Regulation of the mammalian pineal by non-rod, non-cone, ocular photoreceptors

In mammals, ocular photoreceptors mediate an acute inhibition of pineal mel atonin by light. The effect of rod and cone loss on this response was asses sed by combining the rd mutation with a transgenic ablation of cones (cl) t o produce mice lacking both photoreceptor classes. Despite the loss of all known retinal photoreceptors, rd/rd cl mice showed normal suppression of pi neal melatonin in response to monochromatic light of wavelength 509 nanomet ers. These data indicate that mammals have additional ocular photoreceptors that they use in the regulation of temporal physiology.