dystrophin-deficient myocardium. Furthermore, BNP and ANP levels were reduced to normal, suggesting the absence of cardiac dysfunction. In aged mice, prevention of ectopic beats as well as echocardiographic amelioration was also demonstrated with improved exercise performance. These findings indicate that AAV-mediated cardiac transduction with microdystrophin might be a promising therapeutic strategy for the treatment of dystrophin-deficient cardiomyopathy.     

Memantine inhibits ATP-dependent K+ conductances in dopamine neurons of the rat substantia nigra pars compacta

1-Amino-3,5-dimethyl-adamantane (memantine) is a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist used in clinical practice to treat neurodegenerative disorders that could be associated with excitotoxic cell death. Because memantine reduces the loss of dopamine neurons of the substantia nigra pars compacta (SNc) in animal models of Parkinson's disease, we examined the effects of this drug on dopamine cells of the SNc. Besides inhibition of NMDA receptor-mediated currents, memantine (30 and 100 microM) increased the spontaneous firing rate of whole-cell recorded dopamine neurons in a midbrain slice preparation. Occasionally, a bursting activity was observed. These effects were independent from the block of NMDA receptors and were prevented in neurons dialyzed with a high concentration of ATP (10 mM). An increase in firing rate was also induced by the ATP-sensitive potassium (K(ATP)) channel antagonist tolbutamide (300 microM), and this increase occluded further effects of memantine. In addition, K(ATP) channel-mediated outward currents, induced by hypoxia, were inhibited by memantine (30 and 100 microM) in the presence of the NMDA receptor antagonist (5S, 10R)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate (MK-801) (10 microM). An increase in the spontaneous firing rate by memantine was observed in dopamine neurons recorded with extracellular planar 8 x 8 multielectrodes in conditions of hypoglycemia. These results highlight K(ATP) channels as possible relevant targets of memantine effects in the brain. Moreover, in view of a proposed role of K(ATP) conductances in dopamine neuron degeneration, they suggest another mechanism of action underlying the protective role of memantine in Parkinson's disease.     

Systemic infusion of naloxone reduces degeneration of rat substantia nigral dopaminergic neurons induced by intranigral injection of lipopolysaccharide

A massive degeneration of dopamine-containing neurons in the substantia nigra (SN) in the midbrain is characteristic of Parkinson's disease. Inflammation in the brain has long been speculated to play a role in the pathogenesis of this neurological disorder. Recently, we reported that treatment of primary rat mesencephalic mixed neuron-glia cultures with lipopolysaccharide (LPS) led to the activation of microglia, resident immune cells of the brain, and subsequent death of dopaminergic neurons. The LPS-induced degeneration of dopaminergic neurons was significantly attenuated by the opiate receptor antagonist (-)-naloxone and its inactive isomer (+)-naloxone, with equal potency, through an inhibition of microglial activation and their production of neurotoxic factors. In this study, injection of LPS into the rat SN led to the activation of microglia and degeneration of dopaminergic neurons: microglial activation was observed as early as 6 h and loss of dopaminergic neurons was detected 3 days after the LPS injection. Furthermore, the LPS-induced loss of dopaminergic neurons in the SN was time- and LPS concentration-dependent. Systemic infusion of either (-)-naloxone or (+)-naloxone inhibited the LPS-induced activation of microglia and significantly reduced the LPS-induced loss of dopaminergic neurons in the SN. These in vivo results combined with our cell culture observations confirmed that naloxone protects dopaminergic neurons against inflammation-mediated degeneration through inhibition of microglial activation and suggest that naloxone would have therapeutic efficacy in the treatment of inflammation-related neurological disorders. In addition, the inflammation-mediated degeneration of dopaminergic neurons in the rat SN resulting from the targeted injection of LPS may serve as a useful model to gain further insights into the pathogenesis of Parkinson's disease.     

