Abstract
Purpose :
Pure S cones and hybrid S/M cones are ultraviolet (UV)-sensitive in mice. Analysis of pure S cones using UV-elicited electroretinograms (ERGs) has not been reported. Our goal was to isolate pure S cones responses in UV ERGs.
Methods :
C57BL/6J mice (ages 8–10 weeks) were used in all experiments. The light-emitting diodes (LEDs) used to elicit the ERGs emitted either UV (λ=365 nm, Nichia, Japan) or green light (λ=525 nm, Nichia) fitted with the S-opsin or M-opsin spectrum. To confirm that LEDs stimulate S-opsin or M-opsin, we performed experiments using UV band-pass (U330, HOYA, Tokyo, Japan) and UV sharp-cut filters (L42, HOYA). We examined how bluish-green LEDs (λ=510 nm, Nichia), which suppress the rod-activity, effect UV- or green-elicited ERG responses. We analyzed UV- and green-elicited ERG responses using a bright green background (λ=540 nm, 25,000 cd/m2) to intensely bleach M-opsin.
Results :
The UV LED responses were extinguished significantly (p=0.03) by the UV cut-off filter, which did not differ from the UV band-pass filter (p>0.5). The responses elicited by the green LEDs were extinguished significantly by the UV band-pass filter (p=0.03) and did not differ with the UV cut-off filter (p>0.5). The implicit times of the ERGs elicited by the UV and green LEDs, in which the a- and b-waves were present with and without filters, did not differ significantly (p>0.5 for both comparisons). The presence of rod-saturating background light did not affect the amplitude of the ERGs elicited by UV LED stimuli; the responses in the green-LED-elicited ERGs decreased depending on the intensity of the background light. The bright green background suppressed green-elicited ERG responses to 5% of the maximal response for 5 min. UV-elicited ERG responses decreased to 24% within 1 sec, but the suppression decreased during this time and recovered to 94% after 3 min.
Conclusions :
Our ERGs detected the responses of S-opsin and M-opsin. We isolated pure S cone responses in the UV-elicited photopic ERGs under a bright middle-wave background.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.