Fig. 3.

Inhibition of entorhinal PNs blocked the antiepileptic effect of entorhinal LFES. a) An AAV construct encoding Cre-dependent eNPHR3.0-eYFP (pAAV-EF1α-DIO-eNPHR3.0-eYFP) was injected into the EC of CaMKIIα-Cre mice to generate CaMKIIα-NPHR^EC mice (referred to as “CaMKIIα-NPHR”). b) Histological images showing that eNPHR3.0-eYFP (triangles) was expressed in the EC and some hippocampus sub-fields (projection fibers). c) Representative peri-event rasters and d) statistical data form four mice showed that yellow light stimulation (593 nm, 20 Hz) reduced the firing rate of PNs but had no significant effect on INs in the EC (paired t-test). e) Schematic used in experiments to simultaneously deliver light and LFES to the EC during kindling. Black rectangle indicates kindling stimulation, the green rectangle indicates LFES and the yellow rectangle indicates yellow light stimulation. f) Entorhinal yellow light stimulation accelerated hippocampal kindling acquisition and attenuated the antiepileptic effect of entorhinal LFES in CaMKIIα-NPHR^EC mice (two-way ANOVA for repeated measures followed by LSD post hoc test). Black rectangle indicates kindling stimulation while the yellow rectangle indicates yellow light stimulation. The control and LFES groups received no photo-stimulation. g) Entorhinal yellow light stimulation promoted the kindled seizures and attenuated the antiepileptic effect of entorhinal LFES in CaMKIIα-NPHR^EC mice (Kruskal-Wallis followed by the Mann-Whitney U test). Black rectangle indicates kindling stimulation while the yellow rectangle indicates yellow light stimulation. The control and LFES groups received no photo-stimulation. h) Representative EEGs. Data are displayed as mean ± SEM. *p < 0.05, **p < 0.01 and ***p < 0.001 compared to the control or baseline; and ^&&p < 0.01, ^&&&p < 0.01 compared to the LFES group.