Centonze Diego, Gubellini Paolo, Pisani Antonio, Bernardi Giorgio, Calabresi Paolo
Clinica Neurologica, Dipartimento di Neuroscienze, Università Tor Vergata, Rome, Italy.
Rev Neurosci. 2003;14(3):207-16. doi: 10.1515/revneuro.2003.14.3.207.
Two distinct forms of synaptic plasticity have been described at corticostriatal synapses: long-term depression (LTD) and long-term potentiation (LTP). Both these enduring changes in the efficacy of excitatory neurotransmission in the striatum have a major impact on the physiological activity of the basal ganglia and are triggered by the stimulation of complex and independent cascades of intracellular second messenger systems. Along with the massive glutamatergic inputs originating from the cortex, striatal neurons receive a myriad of other synaptic contacts arising from different sources. In particular, while the nigrostriatal pathway provides this brain area with dopamine (DA), intrinsic circuits are the main source of acetylcholine (ACh) and nitric oxide (NO). The three neurotransmitter systems interact with each other to determine whether corticostriatal LTP or LTD is triggered in response to repetitive synaptic stimulation. Two distinct subtypes of striatal interneurons produce ACh and NO in the striatum. These interneurons are activated by the cortex during the induction phase of striatal plasticity, and stimulate, in turn, the intracellular changes in projection neurons required for LTD or LTP. Interneurons, therefore, exert a feedforward control of the excitability of striatal projection neurons by ensuring the coordinate expression of two alternative forms of synaptic plasticity at the same type of excitatory synapse. The integrative action exerted by striatal projection neurons on the converging information arising from the cortex, nigral DA neurons, and from ACh- and NO-producing interneurons dictates the final output of the striatum to the other structures of the basal ganglia.
在皮质-纹状体突触处已发现两种不同形式的突触可塑性：长期抑制（LTD）和长期增强（LTP）。纹状体中这些兴奋性神经传递效能的持久变化对基底神经节的生理活动有重大影响，并由细胞内第二信使系统复杂且独立的级联刺激所触发。除了源自皮质的大量谷氨酸能输入外，纹状体神经元还接收来自不同来源的大量其他突触联系。特别是，黑质-纹状体通路为该脑区提供多巴胺（DA），而内在回路是乙酰胆碱（ACh）和一氧化氮（NO）的主要来源。这三种神经递质系统相互作用，以确定在重复突触刺激时是否触发皮质-纹状体LTP或LTD。纹状体中间神经元的两种不同亚型在纹状体中产生ACh和NO。在纹状体可塑性的诱导阶段，这些中间神经元被皮质激活，进而刺激LTD或LTP所需投射神经元的细胞内变化。因此，中间神经元通过确保在同一类型兴奋性突触处两种交替形式的突触可塑性的协调表达，对纹状体投射神经元的兴奋性施加前馈控制。纹状体投射神经元对源自皮质、黑质DA神经元以及产生ACh和NO的中间神经元的汇聚信息所施加的整合作用，决定了纹状体向基底神经节其他结构的最终输出。
