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Exp Eye Res January 1, 2017; 165 90-95.

Melatonin signaling affects the timing in the daily rhythm of phagocytic activity by the retinal pigment epithelium.

Laurent V , Sengupta A , Sánchez-Bretaño A , Hicks D , Tosini G .

Earlier studies in Xenopus have indicated a role for melatonin in the regulation of retinal disk shedding, but the role of melatonin in the regulation of daily rhythm in mammalian disk shedding and phagocytosis is still unclear. We recently produced a series of transgenic mice lacking melatonin receptor type 1 (MT1) or type 2 (MT2) in a melatonin-proficient background and have shown that removal of MT1 and MT2 receptors induces significant effects on daily and circadian regulation of the electroretinogram as well as on the viability of photoreceptor cells during aging. In this study we investigated the daily rhythm of phagocytic activity by the retinal pigment epithelium in MT1 and MT2 knock-out mice. Our data indicate that in MT1 and MT2 knock-out mice the peak of phagocytosis is advanced by 3 h with respect to wild-type mice and occurred in dark rather than after the onset of light, albeit the mean phagocytic activity over the 24-h period did not change among the three genotypes. Nevertheless, this small change in the profile of daily phagocytic rhythms may produce a significant effect on retinal health since MT1 and MT2 knock-out mice showed a significant increase in lipofuscin accumulation in the retinal pigment epithelium.

PubMed ID: 28941766
Article link: Exp Eye Res
Grant support: R01 EY022216 NEI NIH HHS , R01 EY026291 NEI NIH HHS , U54 NS083932 NINDS NIH HHS , S21 MD000101 NIMHD NIH HHS, G12 RR003034 NCRR NIH HHS , U54 RR026137 NCRR NIH HHS

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