Wrinkles on the face and hands are a normal sign of aging.

A wrinkle is a fold, ridge or crease in the skin. Skin wrinkles typically appear as a result of aging processes such as glycation or, temporarily, as the result of prolonged (more than a few minutes) immersion in water. Wrinkling in the skin is caused by habitual facial expressions, aging, sun damage, smoking, poor hydration, and various other factors.^[1] With prolonged water exposure, the outer layer of skin starts to absorb water. The skin doesn't expand evenly, causing it to wrinkle. Depletion of water in the body, as occurs with dehydration, can also cause this puckering of the skin.^[2] Cortisol causes degradation of skin collagen.^[3]

[edit] Aging wrinkles

In humans, collagen is very stable. Unlike some human cells of the body that are constantly dying and replicating, collagen cells will not be replaced for around 30 years. As a result. these old collagen cells breakdown and according to research, it is this fragmented collagen that causes wrinkles. Fragmented collagen also leads to skin tearing and bruising easier than it otherwise would.^{[citation needed]}

[edit] Tretinoin

Although the exact mode of action of tretinoin is unknown, current evidence suggests that tretinoin decreases cohesiveness of follicular epithelial cells. Additionally, tretinoin stimulates mitotic activity and increased turnover of follicular epithelial cells.^[4] Tretinoin is better known by the brand name Retin-A.

[edit] Glycosaminoglycans

Glycosaminoglycans (GAGs) are produced by the body to maintain structural integrity in tissues and to maintain fluid balance. Hyaluronic acid is a type of GAG that promotes collagen synthesis, repair, and hydration. GAGs serve as a natural moisturizer and lubricant between epidermal cells to inhibit the production of matrix metalloproteinases (MMPs). Topical glycosaminoglycans supplements can help to provide temporary restoration of enzyme balance to slow or prevent matrix breakdown and consequent onset of wrinkle formation.^[5]

[edit] Botox

Botulinum toxin is a neurotoxin protein produced by the bacterium Clostridium botulinum. Botox is manufactured by Allergan Inc (U.S.) for both therapeutic as well as cosmetic use. Besides its cosmetic application, Botox is used in the treatment of other conditions including migraine headache and cervical dystonia (spasmodic torticollis) (a neuromuscular disorder involving the head and neck).^[6]

[edit] Restylane

Restylane is a non-animal, stabilized hyaluronic acid produced by Q-med in Sweden. The wrinkle-resolving gel is worldwide the most commonly used dermal filler since it was introduced in 1996. Particularly effective is when it is used in a special injection technique; The Fern Pattern Technique. This technique was introduced by the Dutch cosmetic doctor Tom van Eijk in Sweden in 2005. The article on the subject was published in the Journal of Drugs in Dermatology, August 2007.

[edit] Pruney fingers

A wrinkled finger after a warm bath

The wrinkles that occur in skin after prolonged exposure to water are sometimes referred to as pruney fingers or water aging. This is a temporary skin condition where the skin on the palms of the hand or feet becomes wrinkly. This wrinkling effect most likely developed as an evolutionary advantage for better grip in water.

In recent past the common explanation was based on water absorption in the keratin-laden epithelial skin when immersed in water;^[7], this caused the skin to expand, resulting in a larger surface area and forcing it to wrinkle. Usually the tips of the fingers and toes are the first to wrinkle because of a thicker layer of keratin and an absence of hairs which secrete the protective oil called sebum.

In 1935, Lewis and Pickering already found that the skin in the median nerve distribution failed to wrinkle in patients with median nerve palsy. This suggested a mechanism other than simple water absorption. Recent research shows that wrinkling is related to vasoconstriction ^[8][9]. Water probably initiates the wrinkling process by altering epidermal electrolyte homeostasis as it diffuses into the porous skin of the hands and soles via their many sweat ducts. Altered epidermal electrolyte homeostasis would lead to a change in membrane stability of the surrounding dense network of nerve fibers and trigger increased vasomotor firing with subsequent vasoconstriction. Vasoconstriction, through loss of volume, leads to negative digit pulp pressure resulting in a downward pull on the overlying skin, which wrinkles as it is distorted ^[10].

This insight resulted in bedside tests for nerve damage and vasoconstriction. For instance a patient with Diabetic neuropathy caused by Diabetes mellitus will have a different finger wrinkling pattern than a healthy subject. Wrinkling is often scored with immersion of the hands for 30 minutes in water or EMLA cream with measurements steps of 5 minutes, and counting the number of visible wrinkles in time. Not all healthy persons have finger wrinkling after immersion, so it would be safe to say that sympathetic function is preserved if finger wrinkling after immersion in water is observed, but if the fingers emerge smooth it cannot be assumed that there is a lesion to the autonomic supply or to the peripheral nerves of the hand^[11].

[edit] Animals with wrinkles

Shar Pei puppies

Examples of wrinkles can be found in various animal species that grow loose, excess skin, particularly when they are young. Several breeds of dog, such as the Pug and the Shar Pei, have been bred to exaggerate this trait. In dogs bred for fighting, this is the result of selection for loose skin, which confers a protective advantage. Wrinkles are also associated with neoteny, as they are a trait associated with juvenile animals.

[edit] References

[edit] External links

Look up wrinkle (skin) in Wiktionary, the free dictionary.

• Medline: Skin Aging