Orexin B Enhances the Synaptic Transmission from LGN to Orexin-sensitive Neurons in L6b of Visual Cortex / 中山大学学报(医学科学版)

ABSTRACT

@#【Objective】To unmask the effect of Orexin B on the synaptic transmission between feed-forward projection from the lateral geniculate nucleus（LGN）to orexin-sensitive neurons in layer 6b（L6b）of visual cortex（VC）.【Methods】C57 mice at P25-P30 were used for micro-injection of CTB555 and ChR2-EGFP into LGN to label the neurons feedback projection to LGN from L6b and the feed-forward projection from LGN to the neurons in L6b of VC respectively. The EPSC in L6b cells was intracellularly recorded from the neurons labeled by CTB555.【Results】The neurons feedback projection to LGN in L6b are mainly pyramidal neurons, and the most of these cells are activated by orexin B，called orexin- sensitive neurons. Orexin B enhanced the NMDAR-mediated postsynaptic current in orexin-sensitive neurons in L6b by electrical or optical stimulation on the LGN projection to VC［electrical stimulation：（125.1 ± 3.7）%，optical stimulation：（123.8 ±3.8）%. In the case of OX2R′s blocker，the effect of Orexin B on EPSC amplitude disappeared with significant statistical significance，P < 0.05］，thus，strengthening the synaptic transmission between LGN and orexin-sensitive neurons in L6b.【Conclusions】Orexin B enhances the synaptic transmission between LGN to pyramidal neurons in L6b of VC.