retinoïdcyclus

The retinoid cycle is a biochemical process essential for vision and other physiological functions. It describes the series of enzymatic reactions that convert vitamin A (retinol) into its various active forms, such as retinal and retinoic acid, and their subsequent regeneration. This cycle is crucial for the photoreceptor cells in the retina of the eye.

In the visual process, light striking the retina causes a change in a molecule called rhodopsin, which contains a form of retinal. This initial light absorption triggers a cascade of events that ultimately leads to the transmission of a visual signal to the brain. After this photochemical reaction, retinal is released and must be regenerated back into its active form to participate in subsequent light detection. This regeneration occurs through a series of steps involving enzymes in the retinal pigment epithelium and photoreceptor cells.

Beyond vision, retinoic acid, a metabolite of retinol, acts as a signaling molecule that plays vital roles in cell growth, differentiation, and development. It binds to nuclear receptors, influencing gene expression. The retinoid cycle ensures a continuous supply of these active forms of vitamin A, supporting both visual function and broader cellular processes throughout the body. Dysregulation of the retinoid cycle can lead to various visual impairments and developmental abnormalities.