磁刺激对帕金森病鼠黑质多巴胺能神经元的保护及其机制

目的探讨重复经颅磁刺激（rTMS）对帕金森病(PD)小鼠黑质多巴胺能神经元及胶质源性神经营养因子（GDNF）的影响。 方法32只雄性C57BL/6J小鼠随机分为生理盐水组、模型组、假刺激组及磁刺激组，每组8只。采用1-甲基-4-苯基-1,2,3,6-四氢吡啶(MPTP)皮下注射，每次15 mg/kg体重，连续注射4次，每次间隔2 h,建立急性PD小鼠模型。磁刺激组小鼠每天接受1 Hz、1 T的磁刺激治疗（共5个序列，25脉冲/序列）,疗程为2周。经rTMS干预后，通过免疫组织化学技术检测黑质酪氨酸羟化酶(TH)和GDNF的表达变化，并借助图像分析系统进行定量分析。 结果模型组、假刺激组TH免疫阳性(TH-ir)和GDNF免疫阳性(GDNF-ir）细胞计数、校正光密度(COD)值较生理盐水组减少(P<0.01)；磁刺激组TH-ir和GDNF-ir细胞计数、COD值均较模型组和假刺激组增加（P<0.05）。相关分析显示黑质区TH-ir和GDNF-ir细胞计数呈明显正相关(r=0.836,P<0.01)，相应的COD值比较亦呈明显正相关(r=0.921,P<0.01)。 结论rTMS明显增加PD小鼠黑质 TH-ir细胞数量和COD值，推测其对黑质多巴胺能神经元具有保护作用，而上调黑质区GDNF的表达可能是其作用机制。     

ISO15189：2012与室间质量评价

室间质量评价作为一种有效的质量控制工具,可以帮助临床实验室发现检验过程中存在的质量问题,促使实验室采取相应的措施提高检测质量。传统的室间质量评价样品具有一定的基质效应,需要对方法进行分组才能确定靶值。理想的室间质量评价使用具有互换性的样品,具有与患者样品一样的性质,在不同测量程序上的结果具有一致性,通过参考系统建立靶值,可以用来评估与参考系统或指定的比对方法的正确度。在数据统计分析时,可以使用能更真实地反映实验室之间检测结果变异性的稳健统计方法,并采用合适的标准对结果进行评价。如果出现不合格结果,需进行彻底调查,系统地评估检测过程中的每一个方面,找出问题的根源,并采取适当的纠正措施。如果项目没有开展正式的室间质量评价计划,应使用替代性评估程序对这些试验进行性能评估。     

电针调节CD8+T细胞对帕金森病模型小鼠黑质区神经元损伤的保护机制研究

目的：观察早期电针干预对CD8⁺T细胞浸润帕金森病(Parkinson’s disease,PD)模型小鼠黑质区酪氨酸羟化酶(tyrosine hydroxylase,TH)及CD8⁺T细胞相关细胞因子表达的影响,探讨早期电针对PD的神经元保护效应及机制。方法：将雄性C57BL/6小鼠随机分为空白组、模型组、电针组、左旋多巴组,每组15只;除空白组外,其余各组均腹腔注射1-甲基-4-苯基-1,2,3,6-四氢吡啶(1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine,MPTP)构建PD小鼠模型。造模成功电针组选取“足三里”“悬钟”进行干预14天,治疗结束后进行转棒、旷场测试,并观察黑质区TH表达及CD8⁺T细胞表型标记物CD103⁺T细胞、干扰素γ(IFNγ)蛋白及颗粒酶B(GzmB)蛋白的表达。结果：造模结束后,模型组小鼠毛色暗淡无光,精神萧瑟,活动减少,肌肉颤动,而电针组及左旋多巴组小鼠精神状态良好。与模型组相比,电针组及左旋多巴组小鼠掉棒潜伏时间延长(P&l...     

大鼠帕金森综合征模型脑内黑质、尾状核及中缝核的超微结构变化(英文)

目的观察大鼠帕金森综合征模型脑内黑质、尾状核及中缝核神经元超微结构变化,为阐述该病的发病机制及筛选有效药物,提供实验依据。方法选用健康成年Wistar大鼠12只,雌雄不限,按随机法选9只为实验组(注射盐酸哌替啶),3只为正常对照组(注射等量生理盐水)。应用透射电镜观察经美兰块染的中脑黑质、脑桥中缝部及尾状核部。结果上述核团神经元的超微结构均发生病理性改变,神经细胞核膜皱缩,核膜凹凸不整,并有局部断裂;线粒体变性,基质浓度降低及空泡化;粗面内质网和高尔基复合体囊腔扩张变性;大量初级溶酶体及脂褐素集聚;出现了髓样体和多泡体等变性结构。结论黑质、尾状核及中缝核神经元超微结构的病理性变化从而导致纹状体-黑质-纹状体锥体外路系环路功能障碍,是引发帕金森综合征的结构基础。     

