Aracri Patrizia, Banfi Daniele, Pasini Maria Enrica, Amadeo Alida, Becchetti Andrea
Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milan 20126, Italy.
Department of Biomolecular Sciences and Biotechnology, University of Milano, Milan 20128, Italy.
Cereb Cortex. 2015 May;25(5):1330-47. doi: 10.1093/cercor/bht326. Epub 2013 Dec 1.
We studied the effect of hypocretin 1 (orexin A) in the frontal area 2 (Fr2) of the murine neocortex, implicated in the motivation-dependent goal-directed tasks. In layer V, hypocretin stimulated the spontaneous excitatory postsynaptic currents (EPSCs) on fast-spiking (FS) interneurons. The effect was accompanied by increased frequency of miniature EPSCs, indicating that hypocretin can target the glutamatergic terminals. Moreover, hypocretin stimulated the spontaneous inhibitory postsynaptic currents (IPSCs) on pyramidal neurons, with no effect on miniature IPSCs. This action was prevented by blocking 1) the ionotropic glutamatergic receptors; 2) the hypocretin receptor type 1 (HCRTR-1), with SB-334867. Finally, hypocretin increased the firing frequency in FS cells, and the effect was blocked when the ionotropic glutamate transmission was inhibited. Immunolocalization confirmed that HCRTR-1 is highly expressed in Fr2, particularly in layer V-VI. Conspicuous labeling was observed in pyramidal neuron somata and in VGLUT1+ glutamatergic terminals, but not in VGLUT2+ fibers (mainly thalamocortical afferents). The expression of HCRTR-1 in GABAergic structures was scarce. We conclude that 1) hypocretin regulates glutamate release in Fr2; 2) the effect presents a presynaptic component; 3) the peptide control of FS cells is indirect, and probably mediated by the regulation of glutamatergic input onto these cells.
我们研究了促食欲素1(食欲素A)在小鼠新皮质额叶2区(Fr2)中的作用,该区域与动机依赖的目标导向任务有关。在第V层,促食欲素刺激了快速发放(FS)中间神经元上的自发性兴奋性突触后电流(EPSC)。这种作用伴随着微小EPSC频率的增加,表明促食欲素可以作用于谷氨酸能终末。此外,促食欲素刺激了锥体神经元上的自发性抑制性突触后电流(IPSC),但对微小IPSC没有影响。通过阻断以下物质可阻止这种作用:1)离子型谷氨酸能受体;2)1型促食欲素受体(HCRTR-1),使用SB-334867。最后,促食欲素增加了FS细胞的放电频率,当离子型谷氨酸传递受到抑制时,这种作用被阻断。免疫定位证实HCRTR-1在Fr2中高度表达,特别是在第V - VI层。在锥体神经元胞体和VGLUT1 +谷氨酸能终末中观察到明显的标记,但在VGLUT2 +纤维(主要是丘脑皮质传入纤维)中未观察到。HCRTR-1在GABA能结构中的表达很少。我们得出以下结论:1)促食欲素调节Fr2中的谷氨酸释放;2)这种作用存在突触前成分;3)该肽对FS细胞的控制是间接的,可能是通过调节这些细胞上的谷氨酸能输入介导的。