Nitric oxide mediates differential effects in mouse retinal ganglion cells

Abstract

Neuromodulators have major influences on the regulation of neural circuit activity across the nervous system. Nitric oxide (NO) is a prominent neuromodulator in many circuits, and has been extensively studied in the retina across species. NO has been associated with the regulation of light adaptation, gain control, and gap junction coupling, but its effect on the retinal out-put, specifically on the different types of retinal ganglion cells (RGCs), is still poorly understood. Here, we used two-photon Ca2+imaging to record RGC responses to visual stimuli to investigate the neuromodulatory effects of NO on the cell type-level in theex vivomouse retina. We found that about one third of the RGC types displayed highly reproducible and cell type-specific response changes during the course of an experiment, even in the absence of NO. Accounting for these adaptational changes allowed us to isolate NO effects on RGC responses. This revealed that NO affected only a few RGC types, which typically became more active due to a reduction of their response suppression. Notably, NO had no discernible effect on their spatial receptive field size and surround strength. Together, our data suggest that NO specifically modulates suppression of the temporal response in a distinct group of contrast-suppressed RGC types. Finally, our study demonstrates the need for recording paradigms that takes adaptational, non-drug-related response changes into account when analysing potentially subtle pharmacological effects.