RT Journal Article
SR Electronic
T1 The Mammalian Cone Visual Cycle Promotes Rapid M/L-Cone Pigment Regeneration Independently of the Interphotoreceptor Retinoid-Binding Protein
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 7900
OP 7909
DO 10.1523/JNEUROSCI.0438-11.2011
VO 31
IS 21
A1 Alexander V. Kolesnikov
A1 Peter H. Tang
A1 Ryan O. Parker
A1 Rosalie K. Crouch
A1 Vladimir J. Kefalov
YR 2011
UL http://www.jneurosci.org/content/31/21/7900.abstract
AB Rapid regeneration of the visual pigment following its photoactivation is critical for the function of cone photoreceptors throughout the day. Though the reactions of the visual cycle in the retinal pigment epithelium (RPE) that recycle chromophore for rod pigment regeneration are well characterized, the corresponding mechanisms that enable rapid regeneration of cone pigment are poorly understood. A key remaining question is the relative contribution of the recently discovered cone-specific retina visual cycle and the classic RPE-dependent visual cycle to mammalian cone pigment regeneration. In addition, it is not clear what role, if any, the abundant interphotoreceptor retinoid-binding protein (IRBP) presumed to facilitate the traffic of chromophore, plays in accelerating mammalian cone pigment regeneration. To address these issues, we used transretinal recordings to evaluate M/L-cone pigment regeneration in isolated retinas and eyecups from control and IRBP-deficient mice. Remarkably, the mouse retina promoted M/L-cone dark adaptation eightfold faster than the RPE. However, complete cone recovery required both visual cycles. We conclude that the retina visual cycle is critical for the initial rapid regeneration of mouse M/L-cone pigment during dark adaptation, whereas the slower RPE visual cycle is required to complete the process. While the deletion of IRBP reduced the amplitude and slowed the kinetics of mouse M/L-cone photoresponses, cone adaptation in bright, steady light and the kinetics of cone dark adaptation were not affected in isolated retina or in intact eyecup. Thus, IRBP does not accelerate cone pigment regeneration and is not critical for the function of mouse M/L-cones in bright light.