Recent research papers by dermatologists continue to stress the need for photoprotection and, more recently, address the need for the repair of photo-aging. Regardless of the origin of the papers, the objectives of the investigators are remarkably similar. Typical contributions document that UVA and UVB irradiation induce similar responses in human skin cells. However, only a few months later, a letter to the same journal asserts that ubiquinone, idebenone and kinetin protect skin less effectively than a topical antioxidant combination of ascorbic acid, vitamin E and ferulic acid. Reactive oxygen substances are formed during aerobic existence in the earth environment. This was considered potentially hazardous for many years and hydrogen peroxide remains one of the most hazardous substances generated during photo-exposure.
The prominent features of photo-aging include alterations in the dermis, such as elastic fibers and microvasculature and the epidermis, such as keratinocytes, Langerhans cells and melanocytes. On the other hand, photo-aged skin has not been studied in depth. M. Toyoda and associates have studied changes in the neurological features of photo-aged skin and compared them with the appearance of photo-protected skin. One of their studies, presented before the Third Annual Meeting of the Japanese Photo-aging Research Society in May 2002, has just been published5 with the following conclusion: photo-aged skin exhibits a notable increase in the densities of dermal and intra-epidermal nerve fibers, and the increase of innervations parallels the severity of photo-damage. The authors assert that chronic UV exposure alters neurogenic factors and that interactions between the cutaneous innervation and mast cells are involved in the photo-aging process.