【作者】 张淑静；

【导师】 陈蕾；

【作者基本信息】 青岛大学 ， 神经生物学， 2009， 硕士

【摘要】 苍白球(globus pallidus,GP)被认为是基底神经节神经传递的整合中心,通过支配基底神经节多个核团从而调节机体正常运动功能。5-羟色胺(5-hvdroxytryptamine,5-HT)是位于中枢及外周的单胺类物质。自从20世纪50年代在哺乳动物中枢神经系统发现5-HT以来,大量实验表明5-HT作用复杂,参与行为和其它生理活动的调节。形态学研究已证实,苍白球接受来自中缝背核的5-HT能神经支配,而且苍白球神经元突触后膜和前膜均表达多种5-HT受体亚型。目的:观察5-HT对正常大鼠和6-羟多巴胺(6-hydroxydopamine,6-OHDA)帕金森病模型大鼠苍白球神经元放电频率的影响,以及5-HT对6-OHDA帕金森病模型大鼠旋转行为的影响。方法:本实验采用三管玻璃微电极细胞外电生理学记录、6-OHDA帕金森病大鼠模型的制备以及埋管术等实验方法。结果:1.在正常大鼠苍白球记录到42个神经元,压力注射0.1 mM 5-HT可以兴奋其中的21个神经元(50%),放电频率由14.8±2.1 Hz升高到19.6±2.5 Hz(P＜0.001),平均增加38.6±6.2%;0.1mM 5-HT还可以抑制其中4个神经元(9.5%),使其放电频率由10.8±4.9 Hz降低至7.1±3.0 Hz,平均降低30.8±4.1%。2.在帕金森病模型大鼠损毁侧苍白球所记录的37个神经元,0.1 mM 5-HT可以增加其中16个细胞的放电频率(43.2%),放电频率由10.3±1.1 Hz升高至13.7±1.4 Hz(P＜0.001),平均增加35.7±4.1%;0.1mM 5-HT还可以抑制其中10个神经元(27.0%),使其放电频率由14.0±3.4 Hz降低至8.5±2.4 Hz(P＜0.01),平均降低40.6±5.7%。5-HT在帕金森病模型大鼠损毁侧苍白球神经元所诱发的抑制效应的反应率与正常组相比明显增高,差别有统计学意义(P＜0.05)。3.在帕金森病模型大鼠损毁对侧所记录的41个苍白球神经元中,微量加压注射0.1 mM 5-HT可以兴奋其中25个神经元(61.0%),放电频率由13.4±1.6 Hz升高至18.3±2.0 Hz(P＜0.001),平均增加40.8±4.9%;0.1mM 5-HT可以抑制其中4个神经元(9.8%),使其放电频率由18.6±4.8 Hz降低至11.7±4.3 Hz,平均降低42.5±12.5%。5-HT在损毁对侧苍白球神经元所诱发的抑制效应的反应率与损毁侧相比降低,差别有统计学意义(P＜0.05);与正常组相比,没有明显差异。4.进一步实验观察了苍白球5-HT对单侧6-OHDA帕金森病模型大鼠旋转行为的影响。苍白球微量注射5-HT(0.1mM)不能使大鼠产生明显的旋转行为及姿势改变。腹腔注射阈下剂量左旋多巴(3,4-dihydroxy-L-phenylalanine,L-DOPA,3 mg/kg)仅产生微弱的对侧自发性旋转行为(31.0±14.7 r/h)。而苍白球微量注射5-HT则可以明显增加阈下剂量L-DOPA所诱发的大鼠对侧自发性旋转圈数(189.0±58.6 r/h)。结论:电生理学研究结果揭示5-HT可以兴奋苍白球神经元,使其放电频率增加。行为学实验进一步表明在6-OHDA帕金森病模型大鼠,5-HT可以增强L-DOPA所诱发的旋转效应。本实验结果为进一步探讨帕金森病的发病机制以及可能的辅助治疗措施提供了理论和实验依据。更多还原

【Abstract】 The globus pallidus is becoming increasingly thought of as the central integrator of basal ganglia neurotransmission.By innervating all the basal ganglia nuclei,the globus pallidus plays an important role in normal movement regulation.5-hydroxytryptamine (5-HT) was discovered in the mammalian central nervous system in 1950s.An enormous amount of experimental evidence has revealed the pivotal role of this biogenic amine in a bewildering diversity of behavioral and other physiological processes.Morphological studies have revealed that the globus pallidus receives abundant serotonergic innervations from raphe nuclei.Furthermore,both pre- and postsynaptic membrane of pallidal neurons expresses several 5-HT receptor subtypes.Object:To study the effects of 5-HT on the firing rate of globus pallidus neurons in normal and parkinsonian rats and behavioral effects of 5-HT on rotational behavior in parkinsonian rats.Methods:In vivo extracellular single unit recordings,6-hydroxydopamine(6-OHDA) lesion and cannulae embedding were used in the present study.Results:1.Micropressure ejection of 0.1 mM 5-HT predominantly produced excitation on globus pallidus neurons.In 21 out of 42 (50.0%) pallidal neurons,0.1 mM 5-HT increased the firing rate from 14.8±2.1 Hz to 19.6±2.5 Hz(P＜0.001).The average increase was 38.6±6.2%with regard to basal values. In four neurons(9.5%),5-HT decreased the spontaneous firing rate by 30.8±4.1%.The average basal firing rate of these neurons was 10.8±4.9 Hz.2.In 6-OHDA lesioned rats, micro-pressure ejection of 0.1mM 5-HT increased the spontaneous firing rate of 16 out of 37(43.2%) pallidal neurons from 10.3±1.1 Hz to 13.7±1.4 Hz(P＜0.001),The average increase was 35.7±4.1%.In 10 neurons(27.0%),5-HT decreased the spontaneous firing rate from 14.0±3.4 Hz to 8.5±2.4 Hz(P＜0.01),The average decrease was 40.6±5.7%.The reaction rate of the inhibitory effects of 5-HT on pallidal neurons increased on the lesioned side ofparkinsonian rats(P＜0.05 compared to normal).3.On the unlesioned side, micro-pressure ejection of 5-HT(0.1 mM) increased the firing rate of 25 out of 41(61.0%) pallidal neurons from 13.4±1.6 Hz to 18.3±2.0 Hz(P＜0.001).The average increase was 40.8±4.9%.5-HT also inhibited 4(9.8%) pallidal neurons by 42.5±12.5%.The reaction rate of the inhibitory effects decreased compared with that of the lesioned side(P＜0.05). There was no difference in the reaction rate of inhibitory effects between the unlesioned side and normal rats.4.In behaving rats,intrapallidal microinjection of 5-HT(0.1mM) alone did not induce any motor behavior or postural asymmetry in the unilaterally 6-OHDA-lesioned rats.However,when infused concomitantly with a subthreshold dose of 3,4-dihydroxyphenylalanine(L-DOPA,3 mg/kg i.p.),which can induce modest contralateral rotational behavior(31.0±14.7 r/h),5-HT significantly potentiated the number of contralateral rotations(189.0±58.6 r/h).Conclusion:Our in vivo electrophysiological study suggests that 5-HT mainly produces excitatory effects on globus pallidus neurons.Behavioral study further indicates that intrapallidal infusion of 5-HT potentiates L-DOPA-induced rotational behavior in 6-OHDA induced parkinsonian rats.The present findings may provide a rationale for further investigations into the potential of pallidal 5-HT system in the adjunctive therapy of Parkinson’s disease.更多还原