Cesa R, Strata P
Department of Neuroscience and National Institute of Neuroscience-Italy, University of Turin, Corso Raffaello 30, 10125, Turin, Italy.
Neuroscience. 2009 Sep 1;162(3):624-32. doi: 10.1016/j.neuroscience.2009.02.061. Epub 2009 Mar 9.
Purkinje cell (PC) dendrites are made by a proximal dendritic domain, which is provided with scattered clusters of spines innervated by a single climbing fiber (CF) and by a distal domain with a high density of spines innervated by parallel fibers (PFs). Following block of electrical activity a spine increase occurs in the proximal domain and the new spines are innervated by the PFs while the number of synaptic contacts formed by the CF is reduced. Also the GABAergic input expands its territory of innervation on the proximal domain, which undergoes a profound restructuring of the glutamate and GABA receptors. Excitatory-like postsynaptic assemblies appear not only on the new spines, but also on the smooth region of the dendrite and both of them may be innervated by GABAergic terminals. In this case GABA receptors coexist with the glutamate receptors leading to the formation of hybrid synapses. In contrast, PF synapses contain solely glutamate receptors. Thus, the expression of glutamate receptors appears to be an intrinsic property of the PC, while the expression of the GABA receptors is induced by the presence of GABAergic terminals. The data highlight an important feature of the CF input; its electrical activity, in addition to inducing a powerful phasic excitation and a tonic inhibition, controls the finer architecture of the cerebellar cortex.
浦肯野细胞(PC)的树突由近端树突域和远端树突域组成,近端树突域有散在的棘突簇,由单根攀缘纤维(CF)支配,远端树突域有高密度的棘突,由平行纤维(PFs)支配。电活动阻断后,近端树突域出现棘突增加,新棘突由PFs支配,而CF形成的突触接触数量减少。此外,GABA能输入在近端树突域扩展其支配区域,近端树突域经历谷氨酸和GABA受体的深刻重组。兴奋性突触后组件不仅出现在新棘突上,也出现在树突的平滑区域,两者都可能由GABA能终末支配。在这种情况下,GABA受体与谷氨酸受体共存,导致形成混合突触。相反,PF突触仅包含谷氨酸受体。因此,谷氨酸受体的表达似乎是PC的固有特性,而GABA受体的表达是由GABA能终末的存在诱导的。这些数据突出了CF输入的一个重要特征;其电活动除了诱导强大的相位性兴奋和紧张性抑制外,还控制小脑皮质的精细结构。