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. Author manuscript; available in PMC: 2020 Jun 1.
Published in final edited form as: Neuroscience. 2019 Apr 11;408:400–417. doi: 10.1016/j.neuroscience.2019.04.005

Figure 3.

Figure 3.

The μ-opioid-specific agonist DAMGO inhibits intrinsic light responses of ipRGCs in isolated retinas. Ai: Multielectrode array (MEA) recording of the light responses a representative ipRGC in response to a 20 s stimulation (3.9 × 1015 photons cm−2 s−1 at 470 nm, black bar) a P10 rat retina in the presence of increasing concentrations of MOR-selective agonist DAMGO (0.01–10 μM) followed by application of MOR-selective antagonist CTOP (10 μM). Light-evoked ipRGC spiking was greatly attenuated by DAMGO in a dose-dependent manner, and rescued by consecutive application of CTOP. Aii: Cumulative ipRGC light response data obtained in increasing concentrations of DAMGO (0.01–10 μM) followed by CTOP as in Ai. Data is shown as Average ± SEM, n=43 from 3 retinas. *: p<0.05; **: p<0.001. Aiii: Delay of the 1st light-evoked spikes of representative ipRGCs (Cell 1–4) recorded by MEA in the presence of increasing concentrations of MOR-selective agonist DAMGO (0.01–10 μM) followed by application of MOR-selective antagonist CTOP (10 μM). Aiv: Cumulative data summarizing 1st spike delays ipRGC light response as in Aiii. DAMGO significantly increased the 1st spike delays in all instances, whereas consecutive CTOP treatment resulted in a delay close to that observed in control. Average ± SEM, n=43 from 3 retinas. *: p<0.05; **: p<0.001. B: Simultaneous application of DAMGO (1 μM) and CTOP (10 μM) did not alter light-evoked ipRGCs firing. Data is shown as Average ± SEM, n=60 from 2 retinas C: CTOP (1 and 10 μM) application does not alter light-evoked ipRGCs firing. Dots and error bars representing Average ± SEM were omitted for better visibility of the lines connecting the average values; n=52 from 3 retinas. Di: Dose-response curve of the duration of the ipRGC light responses in DAMGO (1nM-10μM). Data are plotted as a percentage of light response under control conditions (synaptic blocker cocktail without DAMGO). Parenthetical numerals indicate the number of retinas studied for each DAMGO dose. Every retina was exposed to a single DAMGO concentration. Error bars represent ± SEM. Dii: Dose-response curve plotting the number of spikes recorded in ipRGCs during the 20 s light stimulus as a function of the applied DAMGO concentration; data normalized as in Di. Parenthetical numerals indicate the number of retinas studied for each DAMGO dose.