Figure 4.

The Y₁ and Y₅ receptor agonist (Leu³¹, Pro³⁴) − NPY increases the response of OFF-type RGCs to light offset. (a) RGC spontaneous spiking rate quantification after the application of 1 µM NPY, 1 µM (Leu³¹, Pro³⁴) − NPY, 1 µM NPY_13–36, or a drug-free solution (control) for 10 min and upon 60 min of washout was recorded in ex vivo retinas using a MEA. A decrease in RGC spiking rate was observed over time, though no effects were found for drug treatments. (b) Examples of peri-stimulus time histograms and raster plots for ON-type RGC and OFF-type RGC responses are shown for seven consecutive stimulus blocks. White rectangles indicate duration of light period. (c) Quantification of initial burst to light onset of ON-type RGCs after application of the same drug treatments as in (a). No effect was found for the different drug treatments compared with control. (d) Quantification of initial burst to light offset of OFF-type RGCs after application of the same drug treatments as in (a). The application of 1 µM (Leu³¹, Pro³⁴) − NPY for 10 min was able to increase the magnitude of OFF-type response compared with control. All data were normalized to the values obtained before drug application (baseline). Data are presented as mean ± SEM of n = 3 to 4 independent experiments. *p < .05, compared with control. Kruskal-Wallis followed by Dunn’s test.