Differential regulation of feeding rhythms through a multiple-photoreceptor system in an avian model of blindness

VALDEZ, DIEGO JAVIER; NIETO, PAULA SOFIA; DIAZ NICOLAS M; GARBARINO-PICO, EDUARDO; GUIDO, MARIO EDUARDO

FASEB JOURNAL

FEDERATION AMER SOC EXP BIOL

Lugar: Bethesda; Año: 2013 vol. 27 p. 1 - 11

0892-6638

All organisms have evolved photodetection systems to synchronize their physiology and behavior with the external light dark (LD) cycles. In non-mammalian vertebrates, the retina, the pineal organ and deep brain can be photoreceptive. Inner retinal photoreceptors transmit photic information to the brain for regulating diverse non-visual tasks. We previously reported that even after preventing extra-retinal photoreception, blind GUCY1* chickens lacking functional visual photoreceptors could perceive light that modulates physiology and behavior. Here we investigated the contribution of different photoreceptive system components (retinal/pineal and deep brain photoreceptors) to the photic entrainment of feeding rhythms. Wild-type (wt) and GUCY1* birds with head occlusion to avoid extraocular light-detection synchronized their feeding rhythms to a LD cycle with L>12 lux, whereas at lower intensities blind birds free-ran with a period >24 h. When released to constant light (LL), both wt and blind chickens became arrhythmic; however, after head occlusion, GUCY1* free-ran with a 24.5 h period. In enucleated birds, brain illumination synchronized feeding rhythms, but in pinealectomized birds only responses to high intensity L (≥800 lux) were observed, revealing functional deep brain photoreceptors. In chickens, a multiple photoreceptive system including retinal and extraretinal photoreceptors, differentially contributes to the synchronization of circadian feeding behavior.