February 22, 2009
Skin Aging and the search for the fountain of youth?
There are two age related process working constantly to change appearance. Typically, with time there is a noticeable increase in the number of skin creases.
• The first of these processes which result in increased creases is called skin aging. This is an intrinsic process meaning, the body is genetically programmed with time to create biological processes that result in increased creases.
• The second process is called photoaging or extrinsic aging. Photoaging can speed up the natural process making individuals look older than their stated age. Photoaging is the result of exposure to sunlight, more specially the ultraviolet rays of sunlight (UVB). The more one is exposed to ultraviolet sun rays the greater the risk of skin cancers and the faster the skin ages.
This process begins with a redistribution of fat, decreased elasticity, and a loss of bone mass. This results in a pronounced crease around the nose (nasolabial fold) and a reduction in collage and hyaluronate production. With age the skin’s immune system is also weakend, leaving the individual at higher risk for infections.
How does ultraviolet sunlight age skin?
In the skin there are UVB (280-400nm) absorbing particles called chromophores. Chromophores are mainly DNA and RNA (nucleic acids) and proteins. Collagen and elastin proteins absorb UVB in the range of 290 nm. Some of the other chromophores include flavins, porphyrins and quinines. DNA and RNA exposure to UVB is of major concern as UVB rays damage the DNA and RNA of cells. This damage is the precursor for many of the cell changes associated with skin aging, including skin cancer.
UVA (320-400 nm) is the more common energy in sunlight and represents 96 % of sunlight. UVA has indirect effects on the skin. UVA photosensitizes skin chromophores such as Vitamin A, Vitamin A derivatives, flavins and melanin. The photosensitization of these chromophores by UVA results in a depletion of these molecules in the skin. The exact effect of this depletion on the skin is unknown. However, while UVA depletes the Vitamin A levels in the skin, UVB damages the skin’s DNA, RNA and proteins or skin cell components responsible for the normal growth of skin.
How do Retinoids Work?
Retinoids are natural and synthetic vitamin A derivatives. These molecules dissolve easily in body fat. The biologically active form of retinoids regulates DNA gene expression. The genes that are regulated by retinoids control cell growth and maturation. Retinoids have also been shown to increase hyaluronate and collagen, two essential molecules for healthy skin which are depleted by UV light. Retinoids appear to act by increase the production of hyaluronate and collagen.
Retinoids are also good antioxidants. The trap damaging high energy particles and protect DNA and proteins from damage, notably photochemical damage. For this reason retinoids are felt to be good candidates to treat skin aging and photoaging. Furthermore, retinoids share a common chemical structure containing several conjugated double bonds that enable them to trap free radicals and absorb UV radiation from the sun, thereby protecting cellular targets such as DNA, lipid membranes, or proteins by preventing direct photochemical damage or UV-induced oxidative stress.
Therefore, retinoids may be beneficial in treating skin aging and photoaging because of their biologic, chemical, and physical properties, which act at several levels
Related Posts
Filed under Skin Care by skinmd
Leave a Comment