Disruption of Melatonin Signaling Leads to Lipids Accumulation in the Liver of Melatonin Proficient Mice.

Melatonin signaling via melatonin receptor type 1 (MT) and type 2 (MT) plays an important role in the regulation of several physiological functions. Studies in rodents and humans have demonstrated that disruption of melatonin signaling may affect glucose metabolism, insulin sensitivity, and leptin levels. Accumulating experimental evidence also indicates that in rodents the administration of exogenous melatonin has a beneficial effect on the blood lipid levels.

The circadian clock mediates the response to oxidative stress in a cone photoreceptor‒like (661W) cell line via regulation of glutathione peroxidase activity.

: The mammalian retina contains an autonomous circadian clock that controls many physiological functions within this tissue. Our previous studies have indicated that disruption of this circadian clock by removing from the retina affects the visual function, retinal circuitry, and cone photoreceptor viability during aging. In the present study, we employed a mouse-derived cone photoreceptor‒like cell, 661W, to investigate which molecular mechanisms of the circadian clock may modulate cone photoreceptor viability during aging.

Circadian Regulation of Retinal Pigment Epithelium Function.

The retinal pigment epithelium (RPE) is a single layer of cells located between the choriocapillaris vessels and the light-sensitive photoreceptors in the outer retina. The RPE performs physiological processes necessary for the maintenance and support of photoreceptors and visual function. Among the many functions performed by the RPE, the timing of the peak in phagocytic activity by the RPE of the photoreceptor outer segments that occurs 1-2 h.

Photoreceptor Degeneration in Homozygous Male Per2 Mice During Aging.

The Per2 mouse model developed by Takahashi laboratory is one of the most powerful models to study circadian rhythms in real time. In this study, we report that photoreceptors degenerate in male Per2 mice during aging. Young (2.

Dopamine 2 Receptor Signaling Controls the Daily Burst in Phagocytic Activity in the Mouse Retinal Pigment Epithelium.

Purpose: A burst in phagocytosis of spent photoreceptor outer fragments by RPE is a rhythmic process occurring 1 to 2 hours after the onset of light. This phenomenon is considered crucial for the health of the photoreceptors and RPE. We have recently reported that dopamine, via dopamine 2 receptor (D2R), shifts the circadian rhythm in the RPE.