Uniformity and specificity of function of monoaminergic receptors in the caudate nucleus and nucleus accumbens

1.本实验观察了氟哌啶醇和舒必利对接受丘脑束旁核输入的大鼠延髓核神经元的作用，并探讨了它们是否拮抗外源性多巴胺和甲基苯丙胺的作用。结果表明，外源性多巴胺和内源性多巴胺都对中脑背外侧核神经元活动产生抑制作用.甲基苯丙胺还抑制丘脑束旁核传入的延髓核神经元，可能是通过腹侧被盖区的多巴胺能神经末梢释放多巴胺.使用麻醉猫进行微离子电渗研究，以确定是否depamine D-1和D-2受体共存于相同的尾状核神经元，接收从黑质的输入，其中黑质刺激引起的尖峰被多潘立酮，一种选择性的D-2拮抗剂阻断。结果表明，抑制性D-1受体和兴奋性D-2受体共存于同一个尾状核神经元上.用细胞内记录技术研究了低（1 <mu>M）和高（100 <mu>M）浓度多巴胺对大鼠尾状核神经元的作用。结果表明，尾状核神经元突触后部位至少存在两种多巴胺受体亚型，即D-1和D-2受体，分别介导神经元对多巴胺的抑制性和兴奋性反应.用脑片法观察了多巴胺D-2受体选择性激动剂溴隐亭对大鼠尾状核神经元的作用。结果提示，溴隐亭和低浓度多巴胺激活多巴胺D-2受体介导尾状核神经元兴奋。

1. Electrophysiological study was performed to examine the actions of haloperidol and sulpiride on the nucleus accumbens neurons of rats receiving input form the parafascicular nucleus of thalamus, and to investigate whether or not the drugs antagonize the effects of exogenously applied dopamine and methamphetamine. The results indicated that exogenously applied dopamine as well as endogenously released dopamine produced an inhibition of the neuronal activities in the nucleus accumbens.2. Methamphetamine also inhibited the nucleus accumbens neurons receiving input from the parafascicular nucleus of thalamus, probably by releasing dopamine form dopaminergic nerve terminals from the ventral tegmental area.3. Microiontophoretic studies using anesthetized cats were performed to determine whether or not depamine D-1 and D-2 receptors co-exist in the same caudate nucleus neurons that receive inputs from the substantia nigra, and in which spikes elicited by nigral stimulation were blocked by domperidone, a selective D-2 antagonist. The results strongly suggested that the inhibitory D-1 and excitatory D-2 receptors co-exist on the same caudate neurons.4. Effects of dopamine at low (1<mu>M) and high (100<mu>M) concentration on the rat caudate nucleus neurons were examined in a slice preparation using an intracellular recording technique. The results indicated that the postynaptic sites of caudate nucleus neurons have at least two subtype of dopamine receptors, D-1 and D-2 receptors, that mediate inhibitory and excitatory responses of the neuron to dopamine, respectively.5. Effects of bromocriptine, a selective agonist for dopamine D-2 receptor, on the rat caudate nucleus neurons were examined in a slice preparation. The results implied that dopamine D-2 receptors activated by bromocriptine and a low concentration of dopamine mediated an excitation of the caudate nucleus neurons.