抑颤汤对帕金森病大鼠旋转行为、黑质细胞及神经递质的影响

目的:探讨抑颤汤治疗帕金森病在脑黑质细胞及神经递质方面的作用机制。方法:运用6-羟基多巴诱发法建立帕金森病大鼠模型,通过随机分组,观察抑颤汤对帕金森病大鼠行为特征的影响;采用脑组织液微透析技术,用高效液相色谱法测定各组大鼠脑组织细胞外液中儿茶酚胺类物质含量的变化,并分别用光镜和电镜观察各组大鼠脑黑质细胞的形态学变化。结果:治疗后40min旋转次数抑颤汤组为(61.63±17.93)次,生理盐水组为(340.90±52.97)次,表明抑颤汤能明显改善帕金森病模型大鼠的旋转行为(t=2.762,P<0.01);帕金森病大鼠损毁侧脑组织透析液中3,4-二羟基苯酸(DOPAC)、高香草酸、多巴胺、5-羟色胺水平明显低于未损毁侧(P<0.05或P<0.01),治疗后抑颤汤组含量则明显高于生理盐水对照组(P<0.05或P<0.01),而未损毁侧各递质的含量3组比较差异均没有统计学意义(P>0.05);病理学观察,大鼠受损侧脑黑质神经细胞数量抑颤汤组明显比生理盐水组多,且神经元体积较饱满,结构较清晰,细胞内高尔基氏体、线粒体等接近正常。结论:抑颤汤能减轻帕金森病模型大鼠脑黑质细胞的受损程度,促进其修复,改善黑质纹状体系统的分泌功能,提高脑组织中内源性儿茶酚胺类物质的含量,从而改善帕金森病大鼠的旋转行为。     

大鼠胚胎中脑多巴胺神经元的分离培养与鉴定

背景：神经细胞移植治疗是最有希望治愈帕金森病的方法之一。目的：探讨大鼠胚胎中脑多巴胺神经元分离、培养与鉴定的方法。方法：解剖分离E14dSD大鼠胚胎中脑组织,制备单细胞悬液,以神经细胞培养液培养,观察其生长情况并进行RT-PCR和免疫组织化学鉴定。结果与结论：在神经细胞培养液中,细胞生长良好。RT-PCR和免疫组织化学结果显示大多数细胞表达多巴胺神经元特异性分子标志。证实实验成功建立了大鼠胚胎中脑多巴胺神经元分离培养与鉴定的方法。     

大鼠胚胎中脑多巴胺神经元的分离培养与鉴定

背景:神经细胞移植治疗是最有希望治愈帕金森病的方法之一.目的:探讨大鼠胚胎中脑多巴胺神经元分离、培养与鉴定的方法.方法:解剖分离E14d SD大鼠胚胎中脑组织,制备单细胞悬液,以神经细胞培养液培养,观察其生长情况并进行RT-PCR和免疫组织化学鉴定.结果与结论:在神经细胞培养液中,细胞生长良好.RT-PCR和免疫组织化学结果显示大多数细胞表达多巴胺神经元特异性分子标志.证实实验成功建立了大鼠胚胎中脑多巴胺神经元分离培养与鉴定的方法.     

Hyperpolarization of substantia gelatinosa neurons evoked by mu-, kappa-, delta 1-, and delta 2-selective opioids.

With whole-cell recordings of substantia gelatinosa (SG) neurons from rat spinal cord slices, we investigated the effects of bath application of highly selective delta(1), delta(2), kappa and mu opioid agonists on membrane potential and conductance. Each agonist was applied at 0.5 to 1 micromol/L and evoked robust hyperpolarizations and conductance increases in a subset of neurons. The response magnitude means were similar across agonists at several concentrations; no excitatory effects were observed. Nine of 55 (16%) were hyperpolarized by delta(1) opioids, 2 of 45 (4%) by delta(2), 8 of 59 (14%) by kappa, and 35 of 67 (52%) by mu opioids. To test the hypothesis that SG neurons may be hyperpolarized by multiple opioid subtype agonists, we applied 2, 3, or 4 selective agonists to individual neurons. Most neurons were hyperpolarized only by mu opioids; however, a minority were hyperpolarized by multiple subtype-selective agonists. These results indicate that delta(1)- and delta(2)-selective opioids can also evoke robust hyperpolarizations in spinal SG neurons, that the relative abundance of hyperpolarizing responses was mu > > delta (1) approximately equal kappa > delta(2), and that some SG neurons can be hyperpolarized by more than 1 opioid subtype-selective agonist. These powerful inhibitory postsynaptic responses likely contribute to analgesia evoked by spinally and systemically administered opioid subtype-selective agonists.