Fig. 1

Exogenous serotonin reduces light-evoked response in ON–OFF but not in ON RGCs. A Effects of serotonin in ON RGC subtype. (i) Micrograph of a typical ON RGC filled with AlexaFluor488 (40x; scale bar = 10 µm; arrowhead indicates axon at the ganglion cell layer (GCL) border). INL, inner nuclear layer; IPL, inner plexiform layer. (ii) Representative traces of the L-EPSC evoked by a 0,5 s light pulse (black rectangle) under basal conditions (control, black) and after bath application of 5-HT (50 µM) for 10 min (gray). (iii) Time course and summarized graphs showing no changes in amplitude and synaptic charge (Q) of L-EPSC evoked in ON RGCs following 5-HT application. B Effects of serotonin in ON–OFF RGC subtype. (i) Micrograph of a typical ON–OFF RGC (40x; scale bar = 10 µm; arrowhead indicates axon at the GCL border). (ii) Representative traces of the L-EPSC recorded in basal conditions (control, black) and after bath application of 5-HT (gray). (iii) Time course and summarized graphs showing the reduction induced by 5-HT in both the ON and OFF component of the L-EPSC. Statistical differences were assessed by paired t-test comparison of the means. *p < 0,05. (ON RGCs: n = 3 cells/3 animals, ON–OFF RGCs: n = 5 cells/5 animals)