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

1.通过电生理实验观察氟哌啶醇和舒必利对接受丘脑束旁核传入的大鼠伏隔核神经元的作用，以及是否拮抗外源性多巴胺和甲基苯丙胺的作用。结果表明，外源性应用多巴胺和内源性释放的多巴胺均对伏核神经元活动产生抑制作用。甲基苯丙胺也抑制了从丘脑束旁核传入的伏核神经元，可能是通过从腹侧被盖区的多巴胺能神经末梢释放多巴胺。用麻醉猫进行了微离子电泳法的研究，以确定多巴胺D-1和D-2受体是否共存于接受黑质传入的同一尾状核神经元中，其中刺激黑质引起的棘波可被选择性D-2拮抗剂多潘立酮阻断。上述结果强烈提示，抑制性D-1受体和兴奋性D-2受体共存于同一尾状神经元。采用细胞内记录技术，观察了低浓度和高浓度多巴胺对大鼠尾状核神经元的影响。结果表明，尾状核神经元突触后部位至少存在D-1和D-2两种亚型的多巴胺受体，分别介导神经元对多巴胺的抑制和兴奋反应。用脑片制片法观察了多巴胺D-2受体选择性激动剂溴隐亭对大鼠尾状核神经元的影响。结果提示，溴隐亭和低浓度多巴胺激活的多巴胺D-2受体介导了尾状核神经元的兴奋。

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